摘要:

464 PICRERING : THE COLOUR INTENSITY OFL.-The C'olour Intensity of I r o n and CopperCompounds. *By SPENCER UMFREVILLE PICKERING.THAT the so-called ferric salts of organic acids are re-ally ferri-compounds, similar to the cupri-compounds, with the metal in theelectronegative portion of the molecule, has been already provedby electrolysis (T., 1913, 103, 1359).One of the most marked features of the cupri-compounds is theirgreat colour-intensity, this being about nineteen times that ofcopper in inorganic salts. A similar feature exists in the case ofthe ferri-compounds, but since there are two atoms of iron in themolecule, two different intensity values are possible, one of themprobably about double the magnitude of the other, according asone o r both atoms are united with the carbon atom; the ferric salt,*C(OH),The facts established below bear out this view.Of the eightinstances available, four show a molecular colour-intensity' of(average) 20.2, and four, a value of (average) 10, (that of iron ina solution of the chloride containing 100 grams of iron per litrebeing taken as unity), and in three of the latter, a constant ofabout 20 is also recognised when the strength is increased beyondcertain limits.The ferri-compounds are found to be more stable than the corre-sponding cupri-compounds, owing t o quadrivalence not being anabnormal condition of the iron atom. Thus, i t is only in somecases, and when the solutions are concentrated, that the cupri-compounds contain the whole of the metal in this condition; dilu-tion (except in one or two instances) converting it into a cupricsalt, and, as will be shown below, the addition of the correspondingacid doing the same.With the ferri-compounds, however, thecolour-intensity is generally constant throughout a considerablerange of dilution, and is not affected by the addition of the corre-sponding acid.Where inorganic copper salts form blue solutions, the colour-intensity is independent of the nature of the acid radicle, of thestate of the dilution, and of the presence of excess of the corre-* For abstract, see P., 1913, 29, 192IRON AND COPPER COMPOUNDS. 465sponding acid, although, beyond a certain point, excess of suchacid alters the nature of the colour. With ferric chloride, nitrateand sulphate, the colour-intensity is nearly the same in the caseof concentrated solutions, and is approximately constant throughouta considerable range of concentration; there is, however, no realconstancy, and the values alter continuously on dilution, thusnecessitating the conclusion that a t least two forms of iron withdifferent colour-intensities are present.From the fact that excessof acid deprives the solutions more or less entirely of any yellowcolour, substituting for it a faint amethyst colour, i t is probablethat such is the real colour of electropositive iron, and that theyellow colour of ordinary solutions, and the variation of the colourintensity of these, are due to the presence of electronegative iron,that is, iron united directly with the chlorine, nitrogen, sulphur,etc., in the same way as i t is with the carbon in ferri-compounds.I n the rase of the sulphate, a constant value of 21 is attained ondilution, almost identical with that of Fez in the carbon compounds.The change of Fe into Fe, and vice versa, is immediate on alteringthe s t a b of dilution.With a large excess of acid added to the inorganic ferric salts,the yellow colour reappears, but is then of a lemon tint, and notcomparable with that of neutral solutions.When dilution is extended beyond a certain point (approximatelythe same in all cases), the solutions become unstable, and, frombeing nearly colourless when first prepared, they gradually changeto a deep yellow in the course of several days, the molecular colour-intensity with the weakest solutions attaining a constant value ofabout 137; this is due to the hydrolysis of the normal ferric saltinto free acid and colloidal ferric hydroxide.The latter, whenobtained by dialysis, gives a value of 134 for its colour-intensity.The transformation is not reversible.By heating solutions of certain concentr.ations, hydrolysis of theferri-compound present into another form of soluble hydroxideoccurs; this has a colour-intensity of about 280, and graduallychanges into the lighter hydroxide. Weak solutions of the organicferri-compounds are also hydrolysed by protracted heating intothis colloidal hydroxide.Solutions of the formate, acetate and propionate, whether con-centrated or dilute, appear to be similar to the most dilute solu-tions of the inorganic salts, and consist of acid phis colloidal ferrichydroxide; but by prolonged heating a t looo (if the solutions arenot too dilute), they are converted into the ferri-compounds witha colour-intensity of about 20.These are stable.+ 466 PICKERING) : THE COLOUR INTENSITY OFThe normal ferric organic salts, metameric with the ferri-com-pounds, have not yet been obtained as solids,* but are formed, insome cases (racemate, glycerate, malate, etc.) by the prolongedheating of fairly concentrated solutions of the ferri-compounds,the colour-intensity falling to what it is in inorganic salts. Theferric salts thus formed are unstable, and, in the cold, graduallyrevert to the ferri-compounds.I n other cases, the heating pre-cipitates a basic, or, possibly, sometimes, the normal salt.The ferri-compounds appear, in most instances, to dissolve excessof ferric hydroxide, just as the inorganic salts do, converting itinto colloidal hydroxide ; this has interfered with the examinationof the colour-intensity of the basic ferri-compounds of the typeR JI ,Fe2,F%03.Where the character of the colour is the same, and where con-stant values for the intensity are found to apply in a number ofdifferent cases, it seems certain that such const*ants must be con-ditioned by the character of the connexion of the iron with theother atoms in the molecule, that is, whether it is pseudo-tervalento r quadrivalent, whether it is in the electropositive or electro-negative portion of the molecule, etc.; but it appears equally certainthqat the character and number of the other atoms in the moleculemay affect the vibration of the iron atom, and hence producemodification in the intensity and quality of the colour. We may,therefore, expect that the constancy of the values will not alwaysbe absolute, and that instances will occur where differences oftint render comparison impossible. The oxalate, ferricyanides,thiocyanates, malate and ethylsuccinate are all instances wherethe tint is not comparable with that of the other compounds, nor,in most cases, with that of each other.Effect of Acids o n the COlOlLr of the Copper Compounds.The resalts entered in table I show that the addition of thecorresponding acid to an inorganic salt of copper is without effecton the colour-intensity, so long as the tint is unaltered.With thesulphate, this is so up to 2H,S0,:CuS04, and almost so up to12'5R,SO, : CuSO,;. with the chloride, there is no alteration upto 0.5HC1: CuCl,, but with 1.4HCl a difference in tint is notice-able, and with more acid, the well-known change to greenbecomes evident. With the nitrate, there is constancy up toO-THNO, : Cu(NO,),, beyond which a similar change begins. Thepoints a t which these changes start will vary, of course, with theproportion of water present.* Except the oxalatc, of which the ferri-form has not been obtainedIRON AND COPPER COMPOUNDS. 467TABLE I.-Effect o n the Colour-intenszty of Copper by the Additionof x Gram-molecular Proportions of the Corresponding Acidt o 64 Grams of Copper.Colour-intensity without extra acid taken a,s unity, in each case.The values in brackets are those compared with iron in the chloride.Grams ofcopperCompound.in 100 c.c.*Sulphate . ..................Chloride . . . . . . , . . . . . . . . . . . . . .Nitrate . . . . . . . . . . , . . . . . . . , . . .Formate . . . . . . , . . . . . . . , . . . . . .Acetate . . . . . . . . . . . . . . . . . . . . .Propionate . . . . . . . , . . . . . . . .Lactate . . . . . . . . . . . . . . . . . . , , .Glycollate . . . . . . . . . . . . . . . . . .Glycerate . . . . , . . . . . . . , . . . . . .¶, (cupriglycerate) . . . .Malate ...................... 0.51Maleate .. . . . . . . . . . . , . . . . . , . , 0.031 9Y Y9 9Y Y2.0.002 to 2.00.008 to 0.51-36 to 4.10.012 to 0.71-92 to 4.80.05 to 0.160-4 to 2.50.075 to 3.77.5 to 38.00.052.5 to 12.50.16 to 6.00.024 to 24.0’1.424.3 to 5.70.25 to 0.751.5 to 3.000.120.350.711.182.364.7200.11-02.03.56.011.000.51.02.34.0Relativecolour-intensity.11 (duller blue)10-95 to 0.80 tint altered10.9 tint altered1 (3.0)0-99 to 0.831 (6.0)0.89 to 0.861 (7-0)0-96 to 0-SOl(2.6)1 (2.7)0.88 to 0.840.840.860.620.400.370.360.331 ( > 6-0)0.820.620.520-510.420.391 (> 6.0)0.60.270.210.191 (2.5)1 (9.0)* The values apply to the strength of the solntion taken, and would be reduced inextreme cases by the dilution caused by the addition of t4e acid to four-fifths ofthose entered.With the organic salts, the addition of acid has generally someeffect, but not much in cases where the proportion of normal saltpresent is considerably greater than that of the cupri-form of thesalt ; thus, the formate, glycollate, crystallisable gl-ycerate andlactate, with colour-intensities of 3.0, 2.7, 2.5 and 2.6, respectively,of that of copper as sulphate, show, on the addition of the corre468 PICKERING : THE COLOUR INTENSITY O Fsponding acid, diminutions extending to 17, 16, 16 and 0 per cent.;whereas, with the malate, freshly-prepared glycerate and maleate,where the dour-intensity is 6, 9 and 6, respectively, and wherea large proportion of the salt must be present as the cupri-com-pound, the addition of acid reduces the colour-intensity to one-half, one-third, and to one-fif thy respectively.With the acetateand propionate, however, where the colour-intensity of 6 and 7indicates the presence of a considerable proportion of the cupri-compound (although this has not been isolated, as in the case of themalate and glycerate), the addition of acid produces only the smallreduction of 14 and 20 per cent., this exceptional behaviour beingdue, doubtless, to the weak character of these acids.Organic Iron Compounds.Instlances of organic compounds of iron being required for thisinvestigation, the behaviour of various acids towards freshly-precipitated ferric hydroxide in the dark was examined in the sameway as had been done previously in the case of tartaric, malicand citric acids, the acids being digested with the hydroxide atZOO until the action was complete (T., 1913, 103, 1364).I nprevious cases, it had been found that the hydroxide dissolvedentirely when the proportion taken did not exceed that requiredto form a normal ferric salt, thus affording evidence of the realityof the existence of such salts, or of their metameric ferri-compounds ;with more than one equivalent, some of the excess dissolved (exceptwith tartaric acid), but a certain amount of basic insoluble saltwas also formed, and, as the proportion of hydroxide taken wasincreased, the quantity of basic salt formed also increased,so that the amount of iron remaining in solution actuallydiminished with an increase in the amount taken.The course ofthe action was shown to be the formation of a soluble ferri-com-pound of the f ormu1.a [Rr/3R///,]Fe,,F%0,, and its subsequentgradual transformation into an ordinary insoluble basic salt ofsimilar composition.I n the first twelve instances quoted in table 11, one equivalentof hydroxide dissolves completely, or nearly so, in one of acid;with the ethylsuccinate, only 0.5 equivalent dissolves, and thesolution, therefore, must contain an acid compound. When morethan one equivalent is taken, there is generally some increase atfirst in the amount dissolved, followed by a reduction, and theformation of a larger proportion of insoluble basic salt.Theincrease, however, is inappreciable in the case of the tartrate,oxalate and ethylsuccinate, whilst the subsequent decrease doeIRON AND COPPER COMPOUNDS. 469not occur, so far as the present experiments show, with theglycerate, lactate and the compounds of the fatty acids.TABLE 11.-Ferric Hydroxide Dissolved at 20° b y 1 Equivalent ofA cid.Equivalents of F,O, taken ...Acid.Tartaric ..............................Malic .................................Citric .................................Oxalic ...............................GIycollic .............................Glyceric ..............................Lactic .................................Formic ...............................Acetfic .................................Propionic ............................Maleic .................................Racemic ..............................E thylsuccinic ......................Succinic ..............................Fumaric ...............................Aconitic ..............................Mucic .................................1.0 1-25 2.0 3.0Equivalents of Fe,O, dissolved. -1.001.001.001.001 -001.001.000.981.001.000.960.920.540-86 0.411-18 1.261.23 1.091.01 0.991.08 1-411-04 1.791.24 1.981.21 1.901.24 1.951.22 1-921-03 0.981.09 0.620.55 0.49nil.tracas.nil.action incomplete.-0.150-860.740.821-251-942.542-772.802.780.750.340.30The proportion of hydroxide dissolved in the case of oxalic,maleic, and ethylsuccinic acid, is nearly constant a t 1, 1 and0.5 equivalents, respectively, so long as thO proportion taken doeenot exceed 2 equivalents, and with the lactate the whole of thehydroxide taken is dissolved up to 2 equivalents, this givingevidence of the formation of a compound of such composition.With the last four acids entered in the table, little or no ironpasses into solution, but the hydroxide is converted into an in-soluble salt, a basic salt represented by RN,F%,Fe,O, (when drieda t looo) in the cwe of the succinate, and a normal salt, mixedwith a small proportion of basic salt, in the case of the fumarateand maleate, whilst with the mucate, the conversion of hhe hydr-oxide into a salt is very incomplete.Inorganic Ferric Salts.Solutions.of ferric chloride, each of half the concentration ofthe next more concentrated one, and prepared a t least one monthpreviously, were compared with each other. The values werechecked by Comparing together solutions differing considerably inconcentration, this being possible owing to the more dilutesolutions being as highly coloured as some of the concentrated ones.The molecular colour-intensity of the iron in a solution containing100 grams of the metal per litre was termed unity4'70 PICKERING : THE COLOUR INTENSITY OFIn other cases, a similar comparison was made between themembers of any given series, and these were then compared withthe ferric chloride solutions., Some variation of tdnt was oftennoticed a t certain concentrations, and where that was the case,those results were discarded,The number of instances in which the values remain constantFIG.1.Colour in,te?tsity of ferric ehloride solzltions.10 1 0.01 0'001 0'001Grams of iron per 100 C.C.throughout a series shows that no serious accumulation of errorscan exist.The results of two closely concordant series with the chlorideare summarised in col. I1 of table 111, and are plotted against thelogarithms of the strengths in Fig. 1, ABC and ABD. The valueTABLE III.-Colourjnteizsity of Inorganic FerricI n the split columns, the left half gives the values immediately after preparation,had been obtained.1.001.001-061.292.63291184218223257164134133-- -- -Gramsofironin100 C.C.I.20.913.910.810.06.96-02.51-250.630.310.160.080-040.020.010.0050.00250.00120.00060.00032.613398194140199138130133-Chloride.Colour-intensity .213251274229198178159156Series Iand 11.133224255190150148144138 - -6087185360Series111.111.-- -1.001.001-061.291-611.87173358100142142135-(3.77)(124) - -5680114150152Series 111. Afterheating.2-211.871.65 ---- - -'z: 86116136140(1462.802.31(1.71)- ---1.78GramsFe in100 C.C.VI .13.18.76.53.31.60.80.40.20.10.050.0260-01 30.0060.00030.00160.00080.0004clouds4511413013813713577Nitrate.Colour -intensit y.After heating.Labilesolu-tionsheated.IX.:548-35092125180214287194186185168 -- -1.546.3396782124181220167166161135 -472 PICKERING : THE COLOUR INTENSITY OFare apparently constant from about 12 to 3 grams of iron per100 c.c., but the rise with both more concentrated and more dilutesolutions (see the lower figure on a more open scale) renders i t im-probable that this constancy is real.After rising to' 2.9 at 0.08 percent., the values again fall t o 1.7 a t 0.005 per cent., when thesolutions become too pale for further measurement. The solutionson this falling branch of the curve, however, are not stable, andin about one hour they begin to darken, the change not becomingcomplete until after one to three weeks.The final values yielda curve, which attains and remains a t a maximum of about137. The temporary and permanent values are entered in the leftand right hand halves of col. 11. A t the point where the curvebifurcates-the critical point-the solution becomes opalescent afterseveral days, and sometimes a slight precipitate settles; in somecases, opalescence occurs in a minor degree in solutions of doubleand of half this concent.ration.The results of a third series, given in col. 111, differ slightlyfrom those in the other cases in that the critical point occursearlier, and th.at the subsequent rise in values is more rapid; butas regards general characteristics, and the initial and final values,it shows no- differences.Inappreciable impurities in the samplemay easily produce slight modifications in the actual valuesobtained.Besides the solid (doubtless a basic salt) which causes the opal-escence at the critical point, three or four other solids may separatefrom these golutions. (1.) On being heated to boiling, the more con-centrated solutions give a considerable precipitate of basic salt(approximately Fe : C1= 8 : l), form; ng in maximum quantity insolutions containing 1.2-0-6 per cent. of iron, and not a t all inmore concentrated (2.5 per cent.), nor in more dilute (0.1 per cent.)solutions. (2.) Solutions more dilute than that a t the critical pointoccasionally deposit, after some months, a small amount of basicsalt. (3.) Solutions a t and beyond the critical point, when boiled,deposit a perfectly transparent, brownish-yellow deposit of hydr-oxide on the glass.I n one o r two cases a similar deposit occurredin the cold: this was more frequent with solutions of the bromide.(4.) Solutions of extreme dilution occasionally give, after a time,a precipitate of flocculent ferric hydroxide.The action of heat on the solutions, besides causing precipitationin some cases, induces other changes. Taking, first, solutions whichhave attained a condition of stability in the cold, a considerabledarkening occurs when heated to boiling, but this disappears a tonce on cooling if the concentration is 1.2 per cent.of iron, or more.With more dilute solutions, it is persistent. The values obtaineIRON AND COPPER COMPOUNDS. 473when they are heated just to boiling in quantities of 5-10 c.c.,*and then rapidly cooled, are given in col. IV, those to the leftbeing the ones given immediately after cooling, and those to theright the ones obtained three months later. These are identical,+and the maximum is barely higher than the value for the most. diluteunheated solutions.On the other hand, solutions heated immediately after prepara-tion (labile solutions) give much higher values (left half of eol. V,and Fig. FB), but the intensity diminishes with time, the values inthe right half of the column being those obtained after threemonths, although, apparently, even then, they were still falling inthe case of the more concentrated solutions, and would, probably,in time, all become identical with those of the heated stablesolutions.The freshly prepared solutions near the critical pointdo not become cloudy on heating. At extreme dilution, the valuesfor the heated and unheated stable solutions, and for the heatedlabile solutions, are all identical.The significance of these results will be discussed below (p. 480).Bromide.--The results with this were substantially similar tothose with the chloride, and showed a bifurcation of the figurea t 0.07 per cent. of iron; but detailed examination was impossible,as the cloudiness appearing a t the critical point, appeared, also, inthree of the neighbouring solutions, and a deposit of transparenthydroxide formed in some of the others, whilst with the concen-trated solutions (4.4 t o 0.6 per cent.of iron) the red colour ofbromide predominates over that of the iron, although no freebromine could be detected. All the weaker solutions are yellow.I n the weakest solutions, the colour-intensity did not exceed 55,but the purity of the specimen examined was doubtful. The mini-mum value attained (in branch BC of the figure) was 1.2.Nitrate.-The results with the unheated solutions of this saltwere closely similar to those with the chloride (col. VII, table 111,and Fig. 2). With the heated solutions there is a difference,since both the stable and labile solutions (cols. VIII and IX)give practical!y the same values, and, in both cases, these show (aconsiderable reduction after three months (right hand halves ofthe columns).Sulphate.--This differs from the chloride and nitrate in thatthe values show a much greater rise up to the critical point, andThey form the curve ED in the figure.* The boiling may be protrazted in the case of the more dilute solutions withoutfear of precipitation: observations with solutions of concentrations of 0.06 to 0'16per cent.could not be made owing to their being, or becoming, cloudy. t In another series a slight reduction in intensity was observed during the firstfew days after the heating.VOL. cv. I 474 PICKERING : THE COLOUR INTENSITY OFremain constant a t 21 after that point. The latter solutions, asin the other cases, darken on keeping, but the extent of thisdarkening could not be measured, as they all became cloudy.Colloidal Ferric Hydroxide.-Freshly-precipitated ferric hydroxide250200150100 u *+5 u-+Lr-2 2 5060321FIG.2.Coloicr intensity of fwric nitrrttc so7ictions.10 1 0.1 0 '01 0-001Grains of iron per 100 C.C.was digested for some weeks with solutions of ferric chloride ornitrate, and the resulting liquids were dialysed until nearly freefrom acid. Szmples from the chloride gave the composition ofFe,C16 + 47Fe20, in one case, and Fe2C1, + 21Fe203 in another, andthe mean of series of coiour determinations with them arIRON AND COPPER COMPOUNDS. 475given in table IV. That from the nitrate was represented byF%(NO,), + 32Fe20,.In all cases the colour-intensity is constantthroughout, within the limits of experimental error (table IV), andit is practically the same (about 134) whichever salt is used in itspreparation. The solutions undergo no change on boiling, but, onprolonged heating a t looo, flocculent hydroxide is precipitated.TABLE IV.-Colour-intensity of Organic Ferri-compounds andColloidal Hydroxide.Grams ofiron per100 C.C. Citrate.3-0 21.92-3 19.81.5 17.31-0 12.10-5 10-30-25 10.4Race-mate. Lactate. - 23.8 - 25-5- 21.6- 18-69.1 10.28-2 9.8Glycerate. - A. B.Gly-Malate. Tar- col-trate. late.- -17.5 -15.6 -13.1 18.812.0 18-8- - -20.0 - 29.120.0 - 25.619-6 22.2 -16.8 22.2 22.4--0.1550.0620.0310.0160.0080.0040.0020.0010.0005Mean10.4 8.4 9.7 10-5 18-1 14.4 21.5 24.710.4 9.0 9.1 9.2 18-1 12.3 21.7 20.710.3 9.7 9-2 9.0 17.2 10.8 21.6 17.610.1 10.8 9-4 8-5 17.0 10.9 21.6 16.79.6 11.2 9.3 8.3 18.3 11.5 21.6 17.69.5 11.9 9-8 8.3 19.7 12-2 22.6 28.39.2 12.2 10.3 8.3 20.7 14.2 22.6 18.88.7 12.4 10.7 9.0 20.7 16.2 22.5 19.38-7 12.7 - - 20.7 - 22.6 19.99-7 11.5 9.7 9.1 19.0 {(%::) 22.1 19.6Oxalate, 0-5 to 0-004 per cent., constant at ............................ (?) 1.5Maleate, 0.5 to 0.001 per cent., constant at ........................... (?) 55Ethylsuccinato, 0-5 to 0.001 per cent., constant at .................. ( 9 ) 55Wormate, 0 5 to O.GOO1 per cent., constant at ........................ 159Acetate, 0.5 to 0.0001 per cent., constant at ......................... 169Propionate, 0.5 to 0.0001 per cent., constant a t ...................... 272Hydroxide from chloride, 0-5 to 0.0001 per cent., constant at...... 128Hydroxide from nitrate, 0.5 $0 0.0001 per cent., constant at ...... 139Organic Cornpouitds.The solutions (table IV) were prepared by dissolving moist,precipitated ferric hydroxide a t 20° in the amount of acid calcu-lated to form the normal salt.Dissolution was complete, or verynearly so, except in the case of the ethylsuccinate. Light had t obe excluded; the oxalate is rapidly decomposed by sunlight withthe formation of a ferrous salt; the racemate is similarly unstable,and, to a less extent, the tartrate, glycerate and lactate.At leasttwo preparations and series of determinations, were made in eachcase.The values for the colour-intensi ty are approximately constantI 1 476 PICKERING : THE COLOUR INTENSITY OF‘throughout a large range of concentration from 0.5 per cent. ofiron downwards. With the racemate, however, there is someincrease on dilution, with the citrate, some reduction, and withthe malate and glycollate, there is a reduction followed by anincrease.The average of the values for the weaker solutions of the citrate,racemate, lactate and glycerate A is 10*0, and that for thoae ofthe tartrate, glycollate and glycerate R is double this, namely,20-2.With the citrate, lactate, malate and glycerate A , where thelower constant obtains for dilute solutions, the higher one isindicated for concentrated solutions, although the values must beuncertain owing to the depth of colour of such concentratedsolutions. With the malate, the range throughout which the lowervalue extends would not justify its being termed a constant here.With the concentrat-ed solutions of the glycollate, the value isexceptionally high.Making allowance f o r the fact that some variation in the con-stants might naturally be produced by differences in the characterof the molecules with which the iron is combined, there can belittle doubt that the existence of two constants are here indicated,one of them double the other, as would be the caBe according asone or both the iron atoms had assumed a certain character (forexample, had become electronegative), and the tendency of dilutionis to reduce the higher value t o the lower.With the other compounds examined, the values were constantthroughout, .and the means only are given a t the foot of the table.With the oxalate, maleate and ethylsuccinate, the tint renderscomparison with the chloride impossible.With the first, the tintis greenish, and the intensity between 1 and 2, that is, approxi-mately that of the inorganic salts, to which, in nearly all otherrespects, it resembles. With the latter two, the tint is red, andthe intensity appeared t o be 50 t o 60, but judging by the factthat the colour became too faint for measurement a t about thesame degree of dilution as in the other cases, i t is probable thatthe real value is not above 20.Solutions of the formate, acetate and propionate are evidentlyvery different from those of the other compounds, and exhibit acolour-intensity as high as 159-172.These values are also main-tained when the iron is present. in excess; with 2Fez0, and 3Fez0,t o one equivalent of acetic acid, the values of 150 and 145 were* The two samples of glyceratlr were prepared from different specimens of acid,which may not have been of the same degree of purity, as the “acid” alwayscontains some anhydrideIRON AND COPPER COMPOUNDS. 477obtained, and with similar proportions in the case of propionicacid the values were 156 and 164.Determinations were made with potassium and sodium ferri-cyanides from a strength of 2 to 0*0001 per cent. of iron, and of4 to 0.0001 per cent.of iron, respectively; but the tints, althoughcomparable with each other, are not comparable with that of thechloride. The intensities ,are certainly greater than that of thelatter, estimates giving 6 with the potassium salt, and 18 withthe sodium salt. The intensity is unaltered by dilution.With the ferrocyanides the intensity is inuch less than withferric chloride, and the values alter with dilution. The followingdeterminations were made :Intensity{ Na-salt . . . . . . 0.062Per cent. Iron. 2 1.5 075 038 019 010 0.05K-salt ...... 0-064 0.064 0.064 0.067 0.088 0.101 0-1080.094 0.104 0.104 0.092 0.087 -EfJect of .Excess of 9 cid.With the nitrate, the addition of from 1.2 to 1.8 molecules ofnitric acid to each atom of iron discharges the yellow colour en-tirely, and the liquid becomes of a light amethyst tint, discernibleonly in the case of concentrated solutions.On the further additionof acid up t o 3 to 20 molecules, a strong lemon-yellow colourdevelops; this is of much lower intensity than the yellow of theneutral nitrate, but no exact comparison is possible. The amethystcolour is often noticeable in the solid crystallised nitrate, as it iswith iron alum; also in solutions of ferric salicylate.With the sulphate, the yellow colour does not entirely disappearon the addition of acid, hut becomes reduced t o about one-seventhof its original value, and is lemon-yellow in quality; this yellowincreases in intensity with further additions of acid, reaching toabout onshalf of the intensity of that in the neutral sulphate.With the more concentrated solutions, the coloration a t the pointof minimum intensity is apparently that of a mixture of amethystand yellow.With solutions containing 7, 1.8 and 0.4 per cent.of iron, the minimum coloration is attained with 27, 70 and 90molecules of sulphuric acid respectively. From very concentratedsolutions, acid precipitates the white solid sulphate.With the chloride the addition of acid produces a reduction ofintensity, and an alteration in quality t o the lemon tint, withoutshowing any minimum point or amethyst colour. From 0.2 to 2molecules of hydrochloric acid t o each atom of iron, where tliesolutions contain from 3 t o 0.04 per cent.of iron, the acid reducesthe intensity t o one-third or one-quarter of its original value.The behaviour of the organic ferric salts with excess of th478 PICKERING : THE COLOUR INTENSITY OFcorresponding acids is very different, the reduction in colour-inten-sity in those cases investigated being practically nil. The oxalate,however, is exceptional, behaving in this, as in other respects, likethe inorganic ferric salts, and showing a large reduction on theaddition of acid. The results may be summmised thus :Acetate ...... + 0.23 to 23.0 C,H,O to each Fe No changeMalate ...... +0*12 to 12.0 CJHliOS ,, Fe No changeTartrate ...... +0*09 to 27.0 C,H,O, ,, Fe No changeCitrate ...... +0.14 to 3.4 C6H807 ,, Fe No changeCitrate ......+ 6.8 to 13.4 C,H,O, ,, Fe Reduction extendingto 5 per cent.Oxalate . . ... . + 0.19 t o 16.0 C,H,O, ,, Fe Reduction throughout,extending to 79 percent.Effect of Heat on the Organic Compounds.P6an de Saint-Gilles (Ann. Chim. Phys., 1856, [iii], 46, 47)found that when the acetate was boiled for some hours it becameopaque through the formation of a brick-red ferric hydroxide,which remained in suspension. This has been confirmed as regardssolutions containing 1.5 t o 0.5 per cent. of iron. With a 0.25 percent. solution, however, it was found that only slight opalescenceoccurs, the colour-intensity is appreciably reduced, even in half-an-hour, and becomes constant in twenty-four hours, being reducedfrom 170 to (average) 21.9. This is identical with the value forthe f erri-compounds with 2pe.Such solutions remain unalteredafter the heating (which was done in sealed tubes), and alcoholgives a precipitate with them, which is not the case with theunheated solutions.The formate undergoes similar ch,anges, but the reduction incolour-intensity has not been traced beyond 55, which was reachedin twenty hours at looo. With the propionate, the reduction wastraced to 64 in twenty-four hours.I n all three cases there appears to be an increase of intensitypreceding the decrease. This was most marked with the propionate,where, with a 0.25 per cent. solution, the intensity increased a tfirst to 250. If the heating be then discontinued, the intensityreverts to its original value of 170 in two days.This indicates theconversion of the lighter form of colloidal hydroxide into the darkerform, prior to the production of the ferri-compound with 2Fe.With the other organic ferri-compounds, two diff went changesoccur on heating, according to the concentration of the solutions.When these are concentr.ated (1.5 t o 0.25 per cent. of iron), pro-tracted heating reduces the colour-intensity to, approximately, thevalue obtaining in the case of the inorganic salts, implying theconversion of the ferri-compound into the corresponding normaIRON AND COPPER COMPOUNDS. 479salt with the iron electropositive; in the first three instances quotedbelow, the intensity is reduced to nearly unity; in the other two,the reduction is less complete.The ferric salt formed, however, isunstable, and, in the course of a few days or weeks it reverts tothe original, dark-coloured ferri-compound. I n the case of thelactate, glycollate, maleate, and the strongest tartrate and racematesolutions, the heating produces a precipitate. This, in the oase ofthe racemate, is the basic salt, R,Fe,,Fe,O,; in the case of thetartrate, it is not the corresponding basic salt, but consists of abulky jelly which gradually redissolves in the cold. It may be thenormal salt. The oxalate darkens slightly, but becomes opalescent.More concentrated solutions. More dilute solutions.Intensity reduced. Intensity increased.Recemate ......... From 9 to 1.08 From 12 to 109Malate .............. 20 ,. 1.22 ,) 11 ,, 177Glycerate .........,, 17 ,, 1.30 9 7 8 9; 88Tartrate ............ ?, 22 ,? 7.5 9 9 22 9 , 275Citrate ............ ,, 17 ,, 14.2 19 9 s9 305Lactate ............ cloudy ,) 10 ,, 185With the more dilute solutions, hydrolysis occurs, forming col-loidal hydroxide, and when the heating is further protracted-insome cases more than twenty-four hours being required-this is con-verted into the ordinary, insoluble, flocculent hydroxide. The colloidalhydroxide is unstable, and, in the cold, gradually reverts into theferri-compound from which it was formed. I n most cases, theconversion of the whole of the iron into the colloidal hydroxidecannot be complete before precipitation begins, but it is probablyso in the case of the tartrate and citrate, where maximum valueshave been obtained, identical €or several different concentrations,and where no precipitation occurred after forty-eight, hours’ heating,The mean value in these two cases is 290.Some evidence was obtained that, with solutions of intermediateconcentration, the two actions characteristic of concentrated anddilute solutions, might proceed simultaneously, but a t differentrates, and this would indicate that these represent the changes ofthe two ferri-compounds present, with 2Fe and FeFe, respectively.Attempts were made in the case of the racemate and glycerate toobtain the lighter form of colloidal hydroxide by diluting therecently heated concentrated solutions : but no hydrolysis occurred.- - 480 PICKERING : THE COLOUR INTENSITY OFDiscussion of Results.The main features of the results with the inorganic salts may besuinmarised thus :Chloride.Nitrate. Sulphato. Bromide.Intensity with satur-ated solutions ......Minimum intensitywith concentratedsoh tions ............Position of minimumPosition of criticalpoint.. ................Final maximum in-tensity ............Intensity of colloidalhydroxide .........1.31 1.22 1.29 -0.98 1-01 1-04 -12 t o 3 10 to 2 10 to 5-]per cent.(0.16 to) 0.04 0.02 0.08 0.07- - 135 139;/137- - 139 128134The small rise in intensity with saturated solutions is, doubtless,due to the formation of hydroxide in some form; such solutions,especidly that of the nitrate, give off acid fumes when heated,*and the solid nitrate will do so in sunlight, even a t the ordinarytemperature, the fumes being re-absorbed in the dark.It is equailycertain that the iron in the most dilute solutions is in the formof colloidal hydroxide ; the colour-intensity is that of the hydroxideprepared by dialysis; it will not diffuse through parchment paper,is not affected except by prolonged boiling, and is precipitated byacid as ordinary flocculent hydroxide, just like the dialysisproduct. f-The more concentrated solutions constituting the curve AB mustcontain iron of, at least, two different colour-intensities, but thedarker one cannot be the colloidal hydroxide, f o r the two forms inquestion are convertible immediately into each other by dilution orconcentration, whereas the colloidal hydroxide is formed only verygradually, and its formation is irreversible. This is proved bythe fact that the same result is obtained by diluting a concentratedsolution, either with water or with any more dilute solution onthe curve AB, whereas, if diluted with a solution on the curveBD, instead of with water, the resulting mixture is much darker,and remains permanently so.+ With the sulpliste, only above 100".-f Such precipitation shows that the colloidal hydroxide is incapable of directreaction with acids, and seems to prove that in the insoluble flocculent hydroxidethe state of aggregation, and probably hydration, mnst be intermediatc betweenthat in the colloid and that of the nnimolecular condition which must precede itscombination with an acidIRON AND COPPER COMPOUNDS.481The most probable view is that the darker constituent of themore concentrated solutions (curve ABC) is a f erri-compound,similar to the organic compounds, with the iron united directlyto the nuclear element of the acid radicle. With both atomspresent in this condition, the colour-intensity should be about 20,and, in the case of the sulphate, this value is reached and main-tained from a strength of 0.014 to the limit of the observations(0.0017 per cent.). The lighter constituents of these solutionswould, of course, be electropositive or pseudo-tervalent iron ; whatthe colour-intensity of this is, is uncertain, but the probability isthat it is nil in respect of yellow, and that it would show, if pure,only a slight amethyst colour.That some form of iron possessingsuch characteristics exists, is certain from the results obtained onadding excess of acids to the solutions, and this almost colourlessiron is not the rmult of the formation of acid salts, as the effect ofstill more acid is to produce a, lemon-yellow colour.* On such aview, which is in harmony with the colourless nature of the solidsulphate and nitrate,+ the yellow of the solutions, even a t the mini-mum points, must be due to the presence of some electronegativeiron. It may be objected that this would necessitate the latterbeing present in approximately the same proportion, and to OCCUIa t approximately the same degree of concentration, in all cases.This is, however, not improbable, as it is seen that the formationof colloidal hydroxide (that is, the position of the critical point) isto a large extent independent of the nature of the acid present.The proportion of water may be the main factor in both cases.As the ferri-compound contains the elements of 2E20 over andabove that of the ferric salt, dilution would increase the proportionof the former, as it does in the figure A B ; but the effect of dilutionis two-fold, it favours hydration, but it also separates the dissolvedmolecules from each other, reducing them to the quasi-gaseouscondition.I€ the stability of the ferri-compound under such con-ditions is less than that of the ferric salt, as is most probably thecase, dilution beyond a certain point would begin to increase theproportion of the latter, and the fall in the colour-intensity in theregion BC would be accounted for.The ferric saIt, thus re-generated, not being stable, is gradually hydrolysed, forming col-loidal hydroxide or a basic salt, the latter only a t the critical pointIt seems difficult to explain thiecolour, especially if its intensity is the same in all cases, by the formation ofordinary acid salts, but it may be due to the formation of compounds analogous tothe a-cupricarbonates, wherein an acid radicle displaces the oxygen united to themetal (T., 1911, 99, 801).f The transparent amethyst crystals of the nitrate cannot be washed and driedwithout assuming a yellow tint.* This has not been fully investigated jet482 PICKERING : THE COLOUR INTENSITY OFor, exceptionally, a t some other concentrations.As the proportionof colloidal hydroxide eventually formed (curve BD) increases withthe proportion of ferric salt in the freshly-prepared solution (curveHC, so far as it can be followed), it is legitimate to conclude thatthe hydroxide is derived from the ferric salt, rather than from theferri-compound, which is present in decreasing proportions as thedilution is extended.It remains to1 account for the very deeply-coloured product ob-tained by heating solutions of the chloride from 0.6 to 0-005 percent. concentration. Doubtlas, this, also, is a form of ferric hydr-oxide produced by hydrolysis. As the ordinary colloidal hydroxideis not altered by heat, unless the heating is very prolonged, it isevident that this dark product cannot be formed from it.Now,the proportion of ordinary colloidal hydroxide in unheated solu-tions may be calculated from the curve BD, and thence the relativeproportions of the darker hydroxide in the heated solutions (curveF D ) ; these proportions, rising from nit? at a concentration of about1 per cent., are found to reach a maximum a t a concentration of0.04 per cent.-the exact point a t which the proportion of ferri-compound also reaches a maximum in the solutions before heating-and fall to nil again a t extreme dilution, where the proportionof ferri-compound originally present must, 80 far as the determina-tiom can show, be also nil; the obvious conclusion is that thishydroxide must be the hydrolysis product of the ferri-compound,just as the ordinary colloidal hydroxide is that of the ferric salt.On the assumption that this transformation by heat is complete,and taking the results a t points where the quantities dealt withare not too small for accuracy, the colour-intensity of the darkerhydroxide is given as 260; or, if the curve ED, instead of BD, betaken as giving the proportion of lighter hydroxide in the heatedlabile solutions, the value obtained is 270.Similar calculationswith the nitrate give 306; the mean is 280, which is just doublethat of tlie lighter colloidal hydroxide. This view is confirmed byfinding that the organic ferri-compounds are, as a matter of fact,hydrolysed by heat (although not by mere dilution) forming anunstable colloidal hydroxide, of which the colour-intensity is thesame as that obtained froin the nitrate and chloride, namely,Solutions of the formate, acetate, and propionate of all concen-trations appear to be similar to the most dilute stable solutions ofthe inorganic salts, containing the iron in the lighter colloidal form.The values, about 170, are somewhat higher than those given forthe colloidal hydroxide in other cases, and it is probable that acertain amount of the darker hydroxide is present in them; it275-305 (p.479)THE COLOUR INTENSITY OF IRON AND COPPER COMPOUNDS. 483appears, also, that the whole of the lighter hydroxide present canbe converted into the darker form by heat (250 being reached withthe propionate, p. 478), this being ultimately converted by heat intoinsoluble hydroxide if much water is present, or into the stablef erri-compound if the solutions are more concentrated.The nature of the other organic iron compounds and the trans-formations which they undergo on dilution or heating has beensufficiently noted above (p. 478).Summary.Iron in ferric compounds may exist in five different conditions:(1) Both atoms in the electropositive or hydroxyl position :colour-intensity very small, probably nil as regards yellow light.(2) Both atoms in the electronegative portion of the molecule,directly united to the nuclear element of this portion (ferri-com-pounds) : intensity about 20.(3) One atom in each of the two above conditions: intensity 10.(4) As ordinary colloidd hydroxide by the hydrolysis of electro-positive iron : intensity about 135.(5) As darker colloidal hydroxide, by the hydrolysis of electro-negative iron : intensity about 280.The chloride (and probably bromide) exists in the conditions(l), (4), (5), and either (2) or (3).The sulphate exists as (l), (2), and in one or both the colloidalconditions.The oxalate is a normal ferric salt, with its iron in the con-dition (1).The format-e, acetate and propionate exist normally as (4), butmay, in some cases, probably in all, be obtained in the conditions(2) and (5).The other organic compounds examined exist normally as (2)(tartrate, glycollate, and, probably, maleate and ethylsuccinate),or as (3) (racemate), or else in both these conditions, according tothe concentration of the solution (citrate, lactate, glycerate andmalate). When the more concentrated solutions of them areheated, they form, or tend to form, the normal ferric salt(1) (racemate, malate, glycerate, tartrate and citrate) ; when themore dilute solutions are heated, they hydrolyse into the condition(5) (racemate, malate, glycerate, tartrate, citrate and lactate).The only condition in which none of them has been obtainedis (4).HABPENDEN.VOL. cv. K

ISSN:0368-1645    

DOI:10.1039/CT9140500464

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

484 KIPPING An’b ROBISON :LL--Organic Derivatives of Silicorl. Part XU.The Condensation Prodztcts of D ~ ~ ~ ~ e r ~ ~ l s i l i c c l n e d i o By FREDERIC STANLEY KIPPING and ROBERT ROBISON.IN the present paper we record the results of a further study ofdiplienylsilicanediol and of the open- and closed-chain condensationproducts derived from this diol (Kipping, T., 1912, 101, 2108,2125). The compounds which have now been obtained are of thefollowing types, of which No. IV has not hitherto been described:I.11.11’1. rv.V.VI.HO SiPh,* OH.HO*SiPh,*O*SiPh,*OH.HO*SiPh,*O*SiPh,*O*SiPh2* OH.It will be seen that diphenylsilicone, SiPh,O, and aIso the closed-chain compound, Ph,Si<O>SiPh,, which theoretically might beformed from anhydrobisdiphenylsilicanediol (II), have not yet* I n a previons paper (T., 1912, 101, foot note to p.210) I mentioned thecircumstances which led tc, the pnblication by Martin of a paper on some siliconcompounds (Be?.., 1912, 45, 403), and I poiiitcd out that hc had given a “veryerroneous ” account of diphenylsilicaiiediol ; hnving speiit a good deal of time iutproving the iuaccuracy of his results, I was able t o suggest exactly liow mid why, i nmy opinion, he had fallen into error. In liis reply (T., 1913, 103, 119), Martintried to show that his results were practically iJentical with rniue a i d that I liadimisrepresented him.As to how far there is any resemblance between Martin’s account of dipheiiy1-silicanediol and my own, readeis of the original papers (not Martin’s tabularcomparisons) may judge.Whether 1 used the word isomeride or modification iii~reference to Martin’s two AlodQikntiowen appears to nie to be iiiiiiiateiial. as in niyopinion his two niodifications have 110 existence. I was not critici5ing his views, but;.his experimental results. His 1)aper certainly suggested that lie regarded his.Jfodijkdionen as isomerides, but if, as he now iniplies, he considered them to-be merely different crystallographic forms, then his iiiethods for the conveisioirof the one into the other seem inexplicable.In a later paper (Ber., 1912, 45, 2097), Martin puLlished without niyIbermission some further results of work carried out a t my suggestion and under mysupervision. I think it is only right to say that, after carefully coilsidering all t h eexperimental data at the time, I told hiin that I could not conseiit to t h cpublication of the results.The whole of the evidcnce indicated that all the‘‘ compounds ” subsequently dcscribed by him were complex mixtures and in myoliiiion the structural f o r i i m l ~ he assigns to these compounds arc devoid o ffouudntion. I?. s. K.ORGANIC DERIVATIVES OF SILICON. PART XXI. 485been isolated. Although we have made several attempts to preparethese substances from diphenylsilicanediol and from anhydrobis-diphenylsilicanediol, we have not obtained any indication of theirexistence; these facts, together with the negative results of ourefforts to produce the corresponding benzyl derivatives (Robisonand Kipping, this vol., p.40), seem to show that (a) the simplesilicones, ths analogues of the ketones, cannot be prepared fromthe diols, SiR2(OH)2, owing to the readiness with which the latterundergo condensation, and ( 6 ) a closed-chain consisting of twosilicon and two oxygen atoms linked together alternately is veryunstable compared with one containing three or four atoms of bothof these elements.The conditions under which diphenylsilicanediol and each of itsopen-chain condensation products undergoes change are, on thewhole, very similar to those which are operative in the case of thecorresponding benzyl derivatives. Small quantities of alkalihydroxide, or of piperidine, or of hydrochloric acid bring aboutcondensation, with formation of one or both of the closed-chaincompounds.The action, however, does not consist merely in theelimination of the elements of water ; in all cases, apparently,hydrolysis and condensation occur simultaneously, and the natureof the final product is largely determined by that of the solventemployed and by the other conditions which prevail; thus, althoughanhydrobisdiphenylsilicanediol in ethereal solution seems to bemainly converted into tetra-anhydrotetrakisdiphenylsilicanediol inthe presence of a small quantity of piperidine, an appreciableproportion of trianhydrotrisdiphenylsilicanediol is also produced.Under similar conditions, dianhydrotrisdiphenylsilicanediol doesnot give pure trianhydrotrisdiphenylsilicanediol, but a mixture ofthe latter witn a very considerable proportion of tetra-anhydro-tetrakisdiphenylsilicanediol.That the formation of any closed-chain compound from thecorresponding open-chain compound is a reversible reaction is alsoclearly proved by the preparation of dianhydrotrisdiphenylsilicane-diol from the trianhydro-derivative by thc action of sodium hydr-oxide in acetone-ethereal solution ; sirnilarly, it has been foundthat trisnliydrotetrakisdiphenylsilicanediol may be obtained fromthe tetra-anhydro-compound by hydrolysing the latter with sodiumethoxide in alcoholic chloroform solution, and may be reconvertedinto tetra-anhydrotetrakisdiphenylsilicanediol with the aid ofsodium hydroxide or hydrochloric acid in alcoholic solution.I n view of the facts just stated, it is clear that the relativesolubilities of the two closed-chain compounds in a given sblventwould have a preponderating influence on the relative proportionsK K 486 ICII~PING AKD KOBISON :in which the two substances would be obtained by evaporating asolution of any of the open-chain compounds in the given solventwith a particular reagent.Consequently, the results of experimentssuch as those referred to above give very little information as tothe relative stabilities of the two closed chains, containing, respec-tively, three and four atoms of silicon and of oxygen.It would seem, nevertheless, that a fairly strong inference maybe drawn from a direct comparison of the behaviour of anhydro-bis- and dianhydrotris-diphenylsilicanediol towards hydrochloricacid in methyl-alcoholic solution.Both these compounds arecsonverted into trianhydrotrisdiphenylsilicanediol, and tetra-anhydrot'etrakisdiphenylsilicanediol is not formed in appreciablequantities in either case; but the rapidity with which the condensa-tion occurs in the case of dianhydrotrisdiphenylsilicanediol is verymuch greater than in that of anhydrobisdiphenylsilicanediol. Itseems, in fact, that the closed chain of three silicon and threeoxygen atoms is easily and directly produced from dianhydrotris-diphenylsilicanediol, but that tetra-anhydrotetrakisdiphenylsilicane-diol, in spite of its slight solubility in methyl arcohol, is not formedfrom anhydrobisdiphenylsilicanediol, owing to the relativeinstability of the larger closed chain.A similar conclusion, namely, that the closed chain of threesilicon and three oxygen atoms is the more stable one, may bedrawn from the results of other experiments in which the condi-tions do not favour, although they do not preclude, hydrolysis;thus by the action of heat on diphenylsilicanediol a much largerproportion of trianhydrotris- than of tetra-anhydrotetrakis-diphenylsilicanediol is formed ; again, when dianhydrotrisdiphenyl-silicanediol is heated it is almost quantitatively converted intotrianhydrotrisdiphenylsilicanediol, whereas under similar conditionsanhydrobisdiphenylsilicanediol gives a mixture of approximatelyequal quantities of trianhydrotris- and tetra-anhydrotetrakis-dipheriylsilicanediol (Kipping, Zoc.cit.).From these facts, and from the failure of our attempts to obtaina benzyl derivative corresponding with tetra-anhydrotetrakis-diphenylsilicanediol, we infer that the heterocyclic group of six ismore stable than that of eight atoms.The crystallographic examination of the compounds described inthis paper was carried out by Mr. Vernon Stott under the super-vision of Mr. A. Hutchinson, of the Mineralogical Laboratory,Cambridge; we are greatly indebted to these gentlemen for thereports which they have given usORGANIC DERIVA'I'IVES OF SILICON. PART XXI. 487EXPERIMENTAL.Z~iphenylsilicaizedol.The pure specimens of this compound, prepared more than ayear ago (loc. cit.), have retained their properties; five melting-point tubes containing the crushed powder from one of the speci-mens were heated simultaneously, and in all cases the substanceliquefied with effervescence at 128-1 32O.Diphenylsilicanediol,therefore, is stable a t the ordinary temperature, and the greatdifficulties which attend its isolation (loc. cit.) are due to itssensibility towards alkalis, acids, and other reagents. The crystalsdeposited by the spontaneous evaporation of its solution in ethylacetate were examined.System : anorthic. Subclass : holohedral.a: b : c=0*5657: 1 : 1.700.a = 90°2' ; = 11 1O20' ; y = 87O27'.Forms developed : b(010), nz(llO), p(llO), c(OOl), t(013), ~(116).Angle.110 : 110i i o : oio010 : 001210 : 001Iio : 001010 : 013110 : 013i i o : 013010 : lA0No.161615222626311Table of Angles.Limits.63'2' -65'33'53'10'-55'52'59'34'-6 1'37'89°62'-90030'70°28'-71' 16'7Oo49'-7l057'58"20'-6 1'40'59"26'88'38'Mean.Calculated.64"23' -55'40' -60'51' 60'57'90°11' -70'55' 70"5G'71"19' -60"31' -59'25' 60'1'88'38' 87'51'' The crystals are prismatic in habit. Of the prism faces b , m,and p, b and p are well developed, whilst m is but a small face.The angles of the prism zone, namely, bm=64O23/, m,u=55°40/,pb = 60°57/ all approximate to 60°, and give the crystals a pseudo-hexagonal character. The crystals are terminated by three planesa t each end. These are c(OOl), t(013), and v(i16). The face c(OO1)is quite large, whilst t and v are tiny bevels on the edges cb andcp' respectively.The faces t and v are very bad ones, particularlythe latter, from which no trustworthy measurements could be ob-tained. The faces as a whole were very bad from a goniometricalpoint of view, as may be seen from the range of the angles in thepreceding table.Eflect of Heat 0% Diphenylsilicanediol.Some experiments on the action of heat on diphenylsilicanediolhave already been described (Loc. cit., p. 2137). At 140-180° th488 KIPPING AND ROBISOX :diol loses approximately one molecule of water, and gives as theprincipal product trianhydrotrisdiphenylsilicanediol. Furtherexperiments hhve shown that under these conditions a small pro-portion of the diol is converted into tetra-anhydrotetrakisdiphenyl-silicanediol, but even when these two compounds have been removedas far as possible there remains some oil which is readily soluble inpetroleum containing a little chloroform.As it seemed possible that this oil might contain diphenyl-silicone or diaiihydrobisdiphenylsilicanediol or both these com-pounds, a weighed quantity of the pure substance was heated in axylene bath atl about 125-128O.I n the course of some hours itchanged into a transparent glue, and at the end of about fifteenhours the total loss in weight amounted to 7.5 per cent., but theweight had not become quite constant; the theoretical loss for1 mol. of water is 8.3 per cent. The gelatinous or vitreous massobtained in this way showed no signs of crystallising even whenkept during some months, and it did not crystallise when it wastreated with a little ethyl acetate; this last f a c t showed that,unlike the vitreous product formed at 140-180°, it did notcontain a large proportion of trianhydrotrisdiphenylsilicanediol.The product was fractionally extracted with warm light petroleum,in which it was moderately easily soluble, and finally the wholepassed into solution.The various extracts were then fractionallycrystallised from mixtures of chloroform and light' petroleum, andin this way a small quantity of dianhydrotrisdiphenylsilicanediolwas isolated; the rest of the crystalline material seemed t o consistof a mixture of anhydrobis- and dianhydrotris-diphenylsilicanediol,but a considerable proportion of the original product remained a8an oil.Another sample of the pure diol was heated in a xylene bathat abouf 125-128O; the loss in weight was about 6.8 per cent.at the end of six hours, and 7.8 per cent. at the end of abouttwenty-six hours.From the product, anhydrobis- and dianhydro-tris-diphenylsilicanediol were isolated, but again there remained aconsiderable proportion of an oil, from which crystals could not beobtained, and neither of the closed-chain compounds seemed to havebeen produced.As the loss in weight in these two experiments was not verydifferent from that (8.5 per cent.) required for the elimination ofone molecule of water from one molecule of the diol, and wastherefore much greater than that corresponding with the produc-tion of dianhydrotrisdiphenylsilicanediol, or of a mixture of thiscompound and anhydrobisdiphenylsilicanediol, the results pointedto the formation of diphenylsilicone.The further examination oORGAKIC DERIVATIVES OF SILICON. PART xxi. 489the oily products just referred to did not, however, bear out thisview; when these oils were heated a t about 200° a vigorous effer-vescence occurred, owing t o the liberation of steam, and theproducts, treated with ethyl acetate, immediately crystallised. Thesolids thus obtained gave a small proportion of a very sparinglysoluble powder, and crystals of trianhydrotrisdiphenylsilicanediol,together with what seemed to be tetra-anhydrotetrakisdiphenyl-silicanediol. The behaviour of these oily products was, in fact, justthat of a mixture of anhydrobis- and dianhydrotris-diphenylsilicane-diol. When these oily products were submitted to distillation insteam tho distillate was free from any visible suspended matter;since diphenylsilicone would probably be volatile in steam, thisfact.might be taken as evidence of the absence of this compound.If diphenylsilicone and dianhydrobisdiphenylsilicanediol are notformed when diphenylsilicanediol is heated, i t would seem that apart of the loss which occurs must be due to thO volatilisation ofthe diol or of its condensation products, or to ite oxidation,followed by the volatilisation of some of the products of oxidation.A weighed quantity (0.478 gram) of the diol was therefore heatedin a bromobenzene bath a t a temperature which varied from130-140° in order to ascertain whether a loss greater than thetheoretical would take place.A t the end of six hours the loss was7.1 per cent., a t the end of nine hours 7.8 per cent., at the endof fourteen hours 8.6 per cent'., a t the end of sixteen and a-halfhours 9 per cent., and at the end of twenty-two hours i t was 9.5 percent. During the first period of heating the sides of the weighingbottle containing the substance became coated with oily drops,which extended right up to the neck of the bottle, but no increasein this deposit seemed to occur during the remaining periods.The vitreous product when rapidly heated to and kept a t 200°during about five minutes evolved vapours which could be clearlyseen; the total loss in weight had then reached 10 per cent.It isevident, therefore, that since the loss in weight is not entirely dueto the escape of water vapour, the quantitative results cannot betaken as pointing to the formation of diphenylsilicone. The oilymather, in which the presence of this compound was suspected,is, no doubt, merely a mixture of anhydrobis- and dianhydrotris-diphenylsilicanediol, the separation of which, as already shown, isa task of very considerable difficulty, particularly when only smallquantities of material are available.Action of Heat on Dipherylsilicanediol in Xylene Solution.diol was heated in boiling toluene and boiling xylene solution,As these experiments failed to give the desired products, the pureI490 KIPPING AND ROBISON :is moderately soluble in both these liquids at their boiling points,and the hot saturated solutions give when cooled a considerabledeposit of the unchanged substance; if, however, the solutions areheated for a short time, decomposition sets in, with liberation ofsteam.I n experiments with each of the solvents, in which thesolutions were boiled for a short time only, dianhydrotrisdiphenyl-silicanediol was isolated from the product. A xylene solution whichhad been boiled during one hour gave on evaporation a productwhich was readily and completely soluble in cold chloroform, anddid not, therefore, contain any considerable proportion of theunchanged diol ; from this product a large proportion of trianhydro-trisdiphenylsilicanediol was isolated, and smaller proportions ofanhydrobis- and dianhydrotris-diphenylsilicanediol. There thenremained a relatively very small quantity of a viscid oil, fromwhich crystals could not be obtained.All these results seem toshow that diphenylsilicone and dianhydrobisdiphenylsilicanediolare not formed in appreciable quantities by heating the diol aloneor in solution; the diol first undergoes condensation, givinganhydrobis- and dianhydrotris-diphenylsilicanediol, and if thetemperature is sufficiently high these compounds are almost com-pletely transformed into trianhydrotris- and tetra-anhydrotetrakis-diphenylsilicanediol, the former of which is always produced inmuch the larger proportion.Action of Piperidine on Diphenylsilicanediol.Diphenylsilicanediol undergoes condensation in acetone solutionin the presence of a trace of piyeridine.When such a solutionwas allowed to evaporate spontaneously, it gave a solid, somewhatsticky residue, which was readily and completely soluble in coldchloroform, and therefore did not contain any appreciable propor-tion of the original diol. This residue was gently warmed on awater-bath in order t o expel the piperidine, and then dissolvedin ethyl acetate; the solution ultimately deposited crystals oftetra-anhydrotetrakisdiphenylsilicanediol (m. p. 200°), togetherwith a small proportion of a colourless powder, which was onlysparingly soluble in ethyl acetate, and probably represented acondensation product more complex than tetra-anhydrotetrakis-diphenylsilicanediol. The mother liquors from the tetra-anhydro-compound gave crystals melting indefinitely from about 160° to170°, which were probably a mixture of trianhydrotris- and tetra-anhydrotetrakis-diphenylsilicanediol, but the presence of the formerwas not conclusively establishedORGANIC DERIVATIVES OF SILICON.PART XXI. 491A ction of Ammoluium Hydroxide o n Diphenylsilicanediot.I n the presence of a little a.mmonium hydroxide, diphenyl-silicanediol undergoes condensation in acetone solution a t theordinary temperature, and the solution deposits an oil. From thisproduct, with the aid of chloroform and light petroleum, crystalsmelting a t 113O, which dissolved in a 5 per cent. solution ofpotassium hydroxide, were obtained ; this substance was anhydro-bisdiphenylsilicanediol. In another experiment, carried out in asimilar manner, the oily condensation product gave crystals melt-ing a t 112O, which were insoluble in a 5 per cent.solution ofpotassium hydroxide; this product was dianhydrotrisdiphenyl-silicanediol. The closed-chain condensation products were notobtained in these experiments.The crystals deposited from a mixture of chloroform and lightSystem : anorthic.petroleum were examined goniometrically.Sub-class : holohedral.a : b : c = 0.6536 : 1 : 1.868.a = 92 O 2 8 f ; j3 = 1 15O40' ; y = 86O24f.Forms developed : b(010), m(110), &TO),g(iT4).Table of Angles.Angle.010 : 110110 : 1x0110 : 010010 : 011li0 : 011110 : 011010 : 0011 l O : 001110 : 001011 : 001110 : Ti2010 : ii2 iio : 112No.10101020242418202011242424Limits.61'6' -62'1'60' 10'-6 1'33'56O40'-57O56'29'52'-30'42'52' 18'-53'14'105'44'-106'39'88O38'-89"29'66'41'-67'25'68'26'-68'44'58'8' -59'9'142'43'-143'19'119'5' -1 19'55'105'22'-106'38'Mean.61'36'60'58'57'26'30'22'52'49'106'8'89'4'67'3'68'37'58'38'143'1'119'31'106'1'Calculated. -57'26'52'53'106'14'89'0'69"8'143O2 1 '119'22'106'11'---The forms b, m, and p constitute a prism zone; the forms b andm are large and p small.The angles of the prism zone are:bm = 61O361, mp = 60°58/, p b l = 57O26'. They all approach thevalue 60°, and so the crystals are pseudo-hexagonal. Of the threeterminal forms, c(OO1) is much the large&, q and s being smallfaces on the edges bc and mlc rapectively492 KIPPING AND ROBISON :*4 c t io n, of Pip e ridin e on A n h.y dro b isdi ph e n y 1 silican e dio 1.When anhydrobisdipheuylsilicanediol is heated, it gives tetra-anhydrotetrakis- and some trianhydrotris-diphenylsilicanediol,together with a small proportion of a colourless powder, which isprobably a highly complex condensation product (loc. cit. p. 2133);when treated with acetyl chloride it is converted principally intotetra-anhydrotetrakisdiphenylsilicanediol.I n ethereal solution, in the presence of a small quantity ofpiperidine, it undergoes change, giving a mixture of products,which remains as an oil when the solution evaporates spontane-ously ; from this oil the transparent, rectangular crystals meltinga t about 184-186O (loc.cit., p. 2140) were obtained; this observa-tion eh0u.s that both trianhydrotris- and tetra-anhydrotetrakis-diphenylsilicanediol had been produced, the former, however, inrelatively small quantities. The action of the piperidine, therefore,is two-fold; it not only brings about the condensation of theanhydrobisdiphenylsilicanediol, but also1 hydrolyses some of thiscompound to diphenylsilicanediol, which then undergoes condensa-tion, giving a little trianhydrotrisdiphenylsilicanediol.A ction. of Hydrochloric .4 cid 07% ,.ln,hydrobisd~phe?~ylsilicanediot.When a very small quantity of hydrochloric acid is added to asolution of anhydrobisdiphenylsilicanediol in methyl alcohol, novisible change occurs immediately, but after some time a smallquantity of an oil is deposited.The solution, left to evaporatea t €he ordinary temperature, gives a residue which is partly crystal-line, partly oily. I f tho whole is treated again with methyl alcoholcontaining a little hydrochldric acid, and the solution is left t oevaporate, the residue then contains a larger proportion of thecrystalline product than before. This substance when freed fromoil with the aid of alcohol, separates from ethyl acetate in colourlessprisms, melting a t 188O. It consists of pure trianhydrotris-diphenylsilicanediol. The presence of the tetra-anhydro-derivativein the crude, crystalline product could not be detested.Hydrochloric acid, theref ore, under the conditions stated, doesnot bring about the condensation of anhydrobisdiphenylsilicanediol,but hydrolyses i t to the simple diol, which then undergoes con-densation.Dimhydro trisdip~,ei~,ykilicacrt ediol.The crystals deposited from a mixture of chloroform and lightpetroleum were examinedORGANIC DERIVATIVES OF SILICON.PART XXI. 493System : anorthic. Sub-class : holohedral.a : b : c =0.5068 : 1 : 1.491.a = 90°42/; = 106'561 ; y == 86'30'.Forms developed : b(010), m(110), p(liO), c(OOl), r(012),I I <i 14).Table of Angles.Angle. No. Limits. Menn. Calculated.010: 1lO 6 66'42'-67'21' 66'58'110: 010 10 60'4'-6 1'53' 61'32' 61'2301O:OOl 16 89"7'-90'5 1' 90'19' -11O:OOl 15 74' 16'-Ri028' 75"l' -010:012 1 54'42' 54'42' -110: 012 1 63'1 1' 63"ll' 63'33'010:114 3 67'34'-69'11' 68'36' 69'25'110 : 114 3 120'28' -124'2' 122'47' 120'57'110 : Ti4 3 103'44' -105'14' 104"27' 203'0'-110: 1;o 7 51'4'-52"4' 51'39' -1JO:OOl 8 74"9'-74"55' 74O35' 74'34'110:012 1 94'50' 94'50' 93"54#The dominant forms are: b(010), p(l'iO), and ~(001).Bfanycrystals are simply four-sided prisms, terminated by c planes. Theprism face m is often missing, and when present it is only small.The face r(Ol2) was present on one crystal only. The form u(5'I 4 )was only developed on two crystals, and even then the faces werevery poor ones. This accounts for the divergence between thecalculated and measured angles. The crystals may be described asshort, stumpy prisms.The prism angles show some approach tohexagonal development : b m = 66O58/ ; mp = 51O39' ; pb' = 61O32'.If in the crystals of diphenylsilicanediol t is given the indices(011) instead of (013), then v will become (i12) instead of (116).Ths remaining indices would be unchanged. The axial ratioswould now be 0.5657 : 1 : 0.5666 instead of 0.5657 : 1 : 1.700.Similarly, if in the crystals of dianhydrotrisdiphenylsilicanediolr is made (011) instead of (012), then u would be (112) instead of(114), and the remaining indices would be unaltered. The axialratios would be:instead of 0.5068 : 1 : 1.491.To bring the axial ratios of the crystals of anhpdrobisdiphenyl-silicanedid into line, q would have to be made (031) instead of(Oll), and the ratios would then be 0.6536 : 1 :0*6227 instead of0.6536 : 1 : 1.868.'0.5068 : 1 : 0.7455,The indices of ~(1x2) would then become (332).Action.of Piperidine on Dianhydrotrisdiphenylsilicanediol.When an ethereal solution of dianhydrot#risdiphenylsilicanediol,to which a drop of piperidine had been added, was left to evaporateslowly at the ordinary temperature, i t gave a somewhat brown an494 KIPPING AND ROBISON :oily residue, from which, with the aid of ethyl acetate, there wasseparated a small proportion of a colourless, very sparingly solublepowder. The ethyl acetate solution gave a crystalline deposit, fromwhich pure tetra-anhydrotktrakisdiphenylsilicanediol was isolated.The mother liquors from this compound seemed t o contain tri-anhydrotrisdiphenylsilicanediol, but the latter was not identified withcertainty.It is obvious from these results that dianhydrotris-,like anhydrobis-diplienylsilicanediol, is hydrolysed by piperidine,the products of hydrolysis then undergoing condensation to theclosed-chain compounds.I n these circumstances the nature of the product or productsdoubtless varies with the conditions of the experiment, but acomparison of the results obtained by the action of piperidineon diphenylsilicanediol, anhydrobisdiphenylsilicanediol, and di-anhydrotrisdiphenylsilicanediol seems to show that the principalproduct is in all cases tetra-anhydrotetrakisdiphenylsilicanediol.The A ction of Hydrochloric A cid on Dianhydrotrisdiphenyl-siZicanedio1,The action of hydrochloric acid on dianhydrotrisdiphenylsilicane-diol in methyl-alcoholic solution is very different from that of thesame acid on anhydrobisdiphenylsilicanediol. After a few momentsthe solution becomes quite milky, owing to the separation of anoil, the quantity of which rapidly increases, and when the solutionis evaporated at the ordinary temperature it gives a crystallineresidue, which is free from any appreciable quantity of oil.Thecrystalline product seemed to be practically pure ; when recrystal-lised from ethyl acetate it gave colourless prisms of pure trianhydro-trisdiphenylsilicanediol, melting sharply a t 188O.Trianhiy dro trisdiph e n ylsilicanediol.This closed-chain compound is hydrolysed by alcoholic potassiumhydroxide, and finally gives a solution of the potassium derivativeof diphenylsilicanediol ; when the alcohol is evaporated and theresidue is treated with a slight excess of dilute acetic acid, the diolis precipitated in the usual form (Kipping, loc.cit., p. 2116).If, however, hydrolysis is carried out very cautiously and theprocess is interrupted a t a very early stage, the following reactionmay be realised:SiPh2*0 O<siph .O>SiPb, + H,O = HO*SiPh,*O*SiPh,*O*SiPh,*OH.2For this purpose the trianhydro-derivative (0.25 gram) wasdissolved. in a mixture of acetone and a little ether, and a 3 percent. aqueous solution of sodium hydroxide (0.05 gram) was added;a few seconds later the solution was acidified with dilute acetic acidORGANIC DERIVATIVES OF SILICON. PART XXI.495and the acetone and ether were rapidly evaporated a t the ordinarytemperature in a stream of air. The product wm extracted withether, the ether was evaporated, and the oily residue was treatedwith a little alcohol; the small proportion of insoluble matter,which doubtless consisted of unchanged trianhydrotrisdiphenyl-silicanediol, was then separated by filtration. The alcoholic solu-tion, when rapidly evaporated at the ordinary temperature, gavean oil, which separated from a mixture of chloroform and lightpetroleum in colourless crystals ; this product was pure dianhydro-trisd iphenylsilicanediol.Trianhydrotrisdiphenylsilicanediol, like the corresponding benzylderivative, may also be converted into the open-chain compound byhydrolysing it with hydrogen chloride.The trianhydro-compoundwas dissolved in a mixture of chloroform and acetone, and a fewdrops of concentrated hydrochloric acid were added ; after sixhours the solution was neutralised with ammonium hydroxide,and the solvents were rapidly evaporated at the ordinary tempera-ture. The somewhat pasty residue was extracted with alcohol, andthe solution was filtered from unchanged trianhydrotrisdiphenyl-silicanediol and evaporated ; the oily residue consisted essentiallyof dianhydrotrisdiphenylsilicanediol, which wits obtained in a stateof purity by recrystallisation from a mixture of chloroform andlight petrolgum.Since hydrogen chloride condenses dianhydrotrisdiphenylsilicane-diol, the above hydrolysis is a readily reversible reaction, just ain the case of the corresponding benzyl derivative (Robison andKipping, this vol., p.40). The action of piperidine on tri-anhydrotrisdiphenylsilicanediol was also examined in acetone solu-tion. The product was a mixture, from which a small proportion of apowder, practically insoluble in amtone, wit^ isolated ; the remain-der seemed to consist of a mixture of trianhydrotris- and tetra-anhy drotetrakis-diphenylsilicanediol.The crystals of trianhydrotrisdiphenylsilicanediol, deposited fromethyl acetate solution, were measured.System : orthorhombic. Sub-class : bisphenoidal.Forms developed : a(100), b(010), m(110), ~ ( 1 1 1 ) .a : b : c = 0.7750 : 1 : 0.4993.Table of Angles.Angle. No.100:010 19100: 110 19010: 110 19100: 111 17010: 111 18110:!_11 16110: 111 121 1 1 : l ~ ~ sLimits.89'50'-90'7'37O2 1'-38' 12'51'55'-52'29'59O54'-6Oo 17 '66'58'47'27'50' 34'-5 1 ' 1 3'80'30'-81'27'7 808' -7 ~ 2 9 'Mean.Calculated.90"o' 90'0'37'48' 37O48'52'12' -60'7' 60'3'67'14' -50"48+' 50'50'78O15' 78'23'81'3' 80'57496 KIPPING AND ROBISON :The crystals occur in two well-marked habits. One of these isprismatic, u and b being large faces, whilst the m faces are small.I n other cases the crystals are markedly tetrahedral.7'rianhydro t e t rali isdiphen y Zsilicnnediol,HO*SiPh,*O*SiYh,*O* SiPh,*O*SiPh,*OH.This condensation product of diphenylsilicanediol, the mostcomplex open-chain silicon compound so far obtained, may beprepared by cautiously hydrolysing tetra-anhydrotetrakisdiphenyl-silicanediol,SiPh2*o'SiPh2>0 + H,O = HO~SiPi~;O*SiP~,~O~SiPh~~O~SiPb,.OH O'Si Ph 2*0 S I PI)When the closed-chain compound is warmed with excess ofalcoholic potassium hydroxide, it seems to be completely hydro-lysed, giving the potassium derivative of diphenylsilicanediol, butowing t o the fact that tetra-anhydrotetrakisdiphenylsilicanediol isalmost insoluble in alcohol, the reaction takes place rather slowly.I n acetone solution hydrolysis takes place more rapidly, as thetetra-anhydro-derivative is more soluble in this liquid, but it isdifficult to interrupt the process a t the desired stage.Hydrogenchloride seems to have little effect on tetra-anhydrotetrakisdiphenyl-silicanediol ; when solutions of the substance in acetone or ether,or acetone and chloroform, are treated with a little concentratedhydrochloric acid, and kept during periods varying from thirtyminutes to one day, most of the original compound is recoveredunchanged, and only traces of a product soluble in cold alcoholare obtained.Under the following conditions, however, the partial hydrolysisof tetra-anhydrotetrakisdiphenylsilicanediol may be accomplished.The closed-chain compound is dissolved in chloroform, and a con-siderable excess (5-6 mols.) of an alcoholic solution of sodiumethoxide is added, care being taken to use sufficient chloroform toprevent the precipitation of the anhydro-derivative. After aninterval of not more than one minute, a slight excess of very diluteacetic acid is added, the liquids are well shaken together, the chloro-form solution i s separated, and the aqueous solutmn is extractedwith a little chloroform.The combined chloroform extracts arerapidly evaporated at the ordinary temperature, and the solidresidue is extracted two or three times with cold ethyl alcohol,which leaves undissolved a considerable proportion of the originaltetra-anhydrotetrakisdiphenylsilicanediol. The filtered alcoholicextract is diluted with water and vigorously stirred; the precipi-tated trianhydrotetrakisdiphenylsilicanediol is then separated bORGANIC DERIVATIVES OF SILfCOK. PART XXI. 497filtration, dried in the air, and crystallised several times froma mixture of chloroform and light petroleum.The yield by this method is rather poor, but the crude substanceis not contaminated to any great extent with other products ofhydrolysis ; moreover, the unchanged tetra-anhydrotetrakisdiphenyl-silicanediol, which is recovsred, may be treated again, and theoperations may be repeated until practically the whole of theoriginal substance has been transformed into trianhydrotetrakis-diphenylsilicanediol. When attempts are made to increase the yieldby alloying a longer time to elapse between the addition of thesodium ethoxide and the neutralisation with acetic acid, althougha larger proportion of the tetra-anhydro-compound is hydrolysed,the product is a mixture, from which it is difficult to isolate thecomponents; this is so even when the theoretical quantity ofsodium ethoxide is used.Trianhydrot etra~:isd~~hennylsilicanediol separates from a mixtureof ether and light petroleum in short, colourless prisms; whenheated moderately quickly it melts sharply at 128*5O, but whenheated very slowly it sinters a t about 127O, probably owing toincipient decomposition.The samples for analysis were dried over sulphuric acid:0.1572 gave 0,4091 CO, and 0.0736 H,O.C= 71.0 ; H = 5.2.0.1965 ,? 0.5124 CO, ,? 0.0932 H,O. C=71*1; H=5*3.The molecular weight was determined by the cryoscopic method0.262 in 12.1 benzene gave At -0'12O.C,8H4,0,Si4 requires C = 71.0 ; H = 5.2 per cent.in benzene solution :M.W.=884.0-494 ,) 12.1 ,, ,, A t -0.23'. M.W.=870.C4,R,O,Si, requires M.W.= 811.These results, like those obtained under similar conditions inthe case of the other open-chain condensation products of diphenyl-silicanediol, are higher than the theoretical values, but the extentof association, as indicated by the experimental results, rapidly fallsas the molecular weight of the condensation product rises; this isshown by the following data:MW. M.W. Difference,(Found). (Calculated). per cent.Anhydrobisdiphenylsiicanediol ......... 573 414 38Dianhydrotrisdiphenylsilicanediol . . . . . . 755 613 23Trianhydrotetrakisdiphenylsilicanediol 877 81 1 8Trianhydrotetrakisdiphenylsilicanediol resembles the other twoopen-chain condensation products of diphenylsilicanediol. Itseparates from a mixture of ether and light petroleum in mmsive,transparent prisms, and is readily soluble in chloroform, acetone,and most of the ordinary solvents, but only sparingly so in col498 KIPPING AND ROBISON :ethyl alcohol, and practically insoluble in cold light petroleum.Itdoes-not dissolve appreciably in a 5 per cent. solution of potassiumhydroxide.Conversion of Trianhy dro- into T e tra-anhydro- t e t rak: isdiph eny l-silicanediol.The conversion of trianhydro- into tetra-anhydro-tetrakis-diphenylsilicanediol is easily accomplished. When an alcoholicsolution of the former is warmed with a trace of sodium hydroxide,a crystalli_ne precipitate is soon formed, and in a short time mostof the dissolved trianhydro-derivative has undergone the desiredtransformation ; the air-dried precipitate melts a t 200°, and whenrecrystallised once from ethyl acetate i t melts sharply a t 201°, andconsists of pure tetra-anhydrotetrakisdiphenylsilicanediol.When an alcoholic solution of trianhydrotetrakisdiphenylsilicane-diol is warmed with a few drops of concentrated hydrochloric acid,a precipitate forms much more slowly than when sodium hydroxideis used, and the tetra-anhy dr ot etra kisdip henylsilicanediol which isdeposit.ed is impure; the air-dried precipitate melts from about187O t o about 200°, but when recrystallised from ethyl acetate itgives a deposit of pure tetra-anhydrotetrakisdiphenylsilicanediol.The results of t h s action of sodium hydroxide and of hydrogenchloride vary, however, with the conditions of the experiment; if,for example, an alcoholic solution of trianhydrotetrakisdiphenyl-silicanediol is treated with a drop of concentrated hydrochloricacid and left at the ordinary temperature for a day o r two, itdeposits crystals melting a t about 185*, which probably consistof a mixture of trianhydrotris- and tetra-anhydrotetrakis-diphenyl-silicanediol (Kipping, Zoc.cit., p. 2140). This is due, no doubt, tothe fact that the acid causes both hydrolysis and condensation tooccur, just as it was shown to do in the case of dianhydrotrisdi-benzylsilicanediol (Robison and Kipping, Zoc. c i t . ) .Trianhydrotetrakisdiphenylsilicanediol may also be convertedinto the tetra-anhydro-derivative with the aid of heat. The open-chain compound seems to begin to decompose at about 1 3 5 O , butthe action does not become rapid until the temperature has risen toabout 180-190O; a t this stage the escape of bubbles of steam maybe clearly observed, but when the liquid maw has been' heated a t190-200° during about fifteen minutes, decomposition seems tocease.The cooled product is a vitreous solid, which crystallises onthe addition of a little ether, and from which cold alcohol extractsonly a small proportion of soluble matter; the residue meltsindefinitely a t about 185O, but when repeatedly recrystallised froORGANIC DERIVATIVES OF SILICON. PART XXI. 499hot acetone i t gives pure tetra-anhydrotetrakisdiphenylsilicanediol(m. p. 200O).Although it was thus proved that the open-chain is convertedinto the closed-chain compound by the action of heat, the reactiondoes not take place quantitatively ; the crude tetra-anhydro-deriv-ative is mixed with a certain proportion of some substance whichlowers it0 melting point, and which is only removed with dSculty.This other product is in all probability trianhydrotrisdiphenyl-silicanediol, because the mother liquors from the pure tetra-anhydro-derivative yield a residue which separates from cold ethylacetate in large, transparent rhombs, and these crystals have theproperties of the crystalline mixture of trianhydrotris- and tetra-anhydrotetrakis-diphenylsilicanediol previously described (Zoc.cit.,p. 2140). The formation of trianhydrotrisdiphenylsilicanediolcould be easily accounted for on the assumption that some of thetrianhydrotetralusdiphenylsilicanediol is partly hydrolysed todianhydrotriscliphenylsilicanediol and diphenylsilicanediol by thesteam which is liberated durixg the formation of the tetra-anhydro-compound.I'e traanh ydro t e trakisdiph erylsilicanediol.The well-defined, almost rectangular plates in which thiscompound is sometimes deposited from ethyl acetate solution a tthe ordinary temperature were measured.System : anorthic.Sub-class : holohedral.u.: 6 : c =0.5614 : 1 : 0.5770.a=83O56/; P = 103O52/; y=96O44/.Forms observed: tx{lOO}, b{010}, c{OOl}, m{110}, q{O11},${ l5Of.Table of A ngles.Angle. No. Limits. Mean. Calculated010: 110 3 56'23'-57' 16' 56'56' 57'6g110: 100 4 27'13'-27'48' 27'30' 27"25'010:001 5 94'26'-94'53' 94'37' -110: 001 6 80'39'-8 1'57' 81'8' 50'58'120:OOl 12 7 6' 2 9'-7 7 ' 1 8' 76'544' 76'57a - 64' 5' 010: 011 - -110:011 1 65'27' 65'27' -12O:Oll 1 98'31' 98'31' 99'3'100: 120 10 50'32'-50'46' 50'38' -120: 010 6 44"46'-44'59' 44'504' -100:001 11 7 6 ' 3 1'-7 6' 47 ' 76"41' -190: 011 1 74'38' 74'35' 75O9'The crystals are flat, almost square plates, the pinacoid a{100}being predominant, and the forms b{010} and c{OOl} beingdeveloped along the edges of the plates.VOL.cv. L 500 ORGANIC DERIVATIVES OF SILICON. PART XXI.As diphenylsilicone could not be obtained by heating diphenyl-silicanediol, the action of heat on tetra-anhydrotetrakisdiphenyl-silicanediol was studied; it seemed possible that a t a high tempera-ture the last named compound might decompose, yielding diphenyl-silicone, just as paraformaldehyde, for example, gives formaldehyde.I n order to avoid atmospheric oxidation, a small quantity of thepure substance was heated in a bent tube in an atmosphere ofcoal gas; it distilled at a very high temperature, giving a colourlessdistillate, and no appreciable charring took place. The distillatesolidified immediately to a hard mass, which was free from anyappreciable quantity of oily matter, and melted from about180-185O. On crystallisation from ethyl acetate the product wasdeposited in the well-defined, rectangular plates described above,but these melted indefinitely from about 185-190°, and it wasonly after three or four further recrystallisations that pure tetra-anhydro t&r akisdip henylsilicanediol (m. p. 200-20 1 O) was ob-tained. I n spite of this fact, the original product of distillationseemed to consist almost entirely of the one substance. The smallproportion of impurity which was certainly contained in it, andwhich was so difficult to remove, was not definitely identified, butin all probability it consisted of trianhydrotrisdiphenylsilicanediol.The most soluble deposit obtained from the last ethyl acetatemother liquors melted a t about 180--185O, and contained a verysmall proportion of crystals, which did not become opaque whenheated, but melted at 186-188O; this substance was doubtlesstrianhydrotrisdiphenylsilicanediol. It is obvious from these resultsthat diphenylsilicone is not formed in appreciable quantities underthe above conditions.The authors gratefully acknowledge the financial assistance forwhich they are indebted to the Government Grant Committee ofthe Royal Society.UNIVERSITY COLLEGE,NOTTING 11 AM

ISSN:0368-1645    

DOI:10.1039/CT9140500484

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

THE PRO(11IESSlVE BROMINATION OF TOLUENE. 501LI I. - The Progress h e Bromination 0 f To 1 u enc.By JULIUS BEREND COHEN and PAVITRA KUMAB DGTT.THE general rules of substitution in the benzene nucleus have beenarrived a t mainly from the study of the di-substitution products.The formation of tri-derivatives has been examined only in a fewcases. Cohen and Dakin published a series of papers during1901-1904 on the progressive chlorination of toluene. With theobject of discovering some general rule they studied the orienta-tion of the entrant chlorine atom where one or more were alreadypresent in the nucleus.Their results in the case of chlorination of the isomeric mono-chlorotoluenes may be briefly stated as follows (T., 1901, 79, 1111) :The ortho- and para-compounds yield all the possible isomerides,whereas the meta-compound gives only two out of the four, neitherthe 2 : 3- nor the 3 : 5-compound being formed.The only investigation which we have been able to find on thenature and amount of the products of bromination, is one byA.K. Miller (T., 1892, 61, 1023). Ortho- and para-bromotolueneswere brominated by keeping the substances in contact with thecalculated quantity of bromine for several days with the additionof a trace of iodine. Miller found that the ortho-compound givestwo out of four possible dibromotoluenes, and the para-compoundgives both of the possible derivatives. He also obtained a tribromo-toluene melting at 112-113O from the products of bromination ofpbromotoluene, the substance being identical with the 2 : 4 : 5-tri-bromotoluene (m.p. 11 1-2-1 12.8O) obtained indirectly by Nevileand Winther (Bey., 1880, 13, 970).I n comparing these results with’ those of the chlorination oftoluene considerable discrepancies appear, and in considering thisdifference in the orienting effect of the two halogens we thought itdesirable to repeat Miller’s work and extend it along the samelines as previously followed in studying the chlorination of toluene.It was therefore necessary to prepare a t the outset the six iso-meric dibromotoluenes and such of their derivatives as would affordthe best means of identification. The following table gives a listof these derivatives and their melting points. They have beenprepared for the most part in the same way as the derivatives ofthe dichlorotoluenes (T., 1901, 79, 1111), and hence many of thedetails of the processes have been omitted in this paper.F o r com-parison the melting points of the corresponding dichloro-compoundsare subjoined.L L 502 COHEN AND DUTT:M e l t k g Yoiiits of Berivntives of the Dibromotoluenes.Mono-Substance. nitro-.2 : 3 (m. p. 30-31") 58-59"2 : 4 liquid ............. 79-802 : 5 liquid. ............ 87-882 : 6 (m. p. 5.5") .... 49-50*3 : 4 liquid. ............ 86-873 : 5 (m. p. 39") ...... 124Sulphonyl Sulphon- BenzoicDinitro-. chloride. amide. acids.107-109" 93" 214' 149-150"129-130 86-88 212-213 168-169142-143 73-74 210-211 153161-1 62 101 204 146-147129-130 104-105 212 229-230-\ (156-157 104.5-105j \ liquid 195 213-214Jlelting Points of Derivatives of the Dichlorotoluenes.2: 3 ..................50-5-51.5" 71-72" liquid 222' 163"2 : 4 .................. 54-55 104 71 176 159-1602: 5 .................. 50-51 100--101 45-46 191-192 1532 : 6 .................. 53 121-122 liquid 207 139-1403 : 4 .................. 63-64 91.5-92.5 81 190-191 200-2013 : 5 .................. 61-62 99-100 44-45 168-169 182-183* Nevile and Winther (Bey., 1880, 13, 970 ; 1881, 14, 419), from a preparation ofthe 2 : 6-compo1u1d obtained indirectly from nz-toluidine, give 56.8- 57", to whichthey assign the constitution 2 : 6-dibromo-p-nitrotolueiie. We have recently dis-covered a paper by J. J. Elanksma (Chesn. IVcekbZnd., 1912, 9, 968), in which theauthor gives the melting point of the mononitro-compound as 50" and that of thedinitro-derivative 161" (their constitution being 2 : 6-dtbromo-3-niiro- and 2 : 6-dibromo-3 : 5-dinitro-toluenes respectively), rcsults which agree substantially with ours.It will be seen from the above table that in the case of the di-bromotoluenes the melting points of the dinitro-derivatives and thedibromobenzoic acids present the widest range of temperature,whereas those of the sulphonamides are too close together t o be satis-factorily used as a means of identification.The crystalline appear-ance and solubilities of the barium sulphonates have afforded a use-ful method of distinguishing between the 2 : 5-compound, whichforms highly refractive rhombohedra1 prisms, the 3 : 4-compound,which crystallises in thin plates, and the sulphonates of the 2 : 3-and 2 : 4-compounds, which are much more soluble and crystallisein needles. Advantage was also taken of the insolubility of thesulphonic acid of the 3 : 5-compound.On the same principle we have carried our investigation as faras the tribromotoluenes in order to see in what respects the resultsof bromination of the dibromotoluenes differ from those of chlor-ination of the dichlorotoluenes (Cohen and Dakin, T., 1902, 81,1324).Each of the six isomeric dibromotoluenss was brominatedseparately, and the products in each case were examined by com-paring them with the derivatives of the tribromotoluenes preparedfor this purpose.The tribromotoluenes have been obtained syn-thetically by various methods, and their derivatives, such as nitro-THE PROGRESSIVE RROMINATION OF TOLUENE.503dinitro-tribromotoluenes and tribromobenzoic acids, have also beenobtained. The preparation and constitution of all the six isomerictribromotoluenes have been described by Nevile and Winther (Ber.,1880, 13, 974; 1881, 14, 419), but not of their derivatives.The following table gives a list of the melting points of thetribromotoluenes and their derivatives as determined by ourselves :Substance. Mononitro-. Dinitro-. Benzoic acids.2 : 3 : 4 (m. p. 44-45") . . . 107-108"2 : 3 : 5 (m. p. 53-54"] ... { 88.5-990}2 : 3 : 6 (m. p. 5&-59") . . . 91-92 202-203 not oxidisable2 : 4 : 5 (m. p. 112-113") 130-131.5 278-279 195-1962 : 4 : 6 (m.p. 65-66'). . . 74-75.5 21 7-21 8 1%-1873 : 4 : 5 (m. p. 88-S9") . . . 104-105 211-5 2351 97- 1 99" 197-198"209-210 193-194 67-68The methods adopted for separating and identifying the productswill be referred to individually. I n some cases the melting pointsand solubilities of the dinitro-compounds furnish the best means,whereas in others those of the benzoic acids are most suitable,especially in dealing with the diortho-substituted acids, which arenot esterified by Fischer and Speier's method.While engaged in this investigation we also studied the formationof monobromotoluenes from toluene in order to see whether anytrace of the meta-compound was formed in the reaction. It iswell-known that the first action of bromine on toluene gives theortho- and para-compounds in the proportion of about 40 per cent.of the former to 60 per cent.of the latter. No evidence existsas to the presence'of the meta-compound in the final product, whichmay be due to the small quantity present in the mixture.This was found to be the case, a small quantity of m-bromo-toluene being formed with the ortho- and para-compounds.I n continuation of this investigation the chlorination of the mono-bromotoluenes and the bromination of the inonochlorotoluenes arebeing examined.EXPERIMENTAL.For purposes of reference the experimental part has been sub-divided as follows :I. Bromination of toluene.11. (a) Preparation of the six isomeric dibromotoluenes.( b ) Bromination of the isomeric monobromotoluenes.111.( a ) Preparation of the isomeric tribromotoluenes and their( b ) Bromination of the isomeric dibromotoluenes.derivatives504 COHEN AKD DUTT:PART I.-The Bromanation of Toluene.The bromination was effected by dropping 26.5 C.C. of bromineinto 46 grams of freshly distilled and chemically pure toluenecontaining a few pieces of freshly prepared aluminium-mercurycouple (about 0.5 gram), the operation being conducted in thesame way as in the preparation of bromobenzene (Cohen and Dakin,T., 1899, 76, 894). The product, after being washed with sodiumhydroxide solution, was dried over calcium chloride and distilled.The fraction distilling a t 180-190° was collected separately(40 grams). Twenty-five grams of this fraction were oxidised tobromobenzoic acids by heating in sealed tubes with dilute nitricacid (lHNO, : 3H,O) a t 130-135O for six hours.After cooling,the contents of the tubes were treated with sodium hydroxide solu-tion, and the unchanged bromotoluenes removed by shaking withchloroform. The free acids were then liberated by the additionof hydrochlbric acid to the clear alkaline solution, collected, andcrystallised fractionally from. dilute alcohol.After repeated crystallisation, a fraction was obtained meltinga t 135-145O. This was then converted into the acid chloride bymeans of phosphorus pentachloride in the usual way, and themethyl ester prepared by treating the acid chloride with methylalcohol. The mixed methyl esters were then distilled fractionallyunder diminished pressure.From this a portion was obtainedwhich solidified in the condenser tube, and also in the receiver aftercooling. The solid portions on crystallising twice from dilutealcohol gave 0.3 gram of ester melting a t 29'31O. The meltingpoint of the methyl ester of the metabromobenzoic acid is 31-32O.The only other ester which melts very near t o this is the 2:4-di-bromo-derivative melting a t 33O. I n order to confirm the presenceof m-bromobenzoic acid, 0.2 gram of the ester was hydrolysed withalcoholic potassium hydroxide, and the acid liberated by means ofhydrochloric acid. After crystallising t'wice from hot water, i tmelted a t 155-156O, and thus the presence of m-bromotoluene 'inthe original product was confirmed.The 2 : 4-dibromobenzoic acidmelts at 168-169O.PART 11.-(a). Preparation of the Six Isomeric Dibrortiotoluenes.The 2 : 3-, 2 : 4-, and 2 : 5-dibromotoluenes were prepared fromthe corresponding nitrotoluidines (Cohen and Zortman, T., 1906,89, 49). The 2 : 3-compound was also obtained by Wyiine's methodfrom o-toluidinesulphonic acid, which gave a better yield than thatfrom the nitrotoluidine (T., 1892, 61, 1040), and from 6-bromo-o-toluidins by the method described or1 p. 514. The 2 : 4-compounTHE PROGRESSIVE BROMINATION OF TOLUENE. 505was also obtained by brorninating pnitrotoluene in the presenceof iron (Scheufelen, AnnaZen, 1903, 231, 171), and then reducingthe 2-bromo-4-nitrotoluene (m. p 76-77O) formed in the reaction,and finally replacing the amino-group by bromine.The 2 : 5-corn-pound was also obtained from both m-acetotoluidide and o-aceto-toluidide by bromination, and then replacing the amino-group bybromine.The 3 : 4-compound was obtained from the corresponding nitro-toluidine and also from pacetotoluidide by bromination.The 3 : 5-compound was prepared by removing the amino-groupfrom 3 : 5-dibromo-ptoluidia e by diazotising in alcoholic solution,the latter substance being obtained by brominating pacetotoluidideor ptoluidine itself,The 2 : 6-compound was prepared from 2 : 6-dinitrotoluene byalternate reduction and diazotisation. The conversion of 6-bromo-o-toluidine into dibromotoluene cannot be effected satisfactorilyin the ordinary way; if diazotisation is carried out in hydrobromicacid, the diazoamino-compound is produced, and a very little of thedibromotoluene ; if in presence of hydrochloric acid and subsequenttreatment with cuprous bromide in hydrobromic acid, a mixtureof chlorobromo- and dibromo-toluene is produced.The method finally adopted was as follows: Seventeen gramsof 6-bromo-o-toluidine were dissolved in 100 C.C.of absolute alcohol,to which were added 60 C.C. of hydrobromic acid. Twelve C.C. ofamyl nitrite were then slowly run in keeping the temperature below20°. The mass became almost solid, and was filtered and washedwith alcohol. It was then dissolved in hydrobromic acid and cooledto Oo, and the mixture left in ice for an hour. It was then distilledin steam, the distillate extracted with chloroform, dehydrated overanhydrous sodium sulphate, the chloroform distilled off, and theresidue distilled under diminished pressure from a paraffin-bath.The major portion (12 grams) was collected a t 122O/23 mm.as acolourless liquid (m. p. 5-6O).Before this method was finally adopted, two others given belowwere tried, but these were found to be tedious and inconvenient,and, in addition, gave very poor yields:1. From 2 : 6-dibromo-4-nitro-m-toluidine (Nevile and Winther,Ber., 1880, 13, 974); which again was prepared from m-aceto-toluidide, as described under 2 : 3 : 6-tribromotoluene (see later).2. From 2-bromo-4-nitrotoluene, by bromination in presence ofiron (Scheufelen, An.naZen, 1903, 231, 178).By this method aportion only of the bromonitrotoluene is converted into the 2 : 6-di-bromo-compound when heated in sealed tubes, and the separation oft h e two constituents is very difficult506 COHEN AND DUTT:PART 11.-(b). Z'he Bromiization of the Isomeric Mono bromo-toluenes : Bromination of o-Brontotoluene.The process was carried out in the following way, and was appliedwithout modification t o the other bromotoluenes.Fifty-two grams of o-bromotoluene were dissolved in an equalweight of carbon tetrachloride in a flask provided with a refluxcondenser, and 0.5 gram of aluminium-mercury couple was added.The liquid was cooled in ice, and 12 C.C. of bromine in an equalvolume of carbon tetrachloride were slowly dropped in from atap-funnel attached to the upper end of the reflux condenser.Substitution takes place rapidly; after some time the product waspoured into water, shaken with sodium hydroxide solution, de-hydrated and distilled under diminished pressure.Thirtysevengrams, boiling a t 130--133O/15 mm., were obtained, about 10 gramsof a fraction of lower boiling point, consisting chiefly of unchangedproduct, and about 1 gram boiling above 133O. The process wasrepeated several times with about the same quantity of materialand with similar results.Sulphonation of the Mixed Dibromotoluenes.Thirty-three grams of the above product were mixed with 64grams of fuming sulphuric acid, shaken, and then heated on thewater-bath, until a test sample dissolved completely in water; Aftercooling, the liquid was poured into water and boiled with excessof barium carbonate, filtered, and the residue extracted repeatedlywith boiling water, until no more dissolved.On cooling 37 gramsof the barium sulphonate crystallised, having the appearance oflarge, highly refractive, rhombohedra1 plates, characteristic of the2 : 5-compound. The mother liquors were concentrated to a smallbulk, and deposited 1.5 grams of needles. Both fractions weretreated se,parately with phosphorus pentachloride and subsequentlywith ammonium carbonate, to convert the sulphonyl chloride intothe sulphonamide, and the product crystallised from alcohol. Theless soluble salt crystallising .in plates gave a sulphonamide meltinga t 207O (2 : 5 =210--311°), and the sulphonamide obtained from themore soluble salt, crystallising in needles after three recrystallisa-tions, melted a t 209O (2 :4 =212O).Although, as stated above, themelting points of the sulphonamides afford no definite indicationof the isomerides present in a mixture, the characteristic appar-ance of the barium salt of the 2 : 5-compound distinguishes it quitesharply from the other three isomerides. The results of nitrationand oxidation leave no doubt that the other barium salt is thaTHE PROGRESSIVE BROMINATlON OF TOLUENE. 507of the 2 : 4-compound. The result confirms Miller’s observationthat the main product of bromination of the ortho-compound isthe 2 : 5-derivative.Nitration of the Mixed Dibrornotolaenes.The mixed dibromotoluenes were converted into the dinitro-compounds by heating with fuming nitric acid and concentratedsulphuric acid on the water-bath, pouring into water, and fraction-ally crystallising the product.After repeated crystallisation from alcohol, the substance wasseparated into two fractions, a large fraction crystallising in fineneedles and melting a t 142-143O (2:5=142--143O), and a smallfraction crystallising in prisms with pointed ends characteristic ofthe 2 : 4-compound and melting a t 124-126O (2 : 4=129-130O).The result is in entire agreement with that derived from sulphon-ation. The 2 : 4-compound formed a small proportion of the mixtureand was not quite pure.Very careful examination was made forthe 2 : 6-dinitro-compound, which has a much higher melting pointthan any of the other isomerides, but wibhout result.Oxidation of the Mixed Dibromotoluenes.An attempt was made to repeat Miller’s method of oxidationby boiling the dibromotoluenes with dilute nitric acid a t theordinary pressure, but although the process was repeated withdifferent preparations and different strengths of acids and con-tinued f o r a week a t a time, scarcely any acid was formed, and weare unable to explain Miller’s result.Ullmann’s permanganatemethod was also tried ineffectually. The oxidation was then carriedout in sealed tubes a t 130° with dilute nitric acid (lHNO, : 3H20).Fifteen grams were taken, and a t the end of three hours thematerial was completely oxidised. The solid product was dissolvedin sodium hydroxide solution, shaken with ether to remove impuri-ties, and the acid precipitated with hydrochloric acid.It was thenesterified by Fischer and Speier’s method in the hope of separatingany 2 : 6-compound which would remain unesterified. The amountleft unchanged was, however, so small as to be scarcely weighable,and the absence of the 2 :6-compound confirmed.I n a second oxidation, the mixed acids were separated by frac-tional crystallisation of the barium salts. The acid obtained fromthe main fraction crystallised from alcohol in silky needles meltinga t 150°, which is very nearly the melting point of the 2 : 5-acid. Avery small quantity of the 2:4-acid was also separated, melting,although not sharply, a t 169O508 COHEK AND DUTT:Bromination of m-Brornotol~uene.The meta-compound was brominated in the same manner as theortho-compound.Ten grams of m-bromotoluene gave 11.5 grams,boiling at 139-142O/ 36 mm., which was practically the whole ofthe product. I n a second preparation a small quantity of residuesolidified, and was identified as 2 : 4 : 5-tribromotoluene.Sulphonntion of the Mixed Dibromotoluenes.The sulphonation was carried out as described in the foregoingsection, and the barium salts were extracted with water. Thebarium salt was separated by crystallisation into four fractions.From the first fraction after repeated crystallisation a smallportion was obtained, which, on treatment with phosphorus penta-chloride, gave a sulphonyl chloride melting a t 98-101° (3 : 4, m.p.104-105°), which on being converted into the amide melted a t 2 1 2 O .It was' evidently the 3:4-denvative, and formed only a smallproportion of the whole mixture. The last fraction was treated inthe same way, and gave a sulphonyl chloride melting a t 73-74Oand amide melting at 210-211O. This was evidently the 2 : 5-com-pound. The intermediate fractions were less pure, and were notfully examined. The crystalline appearance of the barium salts inthe last three fractions was also characteristic of the 2 : 5-compound.No indication was obtained of the presence of the 2 : 3-compound.I n order to test for the presence of any trace of the 3 : 5-compound,about 3 grams of the mixed dibromotoluenes were heated on thewater-bath for fifteen minutes with about an equal weight of weaklyfuming sulphuric acid, and then poured into water.A little whiteprecipitate settled on keeping, which was found to be insolublein boiling water, characteristic of the 3 : 5-compound. The residuewas then heated on platinum foil to test for any mineral matter,which was found to be absent, but it burned with a smoky flameand disappeared. From this we infer the presence of a trace of the3 : 5-compound in the bromination product.Nitration of the Mixed Dibromotoluenes.From10 grams of the mixed dibromotoluenes 12 grams of crude nitro-compounds were obtained, which, after several recrystallisationsfrom benzene and light petroleum, gave 3 grams of nearly puredinitro-compound of 2 : 5-dibromotoluene melting at 140-1 42O.The mother liquor on evaporation gave a solid residue of indefinitemelting point, and was therefore re-nitrated and treated in theThe nitration was effected in the same way as beforeTHE PROGRESSIVE BROMINATION OF TOLUENE. 509same way a,s above.I n this way 1 gram of the 2 : 5-compound wasobtained, and the rest of the material consisted of an oily mass,from which a solid separated on keeping, melting completely, butnot sharply, at 123O, and no definite substance could be isolatedfrom it.Oxidation. of the Mixed Dibromotoluen.es.The material was oxidised in sealed tubes a t 13O0, as previouslydescribed in the cme of the products from o-bromotoluene, and gavea product melting indefinitely from 125O to 150O. After repeatedcrystanisation, a pure acid crystallising in needles melting a t 231Owas obtained, which is that of the 3:4-compound.The motherliquors yielded an acid melting at 146-148O, which is the impure2:5-acid, melting at 153O, and formed the main bulk of theproduct. The 3:5-acid was present in too small a quantity to bedetected by this method.These results furnish evidence of the presence of 2:5- as themain product, the 3 : 4-, and- a trace of the 3 : 5-derivatives out of thefour possible isomerides, a result which agrees substantially withthat obtained on chlorination.Brominntion of p-Bromotoluene.I n brominating p-bromotoluene, 20 grams of the substance weretaken, and yielded 13 grams of dibromotoluenes boiling a t135--145O/36 mm.A small quantity of residue solidified, and aftercrystallisation melted a t 1 1 2 O , and was 2 : 4 : 5-tribromotoluene.Only two isomerides can be formed from pbromotoluene, namely,the 2:4- and 3:4-compounds, but as the melting points of t$edinitro-compounds and sulphonamides lie too near together to offera satisfwtory means of identification, recourse was had to oxidationand the formation of the dibromobenzoic acids.Oxidation of t h e Mixed Dibromotolzcenes.The oxidation was performed as previously described, and theproduct was dissolved in a solution of sodium carbonate, and shakenwith ether to remove a small quantity of an oily substance. Theacids were liberated, and converted into the barium salts and frac-tionated. I n this way two fractions were separated.From the lesssoluble portion hydrochloric acid precipitated an acid, whichcrystallised from dilute alcohol in needles, and melted a t 228O(3 : 4-acid). The mother liquor after evaporation to a small bulkwas fractionally precipitated by hydrochloric acid. The lastfraction gave an acid melting a t about 158O, which, after crystal-lisation, melted a t 166-168O (the 2 :4-acid melfs a t 169O), andformed the main bulk of the product510 COHEN AND DUTT:PART 111.-(a) Preparation of the Zsomeric TribromotoluenesI n describing the preparations in this section, the main outlinesof the processes have been indicated, but no details of experimentshave been givqn.2 : 3 : 4-Tribrornotoluei~e,and their Derivatives.The starting point f o r the preparation of this substance was3-bromo-pacetotoluidide, which by nitrating in a, mixture offuming nitric acid and glacial acetic acid a t 5O gave 3-bromo-5-nitro-pacetotoluidide (m. p.2 loo). This substance on boiling withdilute sulphuric acid (equal parts of acid and water) on a sand-bath was hydrolysed to the free base (m. p, 64-65O). The amino-group was then replaced by bromine in the following way:The base was dissolved in glacial acetic acid, the calculatedquantity of concentrated hydrochloric acid added, and diazotisedwith sodium nitrite. The, whole of the substance passed intosolution, which was added to the solution of cuprous bromide inhydrobromic acid. The mixture was then warmed on the water-bath until the evolution of nitrogen ceslsed, and steam passed infor a few minutes.The brown liquid which separated solidified,on cooling, to a crystalline mass, which was then collected, andafter one crystallisation from alcohol was pure. The yield wasalmost theoretical (m. p. 63-65O).The nitro-group was then reduced with iron and acetic acid, andthe baae separated by steam distillation (m. p. 58-59O). I n someexperiments tin and hydrochloric acid were used to reduce thenitro-group, but the yield was very poor. The base was thenconverted into the acetyl compound (m. p. 163*5--164O), which on%rominating in acetic acid gave 2 : 3 : 4-tribromo-rn-acetotoluidide.The bromination takes place slowly, and the mixture must beallowed t o stand before the bromine is completely absorbed.An attempt was made to brominate the free base, either inacetic or hydrochloric acid, but the product obtained was in eachcase 2 : 3 : 4 : 6-tetrabromo-m-toluidine (m.p. 223-224O).2 : 3 : 4-Tribromo-m-toluidine was obtained by hydrolysing theacetyl compound with boiling dilute sulphuric acid (equal volumesof concentrated acid and water). The product was poured intowater, and the solution made alkaline and extracted with ether,which leaves behind any unchanged acetyl compound. Theamino-group was then replaced by hydrogen in the followingway, as the ordinary method gives a very poor yield. The sub-stance was dissolved in ten times its weight of absolute alcohol,and a quantity of concentrated sulphuric acid (about twice thTHE PROGRESSIVE BROMINATION OF TOLUENE.511weight of the base) was added. The sulphate of the baseseparated in finely divided condition. The mixture waa then cooledto about 40°, and a quantity of amyl nitrite slightly in excma ofthe calculated amount was then added. On heating, nitrogen wasevolved, and a clear solution obtained. The product was pouredinto water, when the tribromotoluene solidified, and was collected,dried, and crystallised from glacial acetic acid (m. p. 45-46O). Theyield was theoretical.2 : 3 : 4-Tribrornouvltrotolue?ze.Ten C.C. of fuming nitric acid were placed in a small flask cooledin ice-water. About 5 grams of the tribromotoluene were thengradually dropped in, and the flask was occasionally shaken. Afterhalf-an-hour the product was poured into cold water.The solidnitro-compound was collected, washed with water, and crystallisedfrom alcohol (m. p. 107-108°) :0*1210 gave 0.1808 AgBr. Br = 63.58.CE7H,0,NBr, requires Br= 64.14 per cent.2 : 3 : 4-Tribromodinitrotoluelze was prepared by heating the sub-stance with an equal amount of fuming nitric acid and concentratedsulphuric acid on the water-bath for about an hour, after which theproduct was poured into water, collected and crystallised fromalcohol, from which it separated in prisms melting a t 197-199O.2 : 3 : 4Tribromobenaoic 4 cid.-This was prepared by oxidisingthe tribromotoluene with dilute nitric acid (1 to 4), by heating insealed tubes a t 150-160° for about six hours. The product wasmade alkaline with sodium hydroxide solution, and the unchangedtribromotoluene extracted with chloroform.The free acid wasthen liberated by adding hydrochloric acid to the clear alkalinesolution. The acid was collected, purified by boiling with animalcharcoal in alcoholic solution, and finally crystallised from benzene.It forms colourless needles melting a t 197-198O :0.1246 gave 0.1962 AgBr. Br = 67-00.C7H302Br3 requires Br = 66.85 per cent,2 : 3 : 5-Tm'bromotoluene.1. o-Acetotoluidide, on bromination in acetic acid solution, gave5-bromo-o-acetotoluidide (m. p. 156-157O). An attempt was madeto brominate it further by keeping the substances together over-night, but no action took place. This is probably a case of sterichindrance.The bromotoluidine (m. p.58-59O) was then made the startingpoint, and was prepared by hydrolysing the above acetyl compound512 CoHEN AND DUTl:It was also obtained by direct bromination of o-toluidine, but theyield was poor. The base, on bromination in acetic acid solution,gave 3 : 5-dibromo-o-toluidine (m. p. 45-46O). The amino-groupwas then replaced by bromine by Sandmeyer's reaction, and the2 : 3 : 5-dibromotoluene, thus obtained, melted a t 53-54O.2. I n a second method, the starting point was 5-nitro-o-toluidine,which was formed along with the 2:3-compound in the nitrationof o-acetotoluidide (Reverdin and CrBpieux, Ber., 1900, 33, 2498).It was brominated in acetic acid (Cohen and Raper, T., 1904, 85,1269), and the 3-bromo-5-nitro-o-toluidine, when crystallised fromglacial acetic acid, melted a t 180-181°.The amino-group wasthen replaced by bromine, and the 2 : 3-dibromo-5-nitrotoluene(m. p. 104-105°) was reduced t o 2:3-dibromo-m-toluidine (m. p.83-85O), by means of tin and hydrochloric acid. On replacingthe amino-group by bromine, 2 : 3 : 5-tribromotoluene was obtained,melting a t 53-54O.2 : 3 : 5-Tr'ribromonitrotoluene.Five grams of the tribromotoluene were treated with aboutdouble the amount of fuming nitric acid in the cold. The substancedissolved in a few minutes, and was then poured out into ice-coldwater. After repeated crystallisation from alcohol, both thepossible isomerides were separated, one melting a t 67-68O, and theother a t 88.5-90°, the former being obtained in greater quantity.The constitution of these has not yet been determined:0.0866 (m.p. 67-68O) gave 0.1302 AgBr.0-1390 (m. p. 88*5-90°) gave 0.2090 AgBr.C,H40,NBr3 requires Br = 64.14 per cent.2 : 3 : 5-Tribromodinitrotoluene.-The tribromotoluene was heatedon the water-bath with fuming nitric acid and concentrated sul-phuric acid for an hour, and afterwards poured into water. Oncrystallising several times from glacial acetic acid, the nitro-com-pound was obtained quite pure, and melted a t 209-210°:Br=63*96.Br=63*98.0-2156 gave 0'2904 AgBr. Br=57*31.2 : 3 : 5-Tribromobenzoic acid was prepared by two methods :1. By oxidising the tribromotoluene with dilute nitric acid (1 to3) in sealed tubes a t 135-140° for six hours. The contents of thetube were then dissolved in sodium hydroxide solution, the un-changed tribromotoluene was removed by steam distillation, andthe free acid liberated by means of hydrochloric acid. The acidobtained in this way was coloured slightly yellow, and was de-C,H304N,Br3 requires Br = 57-28 per centTHE PROGRESSIVE BROM LNATION OF TOLUENE. 513colorised by digesting the alcoholic solution with animal charcoal.It crystallised in colourless needles melting a t 193-194O.2.The starting point was anthranilic acid, which, on brominatingin acetic acid solution, gave 3 : 5-dibromo-2-sminobenzoic acid(m. p. 225O). The amino-group was then replaced by bromine(Rosanoff and Prager, J. Amer. Chem. SOC., 1908, 30, 1902).These authors obtained it as yellow needles melting a t 193*5O, buton purifying it in the same way as described above, we obtained itin colourless needles melting a t 193-194O.2 : 3 : 6-Tribromotoluene.1.2-Bromo-5-acetotoluidide was nitrated in the cold ( 5 O ) withfuming nitric acid and glacial acetic acid. Two nitro-compoundswere formed in this way as pointed out by Nevile and Winther(Ber., 1880, 13, 971), who used concentrated sulphuric acid insteadof acetic acid. The crude nitration product, after crystallising onc0from alcohol, melted a t 115-124O, and after repeated crystallisationfrom alcohol, melted sharply a t 125-125-5O. It is 2-bromo-$-nitro-5-acetotoluidide, and forms the main product in the reaction.Another nitro-compound remaining in the mother liquor was pre-cipitated on adding water, and melted indefiniteIy from 90° to l l O o ,and after removing the acetyl group and crystallising several timesfrom alcohol, the product melted at 102-103O.The constitutionof this base was determined in the following way : the amino-groupwas replaced by bromine, and the dibromonitro-compound thusobtained (yellow crystals, m. p. 78-80°) was reduced by meansof tin and hydrochloric acid. The base separated from alcohol incolourless crystals melting a t 5 6-5 7O. Finally the amino-groupwas replaced by bromine, and the tribromotoluene thus obtainedmelted a t 55-57O, and is, therefore, the 2 : 3 : 6-compound, whichmelts at 58-59O. The original substance is, therefore, 6-bromo-2-nitr o-m-toluidine.The 2 : 4 : 5-compound mentioned above was then hydrolysed witiidilute sulphuric acid (equal vols.) on the water-bath, and the baseprecipitated by adding water.On crystallisation from alcohol, thelatter was obtained in reddish-brown needles melting a t 179-181O.It was then brominated in acetic acid solution on the water-bath.The 2 : 6-dibromo-4-nitro-m-toluidine formed in the reaction wascrystallised from glacial acetic acid and alcohol (yellow needles,m. p. 130-133O). The yield was theoretical. Nevile and Win-tlier's method of brominating in sulphuric acid solution with anaqueous solution of bromine was also tried, but it was not sosatisfactory as the one described above514 COHEN AND DUTT:It was observed in this connexion that the crystals first separatingfrom the hot solution were bulky needles, which filled the liquid,but on keeping overnight the mass was transformed into prisms,which deposited a t the botom of the vessel.ThO amino-group wasthen replaced by bromine, and the 2 : 3 : 6-tribromo-4-nitrotoluenecrystallised from acetic acid (m. p. 106.5-107°). The nitregroupwas reduced by means of iron and acetic acid, and the base crystal-lised from alcohol (m. p. 118-119°). The amino-group was thenremoved by diazotising in alcoholic solution, and the tribromo-toluene crystallised from alcohol in colourless needles melting a t2. I n the following method the starting point was 6-bromo-o-toluidine (see above), and gave a better yield. It w a converted intothe acetyl compound, which crystallised from alcohol in colourlessneedles melting at 159*5-161°.One atom of bromine was thenintroduced into it, and the product crystallised from alcohol incolourless needles melting a t 165-5-166.5O. The substance was5 : 6-dibromoaceto-o-toluidide. I& constitution was determined byremoving the amino-group and distilling the product underdiminished pressure. It crystallised on cooling, melted a t 29-30°,and gave a dinitro-compound melting at 106-107°, and is therefore2 : 3-dibromotoluene. As the yields throughout are quite satisfac-tory, this furnishes a useful method for preparing 2 : 3-dibromo-toluene.The acetyl group was removed by boiling with concentratedhydrochloric acid, and the base melted a t 58O. On replacing theamino-group by bromine the tribromotoluene crystallised fromalcohol in needles melting at 58-59O.2 : 3 : 6-Tm'bromonitrotoluene was obtained in the same way asthe .2 : 3 : 5-com~ound, and crystallised from alcohol in light, straw-coloured needles, melting at 91-92O.2 : 3 : 6-Tribromodinitrotoluene was prepared in the same way asthe 2 : 3 : 5-compound, and crystallised from alcohol and acetic acidin light yellow prisms, melting a t 202-203O.2 : 3 : 6-Tribromobenzoic acid could not be prepared by directoxidation.The tribromotoluene was heated in sealed tubes withdilute nitric acid for several days together, first a t 140--145O, andthen at 150-160°, but not a trace of acid was formed. On raisingtho temperature above 170° the substance ww completely destroyed.Different strengths of acid were also used, and the heating wascontinued for about two weeks a t a time, but without any result.Other oxidising agents, for example, chromic acid and potassiumpermanganate, were also tried ineffectually. It is curious that the2 : 4 : 6-tribromo-compound, which is also a diortho-substituted deriv-5 8-5 goTHE PROGRESSIVE BROMINATlON OF TOLUENE.515ative, is easily attacked by nitric acid, whilst the 2 : 3 : 6-compoundis not.2 : 4 : 5-Tribromotoluene.1. From 3-Bromo-p-toZuidine.-The substance was nitrated withconcentrated nitric acid in the presence of concentrated sulphuricacid in the cold, that is, by adding the dry nitrate of the base to-cold concentrated sulphuric acid (Cohen and Dakin, T., 1902, 81,1334).The 5-bromc~2-nitro-ptoluidine crystallised from alcohol inbrown needles, and melted sharply a t 118y1190. The amino-groupwas replaced by bromine, and the product crystallised from alcohol(m. p. 83.5-84.5O). The nitro-group was then reduced by meansof tin and hydrochloric acid, and the base crystallised from alcoholin colourless needles melting at 96-97O. On replacing the amino-group by bromine, 2 : 4 : 5-tribromotoluene (m. p. 112-113O) wasobtained in colourless needles from alcohol.2. Prom 2-Bromo-5-acetotoluididJe, m. p. 101-102°.-Thesubstance was brominated in acetic acid solution, and the 2 : 4di-bromo-5-acetotoluidide (m. p. 168-169O) that was formed wasprecipitated by the addition of water. The acetyl group wasremoved by boiling with concentrated hydrochloric acid, and theamino-group replaced by bromine.The tribromotoluene crystallisedfrom alcohol in colourless needles melting at 112-113O.2 : 4 : 5-Tribromonitrotoluene was prepared in the same way asthe 2 : 3 : 5-derivative. Only one mononitro-compound could beisolated, and this separated from alcohol and acetic acid in colour-less crystals melting at 130-131*5°.2 : 4 : 5-Tribromo&nitrotoZuelze.-This separates from alcohol andglacial acetic acid in colourless crystals melting at 278-279O.2 : 4 : 5-Tribromobenzoic acid was obtained by oxidising thetribromotduene with dilute nitric acid in a sealed tube; it crystal-lises from benzene in colourless needles melting a t 195-196O:0-1278 gave 0.2020 AgBr. Br = 67-24.C,H,O,Br, requires Br = 66.85 per cent.2 : 4 : 6-TribromotoZuene.m-Toluidine was brominated in acetic acid solution with thequantity of bromine calculated to fom tribromotoluidine. Theproduct when crystallised from alcohol melted at 1OO-l0lo.Theamino-group was then removed by diazotising in alcoholic solution.The tribromotduene crystallised from alcohol in colourless needlesmelting at 65-66O.2 : 4 : 6-TribromonitrotoZuene forms colourless crystals melting at74-75-50 :VOL. cv. M 516 COHEN AND DUTT:0.1360 gave 0.2044 AgBr.2 : 4 : 6-Tribromodinitrotoluene separatw from alcohol in colour-less crystals melting a t 217-218O.2 :4 : 6-T?ibromobemzoic acid formed colourless crystals fromalcohol, melting a t 186-187O. This is identical with the acid(m.p. 186G) obtained by Rosanoff and Prager (Loc. cit.) fromtribromoaniline.3 : 4 : 5-Tribromotoluene.From 3-Bromo-p-toZuidine.-This substance on bromination gave3 : 5-dibromo-ptoluidine (m. p. 74-75O), which, on replacing theamino-group by bromine, gave 3 : 4 : 5-tribromotoluene (colourlessneedles from alcohol, m. p. 88-89O). It was subsequently foundthat ptduidine itself could be directly brominated to form thedibromo-compound with equally satisfactory results.3 : 4 : 5-Tribromonitrotoluene separates from alcohol in colourlesscrystals melting a t 104--105O.3 : 4 : 5-Tribromodinitrotoluene forms colourless priems, meltinga t 211-5O.3 : 4 : 5-Tm'bromobenzoic acid crystallises from benzene in colour-less needles melting at 235O.Br = 63.94.C,H,0,NBr3 requires Br = 64.14 per cent.PART 11.-(b).The Brominatiolt of the Six IsomericDi b ro m o t oluelt e s.Bromdnation of 2 : 3-Dibromotoluene.-Ten grams of the dibromo-toluene were dissolved in an equal volume of carbon tetrachloride,*about 0.5 gram of f reshly-prepared aluminium-mercury couple wasadded, and 2.2 C.C. of bromine dissolved in 5 C.C. of the same solventwere then gradually dropped in. Reaction took place very readily,and was prevented from becoming too violent by carefully coolingthe vessel. I n the end a voluminous dark mass was obtained.Water was added to the product, and the mass extracted withcarbon tetrachloride, shaken with sodium hydroxide solution, andthen separated. The carbon tetrachloride was then distilled offon the water-bath, the last traces being removed by aspirating acurrent of air through the hot residue, which was afterwards dis-tilled under diminished pressure.The yield was 9.2 grams boilinga t 190-200°/60 mm.After one crystallisation from alcohol, a major fraction (6 grams)was obtained, melting a t 56-58O (A). The mother liquor, onevaporation, gave a product melting indefinitely from 40° to* In one exporiment no solvent was used and tho product consisted mostly oftetrabromotoluenes together with a little of the tribromo-compoundsTHE PROQRESSIVE BROMINATION OF TOLUENE. 5174 6 O ( B ) . The product ( A ) was convered into the dinitro-com-pound which, after crystallising twice from alcohol, melted sharplya t 202-203O, and is, therefore, the 2 : 3 : 6-compound.The fraction (B) was also converted into the dinitro-compound,from which a product was obtained which melted a t 206-208';the 2 : 3 : 5-tribromodinitrotoluene melts a t 209-210°.The pres-ence of the 2 : 3 : 5-compound was further confirmed by the mys-talline appearance of the dinitro-compound ; the dinitro-derivativeof the 2 : 3 : 5-compound crystallises in plates, whilst that of the2 : 3 : 6-compound crystallises in prisms.From the mother liquors of the nitro-compounds of both ( A ) and(B), me have not yet been able to isolate the dinitro-compound of2 : 3 : 4-tribromotoluene (m. p. 197-199O), which, if formed a t all,seems very difficult to detect in this way.The product from a second bromination was heated in a sealedtube with dilute nitric acid in order to prepare the benzoic acids,but without any results.This is a further confirmation of thepresence of the 2 : 3 : 6-compound as the main product, for, as pre-viously stated, this substance is not attacked by nitric acid.It will thus be seen that the result of bromination of 2:3-di-bromotoluene is quite different from that of chlorination of di-chlorotoluene. In the latter case the 2 : 3 :4-compound is the soleproduct, whereas in the former, it is the 2 : 3 : 6-derivative thatforms the main bulk of the proETuct, together with a little of the2 : 3 : 5-derivative, whilst the presence of the 2 : 3 : 4-compound isdoubtful.Bromination of 2 : 4-Dibromotoluene.I n this case, the bromination was effected without the use of asolvent.* The product was dissolved in chloroform, shaken withsodium hydroxide solution, and separated.The chloroform wasthen distilled off, and the residue crystallised from alcohol. I nthis way, 8 grams of a substance were obtained which melted a t109--ill*; the weight of material originally taken being 10 grams.The mother liquor, on evaporation, gave 3.5 grams of a voluminous,pasty mass, which consisted of the unchanged dibromotoluene,mixed with some of the tribromo-compounds.The fraction melting a t 109-11lo was converted into the dinitrGcompound, which, after crystallising from alcohol and acetic acid,melted a t 278-279O ; the 2 : 4 : 5-tribromodinitrotoluene melts atThe second fraction wm similarly converted into the dinitro-compound, from which one fraction melting a t 276-278O (2 : 4 : 5)278-279'.* I n a second experiment, carbon tetrachloride was nsed as solvent and gave thesame result.M M 518 COHEN AND DU":was separated; another fraction melted at 212-215O (probably the2 : 4 : 6-tribro8modinitrotoluene, which melts at 217-218O) ; and twoother portions melted a t 189-193O and 195-205O, but the quanti-ties of these last two fractions were so small that it was hopelessto detect in this way any trace of the 2:3:4-derivative, which isthe third possible isomeride.The product of bromination of the dibromotoluene was thenoxidised by heating in a sealed tube with dilute nitric acid (1 to 3)a t 160° for two days, and the benzoic acids were separated in theusual way.The mixed acids were aterified by Fischer and Speier'smethod, when a small quantity was left unesterified, and was identi-fied as the 2 : 4 : 6-acid. The esterified portion was then hydrolysedwith alcoholic potassium hydroxide. On liberating the free acidand crystallising it from alcohol, it melted a t 192-194O. The2 : 4 : 5-acid melts at 195-196O.Thus the results of bromination of 2 : 4-dibromotoluene agreesubstantially with those obtained in the case of chlorination.Bromination of 2 : 5-Dibromotoluene.Ten grams of material were brominated, using carbon tetmchloride as solvent. In a second experiment the solvent wasomitted, but the product consisted of a mixture of tri-, tetra-, andpent a-b r omot oluenes .The bromination product was treated in the same way as thatfrom 2:3-dibromckoluene.The yield was 11 grams, the substancemelting indefinitely a t 70-looo and boiling at 155--165O/20 mm.A portion was converted into the dinitrecompound, and wascrystallised several times from alcohol and acetic acid. The mainbulk of the product was a substance melting a t 276-278O, identicalwith the dinitro-compound of 2 : 4 : 5-tribromotoluene. Afterrepeated crystallisations another product was obtained, whichmelted a t 200-202° and crystallised in prisms characteristic ofthe 2 : 3 : 6-derivative. No evidence was obtained of the presenceof the third possible isomeride, the 2 : 3 : 5-compound.The oxidation of the bromination product has also been carriedout, but no definite evidence was obtained of the presence of the2:3:5-acid, as it has about the same melting point as the2 : 4 : 5-acid.It will thus be seen that these results agree with those obtainedon chlorination in so far as the same two isomerides are formed,but the proportion is reversed.I n the case of chlorination the2:3:6-compound is the main product, whilst in the present caseit is the 2 : 4 : 5-compoundTHE PKOGRESSIVE BROMINATION OF TOLUENE. 519Bromination of 2 : 6-Dibromotolzterce.The bromination wm effected in the same way as in the case of2 : 4-dibromotoluene. The product was crystallised from alcohol,and melted sharply at 59O. It was then converted into the dinitro-derivative in the usual way. After several crystallisations fromalcohol it melted at 202-203O, which corresponds with the2 : 3 : 6-compound.The mother liquor left after crystallising the brominationproduct was evaporated, and from it a product was obtained whichwas a mixture of the unchanged dibromotoluene and a little ofthe 2 : 3 : 6-compound.2 : 6-Dibromotoluene can only give two tribromo-derivatives, the2:3:6- and 2:4:6-compounds, and of these only one, the former,is produced in ths above reaction.No indication of the presence ofthe 2 : 4 : 6-tribromodinitro-compound (m. p. 217-218O) could bedetected on nitration. The remit is thus in entire agreement withthat of the chlorination of 2 : 6-dichlorotoluene.Brominatiorc of 3 : 4Dibromotoluene.This was brominated exactly in the same way as the previoussubstance. The product, after one crystallisation from alcohol,gave 8 grams of a substance (m.p. 110-112°) from 10 grams ofmaterial originally taken. It was converted into the dinitro-com-pound, which after one crystallisation melted sharply at 278-279O,and was identical with the 2 : 4 : 5-tribromodinitrotoluene. No otherdinitrecompound could be detected in this fraction.The mother liquor on evaporation yielded 3 grams of a viscid oil,which was probably a mixture of the original unchanged substanceand a little of the tribromo-compound. This was also convertedinto the dinitrecompound, from which only one substance (m. p.207-209O) could be isolated after repeated crystallisation. It isthe dinitro-compound of 3 : 4 : 5-tribromotoluene (m.p. 211.5O).This was further confirmed by its crystalline appearance, whichis that of truncated prisms. No trace of the 2:3:4-tribromo-dinitrotoluene (m. p. 197-199O) could be detected in the aboveproduct.This result agrees substantially with that of chlorination, exceptfor the presence of a minute amount of the 3 : 4 : 5-derivative520 THE PROGRESSIVE BROMl NATION OF TOLUENE.Bromination of 3 : 5-Dibromotoluene.This was brominated in the manner already described. Theproduct, on crystallisation from alcohol, melted at 51-53O. Alittle of it was converted into the dinitro-compound, which afterseveral crystallisations from alcohol and acetic acid melted at209--210°, and is identical with the 2 : 3 : 5-tribromodinitro-com-pound. The mother liquor on evaporation gave a mixture of theunchanged dibromotoluene and 2 : 3 : 5-tribromotoluene. The othertribromobluene which is theoretically possible, namely, the 3 : 4 : 5(m. p. 88-89O>, could not be detected by repeated crystallisationof either the bromination product or its dinitro-derivative. Theresult thus agrees entirely with that of chlorination.I n one experiment carbon tetrachloride was used as solvent, but,curiously enough, the product consisted of a mixture of tri- andtetra-bromotoluenes, a material which melted a t a much highertemperature than any of the tribromotoluenes.I n the following table the results of bromination and chlorina-tion are given side by side, the principal product being placed firstin each case, and a trace indicated by brackets.Brominationproducts.Ortho-, para-,Toluene. (meta-).Ortho- 2 : 5 ; 2:4Para- 2 : 4 ; 3:4Meta- 2 : 5 ; 3 : 4 ; (3:5)2: 3 2 : 3 : 6 : 2:3:5Mono-halogencompounds(2:4 2:4:53 (2:4:6)2: 5 3 : 4 : 5 ; (2:3:6)2: 6 2 : 3 : 63: 4 2 : 4 : 5 ; (3:4:5)2 : 3: 5halogencompoundsDi- I 3 : 5Chlorinationproducts.Ortho-, para-.2 : 4 ; 2 : 3 ; 2 : 6 ; (2:5)2:4; 3 : 42:5.; 3:42: 3: 42 : 4 : 5 ; 2 : 3 : 4 ; (2:4:6)2:3:6; 2:4:52:3:62 : 4 : 52: 3: 5Attention is directed to the difference in the orienting effects ofchlorine and bromine produced by chlorination and brominationof ortho-halogen derivatives, an effect which is most marked in thecase of the mono-halogen compound and the 2 : 3- and 2 : 5-dihalogenderivatives.It would appear from this that the orienting effect of the methylgroup is more emphasised in the case of chlorine substitution andof the halogen in the case of bromine substitution. In the highersubstituted derivatives the tendency is to form compounds havingthe symmetrical structure,HARTLEY U- AND B-TRIMETHYL COBALTICYANIDE. 521as was pointed out by Cohen and Dakin (T., 1904, 85, 1274) andCohen and Hartley (T., 1905, 87, 1360).In conclusion, we wish to express our thanks to the ResearchFund Committee of the Chemical Society for a grant towards theexpenses of this investigation.THE UNIVERSITY, LEEDS

ISSN:0368-1645    

DOI:10.1039/CT9140500501

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

HARTLEY a- AND 6-TRIMETHYL COBALTICYANIDE. 521LII1.-a- and B- Trimethyl Cobalticyanide.By ERNALD GEORGE JUSTINIAN ELARTLEY.IN a recent communication (T., 1912, 101, 705) the author describedthe reaction between methyl iodide and silver ferro- and ferri-cyanide reapedively. Since the cobalticyanidss probably possess asimilar constitution to the ferricyanides, it seemed interesting forthe sake of comparison to study the behaviour of silver cobalti-cyanide with methyl iodide.The first experiments were carried out exactly as with the ferri-cyanide, silver cobalticyanide being heated with excess of methyliodide a t about looo in sealed tubes for some hours. A very darkred, solid mass was thus obtained, in which no sign of any crystal-line matter could be- observed.Numerous unsuccessful attempts t oisolate any pure substance from this solid matter by methods similarto those adopted with the ferro- and ferri-cyanides made it evidentthat a t the temperature of the experiment too much decompositionhad taken place t o allow of any satisfactory results. It was subse-quently found that by keeping the temperature a t about 4 5 O thereaction followed a more definite course.The following procedure was found to give the most satisfactoryresults. About 50 grams of the silver salt were heated with a largeexcess of methyl iodide in a closed, thick-walled glass bottle, thetemperature being maintained a t between 40° and 50°.The heating was continued until the solid matter, which firstbecame yellow with the formation of silver iodide, began to show avery slight pink colour; about eight days was usually required.After removing the excess of methyl iodide, the solid matter, whichemitted a strong odour of isocyanides, was extracted several timeswith hot ethyl alcohol.The brownish-yellow solution so obtained,after evaporation over sulphuric acid, deposited a white, crystallinecrust (I), and a second crop of the same substance, but less pure,was obtained after further evaporation-the two crops togethe522 HARTLEY : a- AND 6-TRIMETHYL COBALTICYANIDE.weighing about 3 grams. Finally, a brown oil remained, fromwhich no more crystals could be separated. The method of purify-ing the substance (I), and the account of its analysis and properties,will be more conveniently considered later on in the paper.Thesolid matter that has been extracted with ethyl alcohol was nexttreated in a similar way with boiling water, a very powerful odourof isocyanides being noticeable during this operation. The aqueousextract on cooling deposited a crop of white, hair-like crystals (11)much resembling glass wool. Two or three more crops wereobtained by further evaporation, the later ones usually containinga fair amount of the substance (I) which had escaped extractionwith alcohol, and also some pink, insoluble decomposition product.The crystalline matter, together with these impurities, weighedabout 6 grams. The later crops were boiled with alcohol andfiltered, the solution affording a further yield of the substance (I),which was added to the previous quantity; whilst the portion in-soluble in alcohol was crystallised from water to free it from thepink insoluble matter, and the pr0duc.t was added to the first cropof (11).The total amount of the latter substance was then furtherpurified by several more crystallisations from hot water, about3 grams being finally obtained.Analyses made with material crystallised three times gave thefollowing results :0-1757 gave 0.2656 CO, and 0.0576 H,O.0.1807 ,, 0.2720 CO, ,, 0.0586 H20. c"=41*0; H=3*63.0'2796 ,, 0'1674 CoS04. C0=22*76.CgHgN,Co requires C = 41.53 ; H = 3-48 ; Co = 22.64 per cent.The substance (11) is therefore evidently trimethyl cobalticyanide,(CH3)3CoC,N6, and it will be convenient to distinguish it as thea-compound, since i t will be shown later that the substance (I) isan isomeride. a-Trimethyl cobalticyanide, when pure, crystallisesfrom hot water in very fine, white, silky fibres.It is quite stable,losing no weight a t looo. On more strongly heating it decomposeswithout melting. It is only sparingly soluble in cold, readily so inhot, water, very sparingly so in hot ethyl alcohol, and is practicallycompletely separated from solution in the latter on cooling. It isinsoluble in chloroform, acetone, ethyl acetate, or benzene. I naqueous solution it is neutral, and gives no precipitate withpotassium hydroxide or ammonium sulphide, but is slowly decom-posed on boiling with either of these reagents. When the solidsubstance isxreated with 10 per cent.solution of silver nitrate itrapidly dissolves even in the cold, although the amount of waterpresent may be far less than would be required t o effect solution.After remaining for a few minutes, white, hair-like crystals beginC=41*2; H=3-67HARTLEY : U- AND ,&TRIMETHYL COBALTICYANIDE. 523to form in abundance throughout the liquid, more rapidly if it iswell stirred.A determination of silver in these crystals after washing withalcohol and drying in a vacuum gave the following result in agree-ment with the formula (CH3),CoC6N,,2AgN0,. (Found, Ag = 35.61.Calc., Ag= 36-96 per cent.)A solution of a-trimethyl cobalticyanide mixed with a smallquantity of an ionised cobalticyanide, such as the potassium salt,gives with a soluble silver salt a white, amorphous precipitateresembling silver cobalticyanide, except that after drying it becomesslightly blue.(In consequence of the insoluble nature of the doublenitrate just described, a solution of silver sulphate was used forthis preparation.) On heating this white precipitate it chars andgives off an isocyanide in quantity; it is therefore, presumably, adouble methyl silver cobalticyanide :0.4728 gave 0.2877 AgCl and 0.1735 CoSO,. Ag=45*81;CO = 13.96.3Ag3COC6N6,2( CH3)&0C6N6 requires Ag = 45.44 ; C O = 13'78 percent.It is, of course, essential that sufficient of the trimethyl compoundbe present to give this double salt, for if the potassium salt were inexcess the product would be an indefinite mixture of the above withsilver cobalticyanide.Purification and Analysis of the Substance (I).Although a-trimethyl cobalticyanide is almost completely in-soluble in cold ethyl alcohol, it is appreciably dissolved by thissolvent when boiling.Consequently, the crystalline deposit (I)from the alcoholic extracts was mixed with a certain amount of thea-compound, especially as a considerable volume of alcohol wasneceesary owing to the large bulk of solid matter to be extracted.By recrystallising from as small a quantity of alcohol as possible,the greater part of the a-compound was separated, since it remainedundissolved, but even then the crystals of (I) so obtained werecontaminated with the small proportion of the same substance thathad passed into solution.The material was therefore redissolvedin a fairly large quantity of alcohol, and the solution was sowedwith some freshly prepared crystals of the u-compound ; on coolingthe liquid in an ice-chest, practically the whole of the a-compound,together with some of the substance (I), was deposited. On filteringoff this crop and evaporating the solution, a good second crop of(I) was obtained apparently quite free from the a-compound. Afurther amount of pure material was extracted from the abov524 HARTLEY : a- AND &TRIMETHYL COBALTICYANIDE.impure first crop by a second similar treatment. The two portionswere then added together and purified by further crystallisationeither from ethyl alcohol or from much boiling propyl alcohol, fromeither of which solvents the substance separates in very small, whiteneedles.It can also be recrystallised from water, but it is insolublein all the other usual organic solvents.The samples taken for analysis were from three different prepara-tions; they were all crystallised a t least three times-finally frompropyl alcohol-and dried a t looo for several hours.For the determination of nitrogen it was found necessary to grindthe weighed portion very intimately with copper oxide previous tocombustion, otherwise the percentage of this constituent came outconsiderably too low. Even with this precaution the result is some-what below the theoretical figure :(i) 0.2907 gave 0.1748 CoSO,. Co= 22.88.(ii) 0,1475 ,, 0'2259 C 0 2 and 0-0510 H20.C=41.79;0.1495 gave 0.2303 CO,, 0.0529 H20, and 0-0888 CoSO,.H = 3.86.C=42*03 ; H = 3-96 ; CO= 22.60.(iii) 0.1405 gave 36.6 C.C. N, a t 6-5O and 758 mm. N=31*58.CgHgN6Co requires C = 41.53 ; H = 3-48 ; N = 32-35 ; Co = 22.64 percent.From the method of formation this formula can scarcely be repre-sented as having any other structure than (CH&CoC,N,, so thatthe substances I1 and I must. be regarded as isomerides, and thelatter compound will be distinguished as B-trimethyl cobalticyanide.The two forms, which appear to be produced in about equal quanti-ties, differ from one another both in their physical and chemicalproperties.For instance, the &variety is soluble to a much greater extentthan the isomeride in water, methyl, ethyl, and propyl alcohols.Although no very accurate measurements of this property have beenmade, one o r two rough determinations may be described, whichwere carried out with small quantities for the purpose of ascertain-ing the best conditions for recrystallisation.Five C.C. of water a tabout 7.5O dissolves 0.008 gram of the a- and 0.022 gram of the&form; again, 50 C.C. of boiling ethyl alcohol will just dissolve0.02 gram of the a- and about 0.7 gram of the /?-compound, so thatthe latter is more than thirty times as soluble under these conditions.&Trimethyl cobalticyanide, when mixed with a small quantity ofpotassium cobalticyanide and precipitated with silver sulphatesolution in exactly the same way as has been described with thea-compound, gives, like the latter, a white, amorphous precipitatewhich is a double methyl silver saltHARTLEY : a- AND P-TRIMETHYL COBALTICYANIDE.5250.3028 gave 0.1615 AgCl and 0.1191 CoSO,. Ag=40.15;CO = 14.97.(CH~),COc6N6,Ag3COC6N6 requires Ag = 40.51 ; CO = 14.75 per Cent.A crystalline double salt is precipitated when a fairly concen-trated solution of the P-compound is treated with silver nitrate.This salt is, unfortunately, difficult to obtain pure, since it appearsto undergo slight decomposition after washing and drying in avacuum. It cannot be heated to looo without very considerabledecomposition. The percentage of silver found in several differentpreparations dried in a vacuum was as follows: Ag=28.5, 28.45,29.3, 28.9, which approximates t o the percentage Ag = 29.54, re-quired by the formula 3CH3Coc6N6,4AgN03.It will be seen that in both of these double salts each moleculeof &trimethyl cobalticyanide combines with a smaller proportion ofthe silver salt than does the a-compound.Neither of the isomerides combines with methyl iodide whenheated with the latter in sealed tubes a t looo, although somedecomposition takes place.In this respect they both differ fromthe somewhat similarly constituted substance a-tetramethyl f erro-cyanide, which reacts with methyl iodide quantitatively to formhexamethyl ferrocyanogen iodide (T., 19 13, 103, 11 99).It will be observed that the sum of the weights of a- andB-trimethyl cobalticyanide only amounts to about 25 per cent. ofthe theoretical yield, assuming the reaction to be simplyAg3COC6N6 + 3CH31 = (CH3)COC6N6 + 3AgI.The total weight of solid matter obtained in a preparation carriedout as described shows that actually about three molecules ofmethyl iodide enters into reaction with each molecule of silver salt,but a considerable portion of the product remains as an uncrystal-lisable oil after extracting and isolating the two isomerides.Someexperiments were made to determine the nature of the oily matter.A concentrated solution of the latter in water gave a yellow,crystalline platinichloride moderately soluble in water and insolublein alcohol. This salt, after recrystallising from dilute alcohol andfrom water in order to free it from some amorphous impurity, wasexamined under the microscope, and seems to consist largely ofhexagonal plates resembling the methylamine salt.On ignition aresidue of platinum was left containing only a trace of cobalt, andthe percentage agreed with that required by the formula(CH,NH,)2H2PtC16. (Found, Pt = 41.04, 41.20. Calc., Pt =41*31per cent.)The presence of a methylamine salt can therefore be taken asproved.An aqueous solution of the oil gives with silver nitrate a plentifu526 HARTLEY : a- AND /?-TRIMETHYL COBALTICYANIDE.whitish, amorphous precipitate, which on filtering and dryingbecomes slightly brown.This substance on heating gives off an isocyanide in quantity, andleaves a residue containing silver and cobalt; in fact, it has all theproperties of the double methyl silver cobalticyanide describedabove, and is doubtless a somewhat impure form of that compound.No other definite substance was isolated from the oily residue,which thus apparently consists mainly of methylamine cobalti-cyanide and some trimethyl cobalticyanide, these being preventedfrom crystallising by the presence of some decomposition products.The formation of methylamine cobalticyanide can be explainedon the assumption that the trimethyl compound is partly decom-posed during its preparation into cobalt cyanide and methylcarbyl-amine.The latter substance is capable of reading with methyliodide t o give an additive compound, probably CH,*N(CH3)I:C,which is hydrolysed by alcohol or water, forming CH,*NH,,HI(Wade, T., 1902, 81, 1609).The methylamine hydriodide so produced would quickly react withany unchanged silver cobalticyanide t o give silver iodide andmethylamine cobalticyanide.If this assumption is correct, the solid matter left after extractionwith alcohol and water should contain cobalt cyanide. I n order totest for this, some of the solid was digested with silver nitrate solu-tion, when a pink solution was obtained, which gave the usualreaction f o r a cobalt salt. Some cobalt cyanide treated with silvernitrate in a similar way was found to react a t once, a pink solutionof cobalt nitrate being formed. The above explanation is thereforeprobably correct.The experiments recorded in this paper show that silver cobalti-cyanide differs altogether from silver ferricyanide in its behaviourwith methyl iodide, the latter salt reacting according t o theequation :4Ag,Fe(&N6 f- 24C'HJ = 3[ (CH3)6FeC&?61,,4AgI] + (CH&FeC&N616.No definite evidence has so far been obtained as to the nature ofthe isomerism observed in these trimethyl cobalticyanides, or in theallied compounds a- and P-tetramethyl ferrocyanide previouslydescribed (Eoc. cit.) ; it is hoped, however, that further experimentswill throw light on the problem.These experiments have been carried out in Lord Berkeley'slaboratory a t Foxcombe, near Oxford, to whom the author's bestthanks are due

ISSN:0368-1645    

DOI:10.1039/CT9140500521

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

THE ACTION OF ALDEHYDES ON THE GRTGNARD REAGENT. 527L1V.- The Action oj' Aldehydes on the G r i p ardReagent.By JOSEPH MARSHALL.ALTHOUGH many observers have investigated the reaction occurringbetween magnesium alkyl or aryl haloids and substances containingthe carbonyl group when the magnesium compound was in excess,i t appears that none has hitherto observed that if an excess of analdehyde is added t o an ethereal solution of a magnesium alkylhaloid, on decomposing the product with water there is obtained,along with the secondary alcohol formed in the usual manner, aconsiderable quantity of a substance of higher boiling point. Thepresent paper gives an account of an investigation which owes itsorigin to the fact that, in the residue obtained in the preparationof a large quantity of phenylmethylcarbinol from magnesiummethyl iodide and benzaldehyde, there was present a substancewhich could be distilled in a vacuum a t about 200°, and crystallisedwhen it was allowed to remain a short time.Analyses of this sub-stance gave results from which the empirical formula C,,HI4O wascalculated, and of the many compounds with this empirical formula,the only one which could possibly be formed in this reaction ismethyldeoxybenzoin, C,H,*@H(CH,)*CO*C,H,. This was obtainedby V. Meyer and Oelkers (Ber., 1888, 21, 1297) by the action ofmethyl iodide and sodium on deoxybenzoin, and a comparison ofthe properties of the product of the Grignard reaction with thoseof methyldeoxybenzoin proved that the two substances wereidentical.It was thought that the production of this compound might bedue to the action of a slight excess of benzaldehyde on the first pro.duct of the reaction in a manner indicated by the followingequation :C,H,*CH(CH,)*OMgI + C6H,*CH0 =C6H,*CH(CH3)*CO*C6H, + MgIoOH .. (1)and attempts were made t o increase the yield of this substance bythe addition of a second molecular proportion of benzaldehyde tothe magnesium methyl iodide. It was noticed that the grey,crystalline mass which was produced when one molecular propor-tion of benzaldehyde was allowed to react with one molecular pro-portion of magnesium methyl iodide was converted into a darkbrown, viscous mass when the second molecular proportion ofaldehyde was added, and a t the same time a slight rise in tempera-ture was observed.The mass was not altered in appearance b528 MbRSHALL: THE ACTION OFwarming during several hours on a water-bath, although experi-ments showed that the yield of methyldeoxybenzoin was consider-ably increased by proloriged heating. I f the equation (l), repre-senting the reaction as a double decomposition similar to thattaking place when water is added to the magnesium compound,correctly indicated the manner in which methyldeoxybenzoin isformed, since this compound is readily soluble in ether, it should befound in the supernatant ethereal layer before water is added tothe mixture, whilst the viscous mass referred to above should bechiefly magnesium oxyiodide, mixed with the unchanged Grignardproduct. By treating the two layers separately with dilute acid, itwas found that the ethereal layer contained a small quantity ofbenzaldehyde, but no methyldeoxybenzoin, whilst the viscous massyielded phenylmethylcarbinol and a considerable quantity of methyl-deoxybenzoin.It is suggested that the second molecule of benz-aldehyde combines with the first product of the reaction in thefollowing manner :C6H5*CH(CH3)*OMgI + c6H,*CH0 =C,H,*CH(CH,)*C(C,H,)(OMgI)*OH . . (2)This more complex magnesium compound is then decomposed bythe addition of water, with the formation of methyldeoxybenzoin :C6H5*C'H( CH,)=C( C",H5) (OMgI) *OH + H20 =C6H,*CH((CH3)*CO*C6H, + H,O + MgI-OH . . (3)I n order to determine if the reaction is capable of general appli-cation, experiments were made with other magnesium compounds.By the action of benzaldehyde on magnesium dimethylcarbinyliodide, a quantity of phenyl isopropyl ketone was produced.Asomewhat different result was obtained by heating magnesiumphenyl bromide with two molecular proportions of benzaldehyde, ofwhich reaction benzophenone and benzyl alcohol were the productsinstead of phenyldeoxybenzoin. This result, however, may easilybe explained by assuming the reaction to proceed in a manneranalogous to that expressed by equations (2) and (3), and that thenthe phenyldeoxybenzoin is hydrolysed to benzophenone and benzylalcohol. It is well known that phenyldeoxybenzoin does not existin the ketonic form, but only as the unsaturated triphenylvinylalcohol, C(C~H,)Z:C(OH)*C~H, (H.Biltz, Ber., 1899, 32, SSO), andthe addition of a molecule of water to this substance in the mannerindicated by equation (4) would decompose it, with the formationof the above-mentioned substances :C(C6H5),:C(OH)eC6H5 + H20 =(C,H,),CO + C,H,*CH,*OH . (4)A similar theory would account for the production of a certaiALDEHYDES ON THE GRIGNARD REAGENT. 529amount of benzyl alcohol in the above-mentioned reaction betweenbenzaldehyde and magnesium dimethylcarbinyl iodide. In thiscase, phenyl isopropyl ketone is apparently partly hydrolysed intoacetone and benzyl alcohol:cH( cH,),*C"o* C,H,+ c (CH,), : c( OH) C,H,-+(c'H,),co + C6H,*CH2*OH.An analogous result was obtained when acetaldehyde was allowedto react with magnesium phenylmethylcarbinyl bromide, in whichreaction, however, no trace of a-phenylethyl methyl ketone couldbe found.Instead of this, the products of the reaction were aceto-phenone and phenylethyl bromide, C6H,*CHBr*CH,, the formationof the former being easily explained by the above theory. No ex-planation is offered a t present for the production of the phenyl-ethyl bromide, but it is in agreement with results obtained inexperiments made on the reaction between Grignard reagents andformaldehyde. It was thought that the reagent might react withformaldehyde to produce a substituted acetaldehyde in a mannerexpressed by the equation :R*CH(OMgX)*R' + CH20 =R*CH[CH(OH)*OMgX].R' + R*CH(CHO)*R' . , (5)and that formic ester might react in a similar manner to form sub-stituted acetic esters.The products of these reactions were, how-ever, substituted methyl haloids, along with a certain quantity ofdecomposition products. These reactions appear to consist in theremoval of magnesium oxide from the Grignard product, thus :C6H5*~H(CH,).0MgI = c6H5*CHI*CH3 + MgO,but the mechanism of the reaction is not yet clear. The trioxy-methylene or formic ester disappears during the reaction, with theproduction of a viscous mass similar in appearance to that observedin the earlier experiments, so that it would appear that some com-bination takes place between the Grignard product and the trioxy-methylene or formic ester.Further experiments are in progress, but it was thought that theresults obtained u p to the present were of sufficient interest towarrant their publication.EXPERIMENTAL.Action of Benzaldehyde on Magnesium Methyl Iodide.*Twelve grams of magnesium turnings were allowed to react with20 C.C.of a mixture of 72 grams of methyl iodide and 100 C.C. ofanhydrous ether. When the first violent reaction was over, 100 C.C.* The author is indebted to Mr. J. A. Hartley for assistance in the execution ofthis experiment530 MARSHALL: THE ACTION OFof ether were added, and the remainder of the methyl iodide-ethermixture was allowed to run slowly on to the magnesium, the wholebeing then gently warmed on the water-bath t o effect completesolution of the magnesium. This solution was cooled in ice, and amixture of 52 grams of benzaldehyde and 50 C.C.of ether wasslowly added to it, care being taken that no rise in temperaturetook place. (In an experiment in which phenylmethylcarbinol wasrequired, the usual precaution was not observed, and it was foundthat, instead of almost a theoretical yield of the carbinol, thequantity obtained was only about 20 per cent. of that theoreticallypossible. The principal product of the reaction in this case was aliquid, boiling a t 148-150°/15 mm., which did not react withsodium. On warming with phosphorus pentachloride, this liquidyielded phenylethyl chloride, and it was probably diphenylmethyl-carbinyl ether.) The flask containing the mixture was allowed toremain overnight, and a further quantity of 52 grams of benz-aldehyde mixed with 50 C.C.of ether was slowly added. A veryslight rise in temperature was observed, while the supernatant etherbecame yellow, and the grey, crystalline mass, which constitutedthe first product of the reaction, became viscous. After all thebenzaldehyde had been added, no trace of crystalline structure couldbe observed. The flask was now heated gently on the water-bathduring twelve hours, the only noticeable changes being that theether became less yellow in colour, whilst the viscous mass graduallybecame dark brown. The mixture, after cooling, was poured intodilute sulphuric acid, ice being added to prevent any rise intemperature. The ethereal layer was now separated, washedsuccessively with dilute acid, dilute sodium hydrogen sulphite solu-tion, dilute sodium carbonate solution, and finally with water, andafter dehydration it was submitted to fractional distillation in avacuum.The product was thus divided into two fractions, thcfirst (about 40 grams) boiling below 150°/15 mm., whilst the secondfraction distilled between ZOOo and 220° under the same pressure,and it solidified on cooling. The first fraction contained about20 grams of benzaldehyde, which was separated as the sodiumhydrogen sulphite compound, and the remainder of this fractionconsisted of phenylmethylcarbinol. The second fraction wasdrained, and after recrystallisation several times from alcohol itmelted sharply a t 53O. (Meyer and Oelkers give the melting pointof methyldeoxybenzoin as 53O, whilst Beilstein's " Handbuch "13rd ed., Vol.II., p. 2301 gives 58O.) From 20 t o 30 grams ofpure product were thus obtained in fine, faintly yellow needles.(Found, C = 85-56 ; H = 6.42. C',,H,,O requires C = 85-71 ; H = 6-66per cent.ALDEHYDES ON THE GRIGNARD REAGENT. 531The oxime and semicarbazone of this ketone are difficult to prepare, but a simple means of identifying the substance consists inthe formation of a bromine derivative. I f a solution of brominein carbon disulphide is added to a solution of the ketone in thesame solvent, the colour of the bromine disappears, and heat isdeveloped. No evolution of hydrogen bromide is observed, but oncooling the solution to the ordinary temperature a solid separates,which may be recrystallised from alcohol, in which solvent the sub-stance is not very soluble.The pure product melts a t 159-160°:0.2260 gave 0.2320 AgBr. Br =43*55 per cent.(r,,H,,0Br2 requires Br = 43.25 per cent.The substance is therefore the dibromide of the ketone.An attempt was made to determine whether derivatives of thetautomeric form of the ketone could be obtained. A quantity ofthe ketone was boiled for some time with an excess of acetyl chloride,and the solution was then allowed to cool. Crystals separated,which were collected and recrystallised from alcohol. The sub-stance was not readily soluble in this solvent, and separated fromi t in colourless leaflets, which melted a t 111-112O. It containedchlorine, and an estimation of this element gave a result (C1= 15-52)which agreed with the formula C6H,*C(CH3):CC1.C6H,.(C,,Hl3CIrequires C1= 15.54 per cent.)Attempts were made to hydrolyse methyldeoxybenzoin intoacetophenone and benzyl alcohol, but they were not successful, thesubstance being almost unchanged by boiling with sulphuric acid(lH,SO, : lH20) or by heating with concentrated hydrochloric acidin a sealed tube a t 150O. The only decomposition product thatcould be isolated was a very small quantity of benzaldehyde.Action of Benzaldehyde on Magnesium Dimethylcarbinyl Iodide.This experiment was carried out as in the preceding case, theformation of a brown, viscous mass being again observed. Afterdecomposition of the product with dilute acid, the ethereal extractwas dehydrated and distilled with a fractionating column to pre-vent dimethylcarbinol passing over with the ether. When thethermometer had reached 50° the receiver was changed, and a frac-tion (A) was collected up to 130O.The residue was distilled underdiminished pressure, when two fractions, B (100-150°/ 15 mm.)and C (150-210°/15 mm.), were obtained. The distillate (A) hada strong odour of acetone, and it gave iodoform when treated withiodine and sodium carbonate solution. It was probably a mixtureof acetone and isopropyl alcohol, but the quantity of substance wastoo small to admit of the separation of the two. Fraction (B) wasVOL. cv. N 532 MARSHALL: THE ACTION OFredistilled under the ordinary pressure a t which it boiled, between195O and 220°, leaving a small quantity of residue, which w aadded to (C).The distillate contained a small quantity of phenylisopropyl ketone, for it gave a phenylhydrazone which melted a t126O (Claus, J . pr. Chem., 1892, [ii], 46, 480), but the greater partof the fraction consisted of benzyl alcohol, which was identified byconversion into benzyl chloride and pnitrobenzyl chloride(m. p. 72-73O). The distillate (C) was redistilled under 15 mm.pressure, and a fraction, which boiled steadily a t 165O, was thusobtained. It gave a phenylhydrazone which separated from alcoholin faintly yellow leaflets, melting a t 145O.0.2276 gave 23 C.C. N, a t 19O and 755 mm.This would agree with a formula, CISHl8N2 (N=11.76 per cent.),isomeric with that of the phenylhydrazone of phenyl isopropylketone.An oxime (m.p. l l O o ) was also obtained, but the constitution ofthe fraction (C), which is apparently a ketone, has not yet beendefinitely settled.N=ll.82.Action of Benaaldehyde on Magnesium Phenyl Bromide.A solution of 12 grams of magnesium in a mixture of 75 gramsof bromobenzene and 150 C.C. of ether was dropped very slowly intoa cooled solution of 106 grams (2 mols.) of benzaldehyde in 200 C.C.of ether. A t first a bright yellow solution was obtained, but as theaddition proceeded a viscous oil separated from the ether. Themixture was allowed t o remain overnight, and was then warmedduring twelve hours on the water-bath, after which time the pro-duct was decomposed in the usual manner. Two chief fractionswere obtained on distillation in a vacuum, the former (A) boilingbelow 150°, and the second (B) distilling between 150° and 200°,whilst a small quantity of tetraphenylethane (m.p. 209O) was alsoobtained. The fraction (A) was shaken with sodium hydrogensulphite solution to remove excess of benzaldehyde, and the remain-ing liquid distilled a t 204-208O under the atmospherlc pressure.Boiling with concentrated hydrochloric acid converted this liquidinto benzyl chloride (b. p. 176O), which on nitration gave pnitro-benzyl chloride.Fraction (B) was redistilled, and the greater part or it distilledconstantly a t 180°/15 mm. The distillate did not solidify for someconsiderable time, but the addition of a trace of benzophenone pro-duced instant crystal'lisation of the whole mass.The substance wasrecrystallised from alcohol, when it melted a t 48O, and it did notaffect the melting point of a specimen of benzophenone obtained inThe fraction (A) was therefore benzyl alcoholALDEHYDES ON THE GRIGNARD REAGENT. 533the usual manner.its properties with those of benzophenoneoxime (m. p. 140O).The oxime was prepared, and this agreed inAction of Acetaldehyde on Magnesium Phenyl Bromide.Twelve grams of magnesium were dissolved in a mixture of75 grams of bromobenzene and 50 C.C. of ether, and to this solutionwas slowly added, with cooling, a solution of 45 grams ofacetaldehyde in 90 C.C. of ether. The grey, crystalline mass whichfirst separated became viscous only when the mixture had remainedovernight, and it was then heated during eight hours on the water-bath, decomposed with acid, and, after dehydration, the etherealextract was distilled.The distillate passing over below120°/20 mm. weighed 40 grams, and above that temperature afurther quantity of 7 grams was obtained, whilst no appreciableamount of residue was left. After further fractionation of the firstdistillate, a quantity of substance was obtained which boiled between90° and 100°/15 mm., whilst a small amount of diphenyl (m. p. 70°)was isolated. The distillate, which was evidently a mixture, con-tained a bromine compound, which was identified by allowingsodium t o react with an ethereal solution of the substance.Diphenyldimethylethane (m. p. 1 2 4 O ) was isolated in this reaction,from which it is inferred that phenylethyl bromide was present inthe original distillate.The remaining component of the distillatewas identified as acetophenone. By roughly estimating the amountof the phenylhydrazone formed from a weighed quantity of thedistillate, it was conchded that acetophenone formed about 60 percent. of the product.A ction of Ethyl Formate on Magnesium Diphenylcarbinyl Bromide.A solution of 12 grams of magnesium in a mixture of 50 C.C. ofether and 75 grams of bromobenzene was obtained; t o this wasadded a mixture of 50 C.C. of benzaldehyde in 50 C.C. of ether, andthe whole was allowed to remain for some hours. A solution of40 grams of ethyl formate in 50 C.C. of ether was slowly added,and the mixture was heated for eight hours.The reaction mixturewas now decomposed with dilute acid; the ethereal layer wasseparahed, dehydrated, and distilled under 15 mm. pressure. Threefractions were obtained: (A) 12 grams boiling a t about looo,(B) 26 grams boiling a t 1 7 8 O , (C) 4 grams boiling a t about 250°,as well as a large amount of residue, which was not examined.The fractions were examined in order. (A) consisted of benzylbromide. The liquid, boiling a t 178O, was also a bromo-derivative,and by allowing sodium to react with an ethereal solution of thisN N 534 THE ACTION OF ALDEHYDES ON THE GRIGNARD REAGENT.substance, tetraphenylethane was obtained, so that the originalsubstance must have been diphenylmethyl bromide. This was con-firmed, first, by the preparatio'n of benzhydryl ethyl ether, and,secondly, by the production of benzhydrylamine from it.Thesubstance was not obtained in the crystalline condition; but thiswas probabb due to the presence of some benzhydrol, from whichi t could not be separated by distillation. The fraction (C) solidifiedin the receiver, and it was found to be tetraphenylethane. Itcrystallises from acetic acid in needles, melting a t 2 0 9 O .Action of Ethyl Formate on Magnesium Ph.estylmethylcarbiny1Zodide.The reaction was carried out in a manner similar to that immedi-ately preceding, and from the products, which soon became dis-coloured owing to the separation of iodine, only phenylethyl iodide,diphenyldimethylethane (produced by decomposition of phenyl-ethyl iodide), and a trace of methyldeoxybenzoin were isolated. Asethyl a-phenylpropionate was the product expected in this reaction,the whole of the fraction boiling below 110°/15 mm. (which frac-tion contained the phenylethyl iodide, and should have containedand ethyl a-phenylpropionate produced in the reaction) was boiledwith alcoholic potassium hydroxide solution, but no trace ofa-phenylpropionic acid could be found.A ction of Triolcyme t hylene on Magnesium Phenglmet hylcarbinylIodide.One molecular proportion of dry, finely-powdered trioxy-methylene was added to the Grignard mixture obtained frommagnesium methyl iodide and benzaldehyde, and the whole wasthen heated during several hours on the water-bath. The productsof this reaction were the same as those mentioned in the precedingcase. No trace of a-phenylpropaldehyde could be found,although, as this aldehyde very easily combines with sodiumhydrogen sulphite, it would have been an easy matter to detect itspresence.THE UNIVERSITY, LEEDS

ISSN:0368-1645    

DOI:10.1039/CT9140500527

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

LV..-Phgtin and Phytic Acid.By GEORGE CLARKE.THE name phytin has been applied to a white, amorphous substancewhich has been observed by Palladin (Zeitsch. Biol., 1895, 31, 199)to occur in the seeds of many plants, and yields inositol and phos-phoric acid on hydrolysis under pressure with solutions of mineralacids or alkalis. An examination of the methods used in preparingthe material investigated by previous workers left no doubt thatdifferent substances have been described as phytin, and that thesesubstances were not always homogeneous. This conclusion was con-firmed by the divergent published results representing the composi-tion of phytin (compare Jegorov, Biochem. Zeitsch., 1912, 42, 433,and Plimmer and Page, Biochem. J., 1913, 7, 158).The acid obtained from phytin by the removal of the bases,calcium and magnesium, has been described as phytic acid, but nosalt or derivative of it of undoubted purity has been isolated andanalysed.Many of the substances described as phytic acid havebeen mixtures of phosphoric acid and an organic phosphoric acid.Schulze and Winterstein (Zeitsch. physiol. Chem., 1896, 22, 90 ;1903, 40, 121) prepared phytin by extracting the faf-free seeds ofSinap-s nigra with 10 per cent. sodium chloride solution, coagulatingthe proteins by boiling, and, after cooling and filtering, precipitatingphytin from the cold protein-free sodium chloride solution by heat-ing. The substance thus obtained was identical in properties withthat prepared by the methods recorded below.These authors men-tioned the fact that phytin was less soluble in hot than in coldacetic acid, but did not develop this method of preparation.Winterstein (Ber., 1897, 30, 2299) prepared phytin by extractingseeds with dilute acetic acid and precipitating it from the solutionby ammonia. The free acid was obtained by the removal of thebases by means of oxalic acid, and yielded inositol and phosphoricacid on hydrolysis under pressure with concentrated hydrochloricacid. The substances prepared by the latter methods were un-doubtedly mixed with calcium and magnaiufn phosphates andphosphoric acid.Posternak (Compt. rend., 1903, 137, 202, 338, 439) extractedphytin from various fat-free seeds by means of very dilute hydro-chloric acid, separating the substance by precipitation of the coppersalt, decomposing the latter by hydrogen sulphide, and treatingwith alcohol the Syrupy acid substance obtained by the evaporationof the acid solution.The final product was soluble in water, andthus differed from that obtained by Schulze and Winterstein (Zoc536 CLARKE: PHYTIN AND PHYTIC ACID.cit.) and the present author, which was insoluble. Posternak statedthat the substance prepared by him was free from nitrogen andinorganic phosphates.Treatment with alcohol of the syrupy acid residue obtained bythe latter worker would separate a large amount of inorganic phos-phoric acid from the final product, but an examination of the freeacid liberated from a product obtained by analogous methods, bycarefully fractionating the strychnine salt, showed that i t containedinorganic phosphoric acid. In this connexion it is of interest tonote that Page and Plimmer (Biochem.J., 1913,7, 168) have foundthat samples of commercial phytin always contained inorganic phos-phoric acid.Free phytic acid, obtained by Posternak, was described as a paleyellow, transparent syrup, yielding inosito-1 and phosphoric acid onhydrolysis, and giving no precipitate in the cold, but a characteristicyellow precipitate on warming with ammonium molybdate solution.He ascribed to the acid the formula C,H,O,P,, and the constitutionrepresented by anhydro-oxymethylenediphosphoric acid,[ CH,~O*PO(OH),],O.One of the arguments on which this formula was based was the factthat phytin and phytic acid were not hydrolysed by alkalis, a state-ment that Winterstein (Zeitsch.physiol. Chem., 1908, 58, 121) hassince shown to be incorrect. Neuberg (Biochem. Zeitsch., 1908, 9,557) has brought forward additional evidence to show that theinmito1 ring formation exists in phytin and phytic acid.The methods used in the preparation of the material, on theanalysis of which Posternak based the, formula C2Hs09Pz, did notpreclude the possibility of admixture with phosphoric acid.The phytin previously examined had been prepared by one ofthe methods described, or some slight modification of them.Starkenstein (Biochem. Zeitsch., 1911, 30, 59) has stated thatair-dried commercial phytin contains a considerable quantity ofinorganic phosphoric acid, and that the amount is increased bydrying a t looo.He attributed this to the decomposition of phytininto inositol and phosphoric acid a t that temperature, but did notrecord the isolation of inositol. Anderson (J. Biol. Chem., 1912,11, 473) failed to confirm his conclusions that phytin was so easilydecomposed.The results of experiments recorded in this communication haveshown that the free acid liberated from air-dried phytin of homo-geneous composition-which was separated from admixed mineralPhosphates by precipitation from cold dilute acetic acid by boiling-consisted of a mixture of approximately equal quantities of anorganic phosphoric acid (phytic acid) and phosphoric acidCLARKE: PHYTIN AND PHYTIC ACID. 537A solution of the ammonium salt of the organic phosphoric acid,prepared from a pure strychnine salt, gave no precipitate on warm-ing to 60° with a nitric acid solution of ammonium molybdate, andonly a very slight one on remaining a t that temperature for severalhours.An explanation of the behaviour of phytin is that it is not simplya salt of an inositolphosphoric acid, but a complex substance,possibly a complex calcium-magnesium salt of an inositolphosphoricacid and phosphoric acid, and, on removing the bases, yields thetwo acids.The fact that the composition of pure phytin, preparedas described below, corresponded with no calcium-magnesium saltof a simple acid ester of inositol and phosphoric acid, gave supportto this view. The strychnine salt of the organic phosphoric acid,isolated from the mixture of acids obtained from phytin, on theother hand, gave results on analysis in agreement with salts ofsimple inositolphosphoric acids.Anderson (J. Biol.Chern., 1912, 11, 471) prepared from com-mercial phytin obtained from two sources a series of salts, which onanalysis gave figures corresponding with salts of inositolhexaphos-phoric acid, CGH,O,[PO(OH),],. He described an acid tribariumphytate prepared by precipitation from 0.5 per cent. hydrochloricacid solution by the addition of an equal volume of alcohol. Thissalt was probably one of the purest derivatives of phytic acidhitherto isolated, but i t seemed not impossible from the methodsof preparation that the salt as well as the acid prepared from itmight contain some phosphoric acid.EXPERIMENTAL.Preparation of Phytin.The seeds of Indian field mustards, a mixture of Srussica junceu(H.fil. and T.) and Brassica campestris (Linn.), were extractedwith petroleum f o r several days. The petroleum extract wasseparated by means of a centrifugal machine, and the seeds driedin the sun for a few hours. Twenty-seven kilograms of air-dried,fat-free seeds were extracted for seven days with 100 litres of 4.5per cent. acetic acid. The extract was separated from the seeds ascompletely as possible in the centrifuge, boiled for fifteen minutes,and allowed to cool. This procedure coagulated a large portion ofthe proteins. After remaining overnight, the supernatant extractwas easily syphoned off.The dark brown extract thus obtained wasagain heated to boiling. A small quantity of phytin separated out,but the solution was too dilute and impure for any quantity ofmaterial to be obtained in this manner. Aqueous ammonia wa538 CLARKE: PHYTIN AND PHYTIC ACID.then added to the boiling extract until it was just alkaline, and theboiling continued for a few minutes. A large quantity of dark-coloured precipitate (A) was thus obtained, which was separatedby filtration while still hot, and well washed with boiling water. Thecrude precipitate (A) contained phytin, calcium and magnesium-ammonium phosphates, and a considerable quantity of protein andother organic impurity. It was intimately mixed with 16 litres of8 per cent. acetic acid, and extract,ed for two or three hours withconstant shaking.The extract was separated from the undissolvedorganic impurities by filtration through cloth, boiled, allowed tocool overnight, and the cold solution thoroughly stirred. The un-dissolved and precipitated matter was then easily separated byfiltration through paper, and a perfectly clear filtrate obtained.Aqueous ammonia was added t o the boiling filtrate until it wasjust alkaline, the white precipitate (B) being collected on a filterand washed with boiling water until almost free from ammonia.The white precipitate (B) consisted of phytin and calcium and mag-nesium-ammonium phosphates. It was dissolved in 6 litres of8 per cent. acetic acid, and a very small amount of insoluble matterseparated by filtration.The clear solution thus obtained wasboiled for some minutes. Much phytin was precipitated, and i t wasseparated by filtration through a Buchner funnel while the liquidwas still hot, then well washed with boiling water, and finally withethyl alcohol, 82 grams being obtained. The hot filtrate fromwhich the phytin had been separated was again made alkaline withammonia, and the precipitate (C) separated and washed. It wasdissolved in 2 litres of 8 per cent. acetic acid, and phytin separatedby boiling, filtering while still hot, and washing with water andalcohol as described above. Fifteen grams were obtained. Thefiltrate from this was again subjected to similar treatment, a smallervolume of 8 per cent. acetic acid being used (1 litre), and yielded8 grams of phytin.The residual filtrate on treatment with excessof ammonia yielded a further precipitate, which consisted mainlyof calcium and magnesium-ammonium phosphates, and containedonly a very small amount of carbon.The total yield of phytin was 105 grams, or 0.38 per cent. of theair-dried, fat-free seeds.The following yields of phytin were obtained in other prepara-tions :27.0 kilograms of air-dried fat-free seeds gave 125 grams of phytin = 0.46 per cent.*28*8 ) y Y ) > ) s> 165 > > y , = 0.57 ) )31.5 ,) Y Y 9 7 9 ) 152 Y > ,, = 0.47 ,)Seeds extracted with 0-2 per cent. hydrochloric acid.Very dilute hydrochloric acid can be used instead of dilub acetiCLARKE: PHYTIN AND PHYTIC ACID. 539acid for the extraction of the seeds, and some of the material usedin this investigation was prepared by extraction with 0.2 per cent.hydrochloric acid, the phytin being subsequently purified byseparation from 8 per cent.acetic acid. It was found, however,that the extracts obtained by the use of dilute hydrochloric acidwere more difficult to handle than those obtained by dilute aceticacid.Phytin prepared in the manner described above was a snow-white,amorphous powder, resembling in properties the substance describedby Schulze and Winterstein (Zeitsch. physiol. Chem., 1896, 22, 90).It contained carbon, hydrogen, phosphorus, calcium and mag-nesium, but no trace of nitrogen could be detected. It was in-soluble in hot and cold water, readily soluble in very dilute mineralacids, and soluble in cold, but sparingly so in hot dilute acetic acid.It was precipitated from a cold 8 per cent.acetic acid solution onboiling, completely redissolving when allowed to cool.A solution of phytin in very dilute nitric acid gave an abundantyellow precipitate with acid ammonium molybdate solution onwarming to 60°.The following fractions from different preparations were preparedfor analysis :(A) Fifty grams of phytin dissolved in 2000 C.C. of distilledwater and 100 C.C. of glacial acetic acid. The solution obtained wasquite clear and free from undissolved material. It was heated, notquite to boiling. The precipitated phytin was separated by filtra-tion, well washed with boiling water until free from acid, finallywith alcohol, and dried on a porous plate.Phytinwas again precipitated, separated, washed with boiling water, butnot with alcohol, and dried on a porous plate.(C) Seventy grams of phytin from a separate preparation weredissolved in 2500 C.C.of 5 per cent. acetic acid. The clear solutionwas heated for some time by passing steam into it. The precipi-tated phytin was separated, washed with water and alcohol, anddried.(D) Seventy grams of phytin from a preparation made by ex-tracting mustard seeds with 0.2 per cent. hydrochloric acid, andsubsequent purification by precipitation from 8 per cent. aceticacid, were' dissolved in 2500 C.C. of 5 per cent. acetic acid. Phytinwas separated from the perfectly clear solution by heating, washedand dried.It is somewhat difficult to obtain phytin in an anhydrous con-dition.After heating f o r several hours at l l O o in a vacuum overphosphoric oxide, it still continued to lose weight. When heated(B) The filtrate from A was boiled for fifteen minutes540 CLARKE: PHYTIN AND PHYTIC ACID.under similar conditions a t 180° for five hours it became constantin weight, and remained so after prolonged heating for many hours.The anhydrous substance, dried a t 180° and dissolved in diluteacetic acid, was precipitated again unchanged by boiling.Plimmer and Page (Biochem. J., 1913, 7, 162) have referred tothe difficulty of analysing phytin, and have critically examined themethods of determining calcium and magnesium in the presence ofphosphoric acid.They mention also the difficulty of completelyburning carbon in the presence of phosphoric acid.The following methods were used in the analyses of phytinrecorded below :Curb on and hydro yen.-The anhydrous substance was intimatelymixed with the finest powdered copper oxide.Calcium and 2Clagnesium.-The organic matter was oxidised byconcentrated sulphuric acid. After diluting with water, calciumwas separated from the solution as calcium sulphate by the additionof an equal volume of alcohol, and magnesium estimated in thefiltrate as Mg,P,O,, after the removal of alcohol by evaporationand oxidation with nitric acid as described by Plimmer and PagePhosphorus was determined (after the oxidation of the organicmatter by concentrated sulphuric acid) by means of ammoniummolybdate, and weighed as Mg,P,O,.The following results were obtained on analysis of the fractionsdescribed above, after drying in a vacuum over phosphoric oxidea t MOO:(loc.cit.).Fraction A .0.4176 gave 0.1482 CO, and 0.0620 H,O.0.4866 ,, 0.3044 CaSO, and 0.041 Mg,P,O,. Ca=18*39;0-4421 gave 0.3210 Mg,P,O,.C=9*67; H=1*64.Mg = 1-84.P = 20.21.*0*4866 ,, 0.359 Mg,P,O,. P=20*53.Fraction B.0.4650 gave 0.1694 CO, and 0.0698 H,O.0.4592 ,, 0.2812 CaSO, and 0.0458 Mg,P,O,. Ca=18*01;0.2820 gave 0.2072 Mg,P,07.C=9*93; H=1.66.Mg = 2-18.P = 20.45.* Estimated as Mg,P,O,, after separation of CaSO,CLARKE: PHYTIN AND PHYTIC ACID. 541Fractzon C.0.4330 gave 0.1530 CO, and 0.0756 H,O.0.6210 ,, 0.3880 CaSO, and 0'0520 Mg,P,O,.Ca=18*37;0.4504 gave 0.3370 Mg2P,0,.C =9.63 ; H = 1.94.0.4070 ,, 0.1440 CO, ,, 0.0684 H,O. C=9.65; H=1*86.Mg = 1.83.P = 20.82.Fraction D.0.3758 gave 0.1334 CO, and 0.0530 H,O.0.4950 ,, 0.3100 CaSO, and 0.0404 Mg,P,O,. Ca=18*40;0.3680 gave 0.2736 Mg,P,O,.C =9.68; H= 1.56.*0.4774 ,, 0.1626 CO, ,, 0.0680 H,O. C=9.29; H=1.58.Mg = 1.78.P = 20.69.C12H,,04,P,,Ca,Mg requires C= 9.70 ; H = 1.48 ; Ca = 18.87 ;Mg = 1-61 ; P = 20.88.Cl2H2,O4,Pl,Ca7Mg requires C = 9-82 ; H = 1-34 ; Ca = 19.09 ;Mg = 1-63 ; P = 21.14.C12H,,0,,P,,Ca,Mg requires C = 10.06 ; H = 1.12 ; Ca = 19.58 ;Mg=1*6'7; P=21*67 per cent.The composition of separate preparations of phytin, purified byseparation from cold dilute acetic acid, was constant.Phytin is decomposed by heating under pressure with 30 per cent.sulphuric acid into inositol and phosphoric acid (Posternak, Compt.rend., 1903, 137, 439; Winterstein, Ber., 1897, 30, 2299).Fifteen grams of phytin were heated with 67 C.C.of 30 per cent.sulphuric acid in a sealed tube a t 130° for ten hours. The dark-coloured solution was diluted with water, and calcium sulphate,which had separated out, removed by filtration. Excess of sulphuricacid was removed by treatment with finely powdered barium car-bonate. The solution, which contained inositol, was evaporated toa small bulk, removing from time to time the slight deposits ofmineral matter. The concentrated solution was acidified with twodrops of nitric acid, poured into five times its volume of ethylalcohol, and ether added.Inositol separated out as a viscid mass,which quickly solidified. Yield = 3.5 grams.Six grams of inositol from the above and other similar prepara-tions were boiled for two hours with 50 grams of recently distilledacetic anhydride and 0.5 grams of zinc chloride, and the reactionmixture poured into cold water. Hexa-acetylinositol separated, andwas purified by several recrystallisations from ethyl alcohol. Itmelted sharply a t 211O (uncorr.), and was dried a t l l O o for analysis.Anhydrous substance mixed with powdered lead chromate542 CLARKE: PHYTIN AND PHYTIC ACID.(Found, C = 50.0 ; €I = 5.6.per cent.)takes place in accordance with the following equation :C18H24O12 requires C = 50.0 ; H = 5.5The decomposition of phytin into inmitol and phosphoric acidCl,H,,044PloCa7Mg + 8H20 + 8H2S04 =Fifteen grams of phytin gave 3.5 grams of inositol.2C6H,,06 + lOH,PO, + 7CaS04 + MgSO,.C12H22044P10Ca,Mg requires 3.6 granis of inositol.Examination of the Acid from Phytin, Cl,H,,O,,PloCa,Mg.Seventy grams of air-dried phytin were dissolved in 2.5 litres of5 per cent.acetic acid, and basic lead acetate solution was addeduntil no further precipitate was produced. The lead salt wasseparated, washed with boiling water until free from acetic acid,and decomposed by hydrogen sulphide. Excess of the latter wasremoved from the acid solution by boiling under diminishedpressure, and sufficient cold saturated copper acetate solution addedto precipitate the acid.The copper salt was separated, washedwith boiling water, and deprived of copper by means of hydrogensulphide. The strongly acid solution thus obtained was evaporatedto a syrup under diminished pressure, and treated with 500 C.C. of95 per cent. ethyl alcohol. A large quantity of a white, flocculentsubstance (I) separated. This was coagulated by boiling for a fewminutes, filtered from the alcoholic extract, and washed with alittle alcohol.The white substance (I) contained phosphorus, calcium andcarbon, and readily dissolved in cold water. Its aqueous solutionwas precipitated with cold saturated copper acetate solution. Thecopper salt was decomposed by hydrogen sulphide, and the acidsolution evaporated t o a syrup, This syrup was treated with 95 percent.ethyl alcohol (300 c.c.). A smaller amount of a white sub-stance (11) separated, which was filtered from the alcoholic extractafter boiling, and washed with alcohol. Its aqueous solution wasagain precipitated with copper acetate solution, the copper saltseparated, deprived of copper, and the acid solution treated asbefore. This procedure was repeated until the syrupy acid residuewas completely soluble in 95 per cent ethyl alcohol. About fiveoperations were necessary.The alcoholic solutions of the acid obtained by the above opera-tions were mixed together, evaporated under diminished pressure,and finally dried in a vacuum over sulphuric acid.The acid thus obtained wits a viscid, dark-coloured syrup, freefrom calcium and magnesium.It was very readily soluble iCLARKE: PHYTIN AND PHYTIC ACID. 543water or alcohol, and gave a yellow precipitate with acid ammoniummolybdate solution on slightly warming.Twenty-two grams of acid produced from phytin in the mannerdescribed above were dissolved in 3 litres of water, and 50 gramsof recently precipitated strychnine, in as fine a state of division aspossible, added to ths solution. On heating, nearly all the strych-nine dissolved. A small amount of resinous impurity separated,and was removed. The solution of strychnine salts was evaporatedunder diminished pressure to 1 litre, and allowed to remain over-night. Strychnine phytate separated out in small, colourless,needle-shaped crystals, melting a t 203-204O (uncorr.).This saltwas crystallised many times from water, in which it was onlysparingly soluble. The melting point remained unchanged.Strychnine phytate contains water of crystallisation, which it losesvery slowly on exposure t o air, rapidly when dried a t 115O. Itsaqueous solution gave an acid reaction with blue litmus.Separate fractions of strychnine phytate dried a t 115O gave, onanalysis, the following results (the anhydrous salt was intimatelymixed with the finest powdered copper oxide f o r the estimation ofcarbon and hydrogen) :0*2208 gave 0.4776 CO, and 0.1188 H20. C=58.99; H=5.98.0.2407 ,, 0.5198 C02 ,, 0.1284 H20. C=58.89; H=5.92.0.3510 ,, 0.7560 C02 ,, 0.1832 H2O. C=58.74; H=5*79.0.1762 ,, 0.3816 CO, ,, 0.0950 G O .C =59*05 ; H =5*98.0.1888 ,, 0.4092 C02 ,, 0.0970 H2O. C=59*11; H=5.70.0.2750 ,, 0.5930 CO2 ,, 0.1440 H2O. C=58*80; H=5.81.Mean = 58.92 ; = 5.86.0.3936 gave 0.0934 Mg2P207. P = 6-59.0.4896 ,, 0.1158 MgZP207. P=6.58.0.6090 ,, 0.1440 Mg2P207. P = 6.58.0'5354 ,, 0.1300 Mg2P207. P=6.75.0.4574 ,, 0.1138 Mg2P207. P = 6.92.0.3874 ,, 0*0960 Mg2P207. P = 6-89,Nean = 6-72.0.4176, air-dried salt, lost 0.0302 H,O. H20 = 7-23.0.6916 ,, ,, ,, 0.0480 H2O. H20=6*94.1-2360 ,, ,, ,, 0.0846 H20. H20=6.84.Mean = 7-00.The composition of the strychnine salt agreed with the strychninesalts of several inositolphosphoric acids in which strychnine andphosphorus are in the ratio of 1 molecule of strychnine to 1 atoinof phosphorus ;. for example 544 CLARKE: PHYTIN AND PHYTIC ACID.I.C6H802(HP04)2,2C2,H,02N2 requires C = 59.25 ; H = 5-55 ;P=6.37 per cent.C6H802(HP04)2,2C21H,02N,,4H20 requires H20 = 6.90 per cent.11. C,H802(~P04)4,4C2,H2202~2 requires C = 58.87 ; H = 5-66 ;P = 6-75 per cent.C6H,02(H2P04)4,4@21H220a;N2,8H20 requires H20 = 7.27 per cent.111. C",H,(H2P04)6,6C2,H2202N2 requires c = 59-45 ; H = 5.63 ;P= 6.98 per cent.@6H,(~P04)8,6CZ1H2202N2,12H20 requires H20 = 7.50 per cent.I1 and I11 are acid salts. The acids in formulze I and I1 arecapable of yielding a complex calcium magnesium salt with phos-phoric acid of the composition C,2H,0,,Pl,Ca7Mg, which woulddecompose on removal of the bases and liberation of the free acidinto inositolphosphoric acids and phosphoric acid.The solution from which strychnine phytate (m.p. 203-204O)had separated was further evaporated under diminished pressure.After the separation of a small additional quantity of salt, meltinga t 203-204O, the mother liquors, on concentrating to small bulk,deposited a large quantity of a readily soluble salt (m. p. 252-253O).The amount of this salt was approximately equal to the weight ofstrychnine phytate obtained. It was easily separated in a state ofpurity from the sparingly soluble strychnine phytate, and proved,on examination, t o be strychnine dihydrogen phosphate.0.3130 gave 0-0824 Mg2Pz07. P = 7.32.0.2962 ,, 0.0754 Mg2P207. P=7.08.C21H,20zN2,H,P04 requires P = 7.17 per cent.Phosphoric acid was prepared from the strychnine dihydrogenphosphate described above by decomposing an aqueous solution withexcess of sodium carbonate solution, separating the strychnine, pre-cipitating the phosphate as lead phosphate in the presence of diluteacetic acid, and decomposing the lead salt by means of hydrogensulphide. An aqueous solution of the phosphoric acid was heatedwith sufficient benzylamine t o form benzylamine dihydrogen phos-phate, and the latter salt purified by recrystallisation from water.When dried a t l l O o it gave the following results on analysis:0.3030 gave 0.1642 Mg2P20,.C,H,N,H,PO, requires P = 15-12 per cent.Additional proof that the acid liberated from phytin containsmuch phosphoric acid, in addition t o the organic phosphoric acidalready described, was obtained during attempts to prepare theZ-ment h ylamine salt.Nineteen grams of Z-menthylamine were neutralised by a solutionof the mixed acids prepared from phytin, and an equal volume ofthe same solution was added.This strongly acid solution on slowP = 15.08CLARKE: PHYTIN AND PHYTIC ACID. 545evaporation in a vacuum over sulphuric acid deposited, in the formof rhombic prisms, 15 grams of I-menthylamine dihydrogen phos-phate.After purification and drying a t looo it gave, on analysis, thefollowing result :0.2268 gave 0.0984 Mg,P,O,. P = 12.07.0'3334 ,, 0.1442 Mg,P,O,. P = 12.04.C,,H2,N,H,P0, requires P = 12.21 per cent.The solution from which Z-menthylamine dihydrogen phosphatehad been separated, on further evaporation in a vacuum oversulphuric acid, deposited Z-menthylamine phytate in the form of anuncrystallisable oil.Preparation of Inositol from Strychnine Phytate.Nineteen grams of pure air-dried strychnine phytate (m.p.203-204O) were dissolved in the least possible quantity of boilingwater, and decomposed by a slight excess of aqueous ammonia.Strychnine was separated after remaining overnight, and the solu-tion of ammonium phytate evaporated to dryness and dried in adesiccator over sulphuric acid. Ammonium phytate is a non-crystal-lisable gum, very readily soluble in water. In the presence of afew drops of dilute nitric acid it gives no precipitate with acidammonium molybdate solution on warming t o 60°, but if allowed toremain for several hours a t that temperature a very slight yellowprecipitate is formed, owing to the slow hydrolysis of phytic acid.Five grams of dry ammonium phytate were dissolved in 25 C.C. of30 per cent. sulphuric acid and heated in a sealed tube a t 120-130°for eight hours. The dark-coloured solution was diluted withwater and filtered from a small deposit of carbon. Sulphuric acidwas removed by treatment with barium carbonate, and the solutioncontaining inositol evaporated to small bulk, acidified with a fewdrops of nitric acid, and poured into alcohol. Inositol separated asa solid, crystalline mass (1.5 grams). The hexa-acetyl derivative,prepared by boiling with acetic anhydride and a trace of zincchloride, was purified by crystallisation from ethyl alcohol, andmelted sharply a t 211O (uncorr.). It was dried a t l l O o for analysis.(Found, C = 50.27 ; H = 5-47. C,,H,OI2 requires C= 50.00 ; H = 5-55per cent.).The author desires to express his thanks t o his assistant, Mr.S. C. Banerjee, for valuable help in the preparation of the phytinused in this investigation.THE CEEMICAL LABORATORY,UNITED PROVINCES, DEPARTMENT OF AGRICULTURE,INDIA

ISSN:0368-1645    

DOI:10.1039/CT9140500535

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

546 SMYTHE: THE OXIDATION OF SOMELVL-The Oxidation of Some Benzyl Compounds ofSulphur. Part 11. Benzyl Tetrasulphoxide.By JOHN ARMSTRONG SMYTHE.THE oxidation, by means of hydrogen peroxide, of several mono-and di-sulphidic compounds containing the benzyl radicle formedthe subject of a recent communication (T., 1912, 101, 2076), andwas undertaken in the hope of gaining some insight into the morecomplicated reactions occurring during the oxidation of the tri-and tetra-sulphides. The study of these reactions, and also of theproperties of the chief product, benzyl tetrasulphoxide, is nowcompleted, and the results are recounted in the following pages.The rupturing (with resulting degradation into the mono-sulphidic compounds, sulphuric and benzylsulphonic acids, andsimultaneous production of benzaldehyde) which was found t ocharacterise the disulphidic compounds in the later stages ofoxidation is a feature also of the oxidation of the tri- and tetra-sulphides; by limiting the amount of oxidising agent, however, theoxidation of tetrasulphide, similarly t o that of the disulphide, canbe arrested at an intermediate stage, the corresponding tetra-sulphoxide being produced.The yield of this, under suitable con-ditions, is almost quantitative.The behaviour of benzyl trisulphide is very different, for limitedoxidation, instead of leading to the trisulphoxide, furnishes thetetrasulphoxide, identical in all respects with the compound pre-pared from the tetrasulphide. The yield in this case does notexceed 50 per cent., and the other products of reaction arebenzaldehyde, sulphuric acid, and benzylsulphonic acid.It is to be expected, from analogy to the mono-, di-, and tetra-sulphides, that the first stage in the limited oxidation of the tri-sulphide would consist in the formation of tne trisulphoxide ; thiscompound is evidently either unstable under the conditions ofexperiment or incapable of permanent existence.In the furtherinterpretation of the reaction two possibilities present themselves.The trisulphoxide may be hydrolysed, in a manner similar t othat already postulated in the case of the disulphoxide (Zoc. cit.,p. 2077), into sulphinic acid and a sulphoxylic acid, thus:C%Ph*SO-SO*SO*CH,Ph + H20 =CH,Ph*SO,H + CH,Ph*SO*SOH.The formation of the tetrasulphoxide would then be accountedfor by the oxidation of the sulphoxylic compound (2 mols.), andthe other products of reaction would result from the known decomBENZYL COMPOUNDS OF SULPHUR.PART 11. 547position of the sulphinic acid into benzaldehyde, benzyl disulph-oxide, and sulphur dioxide (Fromm, Ber., 1906, 39, 3308), and thefurther oxidation of the last two of these, the ultimate products ofthese changes being benzaldehyde, sulphuric and sulphonic acids.The other possibility is that the trisulphoxide undergoes inter-molecular reaction, the process being one of autoxidation and reduc-tion, somewhat after the manner of the decomposition of hypo-chlorites into chlorates and chlorides :2CH2Ph*[SO],*CH2Ph = CH2Ph*[SO],*CH2Ph +On this view, the tetrasulphoxide is the direct result of the decom-position of the trisulphoxide, and the other products arise from theoxidation of the disulphoxide.Although this representation has perhaps the merit of simplicity,yet it suffers from the drawback that no disulphoxide has ever beendetected in the numerous experiments which have been made onthe oxidation of the trisulphide; and in view of the proved pro-duction of disulphoxide as a secondary product of oxidation, forexample, in the case of benzoyl benzyl sulphide (T., 1912, 101,ZOSl), there is every reason to expect that, if formed in thisreaction, part a t least would escape further oxidation.On theother hand, the view of the reaction as involving primary hydrolysisbrings it into line with the interpretation of the oxidation pheno-mena of disulphidic compounds, and this advantage may wellcounterbalance the drawback arising from the assumption of anintermediate compound which cannot be isolated.The quantitativeaspect of the reaction, to which considerable attention has beenpaid, is, unfortunately, incapable of deciding between the two views,owing to the subsequent attack of the oxidising agent on the tetra-sulphoxide.From the evidence available, then, the origin of the tetrasulph-oxide in the reaction between hydrogen peroxide and benzyltrisulphide is to be sought in the hydrolysis of the normal productof oxidation, the trisulphoxide, and the subsequent oxidation of oneof the hydrolytic products.Benzyl tetrasulphoxide is in many ways a noteworthy compound,and a brief summary of its properties may be given here, in so faras they serve to bring out its relationships to other organic sulphurcompounds and throw light on its constitution.The compound decomposes a t itsmelting point, 139O, into benzyldisulphide, benzaldehyde, and sulphur dioxide.I n this respect itis analogous to benzyl monosulphoxide, which, when destructivelydistilled a t 210°, yields the same three products, in addition totoluene (Fromm and Achert, Ber., 1903, 36, 534). A somewhatCH2Ph* [ SO]2CE€,P h.VOL. cv. 0 548 SMPTHE: THE OXIDATION OF SOMEdifferent course of decomposition is followed in solution, the pro-ducts b i n g benzyl disulphoxide, sulphur, and sulphur dioxide :CH2Ph*[SO]4*CH2Ph = CH2Ph*[SO],*CH2Ph + S + SO,.This is, apparently, the usual mode of decomposition under avariety of conditions.Thus, treatment with sodium ethoxide yieldsa solution containing sulphide and sulphite, and if benzyl chlorideis also present, then benzyl sulphone and benzaldehyde-benzyl-mercaptal are produced, and both of these substances result fromthe action of sodium ethoxide and benzyl chloride on benzyldisulphoxide. Again, reduction of the tetrasulphoxide withhydrogen sulphide yields sulphur and benzyl disulphide ; and thesame products, in addition to benzyl trisulphide, are formed byreduction with benzyl mercaptan. These reactions find a readyexplanation on the assumption that the tetrasulphoxide is firstdecomposed according to the above equation, and that the primarydecomposition products, sulphur dioxide and benzyl disulphoxide,then enter into reaction with the hydrogen sulphide and mercaptan.The formation of benzyl trisulphide by the action of benzylmercaptan on the tetrasulphoxide is of some interest, although thisdoes not strictly constitute a method for the conversion of thetetra- into the tri-sulphide, since part only of the sulphur of thetrisulphide, comes from the tetrasulphoxide (and hence from thetetrasulphide) ; the remainder of the sulphur, and also the benzylradicles, are supplied by the mercaptan.The converse change,from tri- to tetra-sulphide, has not yet been realised; but sincemetallic reducing agents convert the tetrasulphoxide into benzylmercaptan and hydrogen sulphide, and as these are the reductionproducts, by the same agents, of the tetrasulphide, it may beadmitted that the change has been virtually effected.When warmed with solutions containing hydrogen chloride, thetetrasulphoxide undergoes a curious areaction, reminiscent of themetallic polysulphides, sulphur and hydrogen sulphide being pro-duced.Although the mechanism of this reaction is obscure, someinterest attaches to the formation of a reducing agent under theseconditions, and the reaction has its analogue in that, wherebybenzyl mercaptan is ' produced, in certain circumstances, fromhydrogen chloride and benzyl monosulphoxide (T., 1909, 95, 353).Towards nitric acid (D 1-3) the tetrasulphoxide, like the mono-and di-sulphoxides, is tolerably stable, but it is completely oxidisedby excess of hydrogen peroxide, with formation of sulphuric andbenzylsulphonic acids.A little benzaldehyde is also formed, as inthe oxidation of all other polysulphidic compounds of benzyl.I n the foregoing account the constitution of the oxidation pro-duct of the tri- and tetra-sulphides has been tacitly assumed, aBEKZYL COMPOUNDS OF SULPHUR. PART 11. 549is indicated by the name adopted for the compound. A few wordsin justification of this assumption are therefore necessary. On thissubject two questions arise : first, whether the tetrasulphide, fromwhich the compound is directly derived, is to be represented as asimple chain compound of four sulphur atoms; and, secondly,whether the oxygen in the tetrasulphoxide is uniformly distributedamong the sulphur atoms.The first point has been discussed in a general manner byHolmberg (Annalen, 1907, 359, Sl), who favours the structureR*S*S*S*S*R for the organic tetrasulphides, as against that repre-sented by R*S*S*S*R, the latter being deduced from the method offormation from mercaptans and sulphur chloride, on the groundsof the formal relationship between sulphur chloride, S:SC12, andthionyl chloride, O:SCl,.The production of the tetrasulphoxide from both tri- and tetra-sulphide would be compatible with either view of the constitutionof the tetrasulphide, but it mould argue strongly for the simplechain structure, both of tetrasulphide and tetrasulphoxide, if itcould be proved that the latter contains four sulphoxide groups.With respect to the distribution of oxygen within the tetra-sulphoxide molecule, there are several possibilities, as indicated bythe following formulae :1.CH,Ph~SO,*S*S*SO,*CH,Ph 2. CH2Ph*S*SO2*S0,*S*CH2Ph4. CH,Ph*SO*SO*SO*5O0CH,Ph 3.Of these formulae, No. 1 has b u t little experimental support;No. 2 renders a good account of the resolution of the compound,on heating, into benzyl disulphide and sulphur dioxide; No. 3,notwithstanding its obvious disadvantages, gives, perhaps, the bestrepresentation of the production of the tetrasulphoxide from thetrisulphide, although it leaves unexplained the formation of theother products of reaction, the yield of which is considerable.Thecharacteristic reaction of the tetrasulphoxide, namely, its decom-position into benzyl disulphoxide, sulphur, and sulphur dioxide, isreadily understood on the basis of formula 4, and all the otherreactions of the compound, as well as its formation from the twosulphides, are compatible with it.I n the absence, then, of decisive evidence, the balance of prob-abilities seems in favour of the view that the compound is bestrepresented as in formula 4, and is, in fact, benzyl tetrasulphoxide;and, further, that the tetrasulphide has the simple chain structureC&Ph*S*S*S*S*CH,Ph, in common with t3he other organic tetra-sulphides, as maintained by Holmberg.sCH,Ph*SO*a *SO*CH,Phso20 0 550 SMPTHE: THE OXIDATION OF SOMEEXPERIMENTAL.The benzyl tri- and tetra-sulphides used in the course of thiswork were prepared by the methods already described (T., 1910,97, 1195).A more thorough purification of the tetrasulphide waseffected than was formerly possible, and the melting point foundto be 5 4 O , that is, a little higher than previously stated. (Found,S =41.35. C,,H,,S, requires S =41*34 per cent.) The oxidisingagent was hydrogen peroxide (30 per cent.), glacial acetic acid wasused as solvent, and the treatment of the oxidation-products wassimilar to that described in the first paper of this series (T., 1912,101, 2076).Oxidation of Benzyl Trisulphide.--The reaction between thiscompound and hydrogen peroxide usually sets in spontaneouslyafter twenty-four hours’ contact, and is accompanied by consider-able evolution of heat.The solid oxidation-product crystallisesfrom the solution in the form of minute, snow-white needles afterkeeping a day or two longer. I f the liquors from this are used t odissolve more trisulphide, then immediate reaction sets in on addi-tion of the oxidising agent.The investigation of the solid oxidation-product is beset by morethan ordinary difficulties, and these appear to arise from its in-stability. I n the earlier experiments, the removal of the aceticacid was effected in a current of steam; the residue, on crystallisa-tion, melted a t 108O, and proved to be benzyl disulphoxide.(Found, C = 60.63 ; H =5*69 ; S = 23-57. C,,Hl,O2S2 requiresd: = 60.41 ; H = 5.03 ; S =23*06 per cent.) It will be seen later thatthe disulphoxide frequently results from the decomposition of theoxidation-product.The compound, as produced directly from the oxidation process,has a somewhat variable melting point, 124O to 139O.Attempts topurify it by solution in benzene, in which it is moderately soluble,even in the cold, and fractional crystallisation and precipitation byaddition of light petroleum, did not meet with success; indeed, itwas found that continuous fractionation in this manner, whilst notaffecting greatly the melting point, lowered the content in carbonand sulphur, and presumably increased the oxygen-content. Trialwith various other solvents met with similar lack of success. Theonly method of purification which proved of any service was towarm the compound in glacial acetic acid containing hydrogenperoxide.Slow decomposition takes place, but the presence of theoxidising agent ensures the conversion of the decomposition productsinto soluble compounds; thus, on cooling, the original compound ispartly recovered in a purified condition. This method, howeverBENZYL C0JIPOUNI)S O F SULPHUR. PART 11. 551does not always yield a sample pure enough for analysis, tllougll itis of great value in the treatment of impure residues.The difficulties of investigation are further accentuated by theunsatisfactory character of the melting point. The compoundusually softens a few degrees before melting, and liquefaction occursover several degrees, evolution of gas taking place meanwhile.Thesize of the capillary tube and the rate of heating also cause varia-tion in the temperature of melting.By reason of these peculiarities, many analyses, particularlydeterminations of sulphur, have been carried out with diff ereiitsamples, and it has been found that specimens of low melting pointgive values too high for sulphur, usually 1 or 2 per cent., in extremecases 7 per cent.; with such samples the complete analysis does n o tlead to any formula. Provided, however, the melting point isabove 134O, the sulphur determinations are concordant with oneanother, and a formula is deducible from the complete analysis.The critical examination of the analytical data shows that thechief source of contamination of the oxidation-product is 1111-doubtedly sulphur, and it will be seen later that sulphur is one ofthe products of decomposition of the compound under conditionssimilar to those under which it is formed.The acquisition of apure specimen of the compound is thus, to some extent, a matter ofchance. I n practice it is found advisable to operate with thematerials in the proportion of 10 grams of trisulphide, 100 C.C. ofacetic acid, and 25 C.C. of hydrogen peroxide, and to keep themixture cool during active oxidation. The oxidation-product iscollected, washed with acetic acid, and dried on a porous plate. Ifthe sample melts fairly rapidly at, or above, 134O, effervescingstrongly a few degrees higher, it may be regarded as pure.The mean of four determinations of carbon and hydrogen, andfive of sulphur, made with samples prepared in this way, meltinga t 134--139O, some with and some without subsequent treatmentwith hydrogen peroxide, the deviations not exceeding the ordinaryexperimental limits, gave : Found, C = 45.10 ; H= 3-94 ; S = 34.41.The molecular weight, determined cryoscopically in benzene solu-tion, gave the values 333, 335, 332.Ci4H,,O4S, requires C=44*93;H = 3-75 ; S = 34.23 per cent.The solid oxidation-product of benzyl trisulphide has thus theformula C14H1404S4, and is either benzyl tetrasulphoxide o r ailisomeride; the evidence, summed up in the introduction, points t othe former interpretation.The yield of the tetrasulphoxide varies somewhat, according toconditions, the average being about 50 per cent.Limitation of theamount of hydrogen dioxide used, so that some trisulphide was leftM.W. = 374552 SMYTHE: THE OXIDATION OF SOMEoxidised, failed to furnish any evidence of the trisulphoxide to beexpected in this reaction, or, indeed, of any other solid product, ifa little free sulphur, sometimes separated in the colloidal state, beexcepted.The liquors from the tetrasulphoxide yield a further crop of thecompound on evaporation in a vacuum over potassium hydroxide,and, in addition, a small amount of benzaldehyde (identified as thehydrazone, m. p. 157O) and of benzoic acid derived from it, andrelatively large amounts of sulphuric and benzylsulphonic acids.The last-named was isolated as its barium salt, which gave onanalysis :0.4168 gave 0.1881 BaSO,.0.6498 lost 0.0452 a t l l O o .(C7H7*S03),Ba,2H,0 requires Ba =26.60 ; H,O = 6.98 per cent.0.6498, dehydrated salt, gave 0.2933 BaS04.(C,H7*S03),Ba requires Ba = 28.66 per cent.The yields of the chief products in two experiineiits made with20 and 10 grams, respectively, of the trisulphide, using equivalentamounts of hydrogen peroxide, were : tetrasulphoxide, 48, 41 percent.; benzylsulphonic acid, 36, 41 per cent.; and sulphuric acid,15, 13.5 per cent.Oxidation of Benzyl Tetrasu1phide.-This compound is slowlyoxidised by hydrogen peroxide, several days being required for thecompletion of the reaction, the course of which can be followed bythe change in colour from the lemon-yellow of the tetrasulphide t othe white of the oxidation-product ; no appreciable heat isdeveloped. The analytical proof that the solid oxidation-productis benzyl tetrasulphoxide presented the same difficulties as in theformer case.Recrystallisation of the crude compound from warmacetic acid containing hydrogen peroxide was almost always neces-sary to obtain a pure product. One sample prepared in thismanner, melting a t 134O, decomposing a t 136O, was completelyanalysed as follows :Ba = 26-57.H,O=6.96.Ba = 28.55.0.1624 gave 0.2636 CO, and 0.0596 H,O.0.1162 ,, 0.2957 BaSO,. S=34*94.0.1548 ,, 0.3953 BaSO,. S=35*07.C14H1404S4 requires C = 44.93 ; H = 3.75 ; S = 34.23 per cent.The identity of this preparation, and many such, with the oxida-tion-product of the trisulphide was proved by similarity of reactionsand by melting-point determinations of mixtures, carried out sideby side with those of their constituents. No depression of meltingpoint has ever been observed with such mixtures.The soluble products of oxidation are the same as in the case ofC=44.27; H=4.08BENZYL COMPOUNDS OF SULPHUR.PART 11. 553the trisulphide, namely, benzylaldehyde, sulphuric acid, and benzyl-sulphonic acid. The barium salt of the last was analysed: 0.5196gave 0.2365 BaSO,. (Found, Ba = 26*78. (C,H,*S0,)2Ba,2H,0requires Ba = 26.60 per cent.)The yield of these products varies considerably with the propor-tions of materials used. For equivalent quantities, the yield oftetrasulphoxide reaches 100 per cent., that of sulphuric and benzyl-sulphonic acids being very small.The xield of these acids increases,and that of the tetrasulphoxide decreases, with increase in theamount of oxidising agent, from which it is evident that the formerare produced a t the expense of the latter. This behaviourestablishes a difference between the tri- and tetra-sulphides, for thetrisulphide, even with equivalent quantity of hydrogen peroxide,does not yield more than 50 per cent. of the tetrasulphoxide.React ions of Beii a yl t e t rasulphoxide,It has not been found possible, as yet, to prepare simple deriv-atives of this compound, for all reactions lead to disruption andthe production of compounds containing a fewer number of sulphuratoms in the molecule. The experiments described below haveusually been performed in duplicate with samples prepared bothfrom the tri- and the tetra-sulphide; in no case has any differencebeen observed, so tha% it is unnecessary to name the source of thetetrasulphoxide used.Decomposition by Heat.-(1) When the tetrasulphoxide is heatedt o its melting point, it decomposes vigorously, and sulphur dioxideis evolved.The quantitative determination of the sulphur dioxidewas carried out with a number of different specimens, the gas beingswept out of the decomposition-tube by a stream of carbon dioxide.The results vary by about 2 per cent., both in the case of duplicatesof the same sample and of specimens of different origin, and themean of six determinations gave 25 per cent. of sulphur dioxide.The solid residue, on purification, was identified as benzyl disulphideby its melting point and it-s characteristic reaction with silvernitrate.An appreciable amount of benzaldehyde is also, formedduring the decomposition. The reaction, expressed by the equationCH2Ph*1SO],*CH2Ph = (CE2Ph),S2 + 2S0,corresponds to a yield of 34 per cent. of sulphur dioxide. Thisreaction is clearly the main one, although evidently some side-reaction takes place, evidenced by the production of benzaldehyde,and responsible for the deficiency of sulphur dioxide.(2) Sulphur dioxide is also liberated when the tetrasulphoxide isboiled with aeetic anhydride ; decomposition under these conditionsis much slower than in the former case, although the temperatur554 SMYTHE: THE OXIDATION O F SOMEis practically the same.Most of the gas is disengaged after threehours’ heating, but complete decomposition is only effected aftereight hours, a current of carbon dioxide passing continuouslythrough the liquid. The yield of sulphur dioxide is 28 per cent.,from which i t is probable that the reaction is similar to the fore-going one.(3) I n glacial acetic acid the decomposition takes a differentcourse, the solid products being sulphur and benzyl disulphoxide.The latter, on recrystallisation, melted a t 108O, and gave onanalysis :0.1156 gave 0.2571 CO, and 0.0538 H,O.0*1030 ,, 0.1728 BaSO,. S=23*00.Small quantities of benzaldehyde and benzyl mercaptan are alsoComplete decomposition is oiily attainedThe reactionC=60*64; H=5*17.C,,Hl,02S2 requires C = 60.41 ; H = 5.03 ; S = 23.06 per cent.formed in this reaction.after twelve hours’ heating a t boiling temperature.evidently proceeds, in the main, according to the equation:CH2Ph*[SO],*CH2Ph = (CH,Ph),S,O, + S + SO,.The production of benzyl disulphoxide by distillation in a current ofsteam of the acetic acid liquors from the oxidation of the trisulphidewas mentioned above, and is clearly to be ascribed to this reaction.(4) A change similar to the preceding one is wrought by theaction of benzoyl chloride on a solution of the tetrasulphoxide inpyridine ; sulphur and benzyl disulphoxide are readily recognised asthe solid products of reaction, and the reaction takes place, withdevelopment of heat, immediately the benzoyl chloride is added t othe solution.(5) When iodine solution is added to a warm solution of thetetrasulphoxide in alcohol it is decolorised, a t first very slowly,then with ever-increasing velocity, until the absorption of iodineis instantaneous; a t the same time sulphur is set free, thesolution becomes strongly acid, and the odour of benzyl iodidebecomes apparent.The amount of iodine absorbed is equivalentt o 32 per cent. of sulphur dioxide.This reaction is undoubtedly one of decomposition by heat inthe early stages, the iodine being reduced by the sulphur dioxideset free; probably it is complicated later by the hydrogen iodideproduced.Oxidation R em tiom-Benzyl tetrasulphoxide is slowly oxidisedto sulphuric acid and benzylsulphonic acids under the conditionsof its formation, and thus it comes about that the yield ofsulphuric acid in the oxidation of either tri- or tetra-sulphide variesaccording to the time of contact and the quantity of hydrogenperoxide presentBENZYL COMPOUNDS OF SULPHUR.PART 11. 555I n the case of the trisulphide, oxidation with equivalent amountof hydrogen peroxide, in the minimum time necessary for comple-tion of the reaction, yields about 15 per cent. of sulphuric acid;with excess of oxidising agent, the yield rises after one month to25 per cent., and complete oxidation in warm solution yields, onthe average, 57 per cent. of sulphuric acid.I n the case of the tetrasulphide, insufficiency of hydrogen peroxidealways carries oxidation to some extent beyond the, sulphoxidestage, even though some tetrasulphide remain unattacked ; and thesame remark applies to other sulphur compounds, as, for instance,the disulphide and mercaptan.One, may conclude from this thatthe velocity of sulphide oxidation, although unquestionably greaterthan, is of the same order of magnitude as, that of sulphoxideoxidation.Complete oxidation of the tetrasulphide in warm solution yields,on the average, 68 per cent. of sulphuric acid.The tetrasulphoxide, notwithstanding its readiness to decompose,is only completely oxidised with hydrogen peroxide in acetic acidsolution after warming for several hours on the water-bath; itsstability in this solution is therefore much the same either inpresence or absence of the oxidising agent.The maximum yieldof sulphuric acid is about 62 per cent., and this, as in the case ofthe tri- and tetra-sulphides, corresponds with the oxida5ion of alittle more than half of the sulphur to sulphuric acid, the remainderpassing into the form of benzylsulphonic acid.Two grams of tetrasulphoxide yielded, on complete oxidation,2.95 grams of barium sulphate and 1.4 grams of barium benzyl-sulphonate. (Found, Ba = 26.43. (C,H,*S03)2Ba,2H20 requiresBa=26'60 per cent.) The only other product was a little benz-aldehyde. The yields of sulphuric and benzylsulphonic acids, calcu-lated from these data, are 62 and 42 per cent. Thus the reactionmay be expressed by the equation :CIH2Ph*[S0]4*CH,Ph + 7H202 = 2CH2Ph-S0,H + 2H,S04 + 4H,O,half of the sulphur being oxidised to sulphuric acid and half tosulphonic acid.Some side-reaction, resulting in the formation ofbenzaldehyde and disturbing the quantitative relations, takes placein this as in all the other reactions studied.It may be well, before leaving this subject, to summarise theobservations on the oxidation of these compounds. The tetra-sulphoxide is oxidised directly, and almost quantitatively, tosulphuric and benzylsulphonic acids ; the tetrasulphide is first con-verted into the tetrasulphoxide, which then behaves in like manner.The trisulphide, however, differs in that the reaction, whereby thetetrasulphoxide is produced from it, is accompanied by the simul556 SXYTHE: THE OXIDATION OF SOMEtaneous formation of sulphuric and benzylsulphonic acids; thus, theyield of these acids on complete oxidation of the trisulphide is madeup of two factors, one arising from primary oxidation and decom-position, the other from oxidation of the tetrasulphoxide producedin the first reaction.Reduction Reactions.-Benzyl tetrasulphoxide is rapidly attackedby metallic reducing agents, hydrogen sulphide and benzyl-mercaptan being formed.As these are also the products of reduc-tion of the tetrasulphide, it is probable that this compound isformed in the first stage of reduction of the tetrasulphoxide. Mildreducing agents, like hydrogen sulphide and mercaptan, do notreact directly with the tetrasulphoxide, but in the presence ofhydrogen chloride reduction takes place.The product, however, isnot the tetrasulphide, as might be expected from analogy to thedisulphoxide, for decomposition precedes reduction.(1) When the tetrasulphoxide is suspended in glacial acetic acid,and the liquid saturated with hydrogen sulphide and hydrogenchloride, the compound dissolves, and sulphur is slowly deposited,the amount increasing during several days. The filtrate from thisyields only benzyl disulphide (m. p. 7 1 O ) . Thus it appears that thetetrasulphoxide is first decomposed into sulphur, sulphur dioxide,and benzyl disulphoxide, and the last two products are then reducedby the hydrogen sulphide, yielding, thereby, a further quantity ofsulphur, and, in addition, benzyl disulphide.(2) When the tetrasulphoxide (1 mol.) and benzyl mercaptan(8 mols.) are dissolved in glacial acetic acid, and the solution issaturated with hydrogen Chloride, reaction soon begins, as mani-fested by the production of heat and the precipitation of a smallamount of sulphur.After a few hours a crystalline productseparates, and the reaction is soon completed. This product yields,on fractional crystallisation, two compounds, benzyl disulphide(m. p. 71° : Found, S = 26.07. C14H14S2 requires S = 26-06 per cent.)and benzyl trisulphide (m. p. 49O: Found, S=34.46. Cl,H,,S3reguires S = 34.58 per cent.), the latter in subordinate amount.The explanation of this reaction is to be sought in the decom-position of the tetrasulphoxide, according to the equation :followed by the oxidation of the mercaptan by the sulphur dioxide(T., 1910, 97, 1197):CH2Ph*[SO]4*CH2Ph = CH2Ph*[SO]2*CH,Ph + S + SO,,4CH2Ph*SH + SO, = (CH,Ph),S2 + (CH,Ph)&The disulphide formed in the latter reaction is largely supplernented by the mutual oxidation and reduction of mercaptan anddisulphoxide (Zoc.cit., p. 1199)BENZYL COMPOUNDS OF SULPHUR. PART 11. 557The constituent reactions may be summed up by the equation :CH2Ph*[SO],*CH2Ph + 8CH2Ph*SH =The yield of mixed di- and tri-sulphides calculated from thisequation would be 3.4 times the weight of tetrasulphoxide. I n oneexperiment, 4.3 grams of tetrasulphoxide and 12 grams ofmercaptan gave, after reaction, a small amount of unalteredmercaptan and 12.1 grams of mixed sulphides.The yield of thelatter is thus 3.3 times that of tetrasulphoxide, which is in excellentagreement with the calculated value.,4 ction of Bydrogen Chloride.-Although the tetrasulphoxide isreadily decomposed by hydrogen chloride in the presence of reducing agents, little or no action is observed, even after long keep-ing, when the compound is suspended in acetic acid or alcohol andthe liquid saturated with hydrogen chloride. On warming, how-ever, a remarkable reaction takes place ; sulphur is precipitated,hydrogen sulphide is evolved, and the liquors on treatment yieldbenzyl disulphoxide. The determination of the hydrogen sulphideset free shows that only one-seventh of the total sulphur in thecompound passes into the form of hydride. The mechanism of thisreaction is not yet clear.Action of Alkaline Reagents.-Alcoholic solutions of alkalisreact readily with the tetrasulphoxide, the solutions turning redand giving the tests for sulphides and sulphites.There is evidence,too, of the production of benzyl disulphoxide.More satisfactory results are obtained by the combined action ofsodium ethoxide and benzyl chloride, under similar conditions tothose described in the note following. The reaction takes place incold solution. The excess of alcohol and the benzyl ethyl ether areremoved in a current of steam, and the residue, on extraction withether, yields benzyl sulphone (m. p. 151O: Found, S=13*21.C,,H,,O,S requires S = 13.04 per cent.). On acidifying the liquors,and again shaking with ether, a crystalline substance is extracted(m.p. 61°), which proves to be benzaldehyde-benzylmercaptal, bycomparison with a standard preparation of this compound.These observations, along with the proof given below that benzyldisulphoxide yields both benzyl sulphone and benzaldehydebenzyl-mercaptal on treatment with sodium ethoxide and benzyl chloride,amount almost to a demonstration that the tetrasulphoxide suffers,in alkaline solution, the same decomposition into benzyl disulph-oxide, sulphur, and sulphur dioxide as it does in acid solutions.4(CH2Ph),S, + (CH,Ph),S, + S + 4H2O558 OXIDATION OF SOME BENZYL COMPOUNDS OF SULPHUR.ADDENDUM.T h e Action of Sodium Ethoxide and Benzyl Chloride o n Bemy2Disulpltoxide.This reaction was first studied by Fromm and Palma (Ber., 1906,39, 3316), who established the formation of benzyl sulphone, and,apparently, also of benzyl sulphoxide, although the yield of thelatter was very small and the melting point low.The determina-tion of carbon and hydrogen, however, gave results agreeing toler-ably well with the calculated values. I n a later paper (Ber., 1908,41, 3410), Fromm proved that ptolyl disulphoxide yielded, onsimilar treatment, the corresponding sulphone, but not the sulpli-oxide, and lie remarked that further investigation would be neces-sary in order to settle whether his previous observations on thebenzyl compound were accurate, so far as concerned the formationof the nionosulphoxide.As the point is of some importance in connexion with the lsst-described reaction of benzyl tetrasulphoxide, it was put t o the testin the following manner : 2 grams of sodium were dissolved in SO C.C.of alcohol, 10 grams of benzyl chloride were added, and the mixturebrought into 80 C.C. of alcohol containing 4 grams of benzyl disulph-oxide. The liquid became warm and yellow, undissolveddisulphoxide soon passed into solution, and sodium chlorideseparated out slowly. After keeping three days the materials weredistilled in a current of steam, which removed alcohol and benzylethyl ether. On cooling, the residue was extracted with ether ; onevaporation of the ether a good crop of benzyl sulphone (m. p. 151O)remained. The alkaline solution was now acidified and again dis-tilled in steam, whereby benzaldehyde (identified by its hydrazone)was removed, and the residual liquor yielded to ether a crystallinecompound, melting a t 61°, identified by comparison with a standardpreparation, and by a determination of sulphur, as benzaldehyde-benzylmercaptal. (Found, S = 18.70. C2,H2,S2 requires S = 19-08per cent.)The yield both of sulphone and mercaptal amounted t o 20 percent. of the disulphoxide taken, and no trace of benzyl sulphoxidewas found. It may be noted that the mercaptal is not, apparently,present as such in the alkaline liquor, but is set free, along withbenzaldehyde, by acidification.The author's thanks are due to the Research Fund Committee ofthe Chemical Society for a grant in aid of this investigation.ARMSTRONG COLLEGE,NEWCASTLE-ON-TYNE

ISSN:0368-1645    

DOI:10.1039/CT9140500546

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

THE CONSTITUENTS OF SOLANUM ANGUSTIFOLIUM. 55 9LVII.-The Constituents o f Solanurn Angustgolium :Isolation of u iVew Gluco-alkuloid, Solungustine.By FRANK TUTIN and HUBERT WILLIAM BENTLEY CLEWER.IN several countries in South America, namely, Peru, Bolivia,Paraguay, and the southern portion of the province of BuenosAyres, in the Argentine Republic, a solanaceous plant occurs whichis known as “Duraznillo Blanco.” This plant, which has beenidentified as Solanum angustifolium, Ruiz et Pavon, was brought tothe notice of Dr. Power by Dr. E. H. Colbeck, as being a drugworthy of chemical investigation. It is employed in South Americaas a febrifuge, chiefly in the treatment of entjeric fever. I n Peru itis also used in cases of malaria, but with caution, on account of itsreputed poisonous properties.At the suggestion of Dr.Power, the present authors have there-fore conducted a chemical investigation of the drug in question,which has led to the isolation of a number of compounds, includinga new and interesting gluco-alkaloid.Several species of the extensive genus Solanurn have hithertobeen reported to contain bases which, in addition to their alkaloidalnature, were also glucosides. The name solanine has in all casesbeen applied to such bases, but a perusal of the literature of thissubject reveals a state of great confusion, and makes it appeardoubtful whether any pure gluco-alkaloid has heretofore beenisolated. Thus, the solanine from Solanum Dulcamara has beenstated to possess the formula C42H87015N o r C)5”?Kg2OI8N, and toyield, on hydrolysis, the base, solanidine, CzGH4,O2N. Solanine f rointhe shoots of the potato (8.tuberosum) has been stated t o yieldsolanidine having the formula C40H6102N.More recently, Odd0 and Colombano (Gazzetta, 1905, 35, i, 27)prepared solanine from S. sodomaum, and assigned t o it theformula (C23H3g0,N),,H,0. They stated that it yielded, on hydro-lysis, solanidine, C19H2gON, but the sugar that was also found wasnot identified. A t a later date, the same authors ( A t t i R. Accad.Lincei, 1906, [v], 15, ii, 312) modified their formula for solanineto (C,7H470gN)2,H20. Solanine from the seeds of 8. tuberosum wasthen investigated by Colombano (ibid., 1907, [v], 16, ii, 683), whostated that it differed from the base obtained from S.sodomceum,and had the formula C,,H,,O,,N. The most recent work on thesubject is by Odd0 and Cesaris (Gazzetta, 1911, 41, i, 490), whopropose to designate the bases obtained from the lasbmentioned twospecies of Solanurn as solanine-t and solanine-s respectively. Th560 TUTIN AND CLEN‘EK.latter compound they state to have the formula (C,7~4609N)2,H20,and represent its hydrolysis by the following equ B t’ ion:(C2,H4609N)2,H20 + H 2 0 +H, =Solanine-s.2Cl8H,,ON + C6HlZO, + C6H1,0, + C6H1205.Solanidine. Galactose. ? Dextrose. Illhamuosc.The base described in the present communication, which has beendesignated solangustine, is a t once differentiated from anypreviously described solanines by the insolubility of its salts.Itis considered that it has been definitely established that its forniulais C3,H,,07N, and that, on hydrolysis, i t yields solangustidim,C,,H,,O,N, together with one molecule of dextrose.A summary of the results of the general iiivestigation of theplant will be found a t the end of this paper.EXPERIMENTAL.The material employed in this investigation was obtained froinLima, Peru, and consisted of the leaves, twigs, and flowers of theplant which is there known as “Duraznillo Blanco.” It wasbotanically identified by Mr. E. M. Holmes, F.L.S., as Solarnuinangustifolium, Ruiz et Pavon.A small portion (10 grams) of the dried and ground materialwas digested with Prollius’ fluid, and the resulting extract testedfor an alkaloid. Copious precipitates were then obtained with allthe usual reagents, thus indicating the presence of a considerableproportion of alkaloidal material.Another portion (25 grams) of the dried and ground materialwas extracted successively in a Soxlilet apparatus with varioussolvents, when the following amounts of extract,, dried a t loo”,were obtained :Petroleum (b.p. 35-50’) extractxd 0’60 gram = 2.40 per cent.Chloroform ), 0.36 ,, = 1’44 ,,Ethyl acetate ,, 0.41 ,, = 1’64 ,,Alcohol ), 5.96 ,, = 23.84 ,,Ether ), 0.44 ) ) = 1.76 ) )-- -Total = 7-77 grains= 31 08 per cent.Por the purpose of a complete examination, 30.92 kilograms ofthe dried material were completely extracted with hot alcohol,when, after the removal of the greater part of the solvent,12.73 kilograms of a viscid, dark green extract were obtained.A quantity (3 kilograms) of the above-mentioned extract wasmixed with water, and steam passed through the mixture for severalhours, when only a slight trace of essential oil passed over.Therethen remained in the distillation flask a dark brown, aqueouTHE CONSTITUENTS OF SOLANUM ANGUYTIFOLIUM. 561liquid (A), and a quantity of a soft, dark green resin (B). Thelatter was separated, and repeatedly washed with boiling water,the combined washings being concentrated, and added to the mainbulk of the aqueous liquid.Examination of the Aqueous Liquid (A).It having been ascertained that the extraction of the aqueousliquid (A) with ether could only be slowly and with difficultyeffected, recourse was had to the use of chloroform.After tenextractions ,with the latter solvent, practically nothing more wasremoved, and the extracts, all of which were green, were washedand evaporated. The dark green, resinous residue was dissolvedin a small amount of alcohol, and then largely diluted with ether,when a small amount of dark green, resinous material was pre-cipitated and removed. The latter apparently contained a smallamount of amorphous, alkaloidal material, but nothing definitecould be obtained from it. The ethereal filtrate was shaken witheight successive portions of 1 per cent. hydrochloric acid, when theresulting extracts each yielded reactions for alkaloid. The extrac-tion was then continued with 5 per cent. hydrochloric acid untilthe basic substance ceased to be removed.The extrach so obtainedwere separately examined, but they yielded only brown, amorphousproducts, possessing a strong, basic odour. The amount of theseamorphous, alkaloidal products was not large, and no crystallinesalt could be obtained from them.The first liquid, which had been obtained by extraction with1 per cent. acid, as above described, after being made alkaline anddeprived of base, was re-acidified and extracted many times withether. A small amount of a product was thus obtained whichdeposited some crystals and gave the colour reactions of gallic acid,but the amount was too small f o r further investigation.The ethereal solution, which had been extracted with hydro-chloric acid, as above described, was then shaken successively withaqueous ammonium carbonate, sodium carbonate, and potassiumhydroxide. The first- and lasbmentioned alkalis removed onlysmall amounts of resin, but the sodium carbonate extract yieldeda little slightly impure quercetin, very much larger amounts ofwhich were subsequently shown to be present in the form of thegluco-rhamnoside, rutin.The neutral portion of the ethereal extract of the aqueous liquidconsisted of about 2 grams of dark green, fatty material562 TUTIN AND CIAEWER:The aqueous liquid (A), which had been extracted with chloro-form, as above described, was kept for a few days, when a quantity(6 grams) of a substance was deposited in fan-shaped tufts of lightyellow, microscopic crystals.This substance was very sparinglysoluble in alcohol, and practically insoluble in the other usualorganic solvents, with the exception of pyridine, in which it dis-solved readily. It was most conveniently purified by crystallisa-tion from water, in which it is sparingly soluble. On heating itsintered a t 170°, and melted indefinitely between 185O and 2 2 0 O .(Found, C = 48.9 ; H = 5.7. C,,H3,0,6,3H20 requires C= 48.8 ;I - = 5 * 4 per cent.)This substance was identified as the gluco-rhamnoside, rutin ;this has been shown t o crystallise with 3 molecules of water, whichare somewhat difficultly eliminated on heating (compare Clarke,T., 1910, 97, 1833). It has been shown by A. G. Perkin (ibid.,p. 1776) that the glucosides previously known as osyritrin,myrticolorin, and violaquercetrin, respectively, are also identicalwith rutin.A quantity of the rutin was hydrolysed by heating with dilute,aqueous sulphuric acid, and the resulting liquid extracted withether.Quercetin was then obtained in small, yellow needles, melt-ing a t 314O. (Found, C=59*4; H=3*6. Calc., C=59.6; H=3*3per cent.) It yielded penta-acetylquercetin, which formed soft,colourless needles, melting a t 194O. The acid, aqueous liquid fromwhich the quercetin had been removed was deprived of sulphuricacid and concentrated. On heating with phenylhydrazine acetate,i t readily yielded an osazone, which was collected in two successivefractions. The first fraction, after recrystallisation from dilutepyridine, melted a t 216O, and proved to be glucosazone.The secondfraction was somewhat readily soluble in alcohol, and, after re-crystallisation from this solvent, melted at 18Z0, and was foundto consist of rhamnosazone.Further amounts of rutin were subsequently isolated, as describedbelow, and the total amount obtained was about 55 grams, beingthus equivalent to about 0.75 per cent. of the weight of the plantemployed.The aqueous liquid (A) from which the rutin had been separatedwas extracted fifteen times with amyl alcohol, the resulting liquidsbeing washed and concentrated to a small bulk under diminishedpressure. The liquid obtained by the first extraction yielded onlya quantity of a dark-coloured, viscid product, readily soluble iTHE CONSTITUENTS OF SOLANUM ANGUSTIFOLIUM.563dry amyl alcohol. On concentrating the subsequent extracts, how-ever, a yellow, sparingly soluble solid separated. The latter wascollected, and the material in the filtrate added to the above-mentioned viscid product. I n this way two products wereobtained: (a) the material sparingly soluble in dry amyl alcohol,and ( b ) that readily dissolved by the latter.Examination of the Product (a).The product ( a ) was mixed with water and deprived of amylalcohol by means of steam, the resulting dark brown, aqueoussolution being freed from traces of green material by extractionwith ether. No crystalline substance, however, could be directlyobtained from this solution of the product (a), and it was thereforesought t o obtain some definite compound from it by hydrolysis.Such an amount of sulphuric acid was therefore added to theaqueous solution as to represent about 7.5 per cent.of the totalmixture, whereupon an insoluble product separated in semi-gelatinous granules. The mixture was then warmed on a water-bath for fifteen minutes, after which the dark-coloured solid wascollected on a filter. The filtrate was boiled for one hour in ordert o complete the hydrolysis of any glucoside i t might contain. Onshaking the cooled mixture with ether, and fractionally extractingthe resulting ethereal liquid with various alkalis, a quantity ofquercetin (m. p. 310°), together with some amorphous products,was obtained. It is evident, therefore, that either some rutin, oranother glucoside of quercetin, had been extracted by means of theainyl alcohol, although the latter solvent, in a pure state, does riotappear to dissolve rutin.1solatio)t of 3 : 4-UiAy~l~oryciri~iccniic A cicl.The acid, aqueous liquid which had been extracted with ether, asabove described, was made strongly alkaline with potassiumhydroxide, and boiled for a short time.The liquid was thenquickly acidified and cooled, after which it was extracted withether. On shaking the resulting ethereal liquid with aqueousammonium carbonate, and subsequently acidifying the alkalineliquid, a quantity (4 grams) of a crystalline acid was obtained.The latter separated from water in pale brown prisms, melting a t216O, and was identified as 3 : 4-dihydroxycinnamic acid.(Found,C = 602 ; H =4.6. It yielded3 : 4-dimethoxycinnamic acid, melting a t 180-181°.Calc., C = 60.0; H =4*4 per cent.)VOL. cv. P 564 TUTIN AND CLEWER:Isolutioib of a New Gluco-alkaloid, Solaiigustitie, C3.H,,07N,H,0.The previously mentioned dark-coloured solid which hadseparated on the addition of sulphuric acid to the aqueous solutionof the product (a), as above described, was well washed with boil-ing alcohol, which removed most of the colour. It was theiidigested for some time with slightly diluted acetic acid, when, with-out dissolving to an appreciable extent, it eventually assumed acrystalline form. This substance proved to be the sulphate of analkaloid. I n working up the remainder of the original extract ofthe plant for the sole purpose of isolating a further quantity ofthis sulphate, it was not found necessary to follow the above-described procedure in full.The extract was mixed with waterand distilled in a current of steam for the removal of the alcohol.The resin was then separated from the aqueous liquid, and thelatter extracted many times with amyl alcohol, the extracts beingsubsequently washed with water and concentrated t o a small bulk.The resulting product, part of which consisted of solid materialwhich separated during the concentration, was then mixed withwater, and deprived of amyl alcohol by means of steam. Thedark-coloured, aqueous liquid so obtained was afterwards extractedrepeatedly with ether until the greater part of the material solublein this solvent was removed. It was then treated with sulphuricacid (about 5 per cent.of the weight of the liquid), the mixturewarmed gently for about fifteen minutes, cooled, and the precipi-tated sulphate of the alkaloid collected. The latter was finallypurified in the manner already indicated.I n order to obtain the base from its sulphate, it was necessaryto resort to the employment of warm amyl alcohol, since the alka-loid is insoluble, or nearly so, in all other usual solvents, and thesalt insoluble, or practically so, in everything. The sulpliate wastherefore mix& with warm, aqueous sodium carbonate, and themixture vigorously shaken with successive portions of warm arnylalcohol. The amyl alcohol extracts were then washed, and con-centrated to a small bulk under diminished pressure, when, on cool-ing, the alkaloid separated in the form of hard, pale yellow crusts,which, under the microscope, were seen to consist of aggregates ofsmall crystals.The base so obtained was found to be a newgluco-alkaloid, and has been designated solangustine, with refer-ence to its botanical source. The amount of it isolated corresponded with 0.062 per cent. of the weight of the air-dried drugemployed. Solangustine was recrystallised by dissolving it in alarge volume of hot aniyl alcohol, and then concentrating andcooling the solution. On heating, i t darkens slightly a t about 225OTHE CONSTITUENTS OF SOLASUM ANGUSTIFOLIUM. 565and melts and decoinposes a t 235O. It contains solvent of crystal-lisation, and, when dehydrated, rapidly absorbs water from theatmosphere :0.7457,* on heating a t 130°, lost 0.0233 H,O, after which, onH,O = 3.1.0.0991 * gave 0.2421 CO, and 0.0870 H,O.C=66.6; H=9.7.0.0980 * ,, 0'2386 CO, ,, 0.0832 H20. C=66*4; H=9*4.0.3019 * ,, 6.8 C.C. N, (moist) a t 1 8 O and 754 mm. N=2*6.C33H5307N,H20 requires C = 66.8 ; H = 9.3 ; N = 2-4 ;H20 = 3.0 per cent.It thus appears that solangustine possesses the f orrnula C,,H,,07N,and crystallises with 1 molecule of water, and this conclusion wasborne out by the analysis of its derivatives, described below. Theonly solvent in which solangustine will dissolve a t all readily ispyridine, but it cannot be crystallised from this liquid. Solangus-tine contains no methoxyl group, and its acetyl derivative wasfound to be uncrystallisable.Solungustine Sulphute, (C~H,307N),,H2S0,,3H20.-This salt wasprepared in a state of purity by shaking a solution of the respectivebase in amyl alcohol with dilute, aqueous sulphuric acid.A pre-cipitate then separated, which consisted of small, colourless, acicularcrystals, which did not melt or decompose a t 325O. Solangustinesulphate, like the corresponding base, contains water of crystallisa-tion, and, when dehydrated, it is extremely hygroscopic :exposure to the air, it reabsorbed 0.0231 H20.0.2144, on heating a t 140°, lost 0.0089 q0.0.1583 gave 0.0277 BaS04.H,O=4'1."SO, = 7.2.(CBH5307N)2,H2S04,3H20 requires H20 = 4.1 ; "SO, = 7.4 per cent.Solangustine sulphate appears to be insoluble in all solvents withthe exception of acetic acid, in which it dissolves very sparingly onboiling.No water-soluble salt of solangustine could be obtained, and theabove-described sulphate was the only salt isolated in a crystallinecondition.The hydrochloride and nitrate were amorphous, in-soluble products.Hydrolysis of Solnizgustirze.Formation of Solangustidine, C,,H4,O2N, and Dextrose.A quantity (5 grams) of solangustine was dissolved in 500 c.cof warm amyl alcohol, and 50 C.C. of 15 per cent. hydrochloric acicwere added, together with sufficient alcohol to render the mixturchomogeneous. The liquid was then boiled for six hours, after which* Heated at 130" t o expel amyl alcohol a i d then exposed to the air unticon stall t.P P 566 TUTIN AND CLEWER:i t was cooled, shaken with - a inoderate voluuie of water, and theaqueous layer separated. The latter was found to contain sugar,but no salt of an alkaloid.As, however, the amount of sugarformed was so small as to indicate that hydrolysis had not, beencomplete, fresh quantities of hydrochloric acid and alcohol wereadded to the amyl alcohol liquid, and the mixture again boiled forsix hours. It was found necessary to repeat this treatment fourtimes before sugar ceased t o be formed.The aqueous liquids containing sugar were then made exactlyneutral by the cautious addition of potassium hydroxide, afterwhich they were evaporated t o a small bulk under diminishedpressure. The greater part of the inorganic salt was then removedby precipitation with absolute alcohol, after which the f i h a t e wasdeprived of alcohol, and heated for two hours with aqueous phenyl-Iiydrazine acetate.The osazone which formed was collected andcarefully examined for the presence of rhamnosazone by Perkin’smethod (T., 1910, 97, 1777), when it was found to consist solely ofdextrosazone, melting a t 215O. It is thus evident that solangustinebelongs to the little-known group of gluco-alkaloids.Solnngztstidiiz e Hydrochloride, CT27H,30,N,HCl.-Tlie amyl alcoholsolution from wliicli the sugar had been removed by shaking withwater, as above described, was mixed with water and deprived ofamyl alcohol by means of steam. There then remained in the flaskan aqueous liquid, together with a quantity of a whib solid insuspension.The latter was collected, arid crystallised from absolutealcohol, to which a little alcoholic hydrogen chloride had beenadded, when it formed lustrousplates, which did not melt a t 3 2 5 O .It was most readily obtained crysballine by allowing its solution inboiling alcohol t o evaporate :0.0971 gave 0.2567 CO, and 0.0874 H,O.0.2047 ,, 0.0658 AgC1.t Cl=8*0.0’1913 ,, 0.0609 AgCl. C1=7.9.C,7H,,0,N,HCl requires C = 72.1 ; H = 9.8 ; C1= 7.9 per cent.This substance is thus seen to be the hydrochloride of a basewhich is produced, together with 1 molecule of dextrose, by thehydrolysis of solangustine. It is proposed to designate the hydro-lytic base solungustidine, and its formation may be represented byC=72.1; H=10-0:*Solungustidin e ?hydrochloride is sparingly soluble in amyl alcoholand hot ethyl alcohol, but is insoluble, or practically so, in the otherusual solvents.When i t is dis- It is quite insoluble in water.* Otlicr aiialyses gave C=71.7, 71.8; H = 9 * 9 , 10.0.t By fusion method. $ By Carius’ methodTHE CONSTITUENTS OF SOLBNUM ANGUSTIFOLIUM. 567solved in concentrated sulphuric acid, and the solution kept forsome time, a reddish-yellow, slightly fluorescent liquid is obtained.I n order to isolate solangustidine from its hydrochloride, aquantity of the latter was dissolved in alcohol, and the solutionmade alkaline by the addition of an alcoholic solution of sodiumethoxide. Water was then added, and the precipitated basecollected.As thus obtained, solangustidine was amorphous, andhad no definite melting point. When dry it formed a horn-likemass. It separated from dilute alcohol in amorphous granules, andall attempts to obtain it crystalline resulted in failure. It hadevidently suffered no change by tlie treatment with alkali, since itreadily regenerated tlie crystalline hydrochloride.Solangustidine Hydrobromide, Cz7H,,02N,HBr.-A quantity ofsolangustidine was dissolved in alcohol, and a solution of hydrogenbromide in glacial acetic acid added. The mixture was then con-centrated, when a colourless, crystalline solid separated. The latterwas dissolved in alcohol containing a little hydrogen bromide, andthe solution concentrated, when colourless, lustrous plates, whichmelted and decomposed a t 320°, separated from the boiling liquid.The hydrobromide is somewhat more soluble in alcohol than thecorresponding hydrochloride, but, like the latter, is quite insolublei n water :0.0892 gave 0.2132 CO, and 0.0749 H20.Cz7H,,0,N,HBr requires C = 65.6 ; H = 9.0 per cent.Solangustidin e Nitrate, C,7H,,0,N,HN03.-An alcoholic solutionof solangustidine was acidified with dilute nitric acid, after whichthe liquid was diluted with water until a turbidity was produced.The mixture was then warmed, and allowed t o cool slowly, whencolourless leaflets separated, which become brown a t 260° and meltand decompose a t 290O.The nitrate is practically insoluble inwater, but fairly readily soluble in hot, dilute alcohol :C=65*2; H=9*3.0'0947 gave 0.2362 CO, and 0.0831 H,O.C27H4302N,HN0, requires C = 68.0 ; H = 9.2 per cent.Solangustidine Sulphat e, (C,7H4,0,N)z,H,S04.-An alcoholicsolution of solangustidine was acidified with dilute sulphuric acid,when a white, amorphous powder separated.On boiling the mix-ture for some time the solid became crystalline, forming colourlessleaflets, which do not melt a t 330°, are very sparingly soluble inboiling alcohol, and insoluble in water :C=68*0; H=9*7.0.1938 * gave 0.0508 BaSO,. "SO, = 10.8.(C,7H4,02N)z,H,S0, requires "SO, = 10.4 per cent.* Dried at 130"568 TUTIN AND CLEWER:Solnngustidiiae p'crate was prepared by adding the requisiteamount of picric acid to a solution of the base in alcohol.Itformed yellow needles, which melted and decomposed a t 250O.Attempts were made to prepare the aurichloride and platini-chloride of solangustidine, but they resulted in failure, owing,apparently, to the fact that these derivatives are more readilysoluble than the corresponding hydrochloride.A cetylsolangustidiize, C,iH,202N*CO*CH,.-A quantity (2 grams)of solangustidine hydrochloride was boiled for one hour with aceticanhydride. When cool, the mixture was poured into ether, andthe ethereal solution shaken with aqueous sodium carbonate untilfree from acid. It was then dried and evaporated, and the residuecrystallised twice from ethyl acetate. Colourless, flattened needleswere then obtained, which melted a t 256O:0.1766,* on heating a t 130°, last 0.0032 H,O, which was quailti-0.0923 * gave 0-2530 CO, and 0-0820 HzO.0.3870 t in 21.38 of chloroform gave A t + 0'135O.C,,H,,O3N requires C = 76.5 ; H = 9.9 per cent.tatively reabsorbed on exposure to the air.H,O = 1-8.C=74.8; H=9*9.M.W. =491.0.0854 t ,, 0.2386 CO, ,, 0.0769 HZO. C=76.2; H=10.0.C,,H,,O,N,~H,O requires C = 75.0 ; H = 9.9 ; H20 = 1.9 per cent.M.W. = 455.The material conbained in the mother liquors from the acetyl-solangustidine was not homogeneous, and was found t o containunchanged solangustine. It yielded the pure acetyl derivative onmore prolonged acetylation.Attempts were made to prepare the hydrochloride of acetyl-solangustidine, and, although indications were obtained of theformation of such a compound, it was not found possible to isolateit. This was owing to the fact that the salts of the acetyl basedissociated with extreme readiness, and when crystallised fromalcohol, even in the presence of an excess of acid, they yield theoriginal acetyl compound.Acetylsolangustidine is remarkably stable towards alkalis, since,when boiled for several hours with alcoholic potassium hydroxide,i t is recovered unchanged.When, however, it is heated for a veryprolonged period with concentrated alcoholic potassium hydroxidei t slowly undergoes some change, but the amount of material avail-able was not sufficient to ascertain whether this resulted in theregeneration of solangustidine.When acetylsolangustidine is boiled for some hours with glacialacetic acid and concentrated hydrochloric acid, a yellow-coloured liquid is obtained, which exhibits a remarkably strong,* Air-dried substance..1- Dried at 130"THE CONSTITUENTS OF SOLANUhl ANGUSTIFOLIUM. 569fluorescence.of amorphous material.The reaction product, however, consisted onlyExamination of t h e Product (b).The product ( b ) (p. 563), which consisted of the material readilysoluble in cold, dry amyl alcohol, was of a dark brown, viscidnature, and nothing definite could be directly separated from it.It was dissolved in water, deprived of amyl akohol by means ofsteam, and then treated with sulphuric acid, when a quantity(2 grams) of rather impure solangustine sulphate was obtained,from which the pure salt could only with some difficulty beprepared.The acid filtrate from the crude sulphate, after being boiled,yielded to ether a small amount of quercetin. It was subsequentlymade alkaline with potassium hydroxide, and again boiled for sometime, when it yielded about 2 grams of 3 : 4-dihydroxycinnamicacid. The remainder of the product consisted only of resinousmaterial.The aqueous liquid (A), which had been extracted with amylalcohol, as above described, was kept for some time, when it gradu-ally deposited a further quantity (49 grams) of ruth.Afterfiltration, a portion of it (200 c.c.) was examined for the presenceof any further alkaloidal material. It was rendered alkaline withsodium carbonate, and extracted successively with ether, chloro-form, and amyl alcohol.The firstrmentioned solvent removed avery small amount of alkaloid, possessing a strong odour, Some-what resembling that of coniine, but the amount was insufficientf o r further examination. The chloroform and amyl alcoholremoved nothing.The remainder of the aqueous liquid (A), which amounted to4.5 litres, was concentrated somewhat under diminished pressure,and then treated with an excess of aqueous basic lead acetate.The resulting copious, yellow precipitate was collected and washed,after which it was suspended in water and decomposed by meansof hydrogen sulphide. The filtrate from the lead sulphide was thenevaporated under diminished pressure, when a dark brown, viscidproduct was obtained, from which nothing could be directlyseparated. This viscid, brown material was divided into two por-tions, one of which was heated for an hour with dilute sulphuricacid, but the resulting products were entirely amorphous.Theother portion was heated with aqueous potassium hydroxide in themanner previously described, when it yielded, in addition toamorphous products, a small amount of quercetin and a consider-able quantity of 3 : 4-dihydroxycinnamic acid570 TUTIN AND CLEWER:Isolation of 1-L4spuragir~e.A portion (about one-fifth) of the aqueous liquid (A), whichhad been treated with basic lead acetate, was slightly acidified withacetic acid, and then treated with a solution of mercuric nitratein dilute nitric acid until no further precipitate was produced.The precipitate was collected, washed, decomposed by means ofhydrogen sulphide, and the liquid filtered. The filtrate wasrendered slightly alkaline with ammonia, and then just acid withacetic acid, when it was concentrated under diminished pressureto a low bulk, The brown liquid so obtained was treated withanimal charcoal, after which, on keeping, it deposited a crystallinesubstance in the form of prisms. The latter was collected and re-crystallised from water, when it formed colourless prisms, meltingindefinitely a t 227-238O, and was identified as I-asparagine.Theamount obtained was about 0.25 gram, being equivalent to about0-02 per cent. of the air-dried plant'. (Found," H20=12*0.C,H,0,N2,H20 requires H20 = 12.0. Found,+ C = 36.5 ; H = 6.2.C,H,0,N2 requires C = 36.4 ; H = 6.1 per cent.)The remainder of the aqueous liquid (A) was deprived of leadby means of hydrogen sulphide, and concentrated under diminishedpressure t o a low bulk.The resulting syrup deposited no crystals,and no crystalline acetyl derivative could be prepared from it.It readily yielded d-phenylglucosazone (m. p. 212O), and thereforecontained a quantity of a sugar, probably consisting chiefly oflaevulose. It was carefully examined for the presence of rhamnose,but with a negative result.Examination of the Resilk ( B )The resin (B) was a soft, dark green mass, and amounted t o670 grams, being thus equivalent t o about 9.2 per cent. of theweight of the drug employed. It was dissolved in alcohol, mixedwith purified sawdust, and the thoroughly dried mixture extractedsuccessively in a large Soxhlet apparatus with light petroleum(b.p. 35-50°), ether, chloroform, ethyl acetate, and alcohol.Petroleum Extract of t?i,e Resilt.The petroleum extract of the resin was a dark green, fatty mass,and amounted to 540 grams. It was digested with about 2 litresof ether, and the mixture filtered, when a quantity (about 3 grams)* Air-dried substance. t Dried at 130"THE CONSTITUENTS OF SOLANUM ANGUSTIFOLIUM. 571of a solid was removed, which was examined in connexion with theurisaponifiable constituents.The ethereal filtrate was extracted with 10 per cent. hydrochloricacid, when a small quantity of a green, amorphous, alkaloidal pro-duct was removed. It possessed a strong, basic odour, but nothingcrystalline _could be obtained from it.The original ethereal solution was then extracted with aqueouspotassium hydroxide, when a quantity of a flocculent solidseparated. The latter was collected, when it proved to be thepotassium salt of a fatty acid, and was examined in connexion witha larger amount of a similar product obtained later.IsolcctioiL of n Pkytosteroliti, C33H5(i06.The alkaline, aqueous extract, which had been separated frointhe ether and solid material, as above described, was acidified andextracted with ether, when a quantity of a nearly black solidseparated, and was removed.Nothing crystalline could beobtained from it. The ethereal liquid was then shaken withaqueous potassium hydroxide, as before, when some neutralmaterial, which had been occluded during the first extraction withalkali, remained in the ether. The alkaline liquid was thenacidified and extracted with ether, during which operation aquantity (about 5 grams) of flocculent, green material separated,and was collected.This product was heated with acetic anhydride in the presenceof pyridine for half an hour, when, after concentration, colourlessleaflets separated.The latter substance, after recrystallisationfrom petroleum (b. p. 90-120O) and from alcohol, melted a t168-1 69O, and was identified as a tetra-acetylphytostrolin.(Found, C = 69.3 ; €I= 9.2.0.3885, made up to 20 C.C. with chloroform, gave a,-lOO’ in aA quantity of this acetyl derivative was hydrolysed by means ofalcoholic potassium hydroxide, when the resulting phytosterolin(phytosterol glucoside) was obtained.It separated from dilutepyridine in small, colourless crystals, melting a t 300O. (Found,C = 72.6 ; H = 10.5. Calc., C = 72.3 ; H = 10.2 per cent.)The benzoyl derivative was prepared by benzoylation in pyridinesolution. It crystallised from a mixture of chloroform and alcoholin colourless needles, melting a t 200O. (Found, C = 75-9 ; H = 7.8.Calc., C = 75.9 ; H = 7.5 per cent.)Calc., C = 68.7 ; H = 8.9 per cent.)2-dcm. tube, whence [a], - 25-7O.The ethereal solution containing the free, fatty acids, which hadbeen separated by filtration from the crude phytosterolin, as abov572 TUTIN AND CLEWER:described, was evaporated, and the dark green residue esterified bymeans of methyl alcohol and sulphuric acid.The resulting ester,dissolved in ether, was shaken with aqueous potassium hydroxide,when a considerable amount of dark green, phenolic resin was re-moved, from which nothing crystalline could be obtained. Theethereal solution was then dried and evaporated, when, after purify-ing the residual esters by distillation under diminished pressure,they were examined in connexion with a similar product obtainedfrom the combined acids, as described below.The ethereal solution of the neutral constibuents of the petroleumextract was evaporated, and the residue heated f o r two hours withan excess of alcoholic potassium hydroxide. Water was then added,and the mixture repeatedly extracted with ether.During thisoperation a quantity of a flocculent solid separated a t the junctureof the aqueous and ethereal layers. This was collected, when it wasfound t o consist of a mixture of the potassium salts of the higherfatty acids, and its examination will be described later.Zsola tion of Tria cont a n e, C,,H,, .The ethereal solution of the unsaponifiable material, which hadbeen separated from the alkaline, aqueous liquid and the potassiumsalt, as above described, was washed, dried, and evaporated. Theresidue, which amounted to 103 grams, was dissolved in alcohol,with the exception of a small amount of black, tarry material,which was discarded. On cooling the solution, a quantity (5 grams)of a solid separated, which was collected, and distilled underdiminished pressure.The distillate was crystallised twice f roniethyl acetate, when it formed lustrous, colourless leaflets, meltinga t 65'5O, and was identified as triacontane. (Found, C=85*1;H = 14.8. Calc., C =85.3 ; H = 14.7 per cent.)Isolation of a Phytosterol, C27H460.The alcoholic solution of the unsaponifiable material, from whichthe triacontane had been separated, was concentrated, and someethyl acetate and a little water added. On keeping this mixturefor some time a quantity (about 0.5 gram) of colourless leafletsseparated. This product had the properties of a phytosterol, andmelted a t 131°, but it did not appear to be homogeneous. It wasaccordingly converted into the acetyl derivative, which formedcolourless leaflets, melting a t 121°, and the latter crystallisedrepeatedly, both from alcohol and ethyl acetate.On regeneratingthe phytosterol and crystallising it, colourless plates were obtained,which were apparently homogeneous, and melted a t 134O THE CONSTITUENTS OF SOLANUM ANGIJSTIFOLIUM. 5730.2760," on heating a t 120°, lost 0.0138 H20.0,1029 I. gave 0.3160 C02 and 0.1120 H,O.H20=5*0.C=83.8; H=12'1.C,,H,,O,H,O requires H20 = 4.5 per cent.C2TH460 requires C = 83.9 ; H = 11.9 per cent.The liquid from which the crude phytosterol had been removedcontained a considerable quantity of a brown, sweebsmelling oil,from which no further crystalline material could be separated. Itwas examined for the presence of fatty alcohols by the phtlialicanhydride treatment, but with a negative result.Emtiiiticrtioit of t h e Fatty Acids.The nlkaliiie liquid from which the unsaponifiable materialhad been removed by means of ether was acidified and distilIedwith steam.This removed a small amount of a volatile acid havingan odour of valeric acid. The mixture was then extracted withether, when a small amount of phytosterolin separated, and wasremoved. The ethereal liquid was then dried and evaporated, andthe dark green residue esterified by means of methyl alcohol andsulphuric acid. The resulting methyl esters were then freed froma little unchanged acid and much chlorophyll by shaking theirethereal solution with aqueous potassium hydroxide, and then wash-ing i t with water, after which the liquid was dried and evaporated.The residue was then purified by distillation under diminishedpressure, when a quantity (94 grams) of methyl ester was obtained.This product was added to the esters of the free acids previouslymentioned, which amounted t o 118 grams, and the whole hydrolyseclby means of alcoholic potassium hydroxide.The resulting acidswere isolated, and separated into their saturated and unsaturatedcomponents by means of the lead salt, in the usual manner.The Unsaturated Acids.-These acids were converted into themethyl ester, which amounted to 163 grams, and the latter distilledseveral times under diminished pressure, when the following frac-tions were collected: i, Below 215O (16-5 grams); ii, 215-218O(33.9 grams); iii, 218-222O (73-0 grams); iv, 222-225O(16-2 grams)/20 mm.The iodine values of fractions i, ii, iii, and iv were respectively182.5, 200.7, 210.9, and 207.3.Fraction iii, on analysis, gaveC = 77.5 ; H = 11.2 per cent. (Methyl linolate requires C = 77.5 ;H = 11.5 per cent. ; I.V. = 172.7 ; and methyl linolenate requiresC = 78.1 ; H = 10.8 per cent. ; I.V. = 261.)It would therefore appear that the unsaturated acids consistedessentially of linolic and linoleiiic acids.* Air-dried substance. t Dried at 110"574 TUTIN AKD CLEWER:?‘he Satirrccted Futty Acids.-These acids amounted to 40 grams.They were mixed with the fatty acid (6 grams) obtained from thepreviously mentioned sparingly soluble potassium salts, and con-verted into the methyl ester.The latter was fractionally distilledseveral times under diminished pressure, when the following frac-tions were collected : i, Below 200O; ii, 200-205°; iii, 205-210O;iv, 210-215°; v, 215-225O; vi, 225-235O; vii, 235O+ /a0 mm.Fractions i and ii solidified on cooling, and were found to consistof methyl palmitate. They yielded palmitic acid, melting a t 63O.(Found, C=74.9; H=12*5.Fractions iii, iv, and v all yielded impure products, whichappeared to consist of mixtures of palmitic and stearic acids.(Found, C=75.6; H=12.6. Calc. for C,,H320,, C=75*0; H=12.5;for C,,H,,O,, C=76*1; H=12-7 per cent.)Calc., C=75*0; H=12.5 per cent.)Isolation of Cluytziiuic Acid, C,,H4,0,.The above-mentioned fraction vi of the methyl esters partlysolidified.On hydrolysis it yielded an acid, which was crystallisedmany times from alcohol, from acetic acid, and from ethyl acetate,when it melted constantly a t 69O. On being compared directlywith cluytinic acid obtained from C’luyt~ia sirnilis (T,, 1912, 101,2226) and from hops (T., 1913, 103, 1283), it was found t o beidentical with both these preparations. I n order further to estab-lish its identity, however, it was converted into its methyl ester.The latter formed colourless needles, melting a t 47O, and wasidentical with the corresponding derivative prepared from thecluytinic acid of hops (loc. cit.). (Found, C=77.5; H=13.1.C22H4402 requires C = 77.6 ; H = 12.9 per cent.)Fraction vii of the esters, together with the residues of highboiling point which remained in the flasks after the fractionaldistillations, was redistilled, when it solidified on cooling. Oncrystallisation from ethyl acetate it yielded methyl cerotate, meltring a t 60°.On hydrolysis, the latter gave cerotic acid, melting a t78’5O. Calc., C = 79.0 ; H = 1 3 2 percent.)(Found, C= 78.9 ; H = 13.2.Ethereal Extract of the Resitt.This extract of the resin was dark green, and amounted t o46 grams. A portion of it (3 grams) was very sparingly soluble inether, and formed a nearly black powder. The latter was extractedin a Soxhlet apparatus for a short time with ethyl acetate, whenabout 1 gram of crude phytosterolin remained undissolved. Theethyl acetate extract was evaporated, and the residue distilled underdiminished pressure, when, on crystallisation from ethyl acetate, iTHE CONSTITUENTS OF SOLAKUM ANGUSTIFOLIUM.575formed colourless leaflets, meltiiig a t 85O. This product, togetherwith a further amount of similar material, obtained as describedbelow, was found t o consist of a higher fatty acid. It was con-verted into the methyl ester, which formed colourless leaflets, melt-ing constan6ly a t 71O. On hydrolysing the latter, the original acidwas regenerated, and, on crystallisation from acetic acid, its melt-ing point remained unchanged, a t 8 5 O :0.1032 gave 0.3001 CO, and 0.1242 H20. C=79*3; H=13-4.0.0602 ,, 0.1748 CO, ,, 0'0715 H20. C=79*2; H=13.3.C2,H,02 requires C = 79.2 ; H = 13.2 per cent.CNH6002 ,, C=79.6; H=13*2 per cent.It would thus appear that this higher fatty acid was eithermelissic acid or a lower homologue of the latter.The low meltingpoints of the acid and its ester would point to the latter conclusionbeing the more correct.Ths ethereal solution of the more readily soluble portion of theethereal extract of the resin yielded a small amount of green,amorphous, alkaloidal material when extracted with hydrochloricacid. On subsequently shaking it with aqueous sodium carbonatenothing was removed. When, however, the ethereal solution wasshaken with aqueous potassium hydroxide, the greater portion ofthe dissolved material was removed from the ether, a portion of itforming an insoluble potassium salt, which was collected. Thelatter proved to be the salt of the above-described higher fatty acid.The material dissolved by the alkali, which represented thegreater part of the ether extract of the resin, consisted of a darkgreen, phenolic resin, from which nothing definite could beobtained.Chloroform, Ethyl Acetate, and Ak0h01 Extracts of the Resin.The chloroform, ethyl acetate, and alcohol extracts of the resinamounted to 36, 7, and 33 grams respectively.They all consistedof dark green, amorphous resins, from which nothing definite couldbe obtained, with the exception of a small amount of solangustine.The latter was isolated in the form of its sulphate from the alcoholextract of the resin.Summary and Physiological Tests.The material employed in this investigation consisted of theleaves, twigs, and flowers of Solanum angustifolium, Ruiz et Pavon,which had been obtained from Peru,For the purpose of a complete examination, 30.92 kilograms o576 MORRELL AN b BURGEN :the dried inaterial were employed. This material was ground,completely extracted with hot alcoliol, and the resulting extractdistilled in a current of steam.From the portion of the extract which was soluble in water therewere isolated the following substances : (i) Quercetin ; (ii) rutin,C;7H300,6,3H20 ; (iii) I-asparagine ; (iv) a new gluco-alkaloid,solungus tine, C,,H,O,N,H,O. On hydrolysis, solangustine yields~solangustidine, C27H430$T, together with 1 molecule of dextrose.The aqueous liquid also contained small amounts of amorphous,alkaloidal material, and a considerable quantity of a sugar, whichapparently was lzvulose, together with viscid, amorphous products.Some of the latter yielded quercetin and 3 : 4-dihydroxycinnamicacid on treatment with alkalis.The portion of the original extract which was insoluble in wateryielded, in addition to much chlorophyll and resinous material, thefollowing compounds : (i) Triacontane, c30HG2 ; (ii) a phytosterol,c&4@ ; (iii) a phytosterolin (phytosterol glucoside), C33H560ri ;(iv) palmitic, stearic, cluytinic, and cerotic acids, together with amixture of linolic and linoleiiic acids. It furthermore gave a smallamount of the above-mentioned new gluco-alkaloid, solangustine,and a higher fatty acid, which was either melissic acid, C",OHGOO,,or a lower homologue, C,,H,,O,.The following physiological tests were conducted a t the Well-come Physiological Research Laboratories by Dr. H. H. Dale, towhom our thanks are due.An amount of the total alcoholic extract, equivalent to 3.5 gramsof the drug, and 0.48 gram of solangustine, were separately adminis-tered to a dog, but no perceptible effect of any kind resulted. Theamorphous alkaloidal material, which occurred to a small extent i nthe plant, yielded a similarly negative result.THE WELLCOME CHEMICAL RES~M:CH LABORATORIES,LONDON, E.C

ISSN:0368-1645    

DOI:10.1039/CT9140500559

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

576 MORRELL AN b BURGEN :LVIIL-Tlze Polymerisation of Cyunamide.By GEORGE FRANCIS MORRELL and PETER BURGEN.As is well known, cyanamide undergoes, according to conditions,more or less rapid polymerisation into dicyanodiamide, yet thekinetics of the reaction, and the precise conditions under whichit occurs, do not seem to have been investigated. Since a t thepresent time cyanamide and its salts are of importance as fertilisers,a still greater interest attaches t o this subject, and this investigaTHZ POLYMERISATfON OF CYANAMIDE. 577tion was undertaken with a view of obtaining quantitative data as t othe course of the polymerisation, and tlie'influence of catalysts on it.The formation of dicyanodiamide during tlie evaporation ofaqueous solutions of cyanamide was first recorded by Beilstein andGeuther (Annalen, 1858, 108, 99; 1862, 123, 241), and later byDreschel (J.pr. Chem., 1875, [ii], 11, 298), and the influence ofammonia in accelerating the change by Haag (Annalen, 1862, 122,22). Beilstein and Geuther (Zoc. tit.) also make the statementthat a specimen of cyanamide which had been kept f o r severalmonths no longer gave the characteristic reactions for this sub-stance. Baumann (Ber., 1873, 6, 1373), studying the formationof carbamide by the action of mineral acids on cyanamide, observedthat dicyanodiamide was produced as a by-product, and that themore dilute the acid the greater the proportion of dicyanodiamideobtained. He also made the observation that alkali hydroxidesaccelerated the polymerisation, as Haag had previously observed inthe case of ammonia.Whilst the present investigation has in the main confirmed thequalitative statements of these early investigators, it has in itsquantitative aspect brought out the fact, which from statements inbooks of reference one would scarcely have expected, that the poly-nierisation of cyanamide in aqueous solution of even 5137-concentra-tion, and a t elevated temperatures, proceeds with considerablesluggishness, and that, on the other hand, an enormous acceleratinginfluence is exerted by acids and alkalis, even if present inextremely minute quantities.It was found, moreover, that in nocase did the polymerisation proceed as a bimolecular reaction asexpressed by the equation:and evidence was forthcoming that the change resulting in theformation of dicyanodiamide is ionic in character, although a singleexplanation, which wiI1 cover the acceIerating action of both acidsand bases, cannot be put forward.NHZ-CN + NH2*CN = CzH4N4,The Deter m i t i at io n of Cyaiza m ide.I n order to follow quantitatively the course of the polymerisa-tion, it was first of all necessary to find some trustworthy, and a tthe same time rapid, method of determining the amount ofcyanamide present in the solution from time to time.A numberof processes are to be found in the literature,* all involving as their* The original papers dealing with the metbods of deterniination used in thiswork are as folloms : Perotti, Cazzetta, 1905, 35, ii, 228 ; Curo, Zeitsch. angew.Chem., 1910, 23, 2407; Monnier, Cham.&it., 1911, 35, 601 ; Stutzer, Chem. Zeit.,1911, 35, 694 ; and Kappen, Cl2eut. Zeit., 1911. 35, 950578 MORRELL AND BURGEN :main principle the preciRitation of silver cyanamide by means ofan ammoniacal silver solution. With regard, however, to the con-ditions of precipitation and the method t o be adopted for the sub-sequent determination of the cyanamide, much diversity of opinionexists and conflicting results have been put forward, but it appearscertain that concordant results cannot be obtained without strictadherence to specified conditions, owing t o the variable compositionof the silver cyanamide precipitated in varying circumstances. Aconcensus of opinion favours a Kjeldahl determination of thenitrogen in the silver cyanamide precipitate as being, if not abso-lutely accurate, a t least more free from error than titration methods,and uninfluenced by the variability in composition of the precipi-tate.I n view of the absence of any definite information as to themagnitude of possible error involved by the much more easilycarried out titration methods, comparative experiments have beenmade with solutions of partly polymerised cyanamide of variousstrengths to ascertain the conditions necessary for obtaining con-cordant results, and the degree of accuracy attainable.The determinations were first carried out using solutions whichvaried in cyanamide content from normal to half-normal, and con-taining more and more dicyanodiamide as the, percentage of cyan-amide sank.Five C.C. of the solution were measured out, dilutedto 50 c.c., and 20 C.C. of tllis diluted solution used for each deter-mination. Caro’s method, namely, precipitation with aminoniacalsilver acetate, and determination of nitrogen in the precipitate byKjeldahl’s method, was compared with that finally adopted byKappen, namely, the addition of a known excess of ammoniacalsilver solution and titration of the filtrate, and washings withammoilium thiocyanate. The results are shown in the followingtable, the figures referring to 20 C.C. of the diluted solution, or2 C.C. of the original:AT/ 10-HydrochloricN/10-Ammoniacal X/lO-Thiocyanatc N/lO-Silver used acid requiredsilver added. for back titration.for NK-CN. for Kjeldahl.1. 40 C.C. 20.9 C.C. 19-1 C.C. 19.2 C.C.21-3 ,) 18.7 ), 18.7 ,,2. {2 :: 17-8 ,) 18.2 ), 18.6 ,,3.4* {:; :: 21.6 ,, 10-4 ), 10.7 ,,22-5 )) 17-5 ,, -29.2 ,, 10.8 ,, 10.8 ,,- 140 9 ) 134 9 ) 17-0 ,) 17.0 ))The table shows a t once the effect on the titration values of theaddition of a greater o r less excess of silver, the precipitate pro-duced in the former case containing a larger proportion of silverto cyanamide radicle than in the latter. This, according to Stutzer(Zoc. c i f . ) , is due to the formation of double and basic compoundsTHE POLYMERISATION OF CYANAMIDE. 579The Kjeldahl values, however, appear to be practically unaffected,and hence more trustworthy, This is in agreement with Car0 (Eoc.cit.), who states that although the precipitate may vary in com-position, it contains all the nitrogen of the cyanamide, which ityields as ammonia by the Kjeldahl process.Under the above conditions, then, the titration method admitsof considerable error; but it was found by further experiment thatif the precipitation was conducted in extremely dilute solution, avariation in the excess of silver within reasonable limits producedscarcely any measurable difference in the titration results.Themethod finally adopted was therefore as follows: The solutionunder test was rapidly cooled, 5 C.C. were measured out with apipette and diluted to 50 c.c., of which 20 C.C. were taken for eachdetermination. Before precipitation, however, it was again dilutedwith about 100 C.C.of water, and a measured excess of AT/lO-silversolution, also preferably somewlat diluted, and containing about2 per cent. of ammonia, was then added. After remaining forabout thirty minutes, for the very finely divided precipitate t ocoagulate, it was filtered through special '( barium sulphate " filterpaper, and washed first with weak ammonia water, and then withpure water until the washings were free from silver and ammonia.The excess of silver in the acidified filtrate and washings was thendetermined by titration with standard ammonium thiocyanate.The appended table shows the results obtained by the titrationscompared, where necessary, with the Kjeldahl determination on theprecipitate :N/10-Ammoniacalsilver added.{ ;: c;p'{;: ::{:: ::{E ::40 ,, {:; fiN/lO-HydrochloricN/1 O-Thiocyanate N/10- Silver used acid requiredfor back titration.for cyanamide. for Kjddahl.20.60 C.C. 19.40 C.C. 19.30 C.C.10.80 ,, 19.20 ,, 19-30 ,,11.15 ,, 18-85 ,,21-15 ,) 18-85 ,, -20-75 ,, 19-25 ,, -10.80 ,, 19.20 ,, -24.30 ,, 15.70 ,, -10.35 ,, 15.65 )) -29-00 ,, 11-00 ,, 10.50 ,,29.10 ,, 10.90 ,, -13-50 ,, 10.50 ,, 10.40 ,,10.40 ,) - 13.60 ,,30-35 ,) 9.65 ,, 9.35 ),10.70 ,, 9.30 ,, 9-20 ,,-From the results of 1, 2, 3, and 4 it is evident that the titrationmethod can be relied on if carried out as above described. Deter-minations 5 and 6 show, however, that if the excess of silver addedis very great, that ig of the order of four times the amoGnt theo-VOL.cv. Q 580 MOliRELL AND BURGEN :retically required for the precipitation, then the results begin tovary; but a determination of nitrogen in the precipitate still givesconcordant results, agreeing well with the lower titration reading,where only a moderate excess of silver was employed. Hence, inthe experiments about to be described, in every case where theinitial and final values of cyanamide were widely divergent, a p r eliminary series of experiments was made, precipitating throughoutwith the same volume of silver solution. A second series was thenconducted, readings being taken a t the same intervals as before,and a volume of silver added which was just about double theamount found to be required for the precipitation in the pre-liminary series.I n this way the addition of an excessive proportionof silver was avoided.The Polymerisation of CyanQmide in Aqueous Solution.The figures given refer, as before, to 2 C.C. of the original un-(a) Solution maintained a t looo in a boiling-water bath:diluted solution.N / 10-SilverprecipitatedTime in hours. N/lO-Silver added. by cyanamide.0 40 C.C. 19.30 C.C.1 40 ,, 19-20 y y4 40 Y Y 18-85 ),14 26 ,Y 13.00 ,y19 24 YY 10.45 ,)( b ) Solution gently boiled over wire-gauze :Time in hours,0123591523N/10-Silver added.40 C.C.40 Y Y40 Y Y40 Y Y40 9 940 Y Y40 Y Y40 y7N / 1 O-Silverprecipitatedby cyanamide.19.40 C.C.19.20 ,)18-30 y,17-30 ,,15.35 y y12.10 ,)8-60 ,)5.55 ,)( c ) Solution gently boiled over wire-gauze :Time in hours.026101216204N/lO-Silver added.40 C.C.30 y y30 9)20 ¶ Y16 Y Y40 y740 y yNI10-Silverprecipitatedby cyanamide.19-35 C.C.19.00 y y15-50 ,)12-15 y y10.50 ),9.00 ,,7.35 ,,K = l/t log, a/a - x.0.002e0-003e0.016e0.0 19eK = l/t log, a/a - x.0.0045e0-020e0.024e0-026e0-026e0.024e0.024eK = l/t log, ala - x.0-004e0.022e0-026e0-028e0-018e0.019THE POLYMERISATION OE‘ CYANAXIDE.581(d) Solution maintained a t 7 5 O in a thermostat:N / 1 O-SilverprecipitatedTime in hours. N/lO-Silver added. by cyanamide. K =zit.0 160 C.C. 90.60 C.C.10 160 ,) 81-25 ,, 0.02325 160 ,. 67.40 ,, 0.02015 160 9 , 76-35 ,, 0-02420 160 Y 9 71-40 ,, 0.025An examination of these results brings to light several remark-able facts.A t the commencement of the heating, in every case butlittle effect on the titration value was produced, even after theexpiration of from one to two hours, and in the case of series (a),where the solution was not actually boiled, but a water-bath wasused to effect the heating, the period of comparative stabiIity con-tinued f o r some four hours. During the initial stages of the secondperiod, the reaction is characterised by attaining its maximumobserved velocity, a t which it proceeds almost constant for aboutten hours in series (b), ( c ) , and (d), and still longer in series (a).Equal amounts of cyanamide are then polymerised in equalintervals of time, as may be seen a t a glance from the second andthree following readings in each table, and also from the ascendingvalues of “K,” calculated for a unimolecular reaction.A distinctretardation is then observable, but the figures obtained do not agreewell with the velocity of a unimolecular reaction, and are certainlyin even worse agreement with a bimolecular reaction.Since the results of each series of experiments are substantiallythe same, and the method of determination has been shown to betrustworthy, an explanation of the apparently erratic figures mustbe sought in the complicated nature of the reaction itself. Theinitial stability of cyanamide in pure water must be conceded asbeing characteristic of the pure substance.I n order firmly t oestablish this, a further series of experiments was undertaken, usingcarefully recrystallised cyanamide dissolved in distilled water, andheated a t looo in a water-bath in a flask of hard resistance glassprovided with an efficient reflux condenser. The cyanamide wasfound even a t this high temperature to be quite stable in itstitration-value during three hours’ heating :Time in hours. N! 10-Silver nitrate required.0 19-85 C.C.1 29-85 ,,2 19.95 ,,3 19.80 ,,The subsequent acceleration in the rate of polymerisationsuggests, in the light of our knowledge regarding the acceleratinginfluence of bases, the gradual contamination of the solution withQ Q '582 MORRELL AND BURGEN:basic constituents dissolved out of the glass.Such contaminationwould naturally be more rapid in solutions which were actuallyboiled, but the maximum of contamination would eventually bethe same in every case a t the same temperature. The experimentshave confirmed this, for in series ( b ) and (c) the period of stabilityis shorter than in series (a). Yet the final velocity-constantsattained are all' of the same order, series (a) gradually rising to0.019 after nineteen hours, ( 6 ) and (c) being a t that time 0.024and 0.019 respectively. This, furthermore, suggests a reason whythe observed rate of polymerisation in the first stages does notdecrease, the loss in reacting substances being accidentally justcompensated by the additional small quantity of catalyst still enter-ing the solution a t that stage.The linear character of certainperiods of the reaction would on this hypothesis be explained away,but the absence of the expected bimolecular reaction,NH,*CN + NH,*CN = C2H4N4,and the general indication of a unimolecular reaction, still demandsexplanation.An ionic theory of the polymerisation suggests itself as feasible,an ion maintained in the solution in constant concentration reactring with some other constituent to form dicyanodiamide ordicyanodiamide ion. Further information on the catalytic actionof bases was now found to be necessary in order to put a theory ofthis nature to the test. First of all, however, a series of experi-ments was made to demonstrate the influence of the solvent. Ifone or both the reacting substances were ions, either derived fromthe dissociation of cyanamide as an acid, or generated by thepresence of a base, then the use of a less powerfully ionisingsolvent, such as ethyl alcohol, would be expected t o depress therate of polymerisation.This expectation was borne out by experi-ment, as the following table shows:Polymerisation in Alcoholic Solution.Approximately 5N-alcoholic solution maintained a t 75O in athermostat:Time in hours.0510152026N/lO-Silver nitrate required for 0.5 O.C.22-50 C.C.22.45 ,,22-35 ,,22-15 ,,22-16 ,,22-15 ,,A comparison of this series with series (d) above, which wascarried out in aqueous solution of about the same strength underotherwise absolutely similar conditions, shows that whereas iTHE POLYMERISATION OF CYANAMIDE. 583alcohol the cyanamide was almost stable for twenty-five hours, inaqueous solution it had polymerised in the same period to theextent of 25 per cent. Only two explanations appear to hepossible, both are in accord with the ionic theory of the reaction,and both are probably factors in producing the final result.First,the hot alcohol has probably extracted less catalytic matter fromthe glass than the hot water, and, secondly, that which has beenextracted has generated fewer ions in alcoholic solution fromcyanamide, less cyanamidion, that is, than the same amount inaqueous solution.Polymerisation in the Presence of Bases.In the first series of experiments the accelerating action ofammonia was studied and found to be exceedingly pronounced,even when added in minute quantities.So, for example, in theexperiments given in the first table below, where cyanamide washeated a t looo in N/70-ammonia; the 50 C.C. of solution used con-tained only one drop of concentrated solution of ammonia, but yeta t the end of four hours 20 per cent. of the cyanamide had poly-merised, whereas in pure aqueous solution the amount changed inthat time was inappreciable.When an ammonia solution of ten times the above strength wasemployed, polymerisation was almost complete in one and a-halfhours, and a qualitative test made after three hours entirely failedto give the reaction of cyanamide a t all, showing, therefore, thatno condition of equilibrium is attained, but that the formation ofdicyanodiamide proceeds to completion.( a ) Cyanamide heated in a water-bath a t looo in N/70-ammonia :N / 10-Silver nitrate pre-cipitated by 2 C.C.Time in hours.of solution. K = l(t log, aJa -x.0.0 17.5 C.C.0.5 16.0 ,, 0.078e1.0 14.9 ,, 0.062e1-5 14.0 ,, 0.054e2.5 12.6 :, 0.046e4.5 10.6 ,, 0.038e8.5 8.4 9 9 0.025e( b ) Cyanamide heated in a water-bath a t looo in N/7-ammonia:N 10-Silver nitrate precipitatedby 2 C.C. of solution. Time in hours.0.0 18.30 C.C.0.5 6-75 ,,1.0 3-65 ,,1-6 1.40 ,,3.0 0.00 ,,Ammonia is undoubtedly lost during the prolonged heating in-volved in these experiments. The rate of reaction, therefore584 MORRELL AND RURGEN :diminishes more rapidly than it would if the ammonia content couldbe kept constant throughout, and K , which has been calculatedfor series (a) on the unimolecular formula, eventually sinks t o avalue 0.025e, of the same order as that obtained with pure aqueoussolutions of cyanamide.These results led us to study the actionof a non-volatile alkali, and for this purpose sodium hydroxide wasselected. Cyanamide was dissolved in solutions of the base ofwidely varying strengths, from .ii/800 (1 in 20,000) to 2iV (6 in!12-5), heated a t looc, and determinations made in the usual way,with the following results:( c ) Cyanamide heated in N/800-sodium hydroxide solution (1 in20,000) a t looo in a water-bath:Time in hours.0123456N/lO-Silver nitrate pre-cipitated by 2 C.C.of eolution.28-30 C.C.K = l/t log, ala-25.00 ,, 0.054e22-30 ,, 0.049e18.40 ,, 0.038e16.90 ,, 0.037e15.65 ,, 0.033e20.10 ,, 0-045e-X.( d ) Cyanamide heated in N/400-sodium hydroxide solution (1 in10,000) a t looo in a water-bath:N / 10- Silver nitrateN / 1 O-Silver precipitatedTime in hours.nitrate added. by 2 C.C. K = l/t log, a/a - x.1 18 Y , 7.10 ,, 0-115e2 16 9 , 5.70 ?, 0.095e4.25 ,, 0.053e 4 12 ? f0 20 C.C. 9.25 C.C.3 14 ?? 4.80 ,, 0-076~( e ) Cyanamide heated in N / 70-sodium hydroxide solution (1 in1750) a t looo.(1) Preliminary experiment precipitating throughout with 40 C.C.of N / 10-ammoniacal silver nitrate :Time in minutes.0153060Nt10-Silver nitrate precipitatedby 2 C.C. of solution.19-95 C.C.14.50 ,,10-80 ,,6.30 ?,(2) Confirmatory experiment precipitating with decreasingquantities of silver nitrate proportional t’o the amount of unchangedcyanamide present, as explained in the section on the “Determina-tion of Cyanamide ” THE POLYMERIS ATION OF CYANAMIDE.585N/ 10- SilverTime in minutes. nitrate precipitated. K = l/t log, a/a -x.15 12.8 ,) 0-621e0.593e 30 9-1 9 , 45 6.6 9 9 0.558e60 5.0 ,, 0.482e0 18.3 C.C.( f ) Cyanamide heated in N/4-sodium hydroxide solution a t looo.The solution a t the commencement was approximately normal withrespect to cyanamide.(1) Preliminary experiment as above.Time in minutes. N/lO-Silver nitratme precipitated.0 18-3 C.C.15 8.3 1;30 6.1 1 ,45 4.7 9 )60 3.7 s,(2) Confirmatory experiment as above.N/lO-Silver nitrateTime in minutes.precipitated. K = l/t loge a/a-x.15 6-70 ,, 1.736e30 4-75 ,, 0.603e46 3.70 ,, 0.434e60 3-00 ,, 0.364e0 18-25 C.C.(9) Cyanamide (approximately normal solution) heated in(Approximately the com- N / 2-sodium hydroxide solution a t looo.pound NaHN.CN.)(1) Preliminary experiment.Time in minutes.0163060N/lO-Silver nitrate precipitated.18.7 C.C.13.0 ,,9.3 9,5.2 9 ,(2) Confirmatory experiment.N / 10-SilverTime in minutes. nitrRte precipitated.30 8.5 #,K = l/t loge ala - x.0 18-4 C.O.15 12.1 ,, 0.728e0- 6 14e46 6.1 ,* 0-576e60 4.5 #9 0.528e(h) Cyanamide (approximately normal solution) heated inN-sodium hydroxide solution a t looo586 MORRELL AND BURGEX :(1) Preliminary experiment.Time in minutes.0153060N/lO-Silver nitrate precipitated.18.95 C.C.13-60 ,,10.10 ,,6.20 ,.(2) Confirmatory experiment.N/lO-SilverTime in minutes.nitrate precipitated.15 13-60 ,,K = l/t log, a/a - x.0 18.40 C.C.0.525e30 9.90 ,, 0.551e45 7.25 ,, 0.541e60 5.25 ,, 0.560eFrom the above six series of experiments several important factsare a t once obvious. Using equivalent quantities of ammonia andsodium hydroxide (series a and e), the velocity is vastly greaterin the latter case than in the former. On the ionic theory of thereaction, this follows a t once from the fact that the stronger basegenerates a greater concentration of cyanamidion than the equiva-lent amount of the weaker base ammonia.Approximately normal solutions of cyanamide being taken inevery case, the accelerating influence of the base has increased asits concentration rose from N / S O O to N / 4 , and, moreover, the in-crease in the more dilute solutions has been roughly proportionalt o the amount of base present.This will be seen by a comparisonof the initial velocity-constants :Concentration of sodium hydroxide. Velocity-constant .1 in 20,000 0-054e1 ,, 10,000 0-115e1 ,, 1,760 3.621eThe increase in concentration of cyanamidion in dilute sodiumhydroxide solution will also be approximately proportional to theincrease in concentration of hydroxide, according to the equilibriaH,N*CN + NaOH NaHN-CN + H,OI! Na- + H”*CNThen, with regard to the actual courses of the reactions, it willbe seen that although in the three cases just mentioned “R” onthe unimolecular formula is not constant, but gradually decreases,yet the values approximate much more closely on this formula thanon the bimolecular equation. For a purely unimolecular reactionwe should haveH,N*CN + H’N*CN = C,N,H’,THE POLYMERISATION OF CYANAMIDE.587the ion H’N-CN being assumed of constant concentration. I nactual fact?, hwever, cyanamidion is not present in quite constantconcentration, because although the small amount of sodiumhydroxide is constant, yet as the reaction proceeds more and moreof this base is shared by the dicyanodiamide produced. The ionH’N-CN does not, however, decrease a t anything like the same rateas does cyanamide ; if it did, the reaction should appear bimolecular.Apart altogether from the minor question of differences in thedegree of hydrolysis of sodium cyanamide and sodium dicyano-diamide, it is obvious that since the molecular concentration ofdicyanodiamide is only one-half that of the molecular concentrationof the cyanamide from which it was produced, and since both aredissociated primarily as monobasic acids, a larger proportion ofsodium hydroxide will be available for the generation of cyan-amidion than if each dicyanodiamide molecule had demanded asmuch as did the two molecules of cyanamide of which it is com-posed. Hence thk net result is a reaction the rate of whichdecreases more rapidly than a unimolecular, and more slowly thana bimolecular, reaction, which condition is fulfilled by the figuresobtained.The next feature to be considered is the remarkable fact thatwhen the concentration of sodium hydroxide has been increased toN / 4 , the reaction has its maximum observed velocity, the furtherincrease in concentration producing a retarding effect.At thisconcentration half the cyanamide will have been converted intoits sodium compound, which for simplicity’s sake we may imagineas being completely dissociated into Na’ and NH’*CN. The otherhalf of the cyanamide will remain undissociated, and this is pre-cisely the conditions, according to the theory, for the maximumvelocity, each of the reacting masses a t the initial stage havingequal concentrations,NH,*CN + NH’*CN = C2NkH’3.This, of course, can only momentarily be the condition, for as thereaction proceeds more and more base is set free to react with non-ionised cyanamide, until in the final stages there should be nearlysufficient sodium hydroxide to ionise both the dicyanodiamideformed and the small amount of cyanamide remaining.Thisremoval of undissociated substance corresponds with the rapid fallin velocity shown in series (f).Passing on to the final series, (h), with 8-sodium hydroxide, itwill be seen that the reaction now gives almost constant valuesfor K on the unimolecular formula, and, moreover, that it is analmost exactly similar reaction to series (e), where N / 70-sodiumhydroxide was used. The velocity-constants are almost identica588 MORRELL AND BUHGEN :in value, and if the curves are plotted they run almost exactlyparallel t o one another throughout their length.The conditionshere are much more complicated than when very dilute sodiumhydroxide was used. The solution during the reaction containsever-varying amounts of sodium cyanamide, sodium dicyanodiamide,and free sodium hydroxide, and, as the dilution is not great, thenature and exbent of dissociation and hydrolysis must also be factorsin the case. Comparing with series (e), it is probable that herematters are reversed, cyanamidion present initially in large amountcorresponding with undissociated cyanamide in that experiment,and undissociated sodium cyanamide, or cyanamide produced byhydrolysis, present in very small amount, and by compensatinginfluences held a t fairly constant concentration, corresponding withthe cyanamidion in series (e).Polymerisation in Presence of Acids.An ionic theory appears to explain the accelerating influence ofbases, but it is difficult t o see how the e'qually powerful acceleratingeffect of acids can be brought into harmony with the same theory.The addition of a strong acid to cyanamide solutions would resultin the practical removal of even the small amount of cyanamidionoriginally present.Yet this undissociated substance in the presenceof dilute sulphuric acid rapidly polymerises, when warmed, t odicyanodiamide. Hydrolytic side reactions are, however, in thiscase possible, the more concentrated the acid the greater the amountof carbamide produced (Baumann, Zoc.cit.), and in all circum-stances the dicyanodiamide is also hydrolysed to dicyanodiamidine(compare Lidholm, Ber., 1913, 46, 156). This latter substance isa fairly strong base, so that when only a small quantity of acid wasused the solution became after a time quite neutral, and theaccelerating influence of the free acid on the polymerisation therebyceased. When a larger quantity of sulphuric acid was employed( N / 10-solution) the velocity of polymerisation became so muchgreater than that of the subsequent hydrolysis that a t the end ofhalf an hour the solution was still acid, and gave but the slighestreaction for cyanamide with ammoniacal silver nitrate.Cyanamide heated in N / 70-sulphuric acid a t looo :0 19-00 c c.Time in minutes.N/lO-Silver nitrate precipitated by 2 C.C.15 16.45 ,,30 15-10 ,,60 14.40 ,,120 12-65 ,,A t the expiration of 120 minutes the solution had become neutralto litmus paperTHE POLYMERISATLON OF CYANAMIDE. 589Experiments on the Stability of Cyanamide at the OrdinaryTempera tu(r e.Accurate data as to the keeping powers of cyanamide a t theordinary temperature do not seem to be available in the previousliterature. There is only the statement of Beilstein and Geuther(Zoc. cit.), who assert that a sample kept for several months failedto give the reactions of cyanamide. Experiments were thereforemade with two 10 per cent. solutions, one kept in the dark, andthe other in ordinary diffused daylight a t summer temperatures,and also with a sample of the pure solid substance kept for thecomplete exclusion of moisture in a desiccator.The analyticalresults obtained showed that the admission or exclusion of lighthad no appreciable influence on the polymerisation; that the solidwas more stable than the dissolved substance, but that the stabilityof both was of an order quite a t variance with Beilstein andGeuther’s observation. After keeping for six months, in fact,only 8.9 per cent. of the solid was found to have changed, whilstin 10 per cent. solution nearly 35 per cent. of the dissolved cyan-amide had disappeared. The actual figures were as follows:N/lO-Ammoniacal silver nitrate requiredFor 0.5 C.C. For 0-5 C.C. For 0.1 gramof solution of solution of solid0 41.0 V.C. 40-8 C.C. 47-0 C.C.1 40.1 ,, 39.8 ,, 46.5 ,,6 26.9 ,, 27.0 ,, 42.8 ,,f n \Time in months. in daylight. in the dark. subatanw.The stability of the sodium salt a t the ordinary temperature hasnot been accurately investigated, but it has been noticed duringthe preparation of cyanamide from the commercial sodium cyan-amide, supplied by Kahlbaum, that very different yields have con-sistently been obtained from different samples, 50 grams of thecommercial product yielding in the poorest samples as little as5 grams of cyanamide, and as much as 14 grams from the best.This variation is quite possibly due t o the greater or less facilitiesfor polymerisation which have been allowed during the process ofmanufacture, for since the sodium salt in solution polymerises muchmore rapidly than the free cyanamide itself, any undue heat appliedduring the concentration of the mother liquors must inevitablyresult in an extensive amount of polymerisation.NoTE.-since the above paper was read a communication byGrube and Kriiger (Zeitsch. physikal. Qhem., 1913, 86, 65) hasappeared, which confirms from a somewhat different point of viewsome of the results arrived a t in this investigation.THR SIR JOHN CAS@ TECHNICAL INflTITUTIF,LONDON, E.C

ISSN:0368-1645    

DOI:10.1039/CT9140500576

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

590 PURVIS: THE ABSORPTION SPECTRA OF THE VAPOURSL1X.-The Absorption Spectra of th,e Vapours andSolutions of Various Substances Containing TwoBenzene Nuclei.By JOHN EDWARD PURVIS.THE absorption spectra of the vapours of many benzene derivativescontaining one benzene nucleus have been described by the authorin previous communications. This communication gives an accountof the absorption phenomena of the vapours and solutions of variouscompounds containing two benzene nuclei, t o ascertain (1) how farthe vibrations of the molecule, and of the vapour molecule especi-ally, are affected when it contains two benzene nuclei, as in diphenyl,and (2) the nature of the change in the absorption when the twonuclei are united by other atoms, or groups of at,oms, as in diphenylmethane, diphenyl ether, etc.The substances examined were diphenyl (vapour), diphenyl-methane (vapour), diphenyl ether (vapour), phenyl benzyl ether(vapour), diphenylamine (vapour), azobenzene (vapour and solu-tion), azoxybenzene (vapour and solution), p-aminoazobenzene(vapour and solution), diazoaminobenzene (vapour and solution),benzidine (vapour and solution), and p-phenylenediamine (vapourand solution); the latter to compare with benzidine.The experimental methods have been described before.The con-densed cadmium spark, the uranium-molybdenum spark, and thecopper spark were used as the sources of radiant energy. The con-tinuous spe.ctrum of an acetylene lamp was used for the visible partsof the spectra of the coloured substances. The absorption tube forthe investigation of the vapours was usually filled with nitrogen gas.Diphenyl, C,,H,,.-Solutions of the substance have been ex-amined by Baly and Tuck (T., 1908, 93, 1913), who found noclearly defined bands; but in MjlOOO-solutions they noted a some-what rapid extension of the transmitted rays from 1/A3800 toThe vapour of the substance examined by the author in a 200 mm.I / h 4400 (A 2630-A.2270).tube showed the following phenomena :Pressureto, in mm.46 752 The rays were transmitted to A 2130.51 The rays were weaker than at 46" between about A2500to the Cd line 2154 ; the Cd line 2829 was very weak.56 772 The rags were almost completely absorbed between abontA 2530 to the Cd line 2321 ; and the series of Cd linest o 2144 were transmitted moderately well.76AND SOLUTIONS OF VARIOUS SUBSTANCES, ETC.591Pressureto. in mm.61 752 The rays were abnnrbed from about ~ 2 5 5 0 ; but the66 The rays were absorbed from ~ 2 5 7 0 ; but the Cd lines71 802 The rays were absorbed from A 2590.Cd lines 2267, 2194, 2144 were fairly well marked.2194 and 2144 were just visihle.79276 807 Y Y 7 , ,) A 2600.81 812 ,, > Y ,, A 2630.The very weak vapour band corresponds, therefore, with theweak solution band. All the 88 narrow vapour bands of benzenedescribed by Hartley (Phil. Trans., 1907, A, 208, 475) have com-Ato.110115120125135145pletely disappeared.DiphenyZmeth,ane, C,,H,,.-Solutions of the substance have beenexamined previously by Purvis and McCleland (T., 1912, 101,1514), who found a well-defined narrow band a t l/h3700 (h2700),and a wider one a t l/h3800 (h2630), which rapidly widened onthe more refrangible side between l / h 3800 (h 2630) and l / h 4050( ~ 2 4 7 0 ) as the thickness of the solution increased, and graduallythe two bands merged into one large band.The vapour of the substance in a 200 mm.tube a t varioustemDeratures and pressures showed the following phenomena :Pressnrcin mm.7637637 63763763763The rags were feebly absorbed between A 2685-4 2675and between h2650-A2610; they were then trans-mitted to A 2260.The rays were moderately well absorbed betweenA 2 6 8 9 - ~ 2673 and between A 2665-A 2600 ; and thentrammitted to A 2260.The rays were fairly well absorbed between A 2693-A2670,and also between A 2665--h 2580 ; they were then feeblytransmitted to the group of Cd lines beginning atA 2329 which were well detined.The rays were absorbed between A 2698-4 2670, and veryfeebly transmitted to A 2665 ; they were then absorbedt o the Cd lines beginning a t ~ 2 3 2 9 , which were wellmarked to A 2265.The rays were absorbed between A 2710-A 2670, and thenfeebly transmitted to A 2660, after which there wascomplete absorption to the group of Cd lines 2329,2321 and 2313.The rays were completely absorbed from A 2715.The more refrangible vapour band shows very doubtful signs ofbeing divided into two; but, on the whole, the bands are not unlikethe solution bands; there are none of the 88 vapour bands ofbenzene or the 22 of toluene described by Hartley (Zoc.cit.). Theless refrangible band, both of the solution and the vapour, maycorrespond with the series of benzene vapour bands beginning at~ 2 6 7 0 , and the more refrangible band may correspond with thesecond and third series of vapour bands beginning a t ~ 2 6 3 4 an592 PURVIS: THE ABSORPTION SPECTRA OF THE VAPOURS~ 2 6 0 3 , which diffuse into each other, both in the solution and inthe vapour. It is also to be noted that the vapour bands and thesolution bands of diphenylmethane are much weaker than the solu-tion bands of benzene and toluene. The rapid exkmsion of theabsorption on the more refrangible side, both in the vapour andsolution, probably represents traces of the more refrangible benzenesolution bands.BipheityZ Ether, C12H,,0.-The solution of the substance hasbeen shown by Purvis and BIcCleland (Zoc.cit.) to possess twobands, a t l / ~ 3510 (A 2850) and l / ~ 3690 (A 2710), which coalescedinto one large band as the concentration increased. Baly andCollie (T., 1905, 87, 1342) found a similar result with solutions ofanisole, except that the anisole bands were more persistent, andthere was a moderately rapid extension of the rays betweenl / h 3740 (A 2670) and l / h 3910 (A 2560).The vapour of the substances in a 200 mm. tube showed thefollowing phenomena :Pressureto. in mm.78 75478 76083 76688 77193 77698 781The rays were very feebly absorbed between h 2770 to theCd line 2748 ; they were also very weak betweenh 2710-~ 2680, and then transmitted to A 2320.The rays were moderately well absorbed from ~ 2 7 7 5 tothe Cd.line 2748 ; and also between A 2710-~2680 ;they were then transmitted to h 2380.Tho rays were fairly well absorbed from A 2780 to the Cdline h 2748, and also between h 2720-A 2680, and thentransmitted to A 2400.The rays were well absorbed from ~ 2 7 9 0 to the Cd line2748, and also between A 2 7 3 0 - ~ 2630 ; they were thentransmitted to A 2410.The rays were absorbed between a 2795-h 2600, and thentransmitted to a 2400 ; the Cd line 2748 was visible.The rays were absorhed between A 2810-A 2530, exceptthat the Cd lines 2748 arid 2573 were visible, and thenfeebly transmitted to A 2440.The results, therefore, prove that the vapour bands and the solu-tion bands are very similar.All the narrow benzene vapour bandsdescribed by Hartley (Zoc. cit.), and all the 41 narrow vapour bandsof anisole described by Purvis and McCleland (T., 1912, 101, 1514),have completely disappeared. Only two bands remain, which aresimilar t o the solution bands.PhenyE BenzyE Ether, C13Hl,0.-Two solution bands were foundby Purvis and McCleland (Zoc. cit.) a t l / h 3540 (A 2820) andl / h 3640 (A 2750). There was also a fairly rapid extension of therays between 1 / A 3750 (A 2670) and 1 / h 3990 (A 3500) which corre-sponds with that noticed in solutions of anisole, but it is moremarked. As the concentration increased, one large band took theplace of the smaller bandsAND SOLUTIONS OF VARIOUS SUBSTANCES, ETC.593The vapour of the substance in a 200 mm. tube showed thefollowing phenomena :Pressureto. in mm.108 746118 746128 746138 746148 746158 746The rays were feebly absorbed between A 2710-A 2690,and also botween ~2640-A2620, and then trans-mitted to A2250.The rays were a little weak between A 2770--h 2750 ; theywere more strongly absorbed between A 2730-A 2680,and also between A 2650-A 2620, and then they weretransmitted to A 2270.The rays were feebly absorbed between A 2780 to the Cdline 2748; and also completely absorbed betweenA 2730-4 2620, and then transmitted to A 2300.The rays were absorbed between h 2810-A 2510, exceptthat the Cd lines 2748 and 2754 were just visible, andthen they were transniitted to the Cd line 2313.The rays were absorbed from A 2820, except that the Cdlines 2748 and 2573 were just visible.The rays were absorbed from A 2830.The vapour bands are, therefore, very like the solution bands.Allthe narrow benzene vapour bands have completely disappeared, andthere is no trace of the vapour bands of anisole.Diphenylamine, CI2H1,N.-Solutions of the substance have beenexamined by Baly (T., 1907, 91, 1495), who found a large band at1 / ~ 3 5 1 0 (~2850). This was confirmed by Purvis and McCleland(T., 1912, 101, 1514).The vapour of the substance in a 200 mm. tube showed thefollowing phenomena :P)ressureto. in mm.64 75269 76274 77379 78384 79389 800The rays were transmitted to Cd 2144, although theyshowed some weakening between A 2000-A 2780.The rays were weak betwcen ~2900-Ah630, and thenfairly well transmitted to A 2144.The continuous rays were jnst visible betweenA 2950-~ 2350 ; the Cd lines 2748 and 2573 were fairlystrong; and the rays were then well transmitted toA 2194.The rays were well absorbed between ~ 2 9 7 0 to theCd line 2329 ; the other CCi lines to A 2194 were wellmarked.The rays were absorbed from A 2990 ; the Cd lines 2321 to2265 were just visible.The rays were completely absorbed from A 2995.The band is, therefore, comparable with the solution band; allthe narrow vapour bands of aniline described by the author (T.,1910, 97, 1546) have completely disappeared. It is also of someimportance to notice that the band is much stronger than that ofthe diphenyl band, and it is shifted more towards the red end ofthe spectrum.There are no traces of a resolution into either theseven benzene solution bands or the two aniline solution bands594 PITRVIS: THE ABSORPTION SPECTRA OF THE VAPOURSAaoben.ze.ne, C,,H,,,N,.-Two solution bands were found byHartley (T., 1887, 51, 152) between h497-~405 andh341-~286. Baly and Tuck (T., 1906, 89, 982) and Purvis andMcCleland (Zoc. cit.) also investigated the large band in the ultra-violet regions. Hantzsch (Ber., 1913, 46, 1537) discusses thechanges in the colour of aminoazobenzene and of dimethylaminoazo-benzene a.nd of various salts in different solvents. He also givesabsorption curves for the solutions of such substances, and theyare practically the same as the two bands in the curve (Fig.1) asregards the solutions, making allowance for the shift towards thered end in the heavier molecules of the salts. The author hasFIG. 1.Oscillation jrepcencies.18 22 26 30 34 38 42 46Azobeizxeite (continuous line).Azoxybenzew (broken line}.repeated the earlier observations to compare the solution with thesolutions of other azobenzene derivatives described below. Thecurve (Fig. 1) shows a band a t l/h2190 ( ~ 4 5 6 0 ) in the visibleregions of the spectrum, and another verging on the edge of thevisible regions a t 1 / A 3120 (A 3200).The vapour of the substance examined in a 200 mm. tube a tvarious temperatures and pressures showed the following pheno-mena :Pressure7 5 it’.in mm.68 757 The rays were transmitted to A 2120.73 T~ie raps were fairly well absorbed between A 3300-A 2700,78 757 The rags were absorbed between A3330-A2630, and83 The rays were absorbed between A 3340-A 2590, and then88 757 The rays were absorbed from A 3350.and then transmitted to A 2140.then transmitted to A2260.feebly trausmitted to A 2310.75AND SOLUTIONS OF VARIOUS SUBSTANCES, ETC. 595Pressureto. in mm.128 757 The rays were moderately well absorbed beheen138 757 The rays were almost completely absorbed between158These two vapour bands, therefore, correspond with the two solu-tion bands. There is no trace of the narrow benzene bands de-scribed by Hartley (Zoc.c k ) , or of the narrow aniline banks.described by the author (Zoc. cit.). The two bands show no signsof being resolved into a series of narrower bands. To investigatethe absorption band in the visible regions, the rays from anacetylene lamp were used, but there was no trace of any narrowbands.Asoxybenze.~~e, C,2H,,0N,.-Solutions of the substance exhibitone large band. The curve (Fig. 1) shows that this band, l / h 3100(A3230), ranges from the visible regions of the spectrum to theultra-violet regions. It is not unlike the large, more refrangibleband of azobenzene, but there is no trace of the smaller, lessrefrangible band of the latter. The introduction of the oxygenatom has completely eliminated it, and the phenomena suggest aclose connexion between the colour of these compounds and thepartial neutralisation of the residual valencies of the nitrogen atomsby the introduced oxygen atom.The destruction of the colour ofazobenzene in hydrazobenzeiie may be recalled in this connexion.The vapour of the substance in a 200 mm. tube showed thefollowing phenomena :A 4500-A 4100, and then transmitted to A 3500.h 4700-A 4000 ; and then transinitted to A 3550.The rays were completely absorbed from about h 5200. 757to.116126136146156166176Pressurein mm.739739739739739739739The rays were transmitted to A2140 ; but they were Blittle weak between A 3250-4 2850.The rays were fairly well abjorbed between A 3300-4 2800,arid then transmitted to A 2144.The rays were absorbed between A 3360-A 2750, and thentransmitted to A 2230.The r a p were sbsarbed from A 3400; but the Cd lines2748, 2473 and 2313 were visible.The rays were absorbed from A 3700.9, 9 , ,, A3750.9 ) 9 9 ,, ~ 3 8 0 0 .All the narrow vapour bands of benzene and of aniline (Zoc.cit.)have completely disappeared ; one single band remains, which is likethe solution band. The band is also not unlike the more refrangibleazobenzene band, except that, like the corresponding solution band,it is shifted a little more towards the red end of the spectrum.The spectrum was also searched by the light of an acetylene lamp,but no trace of a small, less refrangible band similar to that ofazobenzene was found.VOL. cv.R 596 YURVIS: THE ABSORPTlON SPECTRA OF THE VAPOURSp-Aminoazo benzene, C,,H,,N,.-Pauer (Ann. PhLys. Chem., 1897,[iii], 61, 374) described two weak transmission bands betweenA 340-A 275, and between h 230-A 226. The author has repeatedthe experiments (Fig. 2), and the curve shows a strong band a t1 / A 2550 (h 3920) which ranges from the ultra-violet regions wellinto the visible regions of the spectrum, and with which the colourof the substance is connected. A second much weaker band is alsoshown a t 1 / A 4000 (A 2500).The vapour of the substance examined in a 200 mm. tube a tFIG. 2.Oscillation frequencies.18 22 26 30 34 38 42 46p- Aininoambenzene (continuous line).Dinxoaminobenzene (broken line).various temperatures and pressures showed the following pheno-mena :Pressure739to. 111 mm.130 The rays were transmitted to A 2140, although they werea little wcak between A 3500-A 3000.135 739 The rays were moderately well absorbed betweenA 3550-A 2950, and then transmitted to'h 2140.145 739 The rays were absorbed between h3660-~2900;then transmitted to A2480, and feebly absorbed toA 2329 ; from here they were well transmitted to A 2170.150 739 The rays were absorbed between A 8670-A2870, andbetween h 2500 to the Cd line 2329 ; from here theywere fairly well transmitted to Cd.2134.160 The rays were absorbed between A 3676-A 2800, and thenfeebly trtlnsmitted to A 2560 ; the Cd line 2313 wasvisible.739The visible part of the spectrum was also investigated by thelight of an acetylene lamp, but there was no indication of anyresolution of the strong, less refrangible band into a series ofnarrower bands.All the vapour bands of benzene and anilinAND SOLUTIONS OF VARIOUS SUBSTANCES, ETC. 597(Zoc. cit.) have disappeared. Two large bands remain, a strong oneranging from the ultra-violet to the visible regions of the spectrum,and a weak, more refrangible one. Both these bands are com-parable with the solution bands.Diazouminobenzene, Cl2HIlN3.-The absorption curve (Fig. 2) ofthe solutions shows a strong band a t 1 1 ~ 2 7 7 0 (~3610), rangingfrom the visible regions into the ultra-violet, and with which thecolour of the substance is connected. There is also a second, muchweaker band a t l / h 4250 (A 2350).These two bands are not unlikethe two solution bands of paminoazobenzene, except that they areshifted more towards the more refrangible regions. It is suggestedthat the weak, more refrangible band in both substances is com-parable with the more refrangible band of aniline described byHartley and Huntingdon (Phil. Trans., 1879, 170, I, 257), andof its various derivatives described by the author (Zoc. c i t . ) .Furthermore, the shift of the bands of diazoaminobenzene towardsthe more refrangible regions may be explained by the partialneutralisation of the residual affinities of the azo-nitrogen atoms asa result of their more intimate connexion with the amino-nitrogenatom.The vapour of the substance in a 200 mm. tube a t varioustemperatures and pressures showed the following phenomena :Pressureto.in mm.48 773 The rays were transmitted to A2120.108118128138 773 The rays were wholly absorbed from A 3700.All the vapour bands of aniline and benzene (Zoc. cit.) had com-pletely disappeared. The strong band, and the indications of themore refrangible weak band as shown by the rapid absorptionbetween ~ 2 1 4 0 a t 108O and ~ 2 4 5 0 a t 118O, are comparable withthe solution phenomena.Benzidine, Cl2HI2N2.-The absorption curve of the substanceshows one large band (Fig. 3), the head of which is a t l / h 3610(A 2850). It seems as if the two solution bands of aniline describedby Hartley and Huntingdon (Zoc. cit.) had widened into one largeband.The vapour of the substance in a 200 mm.tube and in an atmo-sphere of nitrogen showed the following phenomena :773773773The rays were transmitted to h2130, but they were aThe rays were very weak between ~3450-A 3050, andThe rays were wholly absorbed between A 3650-4 3050,little weak between A 3350-A 3200.then transmitted to A 2450.and then very feebly transmitted to h 2500598 PURVIS: THE ABSORPTION SPECTRA OF THE VAPOURSPressureto. i n mm.152 767 The rays wcre transmitted to A 2144.162 The rays were transmitted to the Cd line 2194, but theywere nveak between A 2800-A 2550.172 767 The rays were alinost conipletely absorbed hetweenh2850--h2500 : but the Cd lines 2748 snd 2573 werewell marked. The rays were then transmitted t o theCd line A 2265.767No higher temperatures were employed, for a t 172O the substancein the tube became dark coloured, showing that some decompositionhad taken place.The results, however, indicate that there were nonarrow bands like the aniline vapour bands (Zoc. cit.). The singlelarge band is comparable with the solution band.p-P?z,enybenediamiize, C,H,N,.-The solution curve (Fig. 3) showsFIG. 3.Oscillatzon frequencies.28 32 36 40 44 483-52.71.91'10.3I30 7nm. .E 111/100Benzidiize (broken line).p-Phenytenediamine (contiiiuous linej.two bands a t l/h3140 (13180) and l/h4130 (h2420). These arenot unlike the two solution bands of aniline, except that they areshifted more towards the less refrangible regions.I n investigating the vapour of the substance, the absorbing tubewas filled with nitrogen gas before placing it in the heatingapparatus, but there was some decomposition a t the higher tempera-tures. A few observations were, however, made, and the followingnotes describe the phenomena :Pressureto.in mm.110 563 The rays were feeb1.y absorbed hettvcen h 2550-A 2350,The rays120 The 1%) s were fairly well absorbed between A 3250--h 3000,130 763 The rays were coniipletely absorbed between A 3280-3.2900,140 563 The I'RYS weie tiausiuitted to A 3300.150 763 B * 1, Y Y A 3350.thc series of Cd lines being well marked.were also a little weak between A 3200-A 3050.a i d tlieii trausnjitted to A 2600.a i d then feebly transmitted to A 2750.76ANT) SOLUTIONS OF VARIOUS SUBSTANCES, ETC.599The two vapour bands are, therefore, comparable with the solu-All the various vapour bands of aniline (Zoc. cit.) have tion bands.completely disappeared.Discussion of Results.It is clear from the preceding observations that all the narrowvapour bands of benzene are completely obliterated when twobenzene nuclei form either the molecule itself, as in diphenyl, orwhen they are attached to other groups, as in diphenylmethane.Similarly, all the narrow vapour bands of aniline are destroyed insuch duplicated molecules as benzidine. There is also no trace,either in the vapour or the solution of diphenyl, of any band corre-sponding with the well-known benzene solution bands, whereas thevapour and the solution of diphenylmethane show traces of the lessrefrangible solution bands of benzene.I f each benzene nucleus isconsidered as an oscillating or vibrating centre, each may be in-fluenced by its connexion with the other; but, in diphenyl, thecharacteristic vapour bands of the one are neither strengthened inintensity nor increased in number; they are destroyed. On theother hand, in diphenylmethane there is a possibility of morefreedom of movement of the two nuclei; but again there are notraces of any narrow benzene vapour bands. The bands which areexhibited, both in the vapour and solution, are remnants of the lessrefrangible benzene solution bands. I n diphenylamine, the intro-duction of a new vibrating system has even cancelled the traces ofthe benzene solution bands found in diphenylmethane, and theirplace is taken by a strong wide band, which is found both in thevapour and the solution.The solution and the vapour of the ethers also show some residuesof the benzene solution bands, and herein they compare with thesolution bands of anisole.The vibrations of the benzene nuclei andthe oxygen atom mutually react t o such an extent that, again, allthe vapour bands of benzene or phenol or anisole completely dis-appear.Further, the vibrations of the two benzene nuclei in azobenzeneproduce no trace of the numerous benzene or aniline vapour bands,or of the benzene solution bands. There can be little doubt, how-ever, that the orientation of the nitrogen atom is of prime import-ance in the production of the colour and the absorption of thesubstance. It is well indicated by the alteration in the colour andthe absorption phenomena of azoxybenzene, and i t may be explainedby assuming that the residual valencies of the nitrogen atoms arepartly neutrslised by the oxygen atom,The production of the weak, more refrangible band in pamino600 BOUSFIELD : IONISATLON AND THEazobenzene and in diazoaminobenzene may be explained by thepresence of the aniline residue, which acts, to a certain extent, as acomparatively free oscillatory or vibratory system.It is alsoinfluenced by its relative position with the other benzene residue,for in diazoaminobenzene the three nitrogen atoms are considered tobe directly connected with one another. This comparative freedomof the aniline residue, however, does not lead to the production ofany of the numerous vapour bands of aniline. The various vibra-tory or electronic oscillations characteristic of the simple moleculeare neutralised when it is united with other and similar oscillatorygroups. The solution and the vapour phenomena then becomesimilar, except that, as in other instances, the damping effect of thesolvent causes a shift of the solution bands towards the lessrefrangible regions. Even in benzidine, where the diazo-nitrogenatoms are absent, the two aniline residues do not strengthen orincrease the number of the narrow vapour bands of aniline. Thevapour bands and the solution bands are similar, and one strongband takes the place of the two solution bands of aniline. I n thisdirection the duplication of the aniline molecule has a decisiveinfluence, for the two bands of pphenylenediamine are not unlikethose of aniline, except in position, although the numerous vapourbands of aniline are obliterated by the introduction of the secondoscillatory or vibratory amino-group. It is of some interest tomention that the vapour of the duplicated molecule 2-dipyridylexhibits none of the Characteristic vapour bands of pyridine (Purvis,T., 1913, 103, 2283).I desire to thank the Government Grant Committee of the RoyalSociety, by whose assistance a part of the cost of the research wasdefrayed.UWVEI~SITY CHEMICAL LABORATORYCAMBRIDGE

ISSN:0368-1645    

DOI:10.1039/CT9140500590

出版商:RSC    

年代:1914

数据来源: RSC