摘要:

METHYL-ORANGE AND METHYL-RED. 2477CCLV.-Thp Colour Chuszges o f Methyl- Orange andMethyl-Red in Acid Solutioiz.By HENRY THOMAS TIZARD.IT is well known t.hat the colour of an indicator in solution depends,within certain limits, on the concentration of the hydrogen ion (orhydroxyl ion) in the solution. These limits, which vary greatlywith the nature of the indicator? have been determined for a largenumber of indicators by Fels (Zeitsch. Elektrochem., 1904, 10, 208)and Salessky (ibid., p. 205), and a knowledge of them enables us t ochoose, for any given volumetric operation, the indicator that willgive the best results. Conversely, by testing a solution with alarge number of indicators, we can arrive at an estimate of theconcentration of hydrogen ions in it.Friedenthal (Zeitsch.EZeEtrochem., 1904, 10, 114) and Salm (Zeitsch. physikal. Chem.,1906, 57, 471) have measured in this way the degree of dissociationof weak acids and weak bases, and have obtained results agreeingoften to within a few per cent. of those obtained by conductivitymeasurements; but it can hardly be seriously proposed to supersedethe latter, more accurate, although more laborious, method by theformer, except when the acid or base under investigation is extremelyweak. On the other hand, the determination of the degree ofhydrolysis of salts in aqueous solution is often both laborious andat the same time subject t o large percentage errors; a simplecolorimetric method would therefore be of considerable importance,provided that it could be made as accurate as, or more so than, themethods usually employed. Friedenthal’s method cannot be con-sidered accurate enough for this purpose; the difficulty of judgingcolours without employing a suitable apparatus is very great, and,moreover, it is impossible to keep weakly acidic standard solutionsof indicators (for comparison) unchanged for any length of time.It is far better to determine once and for all the relation betweendepth of colour and the concentration of the hydrogen ion2478 TIZARD : THE COLOUR CHANGES OF METHYL-ORANGEFor this purpose only those indicators can be used that are eithercolourless in one form, or exist in two coloured forms which arepractically alike in tint and only differ in depth of colour.For allpractical purposes, methyl-orange sufficiently fulfils the latter con-dition; the complete change of colour of this indicator from alkalineto strongly acid solutions can be followed by matching it againsta suitable standard solution in a tintometer.I have thereforeexamined this change of colour with as great care and accuracyas possible, and have applied the results obtained to the deter-mination of the hydrolysis of aniline salts at different dilutions(see following paper). Veley, in a series of papers (Zeitsch. physikal.Chem., 1906, 57, 147; Trans., 1907, and following years), has t oa large extent opened up the field in this direction; but he workedonly with extremely dilute solutions, where the total colourchange is small, and the error of observation relatively large.Further, he based all his conclusions on empirical relations, whichcan be only approximately true.For these and other reasons,which will be mentioned later, his results can only be consideredqualitative,Theory of the Colour Change.The simplest theory of the d o u r changes of an indicator is thatof Ostwald. According to this, the ions of an indicator have adifferent colour from that of the undissociated molecule. Forexample, the undissociated molecule, NMe,*C,H,*N:N*C,H,*SO,H,is red, whilst the ion, NiMe,*C,H,*N:N*C,H,*SO,', is light yellow.It has recently been proved in many cases, and is probably true inall, that this change in ionisation is accompanied by a change inthe chemical structure of the molecule.According to Hewitt, theundissociated molecule of methyl-orange mainly consists of aninternal compound,?,H,*NH* N: C,H,: Me,so,-- 0 'to which the deep red colour is due. From this point of view,indicators are pseudeacids, the pseudo-acidic form being always inequilibrium with the true acidic form, from which the ions aredirectly derived. It must, however, be emphasised that these con-siderations make no difference whatever to the theoretical treatmentfrom the ionic point of view; for if the undissociated acid exists insolution in two or even more forms, these must always be presentin strictly constant ratios, and hence, for all practical purposes, theacid behaves as if it existed in only one form. This will be assumedto be true for the sake of clearness in the following considerat*ions,but it must be understood that the results obtained have no bearinAND METHYL-RED 1N AClD SOLUTION.2479on the question as to what particular form of the undissociatedmolecule the deep red colour is due.Now let the molecular colour of the ion be taken as unity, andlet that of the undissociated acid be equal t o cl. By this we meanthat if the colour of a solution containing completely dissociatedmethyl-orange is balanced by a height " h " of a standard solutionin a tintometer, the colour of the same solution when excess of acid(hydrochloric) is added, that is, when the indicator is entirely inthe undissociated form, will be balanced by a height=c, x h.Then the molecular colour of a solution containing methyl-orange partly in the undissociated form, and partly in the form ofions, will be somewhere between c1 and 1.Let y equal the fractionundissociated, and therefore (1 - y) the fraction dissociated. Thsmolecular colour of the solution is then obviously given by theequation : . . . . . C = c , y + ( l - 9 ) . (1).Further, if li', is the dissociation constant of the indicator acid,we have by Ostwald's law:Kay = (1 - y) x conc. H' . . . . (2).Eliminating y from (1) and (a), we have:. . . . . (3).c - 1 conc. H' = K,-c1 - cHence, if we know K , and cl, the relation between the molecularcolour C of a solution and the concentration of hydrogen ions itcontains is ckmpleiely determined. R, and c1 can be determinedby measuring the colour of solutions containing varying quantitiesof hydrochloric acid.When y = 112, that is, when the indicator acid is 50 per cent.dissociated, the molecular colour :c1 + 12 'c =that is, is jrxsti midway between the two extreme colours.Further, equation (2) becomes := conc.H'.In a solution, therefore, the colour of which is just midwaybetween the two extreme colours, the concentration of the hydrogenion is equal to the dissociation constant of the indicator acid.Salm (Zoc. c i t . ) has determined in this way the dissociation constantof a large number of indicators. He measured the concentration ofthe hydrogen ions by means of a hydrogen electrode. The methodis of advantage when the two extreme colours of an indicator differwidely, but since only one solution can be conveniently examined2480 TIZAHD : THE COLOUR CHANGES OF METHY L-ORANGEthe results are probably not very accurate, although of the rightorder of magnitude.Now there is another point with regard to methyl-orange andallied indicators which has not been taken into account in the aboveconsiderations. All these compounds contain a substituted amino-group, and are therefore, amphoteric electrolytes.Hence in anacid solution the basic ion, for example,NRMe2* C6H,*N: N*C6H,* SO,H,may be present, as well as the undissociated molecules. To thisbasic ion we must assign a molecular colour, say c2, and its presenceto any considerable extent would greatly affect conclusions drawnfrom colour measurements.Lund6n has, in fact, criticised Veley’sresults adversely from this point of view, but$, as will be shownlater, the basic dissociation constant Kh of methyl-orange is sosmall that no appreciable quantity of the HNMe,R ion is formedeven in AT/20-hydrocliloric acid. On the other hand, that of methyl-red (which differs from methyl-orange in having an ortho-carboxylinstead of a para-sulphonic group) is larger, and in consequence wefind that the basic properties of this indicator have a considerableinfluence on the colour in solutions which are greater thaniV/5000 with respect to hydrogen ions.If we consider solutions which contain only the basic ion and theundissociated acid, and if the fraction of the former present is y’,and therefore that of the latter is (1-y’), then as before:c = c,y:+ cl(l -9’) .. . . . (la).Also, Ostwald’s law gives:SinceX b ( 1 - 9’) = y’ x conc. OH’.Gu conc. OH’ = ~ conc. H’(K, = dissociation constant OC water), the last equation becomes :These two equations are precisely similar in form to equations (1)and (2), and it is evident that we cannot decide at once, with0 Itfurther evidence, whether the ‘‘ dissociation constant,’’ foundKzo colorimetrically, of an amphoteric indicator is really Ka or -.This is especially true when tho dissociation constant is found bySalm’s method. When the whole course of the colour curve isexamined, it is generally possible to see at a glance whether thechange of colour must be attributed to the presence of three coloureJmolecules (basic ion, undissociated molecule, acid ion) in the solu-KAND METBYL-RED IN ACID SOLUTION.2481tion, or only two (compare the curves for methyl-red and methgl-orange).EXPERIMENTAL.To test these equations, and to determine the values of Ka andcl, the depth of colour of methyl-orange solutions of knownstrength in presence of hydrochloric acid ranging from N/20- toN / 100,000 has been investigated. The apparatus employed wasthe Donnan tintometer, used as described, for example, by Sidgwickand Tizard (Trans., 1908, 93, 188). The standard used for com-parison was a faintly acid solution of methyl-orange. It was, ofcourse, unnecessary to know its exact strength, as it was comparedbefore any series of measurements against a neutral solution ofmethyl-orange of known strength.The colours were all referredto this dilution as unit. Veiey (Zoc. cit.) found it impossible t omeasure the depth of colour of a strongly acid (red) solution ofmethyl-orange by comparing it to the same standard that he usedin his colour measurements with weakly acidic (orange) solutions.I found comparatively little difficulty in doing so; the differencemay be partly due t,o the fact that whilst Veley used daylight ashis illuminant, I used the yellow light from a 50 c.p. electriclamp (carbon filament).All the solutions used were made up carefully by weight withconductivity water. They were filtered to remove dust as far aspossible, and kept in steamed-out Jena-glass flasks.It was found impossible to prepare a clear solution of methyl-orange with a concentration greater than N/1000.I n fact, solu-tions of this strength were slightly turbid, but immediately clearedon dilution. The effect of dilution is to cause a slight decrease inmolecular colour, as the following measurements show.Ten C.C. of a neutral solution, N/2000, were taken and diluted inthe tintometer tube.Y for methyl- Height oforange. balaiicing column.10 C.C. N/2000 solution ... . . . . . . .. . . . . .. . 2000 4'6Y 9 9 9 , , + 10 c. c. H,O 4000 4 *39 , ,Y ,) +20 C.C. H,O 8000 4-09 , 1 , ,, +60 C.C. H,O 20,000 4 -0Y l 9 7 ,, + a few dropsN/lO-alkali 20,000 4 *OThis decrease in colour may be due to increasing dissociation;the presence of even a small quantity of undissociated salt mayhave a considerable effect on the colour.I n the experiments withhydrochloric acid, the methyl-orange was used at a dilution ofV=20,000, high enough t o avoid complications of this kind. Thelast colour measurement is important. Methyl-orange is a sodiumsalt; if its corresponding acid were very weak, the salt would b2482 TIZARD : THE COLOUR CT-TANGES OF METHYL-ORANGEconsiderably hydrolysed atl high dilutions. This means that thosolution would contain undissociated acid, which is of a muchdeeper colour than its ions. Addition of alkali would, in this case,diminish the colour by destroying hydrolysis. As a matter of fact,no such effect is observed, and this is strong evidence that theacid of methyl-orange cannot be very weak; on the contra,ry, itmust be considerably stronger than acetic acid.We should there-fore expect its basic dissociation constant, Kb, to be correspondinglysmall. These conclusions are confirmed by the colour measurementswith hydrochloric acid. The latter measurements were carried outin the following way. Ten to 50 C.C. of an ~Y/lO,OOO-solution ofmethyl-orange were placed in the tintometer tube, a suitablequantity of a standard solution of hydrochloric acid added, andthen water added up to twice the original volume of methyl-orange.The concentration of the latter was then N/20,000. That of thehydrochloric acid varied from N / 2 0 to N/100,000; or, if we denotethe ratio (mols. HCl) + (mols. methyl-orange) by '' a," " a '' variedfrom 20,000 + 100,000 = 0.2 to 20,000 + 20 = 1000.I f the height of the balancing column is h', and the heightrequired to balance the same amount of methyl-orange in neutralsolution is h, then the molecular colour of the acid solution isgiven by:1. h' c = k ,that of the neutral solution being taken as unity.Three series of measurements were taken on different days, andwith entirely fresh solutions. The temperature was 25O.Thegreatest deviation in the molecular colour found for any particularstrength of solution was 5 per cent., the usual error being 2 to3 per cent. It was found impossible to reduce the error consistentlybeyond this point.The curve for methyl-orange is drawn by plotting molecularcolour against concentration of hydrogen ions, the latter beingexpressed in inverse powers of 10.There is very little change incolour between H' concentrations of 10-7 (neutral solution) and10-5; after this point the rise in colour is rapid-the middle partof the curve being practically a straight line-until a maximum isreached somewhere about the point conc. H' = 10-2, the colour onlyrising about 5 per cent. in more concentrated solutions. It isobvious from the curve that these changes can be explained if weassume the presence of two coloured substances in the solution.These must evidently be the anion and the undissociated acid, andequations (1) and (2), or (3) may therefore be applied.The concentration of hydrogen ions in the solutions examined isAND METHYL-RED IN ACID SOLUTION.2483however, by 110 means the same as that of the hydrochloric acidadded, as Veley assumed, since the undissociated indicator acidin the solution is formed by a eombination of part of the anion ofthe salt with hydrogen ions derived from the added hydrochloricacid. I n other words, the concentration of hydrogen ion in thesolution is not a / V , where V is the dilution of methyl-orange, buta-Yy being the fraction present in the form of undissociated indicatoracid.This correction is of considerable importance, especially at thev '262116116I -4-extreme dilutions with which Veley worked, and the fact that hedid not take it into account may possibly explain some of hisanomalous conclusions.Equation (2) may therefore be written in the form:&*KY = (1 -y)b-y),where V = 20,000.From the results, the mean values for X , and c1 are found to be :Ka = 4.25 x (at 25').c1 = 18'8.The agreement between calculated and observed va.lues is shownin the following table2484 TIZARD : THE COLOUR CHANGES OF METHYL-ORANGE0.0 10-7" 0.00 (1.00) (1 -00)0'2 10-5.048 0.021 1.37 1'380-4 10-4.746 0.041 1.73 1-680.6 10-4.568 0.060 2-07 2.040.8 10-4.443 0.078 2-39 2.391'0 10-4314 0,096 2.71 2.652-0 1 0 4 .0 4 0 0.177 4-15 4'185 '0 1 o-a.ti34 0.353 7.28 7 '4810.0 10-3.324 0.527 10-4 10.715'0 10-3.144 0.63 12'2 12.025 .O 1 o - a w i 0.74 14.2 14'450 .O 10-2'rn 0.85 16-1 16'3100.0 10-2'305 0 9 2 17'4 17.31000-0 10-1'300 0.99 18'6 18.3Salm found Ka =4*6 x 10-4 as a mean of several values rangingfrom 4.0 to 5.5.The greatest deviation between the observed molecular coloursand those calculated by means of the above equations is 3 percent.It appears therefore that there is no appreciable quantity ofthe positive ion NMqR formed even when the concentration of thehydrogen ion is as high as N / 2 0 , for it is unlikely that the colourof this ion is the same as that of the undissociated molecule. Inthe parallel case of methyl-red, it is distinctly lower, as will beshown later. If we assume that not more than 1 per cent. oftho methyl-orange is present in the form of the basic ion when theconcentration of the hydrogen ion in the solution is we candeduce an upper limit for the basic dissociation constant fromequation (2a), which gives :* Neutral point.!5 x 0.01 = 0.99 x 10-2,Kbor Kb = Kw = 10-14 (at 25').Kb is therefore probably <When a is greater than 1, the increase in colour is approximatelyproportional to the increase in the amount of hydrochloric acidin the solution.Thus, with each successive 0.2 molecule, theincrease in colour (calculated) is 0.37, 0.36, 0.34, 0.32, 0.32. Thisagrees with the observations of Veley, who found that by plottingincrease in colour against concentration of acid added, a straightline was obtained. The relation is, however, evidently onlyapproximately true.At the theoretical neutral point the concentration of hydrogenions is 10-7. Since methyl-orange does not appreciably lighten incolour below a concentration of H * = l O - S , it must be considered abad indicator for accurate volumetric analysis, apart from the factthat, since the change of colour takes place only gradually, it iAND METHYL-RED IN ACID SOLUTION. 2485difficult to get a sharp end-point.On the other hand, the closenessof the results obtained with those required by the simple theoryexpressed by equations (I) and (2) shows that methyl-orange is avery good indicator to use for the quantitative colorimetricestimation of the concentration of hydrogen ions between 10-3 and10-5, that is, between N/1000 and N/100,000.Substituting the values found for R,and c1 in (3), we get forthe relation between concentration of hydrogen ions and molecularcolour of methyl-orange the expression :c-118.8 - c' conc.H' = 4.25 xMethyl-red.I n order to throw further light on the colour changes of indicatorswhich are amphoteric electrolytes, a series of similar colour measure-ments were made with methyl-red, an indicator discovered by Ruppand Loose (Ber., 1908, 41, 3905). Its constitution is expressed bythe formula :NM%*CbH,*N: N*C6H4 0 , H (0).The method of preparation given by these authors is not satisfac-tory, only small yields being obtainable. The following method isrecommended by Mr. T. P. Winmill, who kindly supplied me withthe indicator in the first place.Five grams of anthranilic acid are dissolved in 150 C.C. of waterand 15 C.C. of concentrated hydrochloric acid. To this, 2.5 gramsof solid sodium nitrite are added, and the solution kept for halfan hour.It is then poured into a solution of 4.65 grams ofdimethylaniline in a mixture of 5 C.C. of concentrated hydrochloricacid and 50 C.C. of water. Fifty grams of sodium acetate areadded. On warming to 40°, the red product quickly separates,but the reaction does not appear t.0 be complete for about threehours. The substance is then collected, and can be crystallisedfrom glacial acetic acid.Methyl-red is very insoluble in water ; its saturated solution at theordinary temperature is only about N/100,000. Since it contains a,carboxyl instead of a sulphonic group, we should expect it to be aweaker acid than methyl-orange, and a correspondingly strongerbase. In accordance with this, methyl-red is easily soluble both inacids and in alkalis.Its alkali salts are surprisingly soluble; thepotassium salt can only be obtained by evaporating an alcoholicsolution to dryness, since it is soluble to a considerable extent inether, and deliquescent in air. Since the sodium salt of helianthin(methyl-orange) is somewhat insoluble in water, the difference inbehaviour is striking.Ths yield is almost quantitative.VOL. XCVII. 7 2486 TIZARD : THE COLOUR CHANGES OF METHYL-ORANGEThe pure potassium salt appears to dissolve completely in a verysmall quantity of water, forming a very deep red solution; ondiluting further, the acid separates out. The hydrolysis appearsto be excessive if we accept the value for the dissociation constantof the acid (lO-5), found from the colour measurements, but sincethe solubility of the acid is so small, the appearance may be, decep-tive.It would probably be interesting to investigate further thebehaviour of the alkaline salts of this indicator, but this does notcome within the scope of tho present paper.Since a clear neutral solution of the salt could not be obtained,the saturated solution of the acid was used in the colour measure-ments. I t s strength was found approximately in the following way.A known quantity of the potassium salt was dissolved in a slightexcess of alkali, so as to makG an N/lOOO-solution; 10 C.C. of thiswere then diluted to 1 litre. This N / 100,000-solution contained,of course, a slight, but only a slight, excess of alkali. Ten C.C.wereplaced in the tintometer tube, the same volume of N/lOOO-hydro-chloric acid added, and the colour was measured. Ten C.C. of thesaturated solution of the acid + 10 C.C. of N / 1000-hydrochloric acidwere then measured in the same way. It makes no difference ifthe concentration of hydrogen ions in this solution was slightlygreater than that in the salt solution, for, as will be shown late'r,the molecular colour is at a maximum at this point, and does notchange appreciably between H' concentrations of N / 5000 andN/2000 (see the curve for methyl-red).Since the depth of colour of the two solutions was approximatelythe same, the strength of the acid solution was taken to be roughlythe same as that of the salt solution, namely, N/100,000. Thesaturated solution was usually diluted in the tube up t o about fourtimes its original volume.It has already been pointed out in discussing the results withmethyl-orange, that the concentration of the hydrogen ions in avery dilute solution of hydrochloric acid containing an indicator,is not the same as that of the hydrochloric acid itself, but is lessor greater, as the case may be.In order to allow properly for this,we must, of course, know exactly the quant'ity of indicator present.The uncertainty of the actual dilution of the methyl-red usedmakes, therefore, experiments with hydrochloric acid untrustworthywhen the concentration of the latter falls below a certain amount.For this reason, the most dilute solution of hydrochloric acid usedwas about N/30,000, and the concentration of the hydrogen ion inthis and more concentrated solutions was taken to be the same asthat of the hydrochloric acid present.The remainder of thecurve was determined by measuring the colour in solutions oANT) MEI'FIYL-REET) IN ACID SOLUTION. 8487sodium acetate containing varying amounts of acetic acid. Tlioconcentration of the sodium acetate was J7/500; that of t'hehydrogen ions, when a certain amount of acetic acid, equal to ntinics that of the sodium acetate, is added, may then be easilycalculated by means of Ostwald's law, the dissociation constant ofacetic acid at' 1 8 O (the temperature of measurement) being takenas 1.8 x 10-5. Hence:1.8 x lo-5x conc. HA=conc. A' x conc. H'.Since we may assume the sodium acetate to be completely dis-sociated, the equation becomes :HA conc.H' = 1.8 x 10-5 x -- -- NaA'= n x 1.8 x 10-5.Since the amounts of acetic acid and sodium acetate in thesolution are always large compared to that of the indicator, thecorrection that must be made when strong acids, such as hydrochloricacid, are used is unnecessary.The colour curve obtained in this way is shown on p. 2483.The lower part of the curve is similar to that of methyl-orange,but the colour falls again when the concentration of hydrogen ionsis greater than IT/ 2000 or thereabouts. We must therefore assdmethat two changes take place :I. NMe,. , . COO+H: NMe, . . . C0,H.11. NMe,. . . CO,H+H' Z kHMe, . . C0,H.The colours of the acid ion, undissociated molecule, and basic ionare taken, as before, as 1, cl, and c2 respectively.Since themaximum is very flat, the first change must be nearly completebefore the second begins. Disregarding the latter for the present,then, we may apply the equations:C' = c1y + (1 - y),K a y = (1 - y) x conc. H*,to the lower part of the curve, the concentration of hydrogen ionsbeing calculated in the ways already indicated. For the meanvalues of Kla and cl, we find :~l~ = 1-05 10-5.c1 = 27.6.The temperature was in this case 18O.The following table contains t'he results so obtained :7 2 2488 TTZARD : THE COLOUR CHANGES OF METHYL-ORANGEMolecular Colour of Methyl-red.1.-Experiments wit172 MixtuTes of Sodium Acetate and A cetic Acid..HANan' ?a= -0.00-0050.010'030 -050 *070 '10 '130'20.30.4(3.61 '22.45.0Conc.€1'.10-8'27210-7'0461O-G'74510-6'26810-6.04610-5'90010-5'74510-5'63110-544410-5'26810-5-1431 0 -4.YG710-4.66G10-436.510-4'046Colour ( o h . ) .1-101-261'462'2113 -003 3234.865'867 -8410.212'214'818'622 *o25.2Colour (calc.).1 *021 '221'462.303-103 '844'856 *a47 *7810.211 '814'518.922 -424.82.-Eaperiments with IIydrochloric A cid u p t o N/2000.VHCl. Conc. H'. Colour (obs.). Colour (calc. ).31,000 10-4'491 19.9 21 '021,000 10-4'322 22.3 22.811.000 1c)-"041 24-9 24 89000 10-3.954 25-4 25.3[5000 ]O-Y'69'3 25 3 26 a ]25.6 27 -01 [ZOO0 10-3 301The observed and calculated values closely agree ; in particularthe two series of measurements agree well where they overlap.Thelast colour measurement (in AT/ 2000-hydrochlosic acid) is consider-ably below the calculated value; this is due tto the formation oftho basic ion. In still higher concentrations of hydrogen ions, thecolour sinks further, until it again becomes practically constantwhen conc. H' is greater than 8 / 2 0 . Equations ( l a ) and (2a)apply to this case. If we assume that no acid dissociation takesplace, we get:where g2 is the fraction of the indicator present in the basic form,and c2 is the molecular colour of the basic ion; c1 has already beenfound to be 27.6.Also, if I!b is the basic dissociation constant of the indicator :c =y2c2 + (1 - Y2)C1,K W -yz = (1 -y2) conc.H'.K2,From the colour measurements, we find AND METHYL-RED IN ACID SOLUTION. 24892llolecula.r Colour of itlet hyl-red in Solzit !ions of Hydrochlor,ic A cidgreater than N/5000.VHCI-21020304010021 04101000[5000[2000Conc. H'.10-0'3-J 0-1'010-1'51 O-"OO10-1'310-1'6010-2'32210-2'61s10-3'0010-3'30110-3'699Colour (obs.).18'418'518.818.919'219.921.623'024.825.625.6Colour (calc.).18%18'818-919'119.220'022 '422.624'625.8126 *7]The dilutions V,,, = 2000 and 5000 require further consideration ;i t is evident that the molecular colours at and between thesedilutions cannot strictly be calculated on either of the assumptions :(1) that no basic ion is present, (2) that no acid ion is present.Both these ions as well as the undissociated molecule must be presentto an appreciable extent. By using the dissociation constants givenabove, we can calculate the amount of these ions present, and thusarrive a t the following results :Acid ion. Undiss.mol. Basic ion.YHCl. (1 - y1- y2) K Y2 Col. (calc.). Col. (obs.).2000 0-015 0.788 0.197 25'4 25.65000 0.045 0.868 0.087 25 '6 25.6Hence the whole course of the colour curve is satisfactorilySinceaccounted for.X, = 0.6 x 10-14 a t 18O,we haveIt must not, of course, be assumed that the colours of methyl-orange and methyl-red are the same in equivalent alkaline solution,because the molecular colours of both the acid ions have been takenas unity.As a matter of interest, however, it may be mentionedthat, as far as could be judged, the difference between the twodepths of colour of the two acid ions is but small.As an indicator methyl-red is greatly superior to methyl-orange,as the colour curves show. The visible change, red to yellow, takesplace between and that is, between H' concentrationsof N/200,000 and N/10,000,000. Not onIy therefore is the end-point very much sharper than when methyl-orange is used, but theneutral point so found is very much nearer the theoretical neutralpoint. Methyl-red is, in fact, an extremely sensitive indicator, andshould come into extended use; it is especially valusble for th2490 'IIZARD: THE HYDROLYSIS OFexact titration of moderately weak bases (such as ammonia) bystrong acids.As a means for measuring colorimetrically the concentration ofhydrogen ions in a solution, methyl-red would probably be foundvaluable when such concentration lies between 1 0 - 5 and 10-6.Methyl-orange cannot be used when conc. H' is greater than 10-5.I f methyl-red is used for this purpose, i t would be advisable to referall molecular colours to the maximum colour found when conc. H'lies between N/2000 and Nj5000; this maximum colour can bemeasured very accurately, whilst the extreme yellow colour of theion is somewhat difficult to measure. Taking the maximum colouras 25.6, the theoretical colour of the undissociated molecule is 27.6,and the relation between concentration of hydrogen ions (between10-4.5 and 10-6-5, say) and the molecular colour of the solutioncan be expresed by the equation:1-05 x 10-5(c - 1 ) conc. H' = -. 27.6 - CSummary.The depths of colour of metliyI-orange and methyl-red in solutionsof varying concentrations of hydrogen ions have been measured,From the results, the following constant% have been deduced :Ka. Kb.Methyl-orange (at 25") :Methyl-red (at 18') :NMe,'C,H,'N:N'C,H,'SO,H . . . . . . .. . 4.25 x < 10-44NMe,'C,H,'N:N'C,H,'CO,H ( 0 ) . . . . . . 1 -05 x 3 xThe value of methyl-red s1s an indicator is discussed.Expressions are given connecting the depths of d o u r of methyl-orange and methyl-red solutions with the concentrations of hydrogenion in the solutions.DAVY-FARADAY LABORATORY,ROYAL INSTITUTION

ISSN:0368-1645    

DOI:10.1039/CT9109702477

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

2490 'IIZARD: THE HYDROLYSIS OFCCLVI.---The Hyd~olysis of Aniline SccZts McasuredCo 1 o r ime t r ical I y .By HENRY THOMAS TIZARD.IN the preceding paper it wm shown that the concentration ofhydrogen ions in a solution of methyl-orange, tho molecular coloixrof wliicli is G, is given by the equations :C4-25 x 10-4y= 18.8y+(l -y) . . . . , . . . . . . (1)= (1 -9) x conc. He . . . . . . . . . (2)ANILINE SALTS MEASURED COLORIMETRICALLY. 2491where y denotes the fract,ion of methyl-orange present in the formof undissociated indicator acid.These equations have now been used to determine colorimetricallythe degree of hydrolysis of aniline salts.Aniline Hydrochloride.Aniline hydrochloride was prepared by mixing equivalentquantities of pure concentrated hydrochloric acid and aniline,which was purified in the way recommended by Hantzsch andFreese (Ber., 1894, 27, 2966).The salt was recrystallised fromwater slightly acidified with hydrochloric acid. The colour measure-ments were made in exactly the same way as that described in thepreceding paper. The tempera.ture of observation was 25O. One ofthe chief objections to the measurement of hydrolysis by colorimetricobservations seems to be the difficulty of keeping the temperatureconstant. It was found best to keep the solutions until just beforeuse in a thermostat at bhe required temperature, and then totransfer the requisite amount quickly to the tintometer tube.Since with a certain amount of practice accurate colour measurements can be made very rapidly, the temperature alters only slightlyduring the acbual experiment. I n the experiments communicatedin this paper, it certainly did not vary sufficiently to affect thecolour outside the unavoidable error of observation.The dilutions examined ranged from 1 /ZO- to 1 / 1200-normal.I n a, pure aqueous solution of a salt of a weak base, the con-centration of the hydrolysed base is, of course, equal to that of thefree hydrogen ions in the solution. When, however, an indicator,such as methyl-orange, is also present in the solution, it partlycombines with the hydrogen ions, and the concentration of the latterwill therefore be less than that of the hydrolysed base.Thus, if 12:is the fraction of salt hydrolysed, Vl the dilution of the salt, Vzthat of the indicator, and y (as before) the fraction of the latterpresent in the form of undissociated acid :x: - - - conc.aniline= cow H' + --. VIYvzThis correction is of considerable importance when hydrolysis islarge and the dilut,ion of ths indicator not too great. Thus, totake an example from the following ta,l.de, when V/',=200 andV,=ZO,OOO, the molecular colour is found to be 8-63. Fromequations (1) and (2) we get:y=0*429, conc. 4' = 3-19 x 10-42492 TIZARD : THE HYDROLYSIShenceconc. aniline = 3.19 x += 3.40 xOF0.42930,000The difference between the two concentrations is thus 7 percent. It was not taken into account by Veley in researches of asimilar nature, and this, together with the reasons already putforward in the previous paper, may explain the frequent differencebetween his results and those arrived at by other methods.The hydrolysis constant is given by the equations:x conc.He. K, - conc. C,H,*NH2 x c o w H' - XKb conc. C,H,*NH, 1 -x- - -. - -The following table contains the results obtained :20304060801002003004005006008001000120020,00050,00040,00030,00020,00030,00020,00015,00020,00020,00015,00013,33320,00020,00012.611-911 '410.710'49-868.637-846'976-636'255'865 '484-920.6520'6120.5840-5450.5280.4980'4290.3840.3350.3160.2950.2730-2520.2207'946.715-975.094-764-213-192 *652 '141 *961.781'591 -431.201 -652-072 -513-164 '124.386.808'739-2410.611-914-315'615.7(0'133)(0'142)(0-154)(0.176)(0.204)(0.193)0 '2300.2530.2180.2320'2400.2650'2640.223A 2 per cent.error in colour measurement corresponds on anaverage wit.h an error in the hydrolysis constant of 10 per cent.,so that the fluctuations of the constant from the mean value for thelast eight dilutions are within the error of observations, and,moreover, are not materially greater than those found when othermethods of measurement are employed. The actual mean value ofthe constant for these eight dilutions is:Kw = 0.242 x 10-4, Kbwhereas Bredig (Zeitsch. physikal. Chem., 1894, 13, 239) found byconductivity measurements :The two values are thus practically identical.At higher concentrations, however, the constant is very muchsmaller, and appears to increase quite regularly with the dilution.This difference is too great to be accounted for by the incompletANILINE SALTS MEASURED COLORIMGTRICALLY. 2493dissociation of the aniline hydrochloride, and as the behaviour hasnot been observed when other methods are used, it is presumablydue to the formation of a compound with methyl-orange, whichaffects the colour to a small extent.With aniline acetate, however,no such phenomenon was observed; the colour in a N/2O-solutionof this salt is perfectly normal. The swalled neutral salt actiondiscussed by Szyszkowski (Zeitsch. physikal. Chem., 1910, 73, 269)is apparently unconnected with the above phenomenon, for methyl-orange appears to indicate a higher concentration of hydrogen ionin presence of sodium chloride than the solution contains, whereasthe reverse is true with aniline hydrochloride.On the whole, it is perhaps inadvisable to use concentratedsolutions of salts in colour measurements of this kind.Anzline Acetate.This salt has apparently not been prepared in the solid state.Amixture of equivalent weights of pure aniline and acetic acid willnot solidify when cooled to -20°, but as the liquid is extremelyviscous at this temperature, it is probably supercooled. If theequivalent mixture is kept for some time, acetanilide is formed.The solution used in these experiments was therefore made bymixing equivalent quantities of N/5-aniline and N / 5-acetic acid,both of which were made up accurately by weight from the puresubstances.In a solution of a salt of a weak acid and a weak base, thedissociation constants of which are and Kb respectively, let y bethe degree of dissociation of the salt, and x the fraction hydrolysed;then Ostwald's law gives the two equations :hence :K ~ , z = (1 - X) x COUC.H'K b . X = (L - X) x conc. OH ;or :This is the well-known equation for the hydrolysis of such a salt;it signifies that when the salt is completely dissociated ( y = l ) , thedegree of hydrolysis is independent of the dilution. It has not,however, yet been pointed out, so far as I know, that the con-centration of the hydrogen (and hydroxyl) ions in a solution of aweak salt must always be constant, whatever be the dilution, an2494 HYDROLYSIS OF ANILINE SALTS.whether the salt is completely dissociated or not.once from the above equations, forThis follows atconc. H' = ~ Kmx - - 2/R;: = constant.Y(1 - 4A striking proof of this can be obtained colorimetrically.Theaddition of a few drops of the aniline acetate solution to a neutralsolut'ion of methyl-orange causes the same rise in colour as theaddition of a large quantity. The results of actual experiments areshown below:Aniline acetate.20405080100200500x: (For completeColour. Mean. conc. H'. dissociation).- - - 1'921-921.90 -1 '90 1-91 0.229 x 0.5601-901.91 -1 -90- - -- -- -- -- - -The molecular colour is constant within the errors of observationwhen the concentration of aniline acetate varies from X / 2 0 toN/500.From the colour, the concentration of the hydrogen ionis obtained as before, and t-hen the degree of hydrolysis is calculatedfrom the equation:conc. H' __-- x - - -l - x Ka - -'Ka being 1.8 xArrhenius and Walker(Zeitsch. physikal. Chem., 1889, 5, 18) found that for the samesalt the percentage hydrolysed was 55.5, as a mean of the valuesfor-six different dilutions ranging from V = 12.5 to V = 400.The two methods therefore give practically identical results.From trhe hydrolysis of the chloride, we can calculate :In this way we find x=56'0 per cent.= 4.6 x 1O-I'from that of the acetate:= 3.8 x 10-l'.This difference is within the error of hydrolysis measurement byany method.The colorimetric method used in the investigationseems to give too low values for the hydrolysis constant of thehydrochloride, so that Kt, calculated from the hydrolysis of theacetate is probably more accurate. I n any case the mean value :Kh = 4.2 x 10-lOat 25TUTIN : SYNTHESES Ih’ THE EPINEPHRINE SERIES. PART 11. 2495cannot be far from the truth. The number accepted by LundQn(4.6 x 10-10) appears therefore too high.I n conclusion, the results communicated in the present paper showthat, with proper precautions, hydrolysis can be measured colori-metrically by means of methyl-orange, with an accuracy thatcompares favourably with that att.ained by other methods. Thebase should, however, have a dissociation constant less than 10-7.For bases stronger than this, but weaker than ammonia, methyl-redwill probably be found suitable. Since the apparatus and themethod of working are extremely simple, there is no reason why thecolorimetric method should not come into more extended use.Summary.It is shown that the degree of hydrolysis of aniline salts can beaccurately determined by measuring the depth of colour of methyl-orange in the solution, and then calculating the concentration ofhydrogen ions by means of the equations deduced in the precedingpaper.It is also pointed out that the concentration of hydrogen ions ina solution of a salt of a weak acid and a weak base is always thesame, whatever the dilution and degree of dissociation of the salt.The researches communicated in this and the preceding paperwere carried out in the Davy-Faraday Laboratory of the RoyalInstitution. I should like to express here my thanks to themanagers of the laboratory for the facilities they have placed atmy disposal.DAVY-FARADAY LABORATORY,ROYAL INSTITUTION

ISSN:0368-1645    

DOI:10.1039/CT9109702490

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

TUTIN : SYNTHESES Ih' THE EPINEPHRINE SERIES. PART 11. 2495CCLVIL- Sptlwses in the h''ineph&ae Xeiies. Part 11.The Formation and Pr-operties of Some 2 : 5- and2 : 6-Substituted Pyq-axines and their Convemiorbinto Amino - ke t ones a.nd h i n o - d ike t ones.By FRANK TUTIN.IN a recent communication (Tutin, Caton, and Ham, Trans., 1909,95, 2113) it was shown that the action of ammonia on o-chloro-p-hydroxyacet,ophenone did not result in the formation of o-amino-phydroxyacetophenone, but yielded only resiiious products. Thisresult was considered somewliat, remarkable, inasmuch ::.Y theanalogous chloremp-dihydroxy-ketone readily yields the correspond-ing amine (D.R.-P. 155632). The behaviour of a number o2496 TCTTIN : SYNTHESES IN THE EPINEPHRINE SERIES.PART 11.o-chloroacetophenone derivatives on heating with ammonia hastherefore been invcstigated, with the result that i t has been renderedevident that these compounds may be divided into three classes,according to the products which they yield on this treatment.Thus, w-chloro-mpdihydroxyacetophenone, on treatment withammonia, behaves in a normal manner, yielding the correspondingamine. Only amorphous products result from the interaction ofammonia and o-chloro-p-hydroxy ace top henon e, w-c hloro-o-met hox y-acetophenone, or o-chloro-op-dimethoxyacetophenone. When, how-ever, either w -chloroacetop henon e , w-c hloro-p-methoxy acetophenone,or o-chloro-mp-dimethoxyacetophenone is heated with alcoholicammonia, the principal product of the reaction is a mixture of2 : 5- and 2 : 6-substituted pyrazines, in about equal proportions.The formation of 2 : 5-diphenylpyrazine (11) from o-bromoacetcFphenone and ammonia was studied by Gabriel (Ber., 1908, 41,1127), who showed that, after replacement of the halogen, 3 : 6-di-hydro-2 : 5-diphenylpyrazine (I) was formed, and that this thenunderwent' spontaneous oxidation to the diphenylpyrazine, asfollows :QOPh*CH,\N~I, -+ <CPh*C$>jy -+ N/ CPh'CH,N, .* NH,b H;COPh C H, CP h' \CH.CPh/The last-mentioned author, however, overlooked the fact that2 : 6-diphenylpyrazine is also formed in this reaction, and the modeof production of this compound therefore remains to be explained.Gabriel (Zoc.cit .), however, identified diphenacylamine,(Ph*CO-CH,),NH,as a product of the interaction of o-bromoacetophenone andammonia, and the present author has similarly obtained this base,as a minor product, from o-chloroacetophenone.It is now shown that diphenacylamine (111) and its derivativesare intermediate compounds in the formation of 2 : 6-substitutedpyrazines, f o r they pass into the latter on heating with ammonia.The series of changes which results in the formation of 2 : 6-di-phenylpyrazine (IV) from o-chloroacetophenone and ammonia maytherefore be represented as follows :CE-I,Cl*COPh CH,* COPhNH3 CB,Cl*COPh --+- NH<CH,*COPb -+-H(1.) (11.1(111.)CH:CPh*OH NH, ---f NH< CK:CPh>NH -~N"<C€€:cFh*oH CH:CPhiv. 1y,CH:CPh,N,* \C'H:CPh/(IV.TUTIN : SYNTHESES IN THE EPINEPHRINE SERIES.PART 11. 2497According to this scheme the action of ammonia on diphenacyl-amine first results in the production of 1 : 4-&hydro-2 : 6-diphenyl-p!pa:i?be (V), which then passes into 2 : 6-diphenylpyrazine byspontaneous oxidation. The change might, however, conceivablytake place as follows:(VI.)If this be the case, the intermediate compound will be 3 : 4-di-hydro-2 : 6-dipheqlpyrazine (VI).The change which is here shown to occur on heating compoundsof the type (R*CO*CH,),NH with ammonia does not appear to havebeen observed before, and it therefore seems to afford a new,general method €or the production of 2 : 6-substituted pyrazines.The interaction of ammonia and o-chloro-p-methoxyacetophenoneproceeds similarly t o that of w-chloroacetophenone and ammonia,yielding, as principal products, ppl-dimethoxy-2 : 5-diphenylpyrazine(m.p. 2 2 3 O ) and ppf-dimethoxy-2 : 6-diphenylpyrazine (m. p. 137.5O).The former of these two compounds is of particular interest, as, onfusion, it passes into the “ liquid-crystalline ” state, and this phasepersists over an exceptionally large range of temperature, namely,4 1 ’ 4 O . ppl-D-imethoxy-2 : 5-diphenylpyrazine therefore represents anew addition to the already considerable list of “ liquid-crystalline ”p-anisyl derivatives, but it appears to be the first compound of thisclass in which the anisyl group is attached to a ring. A furtherinteresting property of pp’-dimqthoxy-2 : 5-diphenylpyrazine is thatits solutions exhibit a violet-blue fluorescence, a behaviour whichhas not previously been observed amongst pyrazine derivatives.Furthermore, on the addition of a drop of concentrated hydrochloricor sulphuric acid t o a chlorofcrm solution of this base, a mostbrilliant green fluorescence is produced.ppl-Dimethoxy-2 : 6-di-phenylpyrazine behaves in marked contrast to its 2 : 5-substitutedisomeride, as it fluoresces but slightly, and only in neutral solution,and it does not pass into the “ liquid-crystalline ” state.w-Ch Zoro-mp-dime thoxyac etoph enone yielded minlppl-t e trame t hoxy -2 : 5-diphenylpyrazine (m. p. 208O) and mm1pp’-tetramethoxy-2 : 6-di-phenylpyrazine (m. p. 160O) on treatment with ammonia, neitherof which passes into the “ liquid-crystalline ” state.The formercompound is, however, strongly fluorescent, but only in neutralsolution.It is furthermore shown in the present communication that theseries of changes which result respectively in the formation o2498 TUTIN : SrNTHESES IN THE EPINEPHRINE SERIES. PART If.2 : 5-substituted pyrazines from o-aminoacctophenone or itsderivatives, and in the conversion of diphenacylamine or itsderivatives into 2 I 6-substituted pyrazines, may he reversed bymeans of hydriodic acid. Thus, when 2 : 5diphenylpyrazine isheated with hydriodic acid, reduction followed by hydrolysis occurs,resulting in the formation of two molecules of o-aminoacetophenonehydriodide. Similarly, 2 : 6-diphenylpyrazine, when analogouslytreated, is converted into diphenacy Zarnine hydriodide andammonium iodide.Of course, when employing the pyrazinederivatives containing methoxyl groups, the methyl group is alsoeliminated by the hydriodic acid. This reaction therefore hasafforded a new method of preparing o-amino-p-hydroxyacetophenoneand o-amino-mp-dihydroxyacetophenone, two bases which are ofinterest on account of their physiological activity. The former ofthese bases was previously prepared by the present author in con-junction with Messrs. Caton and Hann (ZOC. cit.) from o-chloro-p-acetoxyacetophenone, whilst the latter base is of special importanceon account of its near relationship t o epinephrine.ppr-Dihydroxydiphenucylamine and mmtppr-tetrahydroxy&phen-ncylamine have been prepared by the action of hydriodic acid onthe previously-mentioned methoxy-2 : 6-diphenylpyrazines.It willreadily be seen from a comparison of the formula: given below thatppl-dihydroxydiphenacylamine (VII) and, especially, mm’ppr-tetra-hydroxydiphenacylamine (VIII) are closely related to the ketonederived from epinephrine (IX), as also to the above-mentioned twoo-aminohydroxyacetophenones :HO/-\CO*CH;NH.CH,*CO/-\OH \-/ \-/( v I r .HO OH(VI TI.)KOHO/-\CO~CH,~NH*CI-I,. \-/(IX.)It was therefore to be expected that these two diphenacylaminederivatives would be possessed of physiological activity, and theirpropert‘ies have accordingly been investigated in the WellcomePhysiological Research Laboratories by Dr. H. H. Dale, to whomthe author is indebted for the following and the subsequentlymentioned physiological experiments.It was found that each ofthese compounds, in the form of salts, when injected intravenouslyinto cats, caused a rise in blood-pressure, pp’-dihydroxydiphenacylTUTIN : SYNTHESES IN THE EPINEPHRINE SERIES. PART 11. 2499aniine (VII) having an action similar to that of the related com-pound, w-amino-p-hydroxyacetophenone (Tutin, Caton, and Ham,Zoc. cit.), whilst the corresponding tetrahydroxy-base (VIII) had agreater activity, more resembling that of the ketone derived fromepinephrine (IX).It has already been mentioned that o-chloro-o-methoxyaceto-phenone and w-chloro-opdimethoxyacetophenone yield only amor-phous products when heated with ammonia, whereas the analogouscompounds containing the methoxyl groups in the rn- and p-positionsreadily yield substituted pyrazines.It theref ore appears that thepresence of a methoxyl group in the o-position with respect to theside-chain precludes the formatim of pyrazines from w-chloroaceto-phenone derivatives, although the reason for this is not apparent.On account of the above-mentioned property of the o-sub-stituted w-chloroacetophenone derivatives here described, it wasimpossible to obtain from them the corresponding o-aminohydroxy-acetophenones in the way which has already been noted in connexionwith the preparation of o-amino-p-hydroxyacetophenone fromw-chloro-p-methoxyacetophenone. Recourse was therefore had tothe use of potassium phthalimide, and by this means derivativesand salts of o-amino-o-hydroxyacetophenone and o-amino-op-di-hydroxyacetophenone have been obtained.When examinedphysiologically, the hydriodide of the o-hydroxy-base was found tobe practically inactive, whilst the corresponding salt of the op-di-hydroxy-base had no greater activity than the analogous p-hydroxy-compound. It is therefore seen that hydroxyl groups in theo-position with respect to the side-chain are devoid of physiologicalactivity in the class of compounds under consideration, a resultwhich is in harmony with a previous observation of Dr. Dale, whofound o-h ydr ox y-fl-p hen ylet h y lamine, /-\CH,*CH2*NH,, to beinert, whilst the analogous pcompound is strongly active (Barger,Trans., 1909, 95, 1123).o-Chloro-o-methoxyacetophenone is formed, together with thecorresponding p-compound, by the action of aluminium chloride onchloroacetyl chloride and anisole. The further action of aluminiumchloride on o-chloro-o-methoxyacetophenone results in the formationof w-chloro-o-hydroxyacetophenone.The latter substance differsfrom the corresponding p-compound, inasmuch as it is quite insolublein aqueous sodium carbonate, thus showing how the relative positionsof the groups in the benzene nucleus affect the acidity of thehydroxyl group.The above-mentioned substituted o-aminoacetophenones, contain-ing a hydroxyl group in the 0-position with respect to the side-chain,OH\-2500 TUTIW : SYNTHESES IN THE EPINEPHRIKE SERIES. PART 11.differ markedly in their properties from the previously-mentionedanalogous compounds which are substituted in the m- or p-position,inasmuch as they condense and oxidise, when dissolved in neutralsolvents, to form 2 : 5-substituted pyrazines.oo'-Dihydroq-2 : 5-dipheltylpprazine and oo'ppt-tetrahydroxy-2 : 5-&iphenylpyraainehave thus been prepared.The two o-substituted o-aminoacetophenones described also showa singular behaviour when benzoylated, either by the Schotten-Baumann method or in pyridine solution, for, when thus treated,they yield benzoyl derivatives of internal anhydrides. It wouldappear possible that these condensation products are 1-b enzoyt-indoxyl aad 6-benzoyloxy-1-benzoyLindoxy1 respectively.Gabriel (loc. cit.), from his work on w-aminoacetophenone, con-cluded that a-amino-ketones of this type were incapable of existencein the free state, but always underwent condensation when liberatedfrom their salts. It is evident, however, from the results given inthe present paper that this is not invariably the case.Thus,o-aminoacetophenone, o-amino-p-methoxyacetophenone, w-amino-mp-dimethoxyacetophenone, and w-amino-o-hydroxyacetophenonecondense spontaneously, yielding pyrazine derivatives in the mannershown by Gabriel. o-Amino-phydroxyacetophenone and o-amino-mp-dihydroxyacetophenone, on the other hand, cannot be causedto condense ; whilst o-amino-op-dihydroxyacetophenone possesses pro-perties between those of these two groups, for it can be obtainedin the free state, although it condenses somewhat readily.EXPERIMENTAL.Interaction of w-Chloroacetophenone and Ammonia.Chloroacetyl chloride was dissolved in an excess of benzene, andone molecular proportion of aluminium chloride added.A violentreaction ensued, and, when this had subsided, ice and hydrochloricacid were added. The aqueous layer was then separated, and, afterwashing the benzene solution with water, the greater part of thesolvent was removed from it,. On adding light petroleum t o theconcentrated liquid thus obtained, o-chloroacetophenone separatedin glistening plates, melting at 59O. The yield was nearlyquantitative.Fifteen grams of o-chloroacetophenone were heated for one anda-half hours at looo in sealed tubes with an excess of alcoholicammonia.After allowing the contents of the tubes to cool, thesolid which had separated was collected, washed with alcohol, andthen extracted repeatedly with boiling xylene. The materialundissolved by this treatment consisted entirely of ammoniumchloride, but on concentrating the xylene extracts, a compounTUTIN: SYNTEESES IN THE EPINEPHRINE SERIES. PART 11. 2501separated in plates, melting at 194O. As thus obtained, this sub-stance possessed a dark bluish-green colour, and was only obtainedcolourless after being treated, in acetic acid solution, with a smallamount of potassium permanganate dissolved in t.he same solvent.When crystallised from xylene after this treatment, it formed large,colourless plates, melting at 194O, and was identified as 2 : 5-diphenyl-pyrazine (Found, C = 79.5 ; H = 5.1.Calc., C = 79.3 ; H = 5.0 percent.)This compound was first prepared by Staedel and Rugheimer(Ber., 1876, 9, 563), who described it under the name of ‘‘ isoindol.”As subsequently obtained by Staedel and Kleinschmidt (ibid.,1880, 13, 836), it was observed to exhibit diverse colours, and theyregarded it as being “ idiochromatic.” Pure 2 : 5-diphenylpyrazineis, however, quits colourless, as ha? been shown by Gabriel (Ber.,1908, 41, ll27), who prepared it by the interaction of w-bromo-acetophenone and ammonia.The original alcoholic filtrate from the 2 : 5-diphenylpyrazine andammonium chloride was evaporated to a low bulk and largelydiluted with benzene. The filtered liquid was then again evaporatedas far as possible, and the residue dissolved in alcoholic hydrogenchloride, when the mixture rapidly became dark brown, but noblue colour was developed (see below).The solution was con-centrated somewhat, and hot ethyl acetate added, when, on coolingthe mixture, a crystalline substance separated in needles, whichwere collected and washed with a mixture of ethyl acetate andalcoholic hydrogen chloride. The product so obtained was dissolvedin the minimum amount of absolute alcohol, and a little alcoholichydrogen chloride added, when it immediately separated in soft,almost colourless needles, melting at about 189O :0.2020 gave 0.1060 AgCl. C1= 13.0.C16HlzNz,HCl requires C1= 13.2 per cent.This substance was identified as 2 : 6-diphenylpyrazine rnono-hydrochZode,* since it yielded 2 : 6-diphenylpyrazine, which formedcolourless needles, melting at 90°.(Found, C= 79-3 ; H = 5.2.Calc., C=79-3; H=5*0 per cent.)2 : 6-Diphenylpyrazine monohydrochloride is almost insoluble inbenzene or ethyl acetate, but it dissolves fairly readily in alcohol,owing to the fact that it becomes, for the most part, dissociated.It is not stable in moist air, and is instantly dissociated whenbrought in contact with water.Gabriel (loc. cit.) did not note the formation of 2 : 6-diphenyl-pyrazine when he investigated the interaction of o-bromoaceto-* It has been found that the pyrazines are tliacidic bases, and yield two series ofsalts (compare following paper).VOL. XCYlI. 8 2502 T’UTIN : SYNTHESES IX THE EPINEPHRINE SERIES.PART 11,phenone and ammonia, but it would appear certain that it musthave been present in the reaction mixture examined by him.The original filtrate from the 2 : 6-diphenylpyrazine hydrochloridewas dark brown, and contained considerable resinous matter. Itwas largely diluted with water, filtered from the precipitated resin,concentrated somewhat, and treated with animal charcoal. Onallowing the clear liquid to cool, a somewhat sparingly solublecompound separated, which melted at about 235O, and was sub-sequently identified as diphenacylamine hydrochloride, a compoundwhich has been described by Gabriel (Zoc. cit.).In a subsequent preparation of the above-described 2: 5- and2 : 6-diphenylpyrazines, a quantity (40 grams) of o-chloroaceto-phenone was heated in an autoclave with an excess of alcoholicammonia, the mixture being subsequently kept for fourteen daysbefore it was worked up.After separating the ammonium chlorideand 2 : 5-diphenylpyrazine in the manner already described, theresidual solution containing the 2 : 6-base, which was of a muchmore pronounced red colour, and appeared to be freer from resinousmatter than that obtained in the previous preparation, was mixedwith a large volume of ether and extracted several times with amixture of concentrated hydrochloric acid (1 part) and water(2 parts). This caused the separation of some brown, resinousmatter, which was removed. The ethereal liquid was thenevaporated, and the red residue dissolved in absolute alcohol, anda solution of hydrogen chloride in the same solvent added.Theliquid then became deep blue, and, on cooling the mixture afteradding some ethyl acetate, a solid separated, which, when collected,was seen to consist of a mixture of white and deep blue needles, theformer predominating. The separation of these two products wastedious, but was eventually effected by taking advantage of thefact that the blue hpdrochloride was somewhat more sparinglysoluble in a boiling solution of hydrogen chloride in absolutealcohol than was the white one, which consisted of 2 : 6-diphenyl-pyrazine hydrochloride. The blue compound crystallised in smallneedles, which had no definite melting point, and were only stablein dry air or in an anhydrous solvent in the presence of a moderateexcess of hydrogen chloride.The amount obtained was only about0-5 gram, and consequently the formula could not be established :0-3506 gave 0-4791 AgCl. C1=33*8 per cenb.The base obtained from this deep blue hydrochloride crystallisedfrom alcohol in small tufts of brilliant scarlet crystals, melting at195O. It was readily soluble in chloroform, ethyl acetate, orbenzene, but only moderately so in alcohol. On exposing a solutionof this scarlet-coloured base in chloroform or benzene to direcTUTIN : SYNTHESES IN THE EPINEPBRINE SERIES. PART 11, 2503sunlight, the colour was discharged in half-an-hour, a compoundcrystallising in yellow needles being formed.Preparation of w-Chloro-0- and -p-methoxyacetophenones.o-C hlorep-met hoxyacetophenone was prepared by Eunckell andJohannssen (Ber., 1897, 30, 1715; 1898,31, 170) by the interactionof anisole and chloroacetyl chloride in the presence of aluminiumchloride.Mr. F. W. Caton, who conducted this operation for thepresent author, found it important to avoid the use of any excessof aluminium chloride and not to employ heat, as the methyl groupis very easily eliminated. With the object of avoiding this hydro-lysis, experiments were made with the use of sublimed ferric chloride,but the yield of condensed product so obtained was only small.One molecular proportion of anisole was mixed with rather morethan an equivalent amount of chloroacetyl chloride, and, afterdiluting the mixture with three times its volume of carbondisulphide, one molecular proportion of powdered aluminiumchloride was cautiously added, the flask being kept cool during thisoperation.After three hours the carbon disulphide was decanted,the residue being decomposed with ice and hydrochloric acid andthe product extracted with ether. The ethereal liquid was thenshaken with aqueous sodium hydroxide, which removed smallamounts of hydrolysed product and red resin, after which the solventwas evaporated. On fractionally crystallising the residue fromalcohol, it was found to consist, for the most part, of w-chloro-p-methoxyacetophenone (m. p. lOZ0), which formed long needles,but the more soluble fraction contained a second substance. Thiscompound formed large, colourless, diamond-shaped plates, which,after being separated mechanically from the greater part of thep-compound and submitted to several recrystallisations, melted at6 9 O :0.2154 gave 0'4571 CO, and 0.0993 H,O.0'2288 ,, 0.1778 AgCl.C1=19*2.CQH,O,C1 requires C = 58.5 ; H = 4'9 ; C1= 19'2 per cent.This substance was evidently o-chloro-o-m ethoxyacet ophenonte,since it readily yielded salicylic acid on fusion with potassiumhydroxide.This appears to be the first time that the formation of an 0-mono-substituted ketone by means of the Friedel and Crafts' reactionhas been noted, although phenyl 0-tolyl ketone has been stated tobe formed by ?,he interaction of toluene and benzoic acid in thepresence of phosphoric oxide (Kollarits and Merz, Ber., 1873, 6,538).o-Chloro-o-methoxyacetophenone is slightly volatile at theC=57*9; H=5'1.8 A 2504 TUTIN : SYNTHESES IN THE EPINEPHRINE SERIES PART 11.ordinary temperature, and sublimes readily on heating.It is morevolatile in steam than is the corresponding p-compound, and maybe approximately separated from the latter by taking advantage ofthis property. When brought into contact with the skin, it causesconsiderable smarting, and it has an extremely irritant action onthe eyes.Attempts to prepare o-met hoxydip hen ylpyrazines by heatingw -c hlor 0-0-me thoxy acet o phenone with alcoholic ammonia in sealedtubes resulted only in the formation of resinous products.o-Chloro-o-h ydroxyacet ophenone.o-Chloro-o-methoxyacetophenone was dissolved in carbon di-sulphide, one molecular proportion of powdered aluminium chlorideadded, and the mixture heated for two hours under a reflux con-denser.The solvent was then removed, and the residue heated at looofor ten minutes, after which ice and hydrochloric acid were added,and the product extracted with ether. On shaking the etherealliquid with a solution of sodium carbonate, nothing was removed,but subsequent treatment with aqueous sodium hydroxide extracteda relatively small proportion of oily matter. The ethereal liquid, onevaporation, yielded a considerable quantity of unchanged u-chloro-o-methoxyacetophenone, this compound being evidently much morestable towards aluminium chloride than is the correspondingpderivative. The oil which had been removed by sodium hydroxidewas dissolved in ether, and light petroleum added, which caused theseparation of a viscid, red product, whereupon the mixture wasshaken with animal charcoal, and filtered.After concentrating thefiltrate, a substance separated in yellow, flattened needles, which,after recrystallisation from alcohol, melted at 101O :0.1238 gave 0.2546 CO, and 0.0490 H20.This substance was therefore o-chloro-o-h ydrox yace toph enone,HO*C6H,-CO*CH,C1. It differed from the corresponding p-com-pound in being insoluble in aqueous sodium carbonate (compareTutin, Caton, and Hann, Trans., 1909, 95, 2118).C=56.0; H=4*4.C,H,O,Cl requires C = 56.3 ; H =4*3 per cent.Intemction of w-Chloro-p-methoxyacetophenone and Am.mnia.o-Chloro-pmethoxyacetophenone was heated in an autoclave forthree hours at l l O o with a large excess of alcoholic ammonia.Whencool, the solid contained in the dark-coloured reaction mixture wascollected and washed, first with alcohol, and subsequently with water.The residue was crystallised from xglene, when it separated inlarge leaflets, melting at 2 2 2 O . The substance, as thus obtainedTUTIN : SYNTHESES IN THE EPINEPHRINE SERIES. PART 11. 2505could not be rendered colourless by recrystallisation, but differentpreparations of it exhibited diverse tints, such as dull green,purplish, or greenish-yellow. It was, however, rendered colourlessby the means previously found useful in the case of 2 : 5-diphenyl-pyrazine (p. 2501), but the melting point was practically unchangedby this treatment.On crystallising the purified substance fromglacial acetic acid or xylene, it formed large, coiourless leaflets, butwhen crystallised from chloroform or ethyl acetate it separated inhexagonal plates :0.1088 gave 0.2947 CO, and 0.0556 H20.0.3246A molecular-weight determination by the cryoscopic method gave0.3153, in 33.2 of phenol, gave At = - 0*30°.C18H,,02N2 requires M.W. = 292.Several attempts were made to estimate the number of methoxylgroups in this substance by Perkin’s modification of Zeisel’s method,but accurate results could not at first be obtained, owing to thegreat stability of the compound. It wits eventually ascertained,however, that the methyl groups axe rapidly eliminated if someglacial acetic acid be added to the hydriodic acid employed:C = 73.9 ; H = 5.7.N=9.8.,, 29.0 C.C. N2 (moist) at 20° and 728 mm.C,,Hl,O,N, requires C = 73.9 ; H = 5.5 ; N = 9.6 per cent.the following result :M.W. =243.0.2096 gave 0.3366 AgI. OMe=21.1.Cl,Hl,N,(OMe), requires OMe = 21.2 per cent.The compound was evidently ppl-dimethoxy-2 : 5-dip72.e~l-pgraaine, CkH,N,(C~H4*OMe),, and its constitution was subsequentlyconfirmed by its conversion by hydriodic acid into oamino-p-hydroxyacetop?Lenone hydriodide and methyl iodide (p. 2520).On heating pp’-dimethoxy-2 : 5-diphenylpyrazine, fusion occurs at223O, and the substance passes into a (‘ liquid-crystalline ” state.This phase persists until a te.mperature of 265’4O is reached, whenthe “ crystalline ” liquid phase instantly passes into the normalliquid state.A t the point of change it can easily be observed thatthe two liquid phases are immiscible, and the “ liquid-crystalline ”product appears to possess the greater density. The reverse change,from the normal liquid to the “ liquid-crystalline ” phase, occursat precisely the same temperature, and is exhibited in a strikingmanner when viewed through crossed Nicol’s prisms. The pointof change from the “ liquid-crystalline ” to the normal liquid phase,and vice versa, of pp’-dimethoxy-2 : 5-diphenylpyrazine is a muchmore delicate criterion of the purity of this substance than is itsmelting point, as a mere trace of impurity causes a very appreciablelowering of the temperature of transition from one liquid phas2506 TUTIN : SYNTRESES IN THE EPINEPHRINE SERIES.PART 11,to the o t h r , whilst an amount of extraneous substance sufficientto cause a depression of the melting point by about 3O completelyextinguishes the ‘‘ liquid-crystalline ” phase.pp’-Dimethoxy-2 : 5-diphenylpyrazine is practically insoluble inether or alcohol, very sparingly soluble in chloroform, benzene, orethyl acetate, moderately soluble in boiling xylene, and more readilyso in glacial acetic acid. Its dilute solution in chloroform exhibitsa violebblue fluorescence, and when a drop of concentrated hydro-chloric acid is added, a yellow colour is produced, accompanied by amost brilliant green fluorescence.The original, dark-coloured, alcoholic filtrate from the ammoniumchloride and pp’-dimethoxy-Z : 5-diphenylpyrazine was evaporatedto dryness, the residue extracted with benzene, the solutionevaporated, and the residue dissolved in absolute alcohol.A solu-tion of hydrogen chloride in absolute alcohol was then added, when,after concentrating the solution, it was mixed with hot ethyl acetate.On cooling the mixture, a compound separated in yellow needles,which were collected, washed with a mixture of alcoholic hydrogenchloride and ethyl acetate, and recrystallised by dissolving themin absolute alcohol, adding alcoholic hydrogen chloride, con-centrating the mixture, and then diluting it with ethyl acetate.Soft, yellow needles were thus obtained, which melted at about0.2420 gave 0.1003 AgC1.C1= 10.3.c,sH,60,N2,Hc1 requires c1= 10.8 per cent.This salt proved to be ppl-dimethoxy-2 : 6-diphenylpyrazine mono-hydrochloride, C4H,N2(C6H,*OMe),,HC1. It dissolves sparingly inethyl acetate or chloroform containing an excess of hydrogenchloride, but is unstable in moist air, and is dissociated by alcoholor water.C,R2N2 (C6H,- OMe),, ob-tained from the above-described salt by treatment with water oralcohol, crystallised from the latter solvent in colourless needles,melting at 137.5O:178-180’ :pp ‘-Dim e t ho x y-2 : 6-d iph en y l p y razine,0.0987 gave 0.2670 CO, and 0-0505 H,O.C,8H,g02N, requires C = 73.9 ; H = 5-5 per cent.ppr-Dimethoxy-2 : 6-diphenylpyrazine is very readily soluble inchloroform, ethyl acetate, benzene, or xylene, but only moderatelyso in alcohol.Its neutral solutions exhibit a slight blue fluorescence,but this is destroyed by the addition of concentrated hydrochloricacid. It does not pass into a “liquid-crystalline” state on fusion.The constitution of pp’-dimethoxy-2 : 6-diphenylpyrazine was subse-quently proved by its conversion by means of hydriodic acid intoC=73*8; H=5.7TUTIN : SYNTEESES IN THE EPINEPHXINE SERIES. PART 11. 2507methyl iodide, ammonium iodide, and pp1-dihydroxydiphenacyl-amine hydriodi.de (p. 2522).The filtrate from the crude ppl-dimethoxy-2 : 6-diphenylpyrazinehydrochloride was dark brown, and contained considerable resinousmatter. It was digested with aqueous hydrochloric acid, filtered,and the filtrate treated with animal charcoal.After concentratingthe liquid thus obtained, it deposited a relatively small amount ofa sparingly soluble hydrochloride. This was recrystallised fromwater, when it formed leaflets, melting at 256O:0.2459 gave 0.1003 AgCl. C1=10*0.This salt was doubtless ppl-dimethoxyd@&enacyZamine hydro-chloride, (MeO*C,H,-CO*CH,),NH,HCl, as it was obtained in amanner analogous to that which resulted in the formation ofdiphenacylamine hydrochloride from w-chloroacetophenone, and itsproperties are strictly analopus to those of the latter salt. More-over, from evidence given in-the latter part of this communication,it is evident that ppl-dimethoxydiphenacylamine must have beenformed during the interaction of ammonia and w-chloro-p-methoxy-acetophenone, since the former base is an intermediate compoundin the production of the above-described ppl-dimethoxy-2 : 6-di-phenylpyrazine.It has already been shown in connexion with the preparation ofthe 2 : 5- and 2 : 6-diphenylpyrazines that if the reaction mixturewere kept for some time before it was worked up, a highly-coloured\y-product was formed, together with these bases.This is also theGse when working with the pmethoxy-derivatives, but in the latterintance several other compounds were also obtained in smallamunh, possibly owing to the fact that the reaction mixture wasexaLined much more fully than in the former case.o-(hloro-p-methoxyacetophenone was heated with alcoholicammohia as above described, but the reaction mixture was kept forthree \eeks before being examined.The ppl-dimethoxy-2 : 5-di-phenylpyazine was isolated as before described, but with the useof chloroorm instead of xylene. The mother liquors then yieldeda small abount of a compound, which formed soft, colourlessneedles, meking at 232-233O. On working up the original filtratefrom the MI-dimethoxy-2 : 5-diphenylpyrazine and ammoniumchloride in tb manner previously described, a mixture of pp'-di-methoxy-2 : 6-dphenylpyrazine and another salt was obtained. Thelatter compound was evidently the p-methoxy-derivative of the bluehydrochloride pnviously described ; it was dark green, and wasseparated from tb3 salt of the pyrazine derivative in a, manneranalogous t o that employed is connexion with the previously-C18H,,0,N,HC1 requires C1= 10.1 per cent2508 TUTlN : SYNTHESES IN THE EPINEPHRINE SERIES.PART IT.described blue compound. The mother liquors from these liydroechlorides yielded, together with traces of other compounds, a sub-stance which formed yellow leaflets, melting at 213--214O, but didnot fluoresce when treated in chloroform solution with hydrochloricacid. The deep green-coloured hydrochloride melted quite in-definitely, owing to dissociation, and this change was also readilybrought about by treatment with any solvent which did not containan excess of anhydrous hydrogen chloride. It yielded a deepcrimson-coloured base, crystallising from alcohol in small, lustrousprisms, which were so dark red as to awear almost black, andmelted at about 165O.This compound, like the corresponding phenylderivative previously described, is decolorised by exposure to directsunlight when dissolved, yielding a yellow substance, which formedneedles (m. p. about 255O) from xylene. The amounts of thesevarious by-products obtained was small, and their investigation wasnot further pursued.Derivatives of o-Ami~to-p-methoxyacetop7Lertone.It would appear that the above-described ppf-dimethoxy-2 : 5-di-phenylpyrazine must have been formed by the condensation of twomolecules of w-amino-p-methoxyacetophenone, followed by spon-taneous oxidation of the resulting ppf-dimethoxy-3 : 6-dihpdro-2 : 5-diphenylpyrazine in a, manner analogous to that which hasbeen shown by Gabriel (Zoc. cit.) to result in the formation of2 : 5-diphenylpyrazine from o-aminoacetophenone.With the object,theref ore, of verifying this conclusion, o-amino-pmethoxyacetcphenone was prepared, in the form of its hydrochloride, as folio+.o-Chloro-p-methoxyacetophenone was heated for some time i T anickel crucible with rather more than one molecular propopionof potassium phthalimide. The reaction mixture was then extflctedwith boiling xylene, and the product which crystallised fr@ thissolvent after concentration was repeatedly boiled witl- largequantities of water for the removal of unchanged phthalimde. Onrecrystallising the residue from xylene, glistening leaflets melting.at 164--165O, were obtained :0.1437 gave 0.3650 CO, and 0.0604 H2,0.o-Phthalimino-p-methoxyacetophenone,C = 69-2 ; P= 4.6.C,,HI3O,N requires C = 69.2 ; H =4*4 per cezt.MeO* C,€€4*CO*CH,*N<CO>C,H co 4,is very sparingly soluble in alcoho'l, ethyl acetat, or chloroform,but dissolves more readily in glacial acetic acid 01 boiling xylene.The above-described phthalide derivative w*s boiled for eighthours with concentrated hydrochloric acid, whea it gradually passeTUTIN : SYNTHESES I N THE EPINEPHRINE SERIES.P A R T 11. 2509into solution. The mixture was then deprived of phthalic acid bymeans of ether, and evaporated to dryness under diminishedpressure. On crystallising the residue from alcohol, o-amino-p-methoxyacetophenone hydrochloride,MeO*C6H4* C'O*C'H,*NH,,HCl,was obtained in small, colourless prisms, which melted and decom-posed at 204O, after having become red:0.2121 gave 0.1408 AgCl.C1=16'4.C,H,,O,N,HCl requires C1= 16.6 per cent.When an alkali is added to an aquepus solution of o-aminep-methoxyacetophenone hydrochloride, no immediate separation ofbase occurs. The mixture, however, rapidly darkens somewhat, and,after some time, a dark-coloured, semi-crystalline product separates.On purification, this yielded pp/-dimethoxy-2 : 5-diphenylpyrazine(m. p. 223O), thus proving that a change analogous to that observedby Gabriel (Zoc. cit.) had occurred.o -A mino-p-me t ho xy ace to ph enone Pla tinichlorid e,(Me0 *C6~4*C;O*CH,oNH2),H2PtCl,.--This derivative crystallised very readily in deep yellow leaflets,and melted and decomposed at 225-228O:0.1434 gave 0.0373 Pt.o-Amino-p-methoxyacetophenone Aurichloride,Pt =26-0.(C,H,102N)2H,PtCI, requires Pt = 26.3 per cent.MeO*C,H4*CO*CH2*NH2,HAuC14.-The aurichloride did not crystallise readily, but was eventuallyobtained in handsome, golden-coloured leaflets, which melted at74O, and evidently contained water of crystallisation :0.2024 gave 0.0762 Au.CgH1102N,HAuC14,H20 requires Au = 37.6 per cent.o - Amino - p - methoxyacetophenone picrate, C9Hl1O,N,C,H,O7N3,formed small, bright yellow leaflets, which? like the preceding com-pound, contained water of crystallisation.It melted and decomposedat 185O.The mercum'chlom'de crystallised very readily in long, colourlessneedles, which melted at 171O.Au = 37.6.o-Chloro-mp-dimetioxyacetophenone.Catechol was methylated by means of methyl sulphate," and theThe veratrole was then resulting veratrole purified by distillation.* Perkiii and Weizmann (Trans., 1906, 89, 1649) state that an almost quanti-tative yield of veratrole may be obtained by treating 100 grams of catechol with75 grams of methyl sulphate and 150 grams of potassium hydroxide.The figure2510 TUTIN : SYNTHESES IN THE EPINEPHRlNE SERIES. PART 11.dissolved in carbon disulphide, an equivalent amount of chloroacetylchloride added, and then one molecular proportion of powderedaluminium chloride introduced. The mixture was heated on awater-bath for two hours, but the reaction which ensued was byno means violent. The carbon disulphide was then removed andthe residue decomposed by ice and hydrochloric acid, the productbeing extracted with ether.On shaking the ethereal liquid withaqueous potassium hydroxide, a small quantity of demethylatedproduct was removed. The ether was then evaporated, and theresidue deprived of a fairly large proportion of unchanged veratroleby means of steam. The non-volatile product was crystallised fro-&alcohol, when it yielded o-chloro-mp-dimethoxyacetophenone,(MeO),C,H,*CO-CH,~Ci, which formed small, colourless prisms,melting at 101O:0.1172 gave 0.2394 CO, and 0.0538 H,O.o-Chloro-mp-dimethoxyacetophenone is moderately soluble inalcohol, but much more readily so in ethyl acetate or chloroform.When in the dry state, it occasions violent sneezing.C=55*8; H=5.1.C1,HllO3C1 requires C = 55-9 ; H = 5.1 per cent.The Imt eraction of o-Chloro-mp-dimethoxyacetophenone andA mmonia.o-Chloro-mp-dimethoxyacetophenone was heated in an autoclavefor three hours at llOo with a large excess of absolute alcoholicammonia.When cool, the solid contained in the reaction mixturewas collected, washed with alcohol, and then extracted many timeswith boiling xylene. The xylene extracts, on cooling, deposited adark red, crystalline powder, melting at 208O. After treatmentwith a small amount of potassium permanganate in glacial aceticacid solution, in the manner previously described, it sep-arated fromglacial acetic acid in light grey needles, which melted at the sametemperature as before this treatment:0.1130 gave 0.2834 CO, and 0-0590 H20.C20HdO4N2 requires C = 68.2 ; 33 = 5.7 per cent.This compound was evidently mmrppr-t etramethoxy-2 : 5-dipherqLpyrazi'lte, C,H4(OMe),*C4H2N2*C,H3(OMe)2, and its constitutionwas subsequently confirmed by its conversion into o-amino-mp-dikhydroxgacetophenone hydriodide and methyl iodide by the action ofhydriodic acid (p.2520). It' is insoluble, or nearly so, in all the usualsolvents with the exception of glacial acetic acid and boiling xylene,and in the latter solvent it dissolves but sparingly. Its much greatergiven are, however, obviously incorrect, since the amount of catechol mentionedwould require theoretically 229 grams of methyl sulphnte and 102 grsnis of thealkali.C=68*4; H=5*8TUTIN : SYNTHESES IN THE EPINEPHRINE SERIES.PART 11. 2511solubility in glacial acetic acid than in any other liquid employedappeared to be due to salt formation, as the solution was orange-yellow, and it was subsequently found that the tetramethoxy-diphenylpyrazines are more strongly basic than the other compoundsof this class described in the present communication. A very dilutesolution of mmfpp/-tetramethoxy-Z : 5-diphenylpyrazine in chloro-form exhibits a strong blue fluorescence, but’ this phenomenondisappears on the addition of a drop of concentrated hydrochloricacid, a non-fluorescent, deep yellow liquid being produced. Onfusion, this pyrazine derivative does not pass into a, “liquid-crystalline” state, as is the case with the corresponding ppl-di-methoxy-compound.The original alcoholic filtrate from the mmlppf-tetramethoxy-2 : 5-diphenylpyrazine and ammonium chloride was evaporated todryness, the residue extracted with benzene, the solution againevaporated, and the product so obtained dissolved in a small amountof absolute alcohol and a solution of hydrogen chloride in the samesolvent added.On cooling the dark brown mixture, a compoundseparated in deep yellow needles. This was collected, washed withalcoholic hydrogen chloride, and recrystallised from absolute alcoholby the addition of a solution of hydrogen chloride in this solvent,when long, deep yellow, soft needles were obtained, which melted atabout195-200°:0.2030 gave 0.0730 AgC1. C1=8-9.C,,H,,04N2,HC1 requires C1= 9.1 per cent.This compound was mm1ppf-tetramethoxy-2 : 6-diphenylpyraainemonohydrochloride, C6H,(OMe),~C4H2~-C,H,(OMe),,HC1.It wasreadily dissociated by water, or by alcohol, unless the latter con-tained an excess of hydrogen chloride. It yielded mmlppl-tetra-metAoxy-2 : 6-diphenyZpyra&e, which, when crystallised fromalcohol, formed long, almost colourless needles, melting at 160° :0.1079 gave 0.2734 CO, and 0.0563 H,O.CmH2,O4N2 requires C = 68.2 ; H = 5-7 per cent.This base was rather sparingly soluble in alcohol, but readily soin benzene, xylene, chloroform, glacial acetic acid, or ethyl acetate,and differed from the corresponding 2: 5-compound, inasmuch asits solutions exhibited no fluorescence. Its constitution was sub-sequently confirmed by its conversion into mm’ppl-tetra~~drozy-diphenucylanzline Iqdhodide, methyl iodide, and ammonium iodideby means of hydridic acid (p.2523).C=68-0; €€=5*82512 TUTIN: SYNTHESES IN THE EPlNEPHRINE SERIES. PART 11.w -Chlo ro-op-dime t hoxyac e tophenone.Resorcinol dimethyl ether was prepared from resorcinol by theaction of methyl sulphate and potassium hydroxide, and purifiedby distillation. The dimethyl ether was then dissolved in carbondisulphide, and the requisite amount of chloroacetyl chloride added.One molecular proportion of powdered aluminium chloride witsthen introduced, when a violent reaction ensued. After removingthe solvent, the residue was treated with ice and hydrochloric acid,the resulting solid being collected and crystallised from .alcohol.A very good yield of small, colourless, prismatic needles, melting at96O, was thus obtained:0.1233 gave 0.2518 CO, and 0.0577 H,O.C1,H1,0,C1 requires C = 55.9 ; H = 5.1 per cent.w -Chloro-op-dime t ?LOX yace t ophenone, ( Me0)2C6H3*C'O-CH2Cl, issomewhat sparingly soluble in alcohol, but much more readily soin ethyl acetate or chloroform.It was formed in much better yieldthan the corresponding mp-compound.Attempts to convert w-chloro-opdimethoxyacetophenone intopyrazine derivatives by heating with alcoholic ammonia resultedonly in the formation of brown resins, just as was the case whenw-chloreo-methoxyacetophenone was employed. It therefore appearsthat the presence of a methoxyl group in the ortho-position withrespect to the side-chain precludes the formation of substitutedpyrazines from w-chloroacetophenone derivatives.Attempts were made to prepare an w-chlorotrimethoxyaceto-phenone by the interaction of chloroacetyl chloride and pyrogalloltrimethyl ether, but without success.C=55.7; H=5.2.w -A mino-op-dih ydro xyace t o p h enone and i t s D erivu tives.It is subsequently shown that the methoxy-2 : 5-diphenylpyrazinesreadily yield w-aminohydroxyacetophenones, the formation of whichwas the primary object of this research.Since, however, nopyrazine derivative could be obtained from w-chloro-opdimethoxy-acetophenone, other means had to be devised for the conversion ofthis compound into the desired dihydroxy-mine.w-Chloro-op-dimethoxyacetophenone was heated in a nickelcrucible at about 160° with rather more than one molecular pro-portion of pot.assium phthalimide until the reaction mixture, whichwas at first fairly fluid, became almost solid.The product w mthen extracted several times with boiling xylem, and the combinedfiltered liquids concentrated to a small bulk. The product whichseparated on cooling wils collected and repeatedly boiled with largTUTIN : SYNTHESES IN THE EPINEPHRINE SERIES. PART Ir. 2513quantities of water until free from phthalimide, after which it wa,srecrystallised from xylene o r glacial acetic acid, when it formedacicular crystals, melting at 188O :0.0903 gave 0.2209 CO, and 0.0394 H,O.w-Phthalimino-op-dimethoxyacet ophemne,C= 66.7 ; H =4%CI8H,,O,N requires C = 66.5 ; H = 4.6 per cent.is insoluble, or very sparingly soluble, in all the usual solvents, withthe exception of glacial acetic acid and boiling xylene, in which itis moderately soluble.The above-described phthalide derivative was boiled with con-centrated hydriodic acid containing some glacial acetic acid, whenit very gradually passed into solution.The mixture was thendiluted with water, and repeatedly extracted with ether for theremoval of the phthalic acid, after which it was evaporated t odryness under diminished pressure. The solid residue was thendissolved in alcohol, the solution concentrated, ethyl acetate added,and the mixture again evaporated somewhat, when o-amino-op-di-hydroxyacetophenone hydriodide, C6H,(OH),*CO*CH,*NH,,HI,separated from the boiIing mixture :0.2196 gave 0.1733 AgI.I = 42.7.0'4535 ,, 0.3405 AgI. I=42*8.o-Amino-opdihydroxyacetophenone hydriodide forms nearlyIt is readily solubleC8Hg03N,HI requires 1 = 43.0 per cent.colourless needles, which decompose a t 25SO.in water or alcohol, but dissolves only sparingly in ethyl acetate.o-A mino-op-dih ydro xyace t o ph enone Hydro ch2orid e,C,H,(OH),*CO*CH,*NH2,HCl.-This salt was prepared by the addition of concentrated hydro-chloric acid to an alcoholic solution of the corresponding hydriodide,when the new derivative immediately separated in needles. Whencrystallised from water or dilute alcohol, it yielded small, hardprisms, which melted at 2SOo, darkening previously :C1= 17.2. 0.3297 gave 0.2292 AgCl.o-A mino-op-dih ydroxyac et opli enone A urichloride,C8Hg03N,HC1 requires c1= 17.4 per cent.C6H3(OH)2*C'O*CH,*NH2,HAuC1,.-The gold salt of o-amino-op-dihydroxyacetophenone was readilysoluble in water, but crystallised from its concentrated solution inorange-coloured leaflets, which, on heating, gradually darkened,and finally melted at 283O.0*1201 gave 0.0467 Au.The dried salt was analysed:Au = 38.9.C8H,0,N,HAuCl, requires Au = 38.9 per cent2514 TUTIN: SYNTHESES IN THE EPINEPHRINE SERIES.PART 11.o-Amino-op-dihydroxyacetophenone Platinichloride,[C6H,(OH)2*C00CH2*NH2]2,H,PtC16.-This derivative was rather readily soluble in water, and crys-tallised from this solvent in fawn-coloured needles, which meltedand decomposed at 247O:0.1037 gave 0.0294 Pt.Pt=28*5.(C,H,03N),H2Pfc16 requires Pt = 28.5 per cent.o -,4 mino,op-dihy dro x yac e toph enone pkra t e, CaHg0,N,C6H,0,N,,crystallised from water in bright yellow needles, which melted anddecomposed at 222O.o - Amino-op-dihydroxyacetop7zenone, C6H,(OH),*CO*CH2=NH,,was prepared from the above-described hydriodide or hydrochlorideby the addition of a hot concentrated solution of sodium carbonateto a similar solution of the respective salt, both liquids havingpreviously been deprived of dissolved air by boiling. The newbase then immediately separated in small, pinkcoloured plates,which, on heating to 310°, suffered some decomposition, but did notmelt :0.1065 gave 0.2240 CO, and 0.0558 H,O.C,Hg03N requires C = 57.5 ; H = 5.4 per cent.w-Amino-op-dihydroxgacetophenone is soluble in both acids andalkali hydroxides, but is insoluble, or practically so, in all the usualsolvents with the exceptiop of pyridine, although when dissolvedin the last-mentioned liquid it suffered change.Attempts to prepare o-amino-op-dimethoxyacetophenone by heat-ing o-phthalimineopdimethoxyacetophenone with hydrochloricacid were unsuccessful, as the methyl groups were partly eliminatedby this treatment, the resulting product being a mixture.C=57.3; H=5.8.oorppr-Tetrahydroxy-2 : 5-diphenylpyrazine.o -Amino-opdih ydroxyace t op henone was boiled with p yridine,when it slowly dissolved, the solution acquiring a yellow colour.The liquid was then concentrated and cooled, when a substanceseparated in yellow needles.This was collected, but when washedwith ethyl acetate, or when dried, it lost pyridine of crystallisation,and became bright orange-coloured. It was unchanged at 326O,but at a higher temperature sublimed in yellow leaflets:C=64.6; H=4*3.C,,H,.O,N, requires C = 64.8 ; H = 4.1 per cent.0.1033 gave 0.2447 CO, and 0.0400 H,O.This substance was evidently oorppr-tetrahydroxy-2 : 5-diphenyEpyrazine, C,H,(OH),.C,H,N,°C6H3(0H)2, and had been formed bythe condensation of two molecules of the original keto-base followedby spontaneous oxidation of the resulting oo’ppl-tetrahydrozyTUTIN : SYNTHESES IN THE EPINEPHliJNE SERIES. PART 11, 25153 : 6-dil~ydro-2 : 5-diphenylpgra:ine. It yielded unstable salts withthe mineral acids, of which the monosulphate wi19 bright orangeand the disulphate intense purple.oo’pp’-Tetrahydroxy-Z : 5-di-phenglpyrazine is very sparingly soluble in glacial acetic acid, morereadily solub!e in pyridine, and insoluble in all the other usualsolvents.oo’ppr-Tetrab enzoyloxy-2 : 5-diphenylpyrazine,C,H,( OBz)zDC*H2N2.C6H3(OBZ)2.-The above-described oo’pp’-tetrahydroxy-2 : 5-diphenylpyrazinereadily underwent benzoylation when treated according to theSchotten-Baumann method, yielding a product which crystallisedfrom ethyl acetate in glistening, colourless leaflets, melting at 2 1 2 O :0.0976 gave 0.2643 C’O, and 0.0356 H,O.C44H2808N‘2 requires C = 74.1 ; H = 3.9 per cent.oorppf-Tetrabenzoyloxy-2 : 5-diphenylpyrazine is somewhat spar-ingly soluble in ethyl acetate and in alcohol, but dissolves readily inchloroform.With the object of preparing the benzoyl derivative of o-amino-op-dihydroxyacetophenone, the hydriodide of this base was dissolvedin water, benzoyl chloride added, and then excess of aqueouspotassium hydroxide introduced, and the mixture shaken for sometime.The pasty product which separated was collected, dissolvedin boiling absolute alcohol, and then submitted to steam distillationfor the removal of the ethyl benzoate which had been formed fromthe occluded excess of benzoyl chloride. The non-volatile residue wasdissolved in alcohol, when, on keeping, a crystalline benzoyl derivativeseparated, but by no means in quantitative yield. The motherliquors from this solid contained an uncrystallisable oil, which, froma subsequent observation, would appear to have been the compoundwhich it was sought to prepare, namely, u-b enzoylamino-op-dib enzoyl-oxyacetophenone, C6H,(OBz),*~o0CH,*N~Bz. The crystallinesolid which was obtained formed small prisms, melting at 136-137O,and, on analysis, was found to be the benzoyl derivative of acondensation product of the base : *C = 73.8 ; H = 4.0.0.1532 gave 0.4106 CO, and 0.0624 H20.C2,H,,0,N requires C = 73.6 ; H = 4-2 per cent.0.2970, in 24 of benzene, gave At = - 0*165*.CZ2Hl5O4N requires M.W.= 357.This cornpound waa therefore the dibenzoyl derivative of aninternal anhydride of o-amino-op-dihydroxyacetophenone, and sincean analogous compound was obtained from a-aminGo-hydroxyaceto-phenone (pa 2518), but not from the related bases containing* The same compound was obtained when w-amino.opdihydroxyacetoy,henonehydriodide was benzoylated in pyridine solution.C = 73.1 ; H =4-5.M.W. = 3752516 TUTIN : SYNTHESES IN THE EPINEPHRINE SERIES.PART I1hydroxyl groups in the m- or p-positions, it would seem likely thatthe o-hydroxyl group was concerned in the anhydride formation. Inview of this consideration, it would appear probable that the sub-stance melting at 136-137O is a dibenzoyl derivative of 6-hydroxy-indoxyl (X):B~o*c,H,<~~>cH, H O * C , H ~ < ~ ~ ~ ~ > C H .(X-) (XI.)6-Hydroxyindoxyl, however, might have been expected to reactin its enolic form (XI), yielding a tribenzoyl derivative.That one of the benzoyl groups was attached to nitrogen wasproved by the conversion of this dibenzoyl derivative int'o o-benzoyl-amino-op-dihydroxyacetophenone by the action of alkali hydroxides.C,H,( OH),*CO*CH,-NHBz.-A quantity of the dibenzoyl derivative melting at 136-137O wasboiled with concentrated alcoholic potassium hydroxide for onehour, when water was added, and the mixture acidified with hydro-chloric acid.A compound then separated in slender, glisteningprisms, melting and decomposing at 260-265O :w-Benzoylamino-op-dih ydroxyacetopkenome,0.1339 gave 0.3267 CO, and 0.0590 H,O.C,,HI30,N requires C = 66.4 ; H = 4.8 per cent.w-Benzoylamino-op-dihydroxyacetophenone is very sparingly solublein alcohol, ethyl acetate, chloroform, or benzene, moderately so inglacial acetic acid, and readily so in pyridine. On prolongedheating with concentrated hydrochloric acid, it yielded o-amino-op-dihydroxyacetophenone hydrochloride and benzoic acid, and onbenzoylation it yielded a compound which appeared to be thetrib enzoyl derivative of the corresponding base.This compoundwas a liquid, and was doubtless identical with the similar productwhich was obtained together with the dibenzoyl derivative meltingat 136-13707 as previously noted.C = 66.5 ; H = 4.8.w -Ph tha Zimko-op-dih ydroxyac eto phenone.During the hydrolysis of w-phthalimineop-dimethoxyacetophenoneby means of hydriodic acid, it was observed that the reaction pro-ceeded in two stages, the methyl groups being much more rapidlyeliminated than was the phthalyl radicle.In one experiment,therefore, the reaction was stopped as soon as the evolution ofmethyl iodide had ceased, the mixture being diluted with waterand cooled. A solid then separated, which was collected andwashed. When recrystallised from acetic acid, this substance formedsmall tufts of short, colourless prisms, which gradually darkenedabove 2550°, and fused at 270°TUTIN : SYNTHESES IN THE EPINEPHRINE SERIES. PART 11. 25170.1835 gave 0.4350 CO, and 0.0637 H;O.w- Pht halimino-op-dih ydrox yacetophenone,C=64*6; H=3.8.C16H,,0,N requires C = 64.6 ; H = 3.7 per cent.is rather sparingly soluble in most solvents. When heated withconcentrated hydrochloric or hydriodic acids, it yielded the corre-sponding amine.w-1'1~ t hdamino-op-dihydroxyacetophenone,C,H,( OH),*CO*CH,*NH*CO*CGH4*C0,H.-The above-described pht halimino-derivative was dissolved inaqueous potassium hydroxide, and the solution boiled for some time.The mixture was then acidified with hydrochloric acid, boiled withanimal charcoal, and the filtered liquid concentrated to a, smallbulk and cooled.The solid which separated consisted largely ofpotassium chloride, but also contained crystals of an organic com-pound. The latter was isolated by extraction with boiling xylene,after which it was finally purified by crystallisation from water.Long, glistening leaflets were thus obtained, which melted a t 227O:C,GHl,O,N requires C = 61.0 ; H =4.1 per cent.0.1372 gave 0.3064 CO, and 0.0519 H,O.C = 60.9 ; H = 4.2.De~ivatives of w-Amino-o-hydroxyacetophenone.Since w-chloro-o-methoxyacetophenone gave only resinous productswhen heated with ammonia, it was necessary to employ potassiumphthalimide for the conversion of this chloro-ketone into the corre-sponding amine, just as was the case with the andogous opdi-methoxy-compound (compare p. 2512).w-Chloro-o-methoxyacetophenone was therefore converted into thecorresponding phthalimino-derivative in a, manner precisely similarto that employed in the case of the op-dimethoxy-derivative. Theresulting o-phtlbalimino-o-methoxyacetophenone,MeO*C,H,*CO*CH2*N<CO>C6H4, cowas very sparingly soluble in most solvents, but was readily purifiedby crystallisation from slightly diluted acetic acid.It formedcolourless, diamond-shaped plates, melting a t 200'5O :0.1553 gave 0.3972 CO, and 0.0632 H,O.This derivative was boiled for three hours with a mixture ofglacial acetic acid and concentrated hydriodic acid. After freeingthe liquid from phthalic acid by extraction with ether, the mixturewas evaporated to dryness under diminished pressure, and theresidue crystallised from a, mixture of ethyl acetate and alcohol.C = 69.5 ; H =4*5.C1,H,,O,N requires C = 69.2 ; H = 4.4 per cent.VOL. xcvir. 82518 TUTIN : SYNTHESES IN THE EPINEPHRINE SERIES. PART 11,Very lustrous, colourless plates were thus obtained, which melted at255O :0.3846 gave 0-3230 AgI.o-S mino-ehydrox yacet ophenone hydriodide,I =45-4.C,H,O,N,HI requires I = 45.5 per cent.HO*C6H4*CO- CH,*NH,,HI,is very readily soluble in water or alcohol, but only sparingly soin ethyl acetate.It does not tend to become discoloured, as is thecase with salts of the analogous bases containing a hydroxyl groupin the met% or parzLposition with respect to the side-chain.A quantity of this hydriodide was dissolved in pyridine andbenzoylated by means of benzoyl chloride. The product crystallisedreadily from ethyl acetate, forming colourless plates, which meltedat 133O :0-1277 gave 0.3538 CO, and 0.0530 H20.C,,H,,02N requires C = 75.9 ; H = 4.7 per cent.This compound was therefore evidently the benzoyl derivative of acondensatdon product of o-amino-o-hydroxyacetophenone, and isdoubtless constituted analogously to the corresponding derivativeof the op-dihydroxy-base (p.2516). It may therefore be l-benzoyl-indoxyl, a compound which does not appear to have been preparedpreviously.ooI-Dih ydroxg-2 : 5-diph eny Zpy razine.A quantity of o-amino-o-h ydrox y acet op henone h ydriodide wasdissolved in water and aqueous sodium carbonate added, the result-ing precipitate being collected, and crystallised from xylene. Asubstance was thus obtained in yellow needles, which melted at259--262O, and were insoluble in dilute acids. The same compoundwas obtained if the solution of the hydriodide were renderedalkaline by means of sodium hydroxide, and then acidified, theresulting precipitate being recrystallised from xylene :C = 75.6 ; H=4-6.0-0904 gave 0.2420 CO, and 0*0400 H20.This substance was evidently a condensation product, and itsproperties indicated it to be oof-dihpdroxy-2 : 5-diphenyZpyrazine,C,H2N,(C6H4*OH)2.It is very sparingly soluble or insoluble innearly a.11 solvents, and forms unstable salts of a bright red colourwhen treated with mineral acids in an anhydrous solvent. Whenheated above its melting point, it sublimed in yellow leaflets.It appears from this result that o-amineo-hydroxyacetophenone,when dissolved, behaves in a manner strictly analogous to thatexhibited by the opdihydroxy-base. That is to say, that twomolecules condense with the formation of 00'-dihydroxy-3 : 6-dGC = '73-0 ; H = 4.9.C,,H,,0,N2 requires c = 72'7 ; H = 4.5 per centTUTIN : SYNTHESES IN THE EPINEPHRINE SERIES.PART 11. 2519hydro-2 : 5-diphenylpyrazine, which then undergoes spontaneousoxidation to the corresponding pyrazine derivative.oot-Bib ensoyloxy-2 : 5-diphenylpyrasine, C,H,N,( C,H4*OBz),, wasprepared by benzoylating the above-described pyrazine derivativein pyridine solution, It formed small, almost colourless prisms,which melted at 185O, but the amount available was not sufficientfor analysis.A ction of Hydriodic Acid on pp/-Dimethoxy-2 : 5-diphenylpgrazine.As previously shown, the methoxy-2 : 5-diphenylpyrazinesdescribed in the present paper, which contain the substituent ethergroupings in the met% and para-positions, are formed by the con-densation of two molecules of an w-aminomethoxyacetophenone,followed by spontaneous oxidation of the resulting dihydropyrazinederivative, as follows (Gabriel, loc.cit.) :The corresponding o-aminohydroxyacetophenones, however, couldnot be caused to condense under any conditions.This behaviour is the reverse of that shown by the ortho-substituted o-aminoacetophenones, for o-amino-o-methoxyaceto-phenone and w-amino-op-dimethoxyacetophenone will not yieldpyrazines, whilst the corresponding hydroxy-derivatives spon-taneously pass into such compounds.With the object therefore of preparing pp'-dihydroxy-2 : 5-di-phenylpyrazine, the action of hydriodic acid on ppl-dimethoxy-2 : 5-diphenylpyrazine was investigated. It was found, however,that this acid alone had only an extremely slow action on thecompound in question, but that if a quantity of acetic acid wereadded to the mixture, a change ensued with moderate rapidity.The product obtained, however, was not the expected hydroxy-diphenylpyrazine, but the reaction proceeded further, fission of thepyrazine nucleus taking place, resulting in the formation of twomolecules of o-amine-p-hydroxyacetophenone (Tutin, Caton, andHann, Zoc.cit.). It was thus shown that the series of reactionswhich result in the formation of pyrazine derivatives from w-amino-acetophenones can be quantitatively reversed by means of hydriodicacid.A quantity of ppl-dimethoxy-2 : 5-diphenylpyrazine was boiled fortwo hours with a mixture of concentrated hydriodic and glacialacetic acids. The liquid was then diluted with water and extractedwith ether for the removal of iodine, after which it was evaporatedto dryness under diminished pressure.On crystallising the residue8 ~ 2520 TUTIN : SYNTHESES IN THE EPINEPHRINE SERIES. PART 11.from ethyl acetate, colourless, prismatic needles were obtained, whichmelted at 230O:0.3435 gave 0.2885 AgI. 1=45*4.w- A mino-p-l~y droxyac e t oph enone h y driodide,C8ff,0zN,HI requires I = 45.5 per cent.HO C6H,*CO*CH,-NHz,HI,is much more soluble in organic solvents than is the correspondinghydrochloride (Tutin, Caton, and Ham, Zoc. c i t . ) . On benzoylation,it yielded o-benzoylaminep-benzoyloxyacetophenone, melting a t173-174O.d ction of Eydriodic A.cid on mmfppf-Tetramethoxy-2 : 5-ifiphe.nyl-pyrazine.mmfpp’-Tetramethoxy-2 : 5-diphenylpyrazine was boiled for twohours with a mixture of glacial acetic and concentrated hydriodicacids, after which the liquid was diluted, extracted with ether, andevaporated to dryness under diminished pressure.The residue wascrystallised from a mixture of ethyl acetate and alcohol, when itformed small, nearly colourless prisms, melting at 247-248O :0-2175 gave 0.1717 AgI. 1=42.7.C8H,03N,HI requires I = 43.0 per cent.This salt was therefore evidently o-amino-mp-dihydroxyaceto-plhenone hydriodide, C6H3(OH)z*CO*GH,*NHz,HI. On renderingits solution alkaline with sodium carbonate, o-amino-mp-dihydroxy-acetophenone separated in nearly colourless leaflets, which graduallydecomposed and melted above 235O. This base has previously beenprepared by another method during the synthesis of epinephrine(D.R.-P.1556321, and the above-described reaction therefore affordsa new means of obtaining this important compound.Action of EydAodic Acid o n 2 : 6-Diphenylpgrazine.As the action of hydriodic acid on the 2 : 5-substituted pyrazineswas found to result in the complete disruption of the pyrazine ring,it was considered of interest to investigate the effect of this reagenton the analogous 2 : 6-substituted bases. It was then found thatthe nitrogen-containing ring was broken in this case also, in thefollowing manner :A quantity of 2 : 6-diphenylpyrazine was heated for several hourswith a mixture of concentrated hydriodic and glacial acetic acids.On allowing the liquid to cool, a sparingly soluble hydriodideseparated. This was collected, and recryst,allised from glacial acetiTUTIN : SYNTHESES IN THE EPINEPHRINE SERIES.PART 11. 2521acid, when it formed flattened needles, which melted and decom-posed at 211O. This salt proved to be diphenacylamine hydriodide,( C6H5* CO CH2),NH, H I :0.1981 gave 0,1217 AgI. 1=33.2.C1,Hl5O2N,HI requires I = 33.3 per cent.This hydriodide was converted into the corresponding hydro-chloride by treatment with hydrochloric acid in alcoholic solution,when glistening leaflets were obtained, which melted at 235O, afterpreviously becoming red. (Found, C1= 12.4. Calc., C1= 12.3 percent.) This salt had all the properties of diphenacylamine hydro-chloride, as described by Gabriel (Zoc. cit.), and it yielded gold andplatinum salts, in agreement with the similar derivatives preparedby him.The original acid filtrate from the diphenacylamine hydriodidewas evaporated to dryness under diminished pressure, and theresidue crystallised from a mixture of ethyl acetate and alcohol.A colourless salt was thus obtained, which dissolved easily in water,and was readily recognised by the usual tests as ammonium iodide.Conversion of Biphenacylamine into 2 : 6-IAphenylpyrazine.Both Gabriel (Zoc.c d . ) and the present author (p. 2502) haveobtained diphenacylamine by the interaction of w-bromo- or chloro-acetophenone and ammonia, and the present author has shown that2 : 6-diphenylpyrazine is also formed in this reaction (p. 2501).Now, since diphenacylamine results when this pyrazine derivativeis heated with hydriodic acid, it appeared to the present author thatthe former base might be the intermediate compound in theformation of the latter by the reaction mentioned.This has beenfound to be the case, for, when one of the above-described salts ofdiphenacylamine was heated with ammonia, 2 : 6-diphenylpyrazinewas regenerated. It is thus seen that the change which results inthe formation of 2 : 6-diphenylpyrazine is capable of reversion bymeans of hydriodic acid, just as has been shown to be the case withthe analogous 2 : 5-substituted pyrazines.A quantity of diphenacylarnine hydrochloride was heated in a,sealed tube for three hours at looo with a large excess of a solutionof ammonia in absolute alcohol.The reaction mixture was thenevaporated to dryness, the residue extracted with benzene, and thebenzene liquids evaporated. The dark-coloured residue so obtainedwas dissolved in a small amount of ethyl acetate, and a solutionof hydrogen chloride in absolute alcohol added, when 2 : 6-diphenyl-pyrazine monohydrochloride (m. p. lS9O) separated. On treatmentwith alcohol, this salt dissociated, yielding 2 : 6-diphenylpyrazine,melting at 90°2522 TLTTIN : SYNTHESES 1N THE EPLNEPHRINE SERIES: PART 11.It is, of course, evident that the interaction of diphenacylamineand ammonia must first result in the formation of a dihydro-2 : 6-diphenylpyrazineY the la-tter then undergoing spontaneousoxidation.Action, of Hydriodic A cid on pp1-Dimethoxy-2 : 6-diphenylp~razine.A quantity of pp'-dimethoxy-2 : 6-diphenylpyrazine wits boiledfor several hours with a mixture of concentrated hydriodic andglacial acetic acids.On allowing the mixture to cool, a verysparingly soluble hydriodide separated in long, colourless needles,which melted and decomposed at 2 5 1 O :0*1050 gave 0.1805 CO, and 0.0392 H20.ClGHl,04N,HI requires C = 46.5 ; H = 3.8 per cent.This salt theref ore was ppl-dihydroxydiphenacyZamine hydriodide,( HO*C,H,*CO0CH2),NH,HI. It was very sparingly soluble inwater, and rather more soluble in alcohol, but was insoluble in coldsolvents in the presence of an excess of hydriodic acid. pp'-Bi-hydroxydiphemcylamine, prepared from this salt, formed dark redcrystals, but as it was very unstable it was not further investigated.ppf-BihydroxydiphenacyZamine Hydrochloride,( HO*C6H,-CO* CH2),NH,HC1.-This salt was prepared by the addition of concentrated hydrechloric acid to an alcoholic solution of the corresponding hydriodide.It crystallised from alcohol in colourless leaflets, or from water inneedles, and melted at 279O.It is less soluble in alcohol than thehydriodide, but dissolves in water more readily than the latter :0.2093 gave 0.0914 AgCl.ppI-Bih y drozydiph enac ylamine Yla tinichloride,C=46*8; H=4*1.C1= 10.8.CuH150,N,HC1 requires C1= 11.0 per cent.[ ( HO°C,H4*C'OoCH2)2NH]2H2PtC16.-This derivative crystallised very readily in buff-coloured needles,which melted and decomposed at 230O:0.1210 gave 0.0241 Pt.Pt=19*9.pp'-BihydroxydiphenacyZamine AurichZoride,(C,,Hl,O,N),H,PtCI, requires Pt = 19.9 per cent.(HO*C,H4*CO*CH,),NH,HAuC1,.-This salt crystallised readily in bright yellow needles, whichmelted at 259O after undergoing some decomposition :0.1012 gave 0.0319 Au. Au=31.5.pp' - Di~~yd?.oxydi~?~enucyla.ntil.2.e @crate, C,,H,,04N,C,H,0,N3,C,,H,,O,N,HAUC~~ requires Au = 31.5 per cent.forms long, bright yellow needles, which melt at 169OTUTIN : SYNTHESES IN THE EPINEPHRINE SERIES. PART 11. 2523Conversion of ppl-Dihydroxydiphenacy2amine into ppf-Dihydroxy.2 : 6-diphenylpyrazhe.ppl-Dihydroxydiphenacylamine hydrochloride was heated for twohours in a sealed tube at looo with a large excess of a solution ofammonia in absolute alcohol. The mixture was then evaporated,and the residue extracted with boiling xylene. On crystallisingfrom glacial acetic acid the material dissolved by the xylene, small,pale yellow prisms, melting at 3 0 5 O , were obtained:0.1210 gave 0.3192 CO, and 0.0496 H,O.This compound wi19 evidently ppl-dihydroxy-2 : 6-diphenyl-pyi-uaine, C4H2N2(C6H4*OH),. It yielded unstable salts with themineral acids, the monohydrochiloride and monosalphate beingorange-coloured, whilst the diszclphute was deep reddish-purple.C=72*5; H=4*5,C,,H,,0,N~2 requires C = 72.7 ; H = 4.5 per cent.Action of Hydriodic Acid on mmfpp~-Tetrumethoxy-2 ; 6-diphenyl-pyrazine.nzmIppl-Tetramethoxy-2 : 6-diphenylpyrazine was heated withhydriodic acid in a manner similar to that described in connexionwith the corresponding dimethoxy-compound. A hydriodide wasthus obtained, which crystallised from acetic acid in colourlessleaflets, and melted and decomposed at 236O:0.1725 gave 0.0918 AgI. I=28*3.rnmlppl-T etrahydroxyd iph enacylamine hydriodide,C,,H,,O,N,HI requires I = 28.5 per cent.[C,H3(0H),*CO*CH2J2NH,HI,is somewhat more soluble in water than the corresponding di-hydroxy-compound. On treating its aqueous solution with alkalis,a yellow colour is produced, but oxidation very rapidly ensues, withthe development of a brown colour.mrnlppf-T e t rahydro x ydiph enac ylamin e I1 ydrochl oride,[C,H3(OH),*CO*CH,],NH,HCl.-This saIt was prepared by the addition of concentrated hydro-chloric acid to an alcoholic solution of the abovedescribedhydriodide, when the new derivative immediately separated. Itcrystallises from water in colourless leaflets, which melt and decom-pose at 264O:0.2687 gave 0.1075 AgC1. C1=9.9.C,,H,,O,N,HCZ requires C1= 10.0 per cent.On treating a solutian of mrnlppl-t e t ra?hydroxydiphenci cy Zami~i r:hydrochloride with auric o r platinic chloride, the respective metalwas quickly deposited. A rnercurichloride was obtained from th2524 TUTIN AND CATON: THE ABSORPTION SPECTRA OFhydrochloride in tufts of small, white needles, but it was unstable,and, on warming its solution, sercurous chloride soon separated.mml p p 1 -Te t rahydrox ydiph enac y Zarni~~e picrat e,[C,H,( OH),-CO *CH,],NH,C6H3O7N3,crystallised readily in tufts of yellow needles, which containedwater of crystallisation, and, when air dried, melted at 112--115°.I n conclusion, the author wishes to acknowledge his indebtednessto Mr. F. W. Caton, B.A., B.Sc., for the preparation and purificationof the o-chloro-o- and p-methoxyacetophenones employed in thisresearch.THE WELLCOME CHEMICAL RESEARCH LABORATOKIES,LONDON, EC

ISSN:0368-1645    

DOI:10.1039/CT9109702495

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

2524 TUTIN AND CATON: THE ABSORPTION SPECTRA OFCCLVIIL-The Absorption Spectra of Some SubstitutedPyraziaes and thew Salts.By FRANK TUTIN and FREDERIC WILLIAM CATON.IN the preceding paper, the preparation of 2 : 5- and 2 : 6-diphenyl-pyrazine, pp’-dimethoxy-2 : 5- and -2 : 6-diphenylpyrazine, andmm’pp’-tetramet%hoxy-Z : 5- and -2 : 6-diphenylpyrazine is described.During the course of this work, certain remarka.ble colour changeswere observed on treating these bases with acids, which suggestedto us that a fuller investigation of the subject might lead tointeresting results. Thus, whilst trhe hydrochloride of 2 : 6-di-phenylpyrazine appeared colourless, the corresponding salts of theanalogous pp’-dimethoxy- and mm’pp’-tetramethoxy-bases werebright yellow and orange-coloured respectively.Furthermore, onadding sulphuric acid to a chloroform solution of pp/-dimethoxy-2 : 5-diphenylpyrazineY a yellow liquid which exhibited an intense,green fluorescence was first produced, whilst on the addition ofan excess of the acid a very deep violet-coloured solution resulted.The further investigation of the bases in question rendered itevident that pyra.zine derivatives, which have hitherto been statedto be monoacidic bases, in reality yield two series of salts, thedi-acid salts being in all cases much more highly coloured thanthe corresponding derivatives containing but one equivalent ofacid. The depth of colour of corresponding salts of analogous baseswas found to increase with the accumulation of methoxyl groups,and to be somewhat greater in compounds of the 2: 5-series thanin the corresponding members of the 2 : 6-series.The colours of the salts obtained will be seen on reference to thefollowing table MOUO-hydrocbioride.Very pale yellowsolution.Practicallycolourlesscry st als.Bright yellowcrystals.Mono-hydrobromide.Pale yellowsolution.Dihydro-chloride.Bright yellowsolution.Yellow solution.Base,2 : 5-Diphenylpyrazine.Monosulphate.( 1 )Palo yellowcrystals.Colourlesscrys tals.2 : 6-Diphenylpyrazine.pp'-Dimethoxy-2 : 5-diphenylpyrazine.Orange-colouredcrystals.Yellow crystals.pp'-Diniethoxy-2 : 6-diphen ylpyrazine.Yellow crystals.Deep yellowcrystals.-Pale yellowcrystals.(Could notformed.Orange-redcrystals.mm'pp'-Te tramethoxy-2 : 5-diphenylpyrazine.snm'pp'-Tetranietlioxy-2 : 6-diphenylpyraziiie.Deep yellowcrystals.Orange-colourodcrystals.Yellow crystals.(Could notformed2526 TUTIN AND CATON: THE ABSORPTION SPECTRA OFd 5 2000X ! 1800*-2 1600 s2N 3 14002kq 1200 s s2Y*+-- 8 1000800I n order therefore t o throw some light on the nature of thesecolour changes, some of the above-mentioned bases and certain oftheir salts have been examined spectroscopically in chloroformsolution. This solvent was chosen as both the bases and their saltsare sufficiently soluble in it, and, although it has a, certain amountof general absorption in the extreme ultra-violet region of thespectrum, it was thought that it would not interfere appreciablywith the results.Moreover, the sa.lts of the pyrazines have muchless tendency to hydrolyse when dissolved in chloroform than inalcoholic solution.*The curves obtained from 2 : 6-diphenylpyrazine, pp’-dimethoxy-‘t ‘ P C!- ’FIU. 1.Oscillation frequencies.2000 2500 3000 3500 40002 : 6-Diphenylpyrazine2 : ti-Diphenylpyrazine hydrocldoride.2 : 6- Dipl~enylpyrazii~e hydrobroinide.- - - - - -- - _2 : 6-diphenylpyrazine, and nznt’pp’-tetramethoxy-2 : 6-diphenyl-pyrazine are shown in Figs. 1, 2, and 3 respectively. From these itis seen that each of the bases shows absorption in the ultra-violetpart of the spectrum, and that salt-formation is accompanied by aconsiderable shift of the bands towards the red end, thus accountingfor the development of colour on treatment with acids.I n thecase of 2 : 6-dipheiiylpyrazine hydrochloride, which is practicaJlycolourless, the absorption bands still lie within the ultra-violet,have a certain excess of the respective acid in the solution.* Even when employing chloroform as a solvent for the salts it was iiecessary tSOME SUBSTITUTED PYRAZINES AND THEIR SALTS. 2527FIG. 2.Oscillation f ~e p uencies.2000 2500 3000 3500 400000 2 2000X% g 1200$10003 -*Y800pp'-Dimethoxy-2 : 6-diphenylpyraxine.- - - - - - pp'-Dimathozy-2 : 6-diphenylpyrzine hydrochloride._ - - pp'-Dimthoxy-2 ; 6-diphe~nylpyrxine hydrobromide.FIG. 3.Oscillation f repuencies.2000 2500 3000 3500 40000 0" 20004Xc;) -f 3 140020 0860 C !z3s40800m dpp'- Tetrccmet hoxtj - 2 ; 6 -diphe?Lylpyrazinc.- - - - - - mm'pp'-Tetru.~tethoxy-2 : 6-diphenylpyrzine hydrochloride.--- nim'pp'- Tetramcthoxy-2 : 6-diphenylpyrazine hydrobromide2528 TUTIN AND CATON: THE ABSORPTION SPECTRA OFregion, but one band shown by the corresponding hydrobromide justextends into the visible part of the spectrum, thus explaining thepale yellow colour of the salt in question. The shift of the absorp-tion bands towards the red end of the spectrum caused by thesubstitution of hydrobromic for hydrochloric acid is not nearly sogreat as that caused by the conversion of the base into its hydr*chloride, thus indicating that the alteration in position of the bandsin the latter case must be due chiefly to salt-formation, and only ina minor degree to the weight or nature of the acid radicle attached.The di- and tetra-methoxy-bases of the 2 : 6-series, and all ofthe salts show two absorption bands, but in the case of 2 : 6-diphenyl-FIG.4.Oscillation frequencies.2000 2500 3000 3500 400000 2 20003 1800 z% 2 1600$ 1400Xm.u-* uh332 12003 1000‘r)Y8002 : 5-Diphenylpyrazine.2 : 5-Diplienylpyrazine hydrochloride. - - - - - -pyrazine only one band is seen. Nevertheless, it is considered mostprobable that the absorption of all three 2: 6-substituted bases is,in reality, similar, the second absorption band of the last-mentionedbase being lost owing to the absorption shown by the chloroformwhich was used as a solvent.The curves yielded by 2 : 5-diphenylpyrazine and its monohydro-chloride, and by pp’-dimethoxy-Z : 5-diphenylpyrazine and the corre-sponding salt of this base, are shown in Figs.4 and 5 respectively.It will be observed in the case of these 2 : 5-substftated bases thatthe curves show only one absorption band, whilst two such areexhibited by the curves obtained from t,he salts. One possiblSOME SUBS'I'I'TUTED PYRBZINES AND THEIR SALTS. 2529explanation of this is that the second absorption band of the2 : 5-substituted bases has been lost owing to the absorption causedby the chloroform, just as is thought likely t o be the case with2 : 6-diphenylpyrazine, as already mentioned. On the other hand,t'he fact .that the band shown by the 2 : 5-substituted bases is muchbroader than either of the bands in any of the other curves obtainedwould suggest that in the bases of the 2 : 5-series the two absorptionbands may have become merged into one.Certain general conclusions may be drawn from the absorptioncurves given, namely, the following: (1) The similarity of theFIG.5.Oscillation frequencies.2000 2500 3000 3500 4000py'-Dimethoxy-2 : 5-diphenylnjrxine.pp'-DimeMoq1-2 : 5-dipkenylpyrclxi.nz hyldTochloride. - - - - - -curves given by the bases and their salts, particularly in the2 : 6-series, indicates that no change other than the rearrangementof valencies necessitated by the change N"' -+ NV occiirs on treatingthe bases in question with acids.(2) That salt-formation causesan increased persistency of the bands, together with a v@ry largeshift towards the red end of the spectrum. This result is similarto, but very much greater than, that which has previously beenobserved in the case of pyridine and its homologues (Hartley, Trans.,1885, 47, 685; Baker and Baly, ibid., 1907, 91, 1122; and Purvis,Proc. Camb. Phil. Soc., 1908, 14, 436). (3) The introduction ofmethoxyl groups causes a shift of the absorption bands towards thered end of the spectrum-an effect which has several times pre2530 TUTIN AND CATON: THE ABSORPTION SPECTRA OFviously been noted by other workers. (4) The position of thesubstituent groups in the pyrazine nucleus affects the position ofthe absorption bands shown by the bases and their salts, the bandsshown by the 2 : 5-substituted compounds being nearer the red endof the spectrum than those shown by their 2 : 6-substitutedisomerides (compare Purvis, Zoc.cit.).The absorption curves given also appear to indicate that theweight of the acid radicle present in a given salt had an effect onthe position of the bands, the hydrobromides being more deeplycoloured than the corresponding hydrochlorides. It would appearpremature, however, to consider this conclusion as proved, withoutconsiderable further evidence obtained by the study of a varietyof salts, for, in every case where the sulphates could be obtained,they were found t o be less deeply coloured than even the corre-sponding hydrochlorides, but their absorption spectra were notexamined.It thus appears that the nature of the acid employedmay have a greater effect than its molecular weight on the colourof the resulting salt.The formation and properties of the salts which were obtainedfrom the pyrazine derivatives under consideration are describedbelow. I n most cases the melting points of these derivatives wereindefinite, and of no value for the purpose of characterisation.Salts of 2 : 5-Diphenyl~raaine.-No salt of this base with oneequivalent of an acid could be obtained in the solid state, but thedihydrobromide and disulphate crystallised readily. On passinghydrogen chloride into a chloroform solution of the base, a yellowliquid was obtained, which doubtless contained the dihydrochloride.Dry hydrogen bromide was passed into a solution of 2: 5-di-phenylpyrazine in glacial acetic acid, and the mixture kept a fewhours.Golden-yellow crystals then separated, which were foundto be 2 : 5-diphenylpyrazine dihydrobromide, C4H,N,(C6H,),,2HBr :0.1527 gave 0.1435 AgBr.C16H,,N2,2HBr requires HBr = 41.1 per cent.This salt was readily dissociated by water, alcohol, or moist air.On heating it with ethyl acetate, it dissolved and partly dissociated,and, on cooling the solution, it mixture of dihydrobromide andbase separated, but no monohydrobromide was obtained.2 : 5-Diphenylpyrazine disulphat e, C4H2N,(C6H,)2,2H,S04, re-sulted on the addition of concentrated sulphuric acid to a solutionof the respective base in ethyl acetate or glacial acetic acid; themonosulphate could not be obtained.2 : 5-Diphenylpyrazine di-sulphate forms yellow plates, which, when exposed to moist air,readily dissociate, yielding the colourless base :HBr = 40-5SOME SUBSTITUTED PYRAZINES AND THEIR SALTS. 25310.2417 gave 0-2570 BaSO,. H2S04=44.7.C16H12~,,2H,S0, requires H,S04 = 45.8 per cent.Although the result of this analysis is not in very close agreementwith the theoretical figures, owing to the readiness with which thesalt dissociates, it nevertheless proves conclusively that the salt hasthe formula indicated above.Salts of 2 : 6-Diphenylpyrazine.--The monohydrochloride of thisbase is described in the preceding paper (p. 2501). It is a prac-tically colourless, crystalline solid.The monohydrobromae, how-ever, is pale yellow, whilst the monosulphate is quite colourless.The dihydrochloride and d'isulphate were obtained in the form ofsolutions, both of which were yellow, but no positive indication ofthe formation of a dihydrobromide could be obtained.2 : 6-Dph en ylpyrasine mono h ydro b romid e, C4H,N, ( C6H 5)2,HBr,separated in pale yellow needles on passing hydrogen bromide intoa solution of the respective base in a mixture of ethyl acetate andalcohol, Like the previously described salts, it readily dissociated :0.1408 gave 0.0840 AgBr.C,,H,,N,,HBr requires HBr = 25.9 per cent.2 : 6-Diphenylpyrazine monosulphat e, C4H,N,(C6H,)2,H2S04,crystallised in quite colourless needles on adding concentratedsulphuric acid to a solution of 2 : 6-diphenylpyrazine in glacialacetic acid:HBr = 25.7.0.1316 gave 0'0934 BaSO,.Cl6H,,N2,H,SO4 requires H,SO, = 29.7 per cent.Salts of ppl-Dimethoxy-2 : 5-diphenylpyrazine.-The monohydro-chloride, monohydrobromide, and monosulphate of ppl-dimethoxy-2 : 5-diphenylpyrazine crystallised readily, and the disulphate wasalso obtained in crystals, although it was very unstable. A solutionof the dihydrobromide was obtained as a deep violet-coloured liquidby saturating a solution of ppl-dimethoxy-2 : 5-diphenylpyrazine inglacial acetic acid with hydrogen bromide; and this salt alsoappeared to be formed on passing dry hydrogen bromide over thesolid base.No positive evidence of the formation of a dihydro-chloride could be obtained.H2S04 = 29.8.p p I- Dim e tho x y-2 : 5-dip h erqlpprazine mono 12 y d ro c hl or id e,C4HBN,(C6H,=OMe),,HC1,was formed by saturating a warm solution of the pyrazine derivativein glacial acetic acid with hydrogen chloride.On cooling, the saltseparated in bright yellow needles :C,,H1602N2,HC1 requires HC1= 11.1 per cent.0.3191 gave 0.1374 AgC1. HC1= 10.9.This salt dissociated much more readily than the correspondin2532 TUTIN AND CATON: THE ABSORPTION SPECTRA OFderivative of the 2 : 6-substituted base, and, when dissolved inchloroform, oxhibits an intense green fluorescence.pp'-Dzm e t hoxy-2 : 5-dipZi enylpyraaine monoliydro b romid e,was prepared in a manner similar to the salt last described.formed orange-coloured needles :C4H,N2( C,H,*'OMe),,HBr,It0.2781 gave 0.1373 AgBr.C,,HIGO2N,,HBr requires HBr = 21.7 per cent.pp'-Dimethoxy-Z : 5-diphenylpyrazine monohydrobromide, likethe corresponding hydrochloride, is fluorescent in chloroformsolutdon.HBr = 21.3.p p -Dim e t h o xy- 2 : 5-diph eny lp y ra zine monosu Zpha t e,C4H2N, ( c,H4 0Me)2,H,S047separated in yellow needles on adding sulphuric acid to a warmsolution of the respective base in glacial acetic acid, and coolingthe mixture.It dissociates readily, and, like the last-mentionedtwo salts, is fluorescent in chloroform solution:0.2700 gave 0.1581 BaS04. HaSO4 = 24.6.C,8H,602N,,H2S0, requires H2W4 = 25.1 per cent.When to a, solution of pp'-dimethoxy-Z : 5-diphenylpyrazine inchloroform, concentrated sulphuric acid was added, a yellowsolution of the monosulphate was first formed, which ex-hibited a brilliant green fluorescence, but on introducing anexcess of the acid the base was dissolved by the latter, yieldingan intensely violet-coloured liquid below the chloroform. Sufficientethyl acetate was then added to render the mixture homogeneous,and the liquid kept a few hours, when pp'-&imethoccy-2 : 5-diphenyl-pgrazine disulphate, C4H,N2(C,H4*OMe),,2H,S04, separated insmall prisms, resembling in colour crystals of potassium per-manganate.This disulphate is very unstable; it dissociates inordinary air, yielding the yellow monosulphate, and, if the air beunusually damp, complete dissociation ensues. The dissociatedmixture may, however, be successively reconverted into the yellowmonosulphate and the deep violet-coloured disulphate by desic-cation :0.1224 gave 0.1200 BaSO,.C,8H1602N2,2H2S04 requires H2S04 = 40.2 per cent.This disulphate dissociated so readily that it could not be washedwith any solvent, and it is owing to this fact that the analysisindicated a, somewhat high percentage of sulphuric acid.Sults of pp'-Dimethoxy-Z : 6-dip,henylpyrazine.--This base readilyyielded a crystalline monohydrochloride, monohydrobromide, andmonosulphate, the first of which has been described in the precedingH,SO, =41*1SOME SUBSTITUTED PYRAZINES AND THEIR SALTS.2533paper (p. 2506). No indication of the formation of a dihydrechloride could be obtained, but the dihydrobromide was obtainedas a very deep violetrcoloured solid by passing dry hydrogen bromideover the solid base.A deep violetrcoloured solution of thedisulphate in concentrated sulphuric acid was formed, but this saltcould not be crystallised.ppl-Dimethoxy-2 : 6-diphenylpyrazine monohydrobromide,C4H,N2(C,H4-OMe)2,HBr,crystallised in deep yellow needles on the addition of a little con-centrated hydrobromic acid to a solution of the base in a mixtureof ethyl acetate and alcohol:0.1685 gave 0.0832 AgBr.This salt is not fluorescent, thus differing from its 2 : 5-substitutedpp f-Dimethoxy-2 : 6-diphenylpyrasine monosulphat e,HBr = 21.3.C18H,,0,N2,HBr requires HBr = 21.7 per cent.isomeride.C4H2~(C,H400Me),,H2s04,was obtained on adding concentrated sulphuric acid to a solutionof the respective base in ethyl acetate.It was not fluorescent, andformed pale yellow needles, which dissociated fairly readily :C18H,,02N2,H,S04 requires H2S04 = 25.1 per cent.mml p p f -T e t ramet hox y-2 : 5-diph eny Zpyrazline. - Theamount of this base available was very small, and therefore onlyits behaviour towards sulphuric acid was investigated. It wasmarkedly more basic than the previously mentioned bases. Whentreated with a small amount of sulphuric acid in glacial acetic acidsolution, it yielded mmfppf-tetramethoxy-2 : 5-diphenyllryrasinemonosulphate, C,H3(0Me),*C4H2N2*C6H3(0Me)z,HzS04, whichformed orange-red needles. If, however, the solution containedany excess of sulphuric acid, the orangecoloured crystals of themonosulphate soon gave place to small, jet-black prisms of the corresponding disulphate, C,H3(0Me),*C4H,N,*C,H~(0Me),,2H2S~~.These crystals possessed a brilliant metallic lustre, and were per-manent in the air, although they were dissociated fairly readily byalcohol.A dilute solution of mm1pp’-tetramethoxy-2 : 5-diphenyl-pyrazine disulphate in concentrated sulphuric acid had an intenselyblue colour. The amount of these salts was not sufficient foranalysis.Salts of mmlppl-T e trame t hoxy-2 : 6-dip~erryZpyrazine.-This basereadily yielded a crystalline monohydrochloride, monohydrobromide,and monosulphate, but no di-acid salt of it could be crystallised.No evidence of the existence of a dihydrochloride could be obtained,but a comppund of a bluish-black colour with a bronze lustre, which0-2635 gave 0.1549 BaSO,.SaltsH2S04 = 24.7.ofVOL.XCVII. 8 2534 ABSORPTION SPECTRA OF PYRAZINES.was doubtless the dihydrobromide, was obtained by passing dryhydrogen bromide over the crystalline base. A deep blue-colouredsolution of the disulphate in concentrated sulphuric acid was alsoobtained.mm'pp/-Tetramethoxy-2 : 6-diphenylpyrazine monohydrochloridehas been described in the preceding paper (p. 251 1). It is deepyellow, and does not dissociate so readily as the previously describedhydrochlorides.mm pp f -Te trame th oxy-2 : 6-diphen ylpy raaine monoh ydro b romide,C6H3(0Me)2*~4H2N20C6H3(0Me)B,HBr, was obtained in orange-coloured needles on passing hydrogen bromide into a solution ofthe respective base in warm ethyl acetate.The amount of productavailable was small, and it wits not analysed.mmfpp~-Tetrarnthoxy-2 : 6-diphenylpyrazke monosulphat e,CGH,( 0Me)2*C4H2N2*C6Hd oMe)z,HzSO&was prepared by adding Concentrated sulphuric acid to a solutionof the respective base in ethyl acetate. It formed yellow needles,which were stable in the air, but were dissociated by alcohol orwater.Two series of isomeric moneacid salts of the 2: 6-substitutedpyrazines are possible, which would be represented respectively bythe following formulce :H ,,CR:CH, ,CR:CH\. HX>N \CR.CH/ ---- N %CR:CH/N<X*(1.) (1Throughout the course of this work, however, no indication ofthe presence of isomerides was observed, and it is therefore probablethat the acid attaches itself to one of the nitrogen atoms morereadily than to the other. I f this be the case, the mono-acidic saltsof the 2: 6-substituted pyrazines are probably represented byformula 11. Furthermore, the fact that no di-acid salt of the last-mentioned bases could be crystallised may be due to these saltsbeing difficult of formation, owing to steric hindrance, but it isquite likely that it is due only to their being more soluble thantheir 2 : 5-substituted isomerides.In conclusion, the authors wish to acknowledge their indebtednessto Dr. J. T. Hewitt, who kindly placed at their disposal thespectroscope with which the curves given in this paper were obtained.THE WELLCOME CHEMICAL EAST LONDON COLLEGE.RESEARCH LABOKATORIEY, LONDON, E. C

ISSN:0368-1645    

DOI:10.1039/CT9109702524

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

ABSORPTION SPECTRA OF DlKETOPYRROLINES. 2535CCLIX.--The Absorption Spectra of Various Diketo-pyrroline Compounds.By JOHN EDWARJI PURVIS.A SERIES of coloured diketopyrrolines have been described byItuhemann (Trans., 1909, 95, 984, 1603; this vol., pp. 462, 1438),and it appeared to be of some interest to study these compounds inrelation to their absorption and constitution; the aim of thiscommunication is to show how far the absorption is connected with(1) the ketonic groups, (2) the replacement of the oxygen of theketonic groups, and (3) the replacement of hydrogen of thearomatic sidechains by various groups.N / 1000-alcoholic solutions of the following substances wereexamined. The method of examination has been described before.?o--co>NH ; dark red.CPh :CPh 2 : 3-Diketo-4 : 5-diphenylpyrroline,>NH;co- coCPh:C( C,H,) 2 : 3-Diketo-4-phenyl-5-tolylpyrrolines (0-, rn-, p ) , 1..-dark red.>NH ; dark 2 : 3-Diketo-l-phenyl-5-p-cumylpyrroline,red.From the absorption curves (Fig. l), it is evident that theabsorptions are all of the same type. The differences correspondwith differences in the shades of red of the different compounds.For example, the ortho-tolyl compound (I) is not quite so darkred as the met* (111) and para- (V) compounds, and the curvesshow these differences, in that the rays are transmitted throughgreater thicknesses of the solution. It is noticeable, also, that thediphenyl compound (11) is a shade darker red than the ortho-tolylcompound, and not so deep red as the meta- and para-compounds.This is also clear from the curves, for the rays are transmittedthrough greater thicknesses than either the met* or para-tolylcompounds. Or, to put it another way, the absorption band ofthe ortho-tolyl compound is not so strong as that of either themeta- or para-tolyl compound; and the absorption band of thediphenyl compound is a little stronger than that of the ortho-tolylcompound, but not so strong as the bands of the metit- or para,-methyl derivatives.N / 10,000-solutions' of the substances were also examined, but nobands were observed in the ultra-violet regions. The positionsGO---GObPh: C(C9Hl,)8 c 2536 PURVlS: THE ABSORPTION SPECTRA OFwhen general absorption begin, expressed in oscillation frequencies,are :Diketodiphenylpyrroline 30 mm.thick .......................... 32469 , 9 9 ,, 10 ,, ,, ........................... 3997Diketo-o-tolylpyrroline 30 ,, ,, ........................... 3603), 9 9 ), 10 ), ,, ........................ 4199Diketo-m-tolylpyrroline 30 ,, ,, ........................ 33209 , Y 2 ,, 10 ), ,, ............ : .............. 3981Diketo-p-tolylpyrroline 33 ,, ,) ........................... 3148,J $ 9 ,, 20 ), ,, ........................... 3965Diketo-p-cumylpyrroline 30 ,, ,, ........................... 31539 , 9 9 ,, 10 ,, ,, ........................... 3593I. N/1000-alcohoEic solution of 2 : 3-dikato-4-phen~l-5-o-tolylpyrroli~.I I I. N/lOOO-alcoholic , , 2 : 3 -diketo-4-phenyl-5-rn-tolyl~jrroline.IV.N/lOOO-alcoholic ,, 2 : 3-diketo-4-phenyl-5-p-cumylpyrroline.V. NJ1000-alcoholic ,, 2 : 3-diketo-4-phenyl-5-p-tolylpyrroli~.11. N/lOQO-alcoholic ,, diketodiphenylpyrrolineVARIOUS DIKETOPYRROLINE COMPOUNDS. 2537Therefore the result of the substitution of hydrogen by analiphatic group in an aromatic side-chain does not fundamentallyalter either the colour or the absorption. The observed bandcorresponds in each case with the colour, and there is no bandproduced in the ultr%violet region.When the two diketo-groups are still left intact, and the sub-stitution in an aromatic sidechain is by the methoxy- or methylene-dioxy-groups, the dark red colour remains unchanged, but anotherFIG. 2.Oscillation frequencies.28 20 22 24 26 28 30 32 34 36 38I.N/ 10,000-alcoholic solution of 2 : 3-dik~to-4-phenyl-5-p-anisyllpyrro~~~e.11. N/10,00Q-alcoholic ,, 2 : 3-diketo-4-phenyl-5-pipermy@yrrolinc.band in the ultr%violet region is produced.two derived substances are:The formulae of these>NH ;TO- co 2 : 3-Diketo-4-phenyl-5-p-anisylpyrroline,2 : 3-Dike to-4-phenyl-5-piperonylpyrroline,CPh:C(C,H,*OMe)dark red.>NH;co---GOCPh : C( C6H,: O,:CH,)Idark red.N / 10,000-solutions were examined, and from the curves (Fig. 2)it will be seen that each substance has two bands. The lessrefrangible band of each corresponds with the bands of the previoussubstances. On the other hand, the more refrangible bands haveno corresponding bands in the original diphenyl compounds, andthey also differ from each other both in position and persistency.I n other words, neither the original colour nor the correspondingabsorption is fundamentally altered by the introduction of 2538 PURVIS: THE ABSORPTION SPECTRA OFmethoxy- or a methylenedioxy-group in an aromatic side-chain, butanother band is produced in the ultracviolet region correspondingwith the new type of side-chain.Further, the phenylhydrazones of the diphenyl compound andof the p-tolyl compound were examined in N / 10,000-solutions.Theconstitutional formulae of these subst,ances are :?(: N *N HPh)*CO>N .CPh====CPh Diketodipheny 1 pyrrolinephen y 1 hydrazone, Ycarmine-red.CP h- 7 : NCPh*NH.CN Diphenylpyrrolinophenazine, I I >CsH4 ; lemon-yellow.Diketopheny l-p-to1 y lpyrrolinepheng lh y drazone,?( :N:NHPh)*COCPh==C( C,H7) >NH ;carmine-red,GPh-- y:N >C,H, ; lemon- Phen yl-p-tolylpyrrolinophenazine,C(C,H,)*NH*C:Nyellow.Considering the carmine-red phenylhydrazones, it will be seenfrom the curves (Fig.3 and 4) that they show two bands. Theless refrangible band corresponds with the single band of theoriginal unsubstituted diketopyrrolines slightly shifted towards themore refrangible side; and the smaller, more refrangible one resultsfrom the introduction of the hydrazine radicle in place of oxygenof one of the ketonic groups. Considering the yellow-colouredphenazine compounds, the curves also show two bands, a smaller,less refrangible one, and a stronger one in the more refrangibleside.That is to say, the successive elimination of the oxygen ofboth the ketonic groups produces a change in colour from darkred, through carmine-red to yellow; a decrease in the intensity ofthe band of the original diketonic substances; and the productionof another band on the more refrangible side, the intensity of whichincreases by the successive elimination of the ketonic groups. It isimportant to notice that the increased weight of the molecule doesnot shift the band or the general absorption towards the red end,as is usually the case. On the contrary, the shift is towards themore refrangible end of the spectrum.General Results and Discussion.To sum up these observations, it is clear (1) that the diketonicstructure means the production of a dark red colour, anda corresponding well-marked absorption band, the positionof which differs slightly, corresponding with differences inthe dark red shade; (2) the introduction of a methyl oVARIOUS DIKETOPYRROLINE COMPOUNDS.2539FIG. 3.Oscillation frequenciPs.18 20 22 24 26 28 30 32 34 36 38\I. N/1OOO -alcoholic solution of diketodiphenylp yrroline.111. NJ10,QOO-alcoholic ,, diphenylpyrrolinophenazine.11. N/10,0OO-alcoholic , , diketodiphenylpyrrolinephenylhydrazonc.FIG. 4.Oscillation frepzcencies.18 20 22 24 26 28 30 32 34 36 38I. N/lOOQ-alcoholic solution of 2 : 3-diketo-4-phenyl-B-p-tolylpyrrolinc.11. N/10,000-alcoholic ,, 2 9 9 , phen ylhydrazone.111. NJ10,OOO-alcoholic ,, phcnyl-p-tolylpyrrolinophenazine2540 ABSORPTION SPECTRA OF DIKETOPYRROLINES.a propyl group in an aromatic sidechain produces nofundamental change either in the colour or in the absorptionband; (3) if either a methoxy- or a methylenedioxy-group isintroduced in an aromatic sidechain, the deep red colour andcorresponding band are still retained, but another more refrangibleband is produced characteristic of the type of the introducedradicle; (4) when one of the oxygen atoms of the diketonic groupsis replaced by the :N*NHPh group, the colour is changed fromm darkred to carmine-red ; the corresponding less refrangible absorptionband is reduced in intensity and its position is shifted towards themore refrangible side; and another weaker band is produced beyondthis on the more refrangible side; (5) the replacement of both oxygenatoms of the diketonic groups, and the production of the phenazine:N ring :N>C,H,, changes the colour from carmine-red t o lemon-yellow,and the corresponding band is also shifted towards the morerefrangible end.This band is also less intense, and the secondmore refrangible band becomes much stronger ; and (6) correspond-ing with these changes in colour and selective absorption, thepwitions of general absorption are shifted towards the morerefrangible region of the spectrum.The observations, then, indicate that the absorption is intimatelyconnected with the presence of a diketonic grouping. Baly andStewart (Trans., 1906, 89, 502) have suggested that the residualaffinities of the dicarbonyl compounds studied by them are oscillatingbetween two extreme phases.But in these compounds it mag beequally valid to say that the maximum valencies of the oxygenatoms come into action, resulting in the production of it closedring produced by the two oxygen atoms, and the consequent pro-duction of absorption. On this suggestion the ring is destroyedby the elimination of the oxygen in the hydrazone linking; theintensity of the original band is lessened, and another band isproduced, accompanied by changes in the colour and absorption inthe visible spectrum from the less to the more refrangible regions.The. further production of the phenazine ring does not whollydestroy the original absorption; it simply decreases it, and anotherband is produced characteristic of the new type of ring.From these considerations, it seems to be difficult to resist theconclusion that the origind band, which corresponds with the deepred colour, is caused by the oscillation or vibration of the originaldiketopyrroline ring, and that it is modified by the eliminationof the ketonic groups. In connexion herewith, it should bementioned that the author found no bands in phenylhydrazine insolutions of N / lo-, N / loo-, N / 1000-, and N / 10,000-strengthTAYLOR : RESEARCHES ON BLEACHING POWDER. 2541through varying thicknesses of 2 mm. to 30 mm. Also, Hartleyand Dobbie (Trans., 1898, 73, 598) found no bands in alcoholicsolutions of pyrrole, and this has been confirmed by the author(this vol., p. 1648).I have again to thank the Government Grant Committee of theRoyal Society, by whose assistance the spectroscope used in thisresearch was obtained, and also Dr. Ruhemann for specimens of thepure substances.UNIVERSITY CHEMICAL LABORATORY,CAMBRIDGE

ISSN:0368-1645    

DOI:10.1039/CT9109702535

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

TAYLOR : RESEARCHES ON BLEACHING POWDER. 2541CCLX.-Besearches on Bleaching Powder.By ROBERT LLEWELLYN TAYLOR.FOR the purpose of this investigation, it was first of all necessaryto devise a method for distinguishing between pure chlorine andhypochlorous acid, and, in a mixture of the two, finding theirproportions.The method used was to pass the gases through a known volumeof N/lO-sodium arsenite. The action of chlorine and of hypo-chlorous acid on sodium arsenite may be represented thus:(1) AqO, + 2C1, + 2H,O = A%O, + 4HC1.(2) As,O, + 2HOCl= As20, + 2HC1.It is plain that, for the same amount of arsenite oxidised, twiceas much hydrochloric acid (or chloride) is produced in the case ofchlorine as in the case of hypochlorous acid. The arsenite (whichmust always be in excess, so that it is not completely oxidised) isthen divided into two equal parts.In onehalf, the amount ofarsenite remaining unoxidised is determined by means of N / 10-iodine solution, and from this the amount oxidised is ascertained.I n the other half, the amount of chlorine is determined by meansof N/10-silver nitrate. In the latter determination the use of anindicator was very soon discarded, although, if a considerableproportion of the arsenite has been oxidised, the arsenate producedacts fairly well as an indicator, and may be used instead of addinga chromate to the solution. Much more trustworthy results, how-ever, are obtained by acidifying the solution with nitric acid,adding a little of the silver solution, boiling for a minute or two,and then filt'ering a portion of the liquid.A little more of thesilver solution is added, drop by drop, to the filtered portion, whic2542 TAYLOR : RESEARCHES ON BLEACHING POWDER.is then returned to the bulk, and this boiled and filtered again.This is continued until the filtered portion gives no further pre-cipitate with the silver solution. As described, the process seemstedious, but in practice it works very well, and the determinationof the chlorine can be made fairly rapidly. In this process, as thesolutions used are all decinormal, and therefore equal to each other,when the oxidising agent is pure chlorine, the amount of silvernitrate used (=amount of chloride present) is the same as theamount of arsenite oxidised.When hypochlorous acid is theoxidising agent, the chloride produced is only half the amount ofarsenite oxidised.The Action of Carbon Diodde on, Bleaching Powder.It is very frequently stated, and probably usually considered, thatcarbon dioxide simply liberates hypochlorous acid from bleachingpowder. A considerable number of observers, however, havepointed out that chlorine is produced when pure carbon dioxideacts on bleaching powder.Thus, Richards and Juncker (Dimgl. Polyt. J., 1874, 211, 31)state that dry bleaching powder is almost undecomposed by carbondioxide. I f about 10 per cent. of water is present, both chlorineand hypochlorous acid are produced.Wolters ( J . p r . Chem., 1874, [ii], 10, 128) refers to the liberationof chlorine by the action of carbon dioxide on bleaching powder,and Lunge and Schappi (Dingl.Polyt. J., 1889, 273, 63) state thatcarbon dioxide expels nearly the whole of the chlorine from bleachingpowder.Dreyfus (Bull. SOC. chim., 1884, [ii], 41, 600) found that carbondioxide has no action on calcium chloride, but, in the presence ofchlorine monoxide, either dry or in aqueous solution, it liberateschlorine.More recently this question, with others relating to bleachingpowder, has been investigated by von Tiesenholt ( J . p r . Chem.,1901, [ii], 63, 30; 1902, [ii], 512; 1906, [ii], 73, 301). Some ofhis conclusions will be referred t o later.In my first experiments, carbon dioxide, in its ordinary moistcondition, after being well washed with water, was passed through aU-tube containing bleaching powder and a sufficient amount ofglass wool to give a free passage for the gas.Carbon dioxide, asordinarily prepared by the action of hydrochloric acid on marble,invariably carries with it a little hydrochloric acid, and, in someof the experiments, this was removed by passing the gas throughglass wool wetted with a solution of silver nitrate, which acts quiteeffectually. When, however, t,he gas is well washed with water, thTAYLOR : RESEARCHES ON BLEACHING POWDER. 2543amount of hydrochloric acid accompanying it is not sufiicientseriously to affect the results. After passing through the bleachingpowder, the gas was passed through a Bunsen U-tube cont,ainingN / 10-sodium arsenite.A considerable number of experiments were made, and thefollowing is an example of ths results invariably obtained. TwentyC.C.of the N / 10-arsenite were used :I.Amount of arsenito oxidised ................................ 8-35 C.C.Amonnt of N/lO-silver nitrate used ........................ 8'4 C.C.It is plain from this that the sole product of the action of carbondioxide on bleaching powder is chlorine. The escaping gas has astrong odour of chlorine, and none at all of hypochlorous acid.The action proceeds very rapidly if the carbon dioxide is quitemoist.In some further experiments, the carbon dioxide was dried bypassing it over calcium chloride. The effect of drying the gas isthat the action becomes much slower, and, as the moisture usuallypresent in the bleaching powder is gradually carried away by thedry carbon dioxide, it soon becomes extremely slow. When thispoint has been reached, the instantaneous acceleration of the actionwhen the drying tube is removed is very striking.The followingthree experiments show that the product is the same with the dryas with the moist gas, namely, nothing but chlorine:11.Arsenite oxidised. Chloride produced.1. 3'4 3 -52. 1 -9 1'953. 6 -55 6'65The slight excess of silver nitrate used may have been due to alittle hydrochloric acid carried over, although the actual amountsare not beyond the limits of accuracy of the method.When carbon dioxide is passed through a solution of bleachingpowder in water, the action is very rapid, but the result is exactlythe same, as the following experiments show :111.Arsenite oxidised.Chloride produced.1. 5 *6 5 -582. 3 -1 3'1The issuing gas again had a strong odour of chlorine, and noneat all of hypochlorous acid2544 TAYLOR : RESEARCHES ON BLEACHING POWDER.Action of Carbon Dioxide on a Mixture of Sodgum Chloride andHypochlorite, and on a Mixture of Bromide and Hypobromite.The mixture of sodium chloride and hypochlorite was preparedby passing chlorine into a moderately concentrated cold solution ofsodium hydroxide. The following experiments show that the act*ionis exactly the same as with a solution of bleaching powder :1.2.IV.Arsenite oxidised. Chloride produced.4 -1 4-126'1 6-13When carbon dioxide is passed through a solution containing amixture of a bromide and a hypobromite there is, as one wouldnaturally expect, an immediate and copious liberation of bromine.It is well known that carbon dioxide acts in a similar way on amixture of iodide and hypoiodite.It appears, from the foregoing experiments, that the action ofcarbonic acid on bleaching powder and similar substances is exactlylike that of any other acid.There has been much discussion asto the actual constitution of dry bleaching powder, but, whateverthat constitution may be, it may be taken that, in solution or inpresence of water, it is, to all intents and purposes, a mixture ofchloride and hypochlorite. The usual explanation of the actionof, say, sulphuric acid (when used in considerable quantity) onbleaching powder is t.hat the chloride and hypochlorite are bothdecomposed, with the simultaneous production of hydrochloric andhypochlorous acids, and that these decompose each other, with theliberation of chlorine.The question is whether or not we mustseek for some other explanation of the action of carbonic acid.There would seem to be no doubt that the action of carbonic acidis exactly like that of other acids. Of course, this involves theconclusion that calcium chloride (or sodium chloride, for example)is decomposed, when in solution, by carbonic acid, with the liberationof hydrochloric acid, and that, therefore, the action of hydrochloricacid on carbonates is a reversible one:CaCOs + ZHClI have tried to obtain some experimental evidence that this isthe case, and not altogether without success.Many years ago Miiller (Journ.Chem. SOC., 1870, 23, 36) statedthat a solution of lead chloride is decomposed when carbon dioxideis passed through it, with liberation of hydrochloric acid and pre-cipitation of it chlorocarbonate, and that some of the liberated acidcould actually be distilled off. He also stated that carbon dioxide,CaCI, + H,CO,TAYLOR : RESEARCHES ON BLEACHING POWDER. 2545under considerable pressure, would decompose sodium and calciumchlorides, when in solution in water, with liberation of hydro-chloric acid. He used ultramarine as an indicator, and stated that,whilst carbon dioxide alone does not decompose ultramarinesuspended in water, even under considerable pressure, if the watercontains common salt dissolved in it the colour of the ultramarineis destroyed.Carbon dioxide,when bubbled through water in which a little ultramarine issuspended, has no effect on it, whether the water contains salt ornot.Under a pressure of a few atmospheres, however, ultramarineis decomposed and decolorised by carbonic acid alone, and I havebeen unable to observe any difference in the action when the watercontained salt as well. The experiments I made were performedin an ordinary sparklet apparatus, in which the pressure attainsfive or six atmospheres. If distilled water with a little ultramarinesuspended in it is placed in such an apparatus, and then the liquidcharged with carbon dioxide in the usual way, there is no immediateeffect, but, in the course of a day or two, the colour of the u l t mmarine gradually disappears.As stated above, the presence ofsalt (or of calcium chloride) in the water makes no apparentdifference in the result.Methyl-orange is, however, a much more delicate indicator foracids than ultramarine. It is usually assumed that the former isnot affected by carbonic acid, but this is not quite correct. I f wellwashed carbon dioxide is bubbled through distilled water containinga little methyl-orange, there is a distinct alteration of the colour,although it does not turn pink. I f , however, the water containsalso a little pure salt, or calcium chloride, or potassium chloride,the colour becomes distinctly pink when the carbon dioxide isbubbled through.The change of colour is most striking in the caseof the common salt, but it is quite evident with the other chlorides.This may be taken as evidence that carbonic acid liberates a sensibleamount of hydrochloric acid in solutions of chlorides, that is to say,the action of hydrochloric acid on carbonates is a reversible one.Of course, the amount of hydrochloric acid thus liberated must beextremely small, but it will be quite sufficient t o explain the actionof carbonic acid on bleaching powder and similar substances. Thesmall amount of hydrochloric acid liberated will be at once decom-posed by the hypochlorous acid liberated simultaneously from thehypochlorite; this will enable the action of the carbonic acid toproceed it5 before, and so there will be a continuous evolution ofchlorine, and, if this is carried away as fast as it is formed, thebleaching powder will be almost completely decomposed.I am unable to confirm the latter observation2546 TAYLOR : RESEARCHES ON BLEACHING POWDER.It may here be noted that if carbon dioxide is bubbled throughwater containing potassium bromide or ammonium chloride andcoloured with methyl-orange, the change of colour is not so strikingas in the case of the three chlorides mentioned above.Pure watercoloured with methyl-orange becomes quite pink when charged withcarbon dioxide in a sparklet apparatus.Von Tiesenholt (Zoc. cit.) explains the production of chlorine whencarbon dioxide acts on bleaching powder by supposing that hypo-chlorous acid is first formed by the action of the carbon dioxide onthe hypochlorite present, and that this acts on the calcium chloride,liberating chlorine :CaCl, + 2HOC1= Cs(OH), + 2C1,.He finds, in confirmation of this view, that chlorine is liberatedwhen a solution of hypochlorous acid is added to calcium chlorideor to common salt.The experiments here described, however, showthat nothing but chlorine is produced by the action of carbonicacid on bleaching powder, so that all the hypochlorous acid whichis liberated must be decomposed. Apparently, if von T’iesenholt’sview is right, hypochlorous acid cannot exist in the presence of asufficient amount of a chloride, so that it would be impossible toexpel any hypochlorous acid from a solution which containschlorides. As will be seen later, however, mixtures of chlorineand hypochlorous acid containing a considerable proportion ofthe latter can be expelled from solutions of bleaching powder.Consequently, whilst it is possible that the action of hypochlorousacid on chlorides may account for some of the chlorine which isproduced in the case of concentrated solutions or the merely moistbleaching powder for example, von Tiesenholt’s explanation wouldnot appear t o be preferable to the one offered above.The Action of Air on Bleaching Powder.Although this was not the order in which the experiments wereactually tried, it will be best to describe first the effect of air fromwhich all the carbon dioxide has been removed.This was done bypassing the air through washing cylinders containing coke wet witha concentrated solution of sodium hydroxide.It was then bubbledthrough a milky solution of bleaching powder (about 5 to 10 percent.), and afterwards through the solution of sodium arsenite.In a31 the experiments with air, it was passed through at a rateof about 10 to 15 litres per hour.Air free from carbon dioxide is practically inert so far as bleach-ing powder is concerned, and naturally all that it can do is tosweep out any chlorine or hypochlorous acid which may happen tobe present. Consequently, the action is very slow, and the experiTAYLOR : RESEARCHES ON BLEACHING POWDER. 2547ments had to be carried on for a long time (from seventy-two toninety-six hours) in order to obtain sufficient oxidising action inthe solution of arsenite to be able to judge what was being carriedover.The following results were obtained in three separateexperiments :V.H ypochlorousArsenite Chloride acid, Chlorine,oxidised. produced. per cent. per cent.1. 1 -08 0.57 90 102. 1 *o 0-45 100 03. 0.8 0'38 100 0The amount of oxidation in these experiments was very little,but they appear to show that a small amount of free hypochlorousacid exists in slr solution of bleaching powder, which is simplyswept out by the passage of air free from carbon dioxide throughit. Probably the free hypochlorous acid is due to the calciumhypochlorite in it dilute solution being slightly hydrolysed, thus :Ca(OC1)2 + 2H,OThis possibly accounts for the fact that solutions of bleachingpowder have an odour of hypochlorous acid.One similar experiment t o the above was made in which thesolution of bleaching powder was kept at a temperature of about40° the whole of the time.In this experiment, also, practicallynothing but hypochlorous acid was swept out, the only differencebeing that, as one would expect, the time required was rather less.Ca(OH)? + 2HOC1.A ction of Ordinary Air on Bleaching Powder.A considerable number of experiments were made with ordinaryair, passing it through a tube containing dry bleaching powder, andthen through the solution of arsenite. A t first the action is ratherslow, but, as the bleaching powder gradually becomes wet, theaction proceeds more and more rapidly.In some of the experi-ments the moisture of the air was purposely increased by passing itthrough's tube containing wet glass wool. In each of the twofollowing series of experiments the same tube of bleaching powderwas used throughout. The time occupied by each experiment variedfrom about twenty-four hours at the beginning to six hours whenthe bleaching powder had become wet25481.2.3.4.5.1.2.3.TAYLOR : RESEARCHES ON BLEACHING POWDER.Arseniteoxidised.4 '452'92-557.07.92 -13.356.0VI.Series 1.H ypochlorousChloride acid,produced. per cent.4-0 112 -56 132.3 106.95 07.95 0Series 2.1 *83 153.1 86-05 0Chlorine,per cent.8987901001008692100The above experiments are selected from a considerable number,and they all tend to show that, at the outset, ordinary air sweepsout from bleaching powder a mixture containing from 80 t o 90 percent.of chlorine, and from 10 t o 20 per cent. of hypochlorous acid,but that, as the action proceeds, the amount of hypochlorous acidgradually diminishes, and at last nothing but chlorine appears.The gradation of the experiments is not the same in the two series,but that is partly due to the fact that some intermediate experimentsin both series were spoiled by going on too long.When ordinary air is passed through a solution of bleachingpowder (not filtered, and containing about 5 to 10 per cent. of thepowder), the proportion of hypochlorous acid swept out is consider-ably greater, as indeed one would expect if we accept the suggestionthat the hypochlorous acid is due t o hydrolysis of the calciumhypochlorite. As in the case of the dry powder, however, theamount of hypochlorous acid gradually diminishes as the experimentproceeds, although it does not disappear altogether.The followingexperiments were made with the same solution of bleaching powder,in the order in which they are given. In experiment No. 4, theproportion of hypochlorous acid appears to have risen slightly, butthe method of determining it is not accurate enough to enable oneto say that the amounts in experiments 3 and 4 were not sub-stantially the same. The action was very slow in the first experi-ment, but much more rapid afterwards:1.2.3.4.VII.Hy pochlorousArsenite Chloride acid, Clil orine,oxidised. produced.per cent. per cent.4'48 2'94 52 489-15 7-27 25 753 *18 2 '88 10 903.34 2.87 16 8TAYLOR : RESEAHCHES ON BLEACHING POWDER. 2549It must be pointed out that the above numbers, showing therelative amounts of hypochlorous acid and chlorine swept out ofthe liquid by the air, do not necessarily represent the actual pro-portions present at any moment in the liquid itself. There is nodoubt that chlorine, being less soluble in water than hypochlorousacid, will be swept out more readily, so that the proportion ofhypochlorous acid actually present in the liquid is certainly greaterthan the above numbers indicate.These results, showing the action of ordinary air on bleachingpowder, are very remarkable.The difference between the actionof ordinary air and air from which the carbon dioxide has beenremoved is, a t first sight, almost incredible. Whereas the lattersimply sweeps out from a solution of bleaching powder (althoughvery slowly) practically pure hypochlorous acid, the presence of thereally very small amount of carbon dioxide which usually existsin ordinary air causes the action to proceed much more rapidly(although not with anything like the rapidity with which purecarbon dioxide acts), and, after a time, has almost the same effect,so far as the product is concerned, as passing pure carbon dioxidethrough it.I have already expressed the opinion that the action of puremoist carbon dioxide on bleaching powder is the same as that ofother acids-it is a mass action, and the carbonic acid decomposesboth the chloride and the hypochlorite.Whilst one may acceptthis explanation in the case of pure carbon dioxide used in com-paratively large quantities, and always locally in large excess, it isimpossible to believe that the small amount of carbon dioxide presentin ordinary air can act in the same way. We must therefore lookfor some other explanat$ion.The Action of Chlorine 0% Alkalis a Reversible Action.I n former papers (Mem. Nanchester Phil. SOC., 1897, 41, No.VIII; Trans., 1900, 77, 725) I have pointed out that the actionof iodine on alkalis is a reversible one. If an alkali is added to asolution of iodine in water or in potassium iodide until the colourjust disappears, the addition of potassium iodide to the solutioncauses the liberation of some of the iodine:2KOH +I, K I + KO1 + H20.The addition of the extra amount of potassium iodide causes thereaction to proceed from right to left in the above expression.Also, and this, too, follows from the fact that the action is reversible,the amount of alkali needed to complete the reaction from left toright and to remove the colour of the iodine is considerably moreVOL.XCVII. 8 2550 TAYLOR : RESEARCHES ON BLEACHING POWDER.than is required by the equation, so that the almost colourlesssolution of iodide and hypoiodite always contains some free alkali.When these experiments were made, similar ones were alsoperformed with bromine and alkalis, but analogous results werenot obtained.The reason of this must have been that too stronga solution of bromine was used, because I find that the reversibilityof the action of bromine on alkalis is quite as striking as that ofiodine if a very dilute solution of bromine is employed. The actionis not nearly so easy to see with ordinary bromine water, but ifthis is diluted with ten to twenty times its bulk of water, and thensodium or potassium hydroxide added drop by drop until the colourof the bromine has disappeared, the addition of a little concentratedsolution of potassium bromide causes a manifest liberation ofbromine. The liberation of bromine is seen still more plainly if,instead of the solution of potassium bromide, a considerable amountof the powdered salt is added.The addition of the extra potassiumbromide causes the action to proceed from right to left:KBr + KOBr + H,O. 2 KOH + Br2It is perfectly reasonable to suppose, then, that the action ofchlorine on alkalis is also a reversible action. This has alreadybeen suggested by von Tiesenholt (Eoc. cit.), who describes it numberof experiments which point to this conclusion. I have been ableto demonstrate, by experiments which are described later, that thisconclusion is correct, and it will be seen that it supplies a perfectlysatisfactory explanation of the action of ordinary air on bleachingpowder, and that it also explains some well-known facts with regardto some bleaching solutions which have been hitherto apparentlyinexplicable.I f we represent the action of chlorine on sodium hydroxide andon slaked lime thus:2NaOH + C1, = NaCl + NaOCl + H,Oand2Ca(OH), + 2C1, CaCl, + Ca(OCl), + 2H,O.*it is plain that the chlorides produced by the action are continuallytending to reverse the reaction, so that, to carry it to a finish fromleft to right, there must always be a considerable amount of freesodium hydroxide or lime present.It is a well-known fact thatbleaching powder always contains a, considerable amount of freelime, and that it is impossible to prepare it otherwise. I f this freelime, or a portion of it, is removed, then the reaction will proceed* It is not suggested that this equation represents what actually occurs in themanufacture of bleaching powder, but simply the condition of equilibrium in whichit exists when wet or in solutionTAYLOR : RESEARCHES ON BLEACHING POWDER.2551in the opposite direction to a greater or less extent, and chlorinewill be liberated.A filteredsolution of bleaching powder was employed, having a specificgravity of 1-03 t'o 1-06 in different experiments. In order to removesome of the free lime, the solution was exposed to air for somehours in a shallow dish, with occasional shaking. The amount offree lime present in such a solution is considerable, and the latterbecomes very milky on exposure to air. The liquid was filteredfrom the precipitated calcium carbonate, and air free from carbondioxide wils passed through it and into the arsenite solution inthe usual way.A number of experiments were made to test this point.The following are some of the results obtained:VIII.Arseniteoxidised.1.4.02. 3.83. 2-64. 5'925. 4-356. 2-27Chlorideproduced.3.163-01.85.154 *041 '52Hypochlorousacid)per cent.26274415850Chlorine,per cent.747356a59250Most of the separate experiments were made with differentportions of the solution, which had been exposed to air for differentlengths of time, so that the extent to which the free lime wasremoved varied. Doubtless this accounts for the irregularity inthe results. In all the above experiments the action was muchmore rapid than was the case with the solution from which noneof the free lime had been removed, the rapidity evidently dependingon the extent to which this removal had been carried.It will benoted that besides the large quantities of free chlorine produced,in most of the experiments the amount of hypochlorous acid sweptout from the liquid was very much greater than was the case withthe solution from which no free lime had been removed. This isquite what one would expect to occur. The hypochlorous acid, asbefore stated, is probably due t o hydrolysis of the calcium hypo-chlorite in the solution. This also is a reversible action, and asone of the products of the hydrolysis is free lime, the removal ofthe lime naturally stimulates this action as well.These experimpla demonstrate quite sufficiently the reversibilityof the reaction betwen chlorine and calcium hydroxide. As thefree lime is more or less removed, the reaction proceeds in theopposite direction, and chlorine is liberated.I n these experimentsthe free chlorine is swept out of the solution, but it is continuallybeing reproduced, the steady removal of the chlorine allowing the8 D 2552 TAYLOR : RESEARCHES ON BLEACHINQ POWDER.reverse action to take place continuously. I f the free chlorine wereremoved from the solution in any other way, by bleaching, forexample, it would in the same way be continually reproduced aslong as any of the bleaching substance remained. It follows fromthis, of course, that the bleaching action of a solution of bleachingpowder will be stiaulated by the removal of free lime from thesolution.The action of ordinary moist air on bleaching powder, both solidand in solution, described on p.2548, is now perfectly intelligible.The carbon dioxide in the air combines with the free lime, and, asthis gradually diminishes and finally practically disappears, thereverse action proceeds freely, and, of course, chlorine is produced.*It is usually understood, and has been frequently stated, that apure solution of hypochlorous acid bleaches more energetically andmore rapidly than free chlorine. It may be doubted whether thisis really the case. I have prepared practically pure solutions ofhypochlorous acid, and compared its action with that of a solutionof chlorine on various colouring matters, and I have failed to findany evidence of the greater activity of hypochlorous acid.Ratherthe contrary. With a solution of indigwarmine, for example, thebleaching action of chlorine is much more rapid than that ofhypochlorous acid-in the case of the latter the action is to bedescribed as sluggish, rather than rapid. This is an importantpoint, because I am strongly of opinion that in the use of solutionsof bleaching powder and similar substances for bleaching purposes,most of the actions generally attributed to hypochlorous acid arereally due to chlorine, and that, in practice, hypochlorous acid playsonly a minor part in bleaching.It is remarkable how the bleaching action of a solution ofbleaching powder is stimulated by the mere removal of the freelime in it. I f a strip of Turkey-red calico is placed in a clearsolution of bleaching powder so that it is completely immersed inthe liquid, and if the liquid is kept in a, closed vessel so that airhas no access to it, there is scarcely any bleaching action at all,even after several days.I f , however, the solution is placed in a* It may be asked i f the removal of free lime by carbon dioxide is a satisfactoryexpIanation of the fact that ordinary air expels chlorine from bleaching powder,would not this also explain the action of pure carbon dioxide on bleaching powder,so that there would be no need to assume, as is done in the first part of this paper,that carbonic acid decomposes clilorides with the liberation of hydrochloric acid ?The author adheres to the latter explanation simply because the action of carbondioxide is so much more rapid than that of air.A stream of carbon dioxide througha solution of bleaching powder liberates chlorine from ten to twenty times morerapidly than air a t its quickest, and the action altogether suggests a rapid andcomplete decomposition, such as is effected by other acids, rather than the meresweeping out of chlorine produced by the reversed action.This will be referred to again laterTAYLOR : RESEARCHES ON BLEACHIXG POWDER. 2553basin or a shallow dish, so that air has free access, and if a smallportion of the red calico is left outside the liquid, so that it isreached by the solution and the air at the same time, the portionoutside is bleached quite rapidly.Further, if the coloured calicois completely immersed in a little of the solution contained, say,in a deep test-tube, and the test-tube is breathed into about halfa dmen times, shaking after each time, the calico is very soonbleached. Also, whilst, as stated above, a fresh solution of bleach-ing powder has very little, if any, bleaching action on a piece ofred calico completely immersed in it, if the solution has been exposedto air in a shallow dish for a few hours, with occasional shaking,then a piece of red calico completely immersed in it is bleachedrapidly.A simple but very striking experiment which illustrates the samepoint is to immerse a strip of ordinary red litmus paper in a freshsolution of bleaching powder. The paper is turned blue, and in ashort time it is bleached.I f , however, immediately after it hasbeen dipped in the solution, it is breathed upon, it is bleachedalmost instantly. A solution of bleaching powder which has beenwell exposed to air, as described above, bleaches litmus paper atonce.I n all these cases the more rapid bleaching action is simply dueto the removal of free lime, and I think it is plain, also, if referenceis made to the experiments, series VIII, on p. 2551, that theprincipal bleaching agent is chlorine, and not hypochlorous acid.Certainly those experiments show that in some cases a considerableproportion of hypochlorous acid is swept out, but in all cases therapidity of the bleaching action is roughly proportional to theextent to which the free lime is removed, and the more com-pletely that is done the greater is the proportion of chlorineliberated.It is a fact, well known in bleach-works, that an old vat is moreactive than a new one.Exposureto air, especially if the liquid is frequently st,irred, gradually causesthe removal of the free lime.If the action of chlorine on lime is, as I think the above experi-ments sufficiently demonstrate, a reversible action, then the reverseaction must be stimulated by the addition of calcium chloride to thesolution. Afterexperiment No. 2 (series VIII) on p. 2551 was finished, a consider-able amount of crystallised calcium chloride was added to the samesolution of bleaching powder and air free from carbon dioxidepassed through it again.The action became considerably morerapid, and the effect of the calcium chloride is seen by a comparisonThe reason for this is obvious.Experiments were made to see if this is the case2554 TAYLOR : RESEARCHES ON 3LEACHING POWDER.of the two experiments.of the calcium chloride.No. 1 was before, No. 2 after, the additionIX.HypochlorousArsenit e Chloride acid, Chlorine,oxidised. produced. per cent. per cent.1. 3.8 3.0 27 732. 4'75 4'73 0 100The solution used in experiment No. 6 (series VIII) was treatedin the same way with the following result:H ypochlorousArseiii tc Chloride acid, Chlorine,oxidised. produced. per cent. per cent.1. 2'27 1.52 50 502. 5.4 4.92 10 90These experiments show plainly that, as anticipated, the reverseaction is greatly increased by the addition of more calcium chloride.Other chlorides, of course, ought to have a similar effect.Thefollowing experiments show the effect of adding common salt to thesolution. As before, the greater part of the free lime in thesolution was removed by exposing it to air. Experiments 1 and 2were successive experiments before the addition of the salt, andNo. 3 shows the effect of the salt.siderable quantity-almost sufficientX.Arsenite Chlorideoxidised. produced.1. 1.75 1 -42. 5-25 4-13. 6.53 6.55The addition of the salt in theThe salt was added in con-to saturate the solution.Hypochlorousacid, Chlorine,per cent. per cent.25 7528 720 100"above experiment caused theaction to proceed much more rapidly.Thus, whilst in experimentNo. 2 it took twenty hours to oxidise 5-25 C.C. of the arsenitesolution, in experiment No. 3, 6.53 C.C. were oxidised in four hours,the carbon dioxide-free air passing through at approximately thesame rate in both experiments.* The apparently complete disappearance of hypochlorous acid indicated inexperiments 2 (IX) and 3 (X) is very remarkable, and seems difficult to explain.It is not claimed, however, that the method used for determining the relativeamounts of chlorine and hypochlorous acid is perfectly accurate. I t is doubtfulwhether it would be possible to detrrmine very small proportions of hypochloronsacid by it. It must also bc borne in mind (see p. 2549) that chlorine is moreeasily swept out from the solution than hypochlorous acid, so that it is possible that2he latter does not altogether disappear.Possibly, also, von Tiesenholt's explanation(see p. 2546) may apply here, and the hypochlorous acid may be all decomposed bythe large quantities of chlorides prescnt in the solutionTAYLOR : RESEARCHES ON BLEACEING POWDER. 2555Experiments were also made to see the effect of the addition ofcalcium chloride and salt to an ordinary solution of bleachingpowder, without removing any of the free lime. The free lime inthe solution, of course, tends to stop the reverse action, so that theeffect of addkg calcium chloride or salt to the solution is not nearlyso great as when the free lime is first removed. The following isthe result of the two experiments tried.To No.1 calcium chloride was added, and to No. 2 common salt- -both in large quantity. The action proceeded very slowly indeedin both experiments, but the results are sufficient to show that,even in ordinary bleaching powder solution, the addition of chlorideshas a sensible effect in reversing the action :H ypochlorousAraeiiite Chloride acid, Chlorine,oxidised. produced. per cent. per cent.1. 2-24 2 '22 0 1002. 2-66 2 '4 10 90It follows from the above experiments that the addition ofcalcium chloride or salt to a solution of bleaching powder mustexercise a stimulating effect on the bleaching action of the solution.This is actually the case. I f some of the free lime has been removedfrom the solution, the effect of the addition of considerable amountsof calcium chloride or salt on the bleaching action is very striking.With bleaching powder solution in its ordinary state, containing theusual amount of free lime, the effect on its bleaching action ofadding calcium chloride or salt is, for the reason pointed out above,not nearly so great, although it is quite sufficiently marked.I understand that it has been found, in actual bleaching, thatthe addition of either calcium chloride or salt stimulates the action,but I am not aware that any satisfactory explanation of thisstimulating effect has hitherto been given.It may perhaps be worththe while of practical bleachers to note that. the addition of calciumchloride or salt has a much greater effect when some of the freelime has been removed-by exposing the solution to air, forexample.Bleaching solutions made by the electrolysis of a solution of salthave latterly come into considerable use, and I understand thatthe fact has been frequently noted that a solution of sodiumhypochlorite thus prepared is more active than a solution of sodiumhypochlorite, containing the same proportion of available chlorine,prepared by the addition of sodium carbonate to a solution ofbleaching powder and allowing the precipitated calcium carbonateto settle.The explanation of this is obvious when it is understoodthat, in preparing the electrolytic bleaching solution, only a smallfraction of the salt in the solution is usually decomposed. Th2556 TAYLOR : RESEARCHES ON BLEACHING POWDER.solution thus differs from that made by the other method by con-taining a large amount of salt, and the effect of this is to increasethe reverse action and so to liberate chlorine in the solution.Also,in the electrolysis of the salt, chlorine and sodium hydroxide areproduced in exactly equivalent proportions, so that there cannotbe a sufficient amount of the latter to absorb the whole of thechlorine. Under these conditions, the reversing action of the excessof salt will naturally be very considerable. The greater bleachingactivity of such a solution is therefore perfectly natural, and exactlywhat one would expect.In addition to the experiments described in this paper, I haveused my method for distinguishing betwen hypochlorous acid andfree chlorine for investigating the action of various acids on bleach-ing powder and similar substances. This investigation is stillproceeding.Summ,ary.1. The action of carbon dioxide on bleaching powder and similarsubstances results in the liberation of chlorine only-no hypochlorousacid. The conclusion is drawn that the action is like that of anyother acid, and that carbonic acid decomposes both the chloride andthe hypochlorite in the bleaching powder. It follows from thisthat the action of hydrochloric acid on carbonates is a reversibleone.2. Ordinary moist air acts on solid bleaching powder, liberating atfirst both chlorine and hypochlorous acid, the former in muchthe larger amount. After a time nothing but chlorine is produced.When ordinary air is passed through a solution of bleaching powder,a mixture of hypochlorous acid and chlorine is swept out, at firstin about equal amounts; but, as the experiment proceeds, the formerdiminishes, and the latter increases to about 90 per cent.3. The action of chlorine on alkalis, like that of iodine andbromine, is a reversible one, as stated by von Tiesenholt. If the freelime in bleaching powder is removed, this causes the reverse actionto proceed, and thus chlorine is liberated. This explains the actionof ordinary air on bleaching powder. The reversibility of the actionalso explains the stimulating effect on bleaching which the additionof calcium chloride or of salt causes in a solution of bleachingpowder.4. I n the ordinary processes of bleaching the active bleachingagent is probably free chlorine, hypochlorous acid playing only aminor part.MUNICIPAL SCHOOL OF TECHNOLOGY,MANCHESTER

ISSN:0368-1645    

DOI:10.1039/CT9109702541

出版商:RSC    

年代:1910

数据来源: RSC

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COLOUR AND CONSTITUTlON OF DIAZONIUM SALTS. PART 111. 2557CCLXL- The Colour und Constitution o f DiazoniumSalts. P a ~ t III. The Diazo-derivatives of 2 7-Naphth ylenediamine.By GILBERT T. MORGAN and FRANCES M. G. MICKLETRWAIT.ALTHOUGH the diazo-derivatives of the diamines of the benzene anddiphenyl series have been extensively studied, owing largely to thecircumstance that in many instances these products are of consider-able industrial importance, yet comparatively little attention hasbeen directed to the diazonium salts of the naphthylenediamines.Of the ten naphthylenediamines, three, namely, the 1 : 2-, 2 : 3-,and 1: 8-compounds, are known to yield cyclic diazoimines (DeAguiar, Ber., 1874, 7, 316; FriedlLnder and von Zakrzewski, Ber.,1894, 27, 764; Morgan and Godden, this vol., p.1707); the remain-ing seven give diazonium salts of varying degrees of stability (Ewerand Pick, D.R.-P. 45549, 45788 ; Badische Anilin- & Sod%Fabrik,The case of 2 : 7-naphthylenediamine has recently been examiuedby Kaufler in connexion with his theory of the stereochemicalconfiguration of naphthalene and other polynuclear hydrocarbons.According to Kaufler, the two nuclei present in naphthalene arebent round, using their two common carbon atoms as axis, so thatthe lateral extremities of the molecule represented by the positions2 : 3 and 6 : 7 become contiguous. This supposed folding of thetwo nuclei would bring the two amino-groups of 2 : 7-naphthylene-diamine into close proximity, and Kaufler claims that the intimateassociation of these two groups is manifested by certain phenomenaof steric hindrance which are advanced in support of hishypothesis * (Annaben, 1907, 351, 154; Ber., 1907, 40, 3251).It is asserted that the amino-groups of 2 : 7-naphthylenediamineexert a mutual inhibiting influence on each other, with the resultthat only one amino-group is diazotisable.I n diazotising the hydro-bromide or the hydrochloride of the diamine, Eaufler and Karrerworked in acetic acid or alcoholic solution, and fobnd that evenD.R.-P. 130475).* It may be pointed out that Kaufler’s view is a t variance with the ideasembodied in the KekulB-Baeyer conceptioii of the naphthalene molecule based on t,hetetrahedral carbon atom and t h e strain hypothesis, and also with the naphthalenemodel advocated by Pope and 13arlow on crystallographic grounds.These con-ceptions, which may be termed respectively the functional and structural repre-sentations of naphthalene, although differing in many respects, concur in placingthe 2 : 3- and 6 : 7-positions, not in contiguity, but a t the lateral extremities of themolecule2558 MORGAN AND MICKLETHWAIT: THE COLOUR ANDwith excess of amyl nitrite only the monodiazonium salt was pre-cipitated (Ber., 1907, 40, 3263).This result is dependent, however, not on steric hindrance, buton experimental conditions. By operating with sodium nitrite ornitrosyl sulphate in moderately concentrated sulphuric acid, theauthors have succeeded in diazotising completely both the amino-groups of the diamine.Probably the diazotisation occurs in twostages, and the isolation of the intermediate amino-diazonium saltsby Kaufler and Karrer is dependent on the insolubility of thesesubstances in the media employed.EXPERIMENTAL.Naphthalene-2 : 7-&isdiazo?zium Sdphate ( I ) ,H SO4*N,*C1,H,-N2* HSO,,&H,OH.Recrystallised 2 : 7-naphthylenediamine (0.5 gram), melting at160-161°, was dissolved in 2 C.C. of cold concentrated sulphuricacid, mixed with 1 gram of ice, and diazotised with 2 grams ofnitrosyl sulphate, the mixture being cooled by further addition of1 gram of ice. The cold filtered solution was carefully added to amixture of two parts of ether and one of alcohol, and if the pre-cipitated sulphate was viscid, more alcohol was added. The lightyellow crystals thus obtained were washed with a mixture of etherand alcohol, and finally with ether; the yield of diazonium sulphatewas 86 per cent.of the calculated quantity. The salt was appreciablysoluble in alcohol, and when precipitated by ether in the presenceof alcohol it retained a definite amount of the latter solvent, evenafter prolonged drying in the vacuum desiccator. The followinganalyses were carried out on different preparations which had beendried for varying periods :0-2116 gave 0.2562 CO, and 0.0562 H,O. C= 33.02 ; H =2.95.0.1385 ,, 0.1688 CO, ,, 0'0334 H,O. C=33.24; H=2.68.0.2020 ), 0'2446 CO, ), 0'0514 H,O. C=33*02; H=2*82.0-07810.2178 ,, 0'2570 BaSO,. S= 16-20.0.1930 ,, 0.2356 BaSO,.S = 16.76.CloHsO8N4S,,&H,O requires C = 33.08 ; H = 2-75 ; N = 14-03 ;S = 16.04 per cent.The bisdiazonium sulphate readily dissolved in water to a clearyellow solution, which was employed in the production of thefollowing diazonium salts.,, 10.0 C.C. N, at 22O and 756 mm. N=14.56.Naphthalene-2 : 7-bis&azonium plathichloride,C,,H,",I,PtC'1,, 2 H,O,separated as a brownish-yellow, crystalline precipitate on addinCONSTITUTION OF DIAZONIUM SALTS. PART III. 2559aqueous chloroplatinic acid to the solution of the bisdiazoniumsulphate. The air-dried salt was not explosive, and could be warmedwithout decomposition :0-1378 gave 0.0964 CO, and 0,0244 H,O. C = 19.08 ; H = 1.96.0'1760 ,, 0.1243 CO, ,, 0-0269 H,O. C=19*26; H=1'70.0.21700.1542 ,, 0'2122 AgC1.Cl=34.02.0.1872 ,, 0.0594 Pt. Pt=31a73.0.1888 lost 0.0114 H20 a t 70-80O.,, 18.0 C.C. Nz at 22O and 756 mm. N=9.42.H20=6*04.C,,H6N4C16Pt,2H20 requires c= 19.16 ; H = 1-59 ; N = 8-94 ;C1= 34.02 ; Pt = 31.15 ; H,O =5-75 per cent.lvaph thalene-2 : 7- b isdkzonium auricht?ode, C1,H6(N2*AuC~,),,was obtained as a reddish-brown, crystalline precipitate on mixingaqueous solutions of chloroauric acid and the bisdiazonium sulphate.The aurichloride was very soluble in alcohol, and even dissolvedslightly in ether :0.1799 gave 0.0936 CO, and 0.0172 H,O. C = 14.19 ; H = 1-06.0.3118 N=6.77.0.1290 ,, 7.7 C.C. N, ,, 20'5O ,, 758 mm. N=6.79.0.1620 ,, 0.2170 AgC1. C1=33*15.0.1834 ,, 0.0834 Au. Au=45*47.,, 18.5 C.C.N, at 20'5O and 760 mm.Cl,H6N4C1,Au requires c = 13.95 ; H = 0.69 ; N = 6.51 ; C1= 33-02 ;Au=45*81 per cent.Naphthalene - 2 : 7 - bisdiaaonium dichromate, C1OH6[IN&Cr20,,separated either in reddish-brown leaflets or brown, nodular crystalson adding chromic acid or sodium dichromate to a dilute solutionof the bisdiazonium sulphate :N = 14-07 ; 0.2184 gave 24.4 C.C. N, at N.T.P. and 0.0824 Cr20,.Cr = 25.81.Cl,H60,N,Cr2 requires H = 14.07 ; Cr = 26-13 per cent.The bisdiazonium dichromate is extremely explosive, and detonateswith a bright flash when gently heated or even on rubbing.The bisdiazonium sulphate gave rise to sparingly soluble diazo-derivatives when added to aqueous solutions of alkali vanadates,mol yb dat es, and tungstat es.The Sandmleyer Reaction with the Bisdiazon/ium Salts of2 : 7-Naphthylenediamine.The purified naphthalene2 : 7-bisdiazonium sulphate (carefullyfreed from any excess of nitrous acid) was dissolved in water andadded to it hydrochloric acid solution of cuprous chloride.2 : 7-Di-chloronaphthalene separated immediately, and was purified bysublimation, when it melted a,t 114-115O, and did not depress th2560 MORGAN AND MICKLETHWAIT: THE COLOUR ANDmelting point of a specimen prepared from naphthalene-2: 7-di-sulphonic acid, for which the aut.hors are indebted to ProfessorArmstrong.This Sandmeyer reaction gave the same result when repeated withthe other bisdiazonium salts of 2 : 7-naphthylenediamine.2 : 7-Bistriazonaphthalene (Naphthylerrte-2 : 7-bisazoimide),2 : 7-Biistriasonaphthalene (11) was obtained as a brownish-whiteprecipitate on adding sodium azide to a well-cooled aqueous solutionof the bisdiazonium sulphats which had been carefully freed fromnitrous acid.The product crystallised from petroleum (b. p.60-80O) in almost colourless leaflets or tabular prisms, whichreddened on exposure to light; it melted at 98O :0.1984 gave 0.4158 CO, and 0.0569 H,O.0-0784C,,H6N6 requires c = 57.14 ; H = 2.85 ; N = 40.00 per cent.2 : 7-Bistriazonaphthalene has a characteristic odour, recallingthat of P-ethoxynaphthalene; it can be partly decolorised by boilingwith methyl alcohol and animal charcoal, and crystallises from thissolvent in very pale pink plates. Cold concentrated sulphuric aciddecomposes the bistriazo-compound with effervescence.The decomposition of the bisdiazonium sulphate with sodiumazide is practically quantitative, and as 2 : 7-bistriazonaphthaleneis only very sparingly soluble in water, its amount can be deter-mined :0.1398 CloH6(NzoHS0,)z,SC,H,*OH gave 0-0741 CloH6(N3)2, melt-ing at 98O, whereas the calculated amount is 0.0736.The aqueous filtrate from the precipitated bistriazo-compound,which contained the alcohol of crystallisation of the bisdiazoniumsulphate, gave a distinct iodoform reaction, thus confirming theanalytical data for this salt.C = 57.14; H =3*18.,, 27.0 C.C.N, at 22O and 760 mm. N=39*84.THEORETICAL CONSIDERATIONS.The f a c t that the 2-aminonaphthalene-7-diazonium salts isolatedby Kaufler and Karrer (Zoc.cit.) and the naphthalene-2: 7-bis-diazonium sulphate described above are yellow compounds affordsadditional evidence in favour of the view that diazonium salts ofnormal constitution display colour when their diazo-complexes areassociated with polynuclear hydrocarbon radicles (compare this vol.,p. 1691).The successive diazotisation of 2 : 7-naphthylenediamine salts iCONSTITUTION OF DIAZONIUM SALTS. PART III. 2561two stages is of interest in connexion with the authors' views onthe constitution of diazonium salts.In the first place, it should be noted that all the available evidencestrongly supports the assumption that the diazotisability of a basedepends on the association of its aminqroup with an unsaturatedorganic complex.This complex need not necessarily be aromaticor even cyclic, but it is, apparently, essential that this group shouldbe unsaturated, for hitherto no amine possessing a fully saturatedradicle has ever been diazotised. The existence of a certain degreeof residual affinity is a necessary condition for the production ofdiazonium salts.I n the aromatic series this residual affinity is supplied by thefourth valency of each carbon atom of the six-membered rings, andthe chemical properties which characterise aromatic amines(oxidation, diazotisation, etc.) may be supposed to- arise from theinteraction of these bases in their tautomeric forms (compare Cain,Trans., 1907, 91, 1051).It cannot be too strongly emphasised that diazotisation is aprocess which takes place only with the undissociatecl salt of anamine, and not with the base itself.Accordingly, the nitrous acidreacts with the salts (for example, the hydrochloride) of the basein the following t,automeric forms :Regarded in this way, diazotisation, which consists in the replace-ment of three labile hydrogen atoms by nitrogen, lea.ds naturallyto the formation of three tautomeric forms of the diazoniunichloride 2562 MORGAN AND MICKLETHWAIT: THE COLOUR ANDIn the special case of the salts of 2: 7-naphthylenediamine, theprogressive diazotisation arises probably from the circumstance thatthe two diazonium complexes represent two phases of the diazo-configuration. If the first formed diazonium complex has the para-hemiquinoid structure, then the second will be in the ortho-hemiquinoid phase, and vice versa :H H H HThe foregoing hypothesis of the constitution of diazonium saltsis based on the assumption that the aromatic amines and their saltsare able to react in the tautomeric imino-forms, a change whichis possible only when the orgapic complex associated with the amino-group is unsaturated.Tautomeric change to the imino-form is possible in the followingnon-aromatic amines, all of which have manifested to some extentthe property of diazotisability :The sminotriazoles (Thiele and Manchot, Annalen, 1898, 303,33) :4-Amino-l: 5-diphenyl-l : 2 : 3-triazole (Dimroth, Frisoni, andMarshall, Ber., 1906, 39, 2925) and aminoant,ipyrine (Knorr andStolz, Anmlen, 1896, 293, 67), represented respectively by formukI and 11:Aminophenylpyrithiazinone (Harries and Klamt, Ber., 1900, 33,1158) and aminotetronic anhydride (Wolf€ and Liittringhaus,AnnuZen, 1900, 312, 133), with formulz I11 and IV:>o NPhoN HO g-CHN H; C-CO(111.) (IV.)In addition to these non-aromatic amines, in which the amino-group is associated with a cyclic structure, an interesting extensionof the diazo-reaction has recently been discovered by K.A. Hofmann,H. Hock, and R. Roth (Ber., 1910, 43, 682, 1087), who find thatunder certain conditions aminoguanidine furnishes diazonium saltsCONSTITUTION OF DIAZONIUM SALTS. PART III. 2563derived, however, not from salts of the base itself, but from amore complex molecule containing two guanidine residues andhaving a greater degree of unsaturation.The diazonium nitrate,for example, is represented by the formula:NH\ C( NH,)*NH-N H-NEven in this compound it is possible to discern in the three doublelinkings a certain analogy to the aromatic diazonium salts.A further extension of the hypothesis that the diazotisability ofan amine depends on the presence in its molecule of an unsaturatedgroup may be put forward to explain why the tendency t o formdiazonium salts is greatest among aromatic amines.I n the aromatic series, unsaturation of the hydrocarbon radicleis due to the fourth valency of each carbon atom of a six-memberedring. In the diazonium complex, three valencies of one of the twonitrogen atoms are employed its follows: one furnishes the attach-ment to an acid radicle; another links the diazegroup with acarbon atom of the ring; and the third forms one of the bonds ofattachment t o the second nitrogen atom.Regarding nitrogen asalways potentially quinquevalent, an assumption which is justifiedby the position of this element in the periodic classification, thenthe diazonium complex itself, like the aromatic nucleus, has alsoan unsaturation represented by six valencies. These two sets of sixvalencies, representing respectively the residual affinities of thearomatic and diazonium complexes, are indicated by dotted lines informulze V and VI, the first of which is the well-known centricformula :I c1NO,*N,*NH*C( :NH)>N.N,C1(V. 1 (VI. 1The authors’ view is that maximum stability of the diazonium saltresults when the residual affinities of the organic radicle and thediazonium complex satisfy each other to the fullest extent. I n anaromatic monodiazonium salt, the residual affiity of the diazo-groupis available for saturating the six fourth valencies of the aromaticring.This conception of the constitution of diazonium salts suggests,also, an explanation of the following facts: (1) the relativeinstability of the bisdiazonium salts of homonuclear aromaticdiamines ; (2) the difficulty sometimes experienced in diazotisingcompletely the salts of these diamines2564 MCKENZIE AND CLOUGH: EXPERIMENTS ON THEThe authors desire to express their thanks to the Research GrantCommittees of the Royal Society and Chemical Society for grantswhich have partly defrayed the expenses of this investigation.ROYAL COLLEGE OF SCIENCE, LONDON,SOUTH KENSINGTON, S. W

ISSN:0368-1645    

DOI:10.1039/CT9109702557

出版商:RSC    

年代:1910

数据来源: RSC

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2564 MCKENZIE AND CLOUGH: EXPERIMENTS ON THECCLXII. -Experiments on the Walden Irwersion. PalatVI. Conversion of the Optically Active a-Hydroxy-a-phenylpopionic Acids into a- Chloro-a-phenyl-propionic Acids.By ALEX. MCKENZIE and GEORGE WILLIAM CLOUGH.THE authors showed in a former paper (Trans., 1910, 97, 1016) thatwhen I-a-hydroxy-a-phenylpro-pionic acid was acted on by thionylchloride at the ordinary temperature there was no evidence thatthe carboxyl group had been attacked, whereas the hydroxy-groupin direct attachment to the asymmetric carbon atom was displacedby the chlorine atom with great readiness.* By this method I- andd-a-chloro-a-phenylpropionic acids were easily obtained in a stateof opt,ical purity, and the interconversion of the optically activea-hydroxy-a-phenylpropionic acids was brought about by aid of theWalden inversion, thus :(by SOC12) Ph c1p h ~ > C < O ~ Me’ C02H + h*/C<CO,H3% ;:i?:,t J%$%r)d- AX 2 c - G &H t- (by SOCI2) d-E>C<E213PhThe results obtained by a further study of this subject are placedon record in the present communication.When the action of thionyl chloride on I-a-hydroxy-a-phenyl-propionic acid is conducted in such a manner that both hydroxy-groups are displaced by chlorine, the resulting chloro-acid chlorideis Zaevorotatory, and on decomposition with acetone containing alittle water it gives I-a-chloro-a-phenylpropionic acid.The inter-* Later, Stoll6 (Ber., 1910, 43, 2471) observed that benzilic acid is convertedinto diphenylchloroacetic acid in a similar matlner when its solution in carbontetrachloride is acted on by thionyl chloride a t the ordinary temperatureWALDEN INVERSION. PAKT VJ.2565conversion of the active hydrosy-acids can be carried out accordingto the scheme: z-g>c<g:2H (by SOC12) + I-Ph>"&, Me$(by iteetonrand I\ ater)+--- Ph\C<C1 d-g>c<EE~ (by AgN03 and water) z - ~ e / cO,H.On the other hand, when I-a-hydroxy-a-phenylpropionic acid isacted on by phosphorus peatachloride, a change of sign of rotationoccurs ; the chloro-acid chloride is in this case dexti-orotatol-y, andit gives d-a-chloro-a-phenylpropionic acid when it is decomposed byaqueous acetone. When the chlorine in the latter product isdisplaced by the hydroxy-group by aqueous silver nitrate, the parenta-hydroxy-a-phenylpropionic acid is regenerated. The followingcycle can thus be effected :P hI-l\le?C<&TThionyl chloride andI ( b y ncetoircphosphorus pentachloride thus behavediff ereniy towards 2-a-hydroxy-a-phenylpropionic acid, inasmuchas the former gives the I-chloro-acid, whereas the latter gives thed-chloro-acid.The action of phosphorus pentachloride is accom-panied with a large amount of racemisation.I n the course of his work on the Walden inversion, E. Fischer(Ber., 1907, 40, 489) found t'hat Ebromopropionic acid is formedfrom d-alanine by the action of nitrosyl bromide, this action beingprobably abnormal; when the ester of d-alanine, however, is actedon by nitrosyl bromide, the resulting compound is t,he ester ofd-bromopropionic acid, thus :cl-alanine -+ I-bromopropionic acidd-alnnine ester -+ J-bromopropionic ester.The conclusion is drawn that the same reagent (iiitrosyl bromide)can act on closely-related substances (for example, acid and ester),in one case normally and in the other case abnormally.This con-clusion was borne out when the behaviour of nitrosyl chloridetowards active leucine (and its ester) and active aspartic acid (andits ester) was examined. Again, silver oxide, which apparentlybehaves abnormally in Walden's experiments with the malic acids,can be used to produce either d- or I-lactic acid from Z-bromo-propionic acid, thus :Lbromopropionic acid -+ d-lactic acid.I-bromopropionylglycine -+ I-lactic acid.VOL. XCVII.8 2566 McKENZIE AND CLOUQH: EXPERIMENTS ON THEBearing these results of Fischer in mind, we decided to investigatethe action of phosphorus pentachloride and thionyl chloriderespectively on the ethyl ester of active a-hydroxy-a-phenylpropionicacid in the hope of throwing some light on the problem as t owhich of these agents acts abnormally on the hydroxy-acid. Thefollowing change, which is accompanied by a, large amount ofracemisation, takes place when ethyl I-a-hydrosy-a-plienylpropionateinteracts with phosphorus pentachloride :(IJ)’ PCI5) d- P h >c<& Et. I- 3 c < g Et ---+ Me“g>C<gp > d-M,>C<:b,Eb.{Unfortunately, the action of thionyl chloride on ethyl d-a-hydroxy-a-phenylpropionate does not proceed smoothly, but we have evidencethat the following change takes place :(by EOCI‘J YhWhen the changes-chloro-acid (by PC15)(by PCIS) d-cbloro-esterI-hydroxy-acid -+-+ I - hydroxy-esterE-hydroxy-acid 3 I-chloro-acid { I-hydroxy-ester (by SOC1-J I-chloro-esterare contrasted, it will be seen that no conclusion can be drawnfrom them as to which of the agents, thionyl chloride or phosphoruspentachloride, causes the Walden inversion when it acts on thehydroxy-acid.It was obviously desirable to prove that the I-chloro-acid corre-sponds in configuration withh the I-chloro-ester.This was done byshowing that the I-chloro-acid chloride (which gives the E-chloro-acid on treatment with aqueous acetone) is converted into theI-chloro-ester on addition to ethyl alcohol, the sign of rotationremaining unchanged.It is accordingly possible to convertI-a-hydroxy-a-phenylpropionic acid into either ethyl I- or ethyld-a-c hlorea-p hen ylpropionat e, thus :(by SOCI.,)+soclz) $>C<C’ COCl ~ (by EtOH) + 7- Mle>C<%,Et P’1EXPERIMENTAL.A ction. of ThLionyZ Chloride on 1-a-Hydroxy-a-phenylpropionic A cid.A mixture of I-a-hydroxy-a-phenylpropionic acid (6 grams) ,prepared by the resolution of the r-acid with morphine (loc. cit.)WALDEN INVERSION. PART VI. 2567and thionyl chloride (20 grams) was kept at the ordinary temperature for two days, and then heated at 80° for one hour. Five gramsof a Zaevorotatory acid chloride boiling at 10&-llOo/10 mm. wereobtained.It was added to a mixture of acetone (20 c.c.) and water(1 c.c.), and after a day the solvent was removed at the ordinarytemperature under diminished pressure. The crude chloro-acid(3 grams) was crystallised once from light petroleum, when the pureZ-acid (Zoc. cit.) was obtained, melting a t 71-7Z0, and having thefollowing specific rotation in benzene solution :This acid gave a dextrorotatory mixture of a-hydroxy-a-phenyl-propionic acids when the displacement of chlorine was effected byaid of aqueous silver nitrate.It is thus possible t o prepare optically pure I-a-chlorea-phenyl-propionic acid even when the temperature of the action with thionylchloride is raised so that t'he carboxyl group of the hydroxy-acid isdisplaced.The laevorotation of the chloro-chloride, prepared from G gramsof the I-hydroxy-acid and 28 grams of thionyl chloride under tem-perature conditions somewhat different from the preceding, wasconfirmed.One gram of the chloro-chloride was added to 7 C.C. ofacetone, and the solution gave a, -4.5O in a 1-dcm. tube.I = 2, c = 7.188, a, - 3*78O, [a] , - 26.3O.Action of Phosphorus Pentachloride on 1- and d-a-Hydroxy-a-phenylpropionic Acids.A mixture of I-a-hydroxy-a-phenylpropionic acid (12 grams) andt'he calculated amount of phosphorus pentachloride (30 grams) wasmaintained at 15O for thirty minutes, by which time the vigorousevolution of hydrogerr chloride had subsided. On heating to 70°, abrisk action again took place ; the temperature was raised from 70°to looo within thirty minutes, and finally maintained at looo forone hour.The action of the phosphorus pentachloride apparentlytook place in two distinct stages. The phosphoryl chloride wasremoved, and the residual oil fractionated under diminishedpressure. Six grams of a colourless oil, boiling at 113-115°/15 mm.,were obtained. This chloro-acid chloride was dextrorotatory, givinga,+3.1O0 in a 1-dcm. tube, and its solution in acetone was alsodextrorotatory. It was added to a mixture of acetone (20 c.c.) andwater (1 c.c.). Next day, the solvent was removed at the ordinarytemperature under diminished pressure, and the residual soIiddrained on porous earthenware. It amounted to 4 grams, meltedat 70--75O, and gave the following value in benzene solut'ion :I = 2, c = 12.7, a, + 0*56O, [a] + 2 * 2 O .Found, C1= 19.2.Calc. C1= 19.3 per cent.8 3 2568 McKENZlE AND CIAUUH: EXPERIMENTS Oh' THEThe resulting acid was thus a mixture of d- and r-a-chloro-a-phenylpropionic acids, and a change of sign of rotation accordinglytook place during the displacement of the chlorine by the hydroxy-group under the following conditions. The acid was shaken for fourhours a t the ordinary temperature with a solution of 5 grams ofsilver nitrate in 20 C.C. of water, and the mixture was then boiledfor one minute and filtered. The hydroxy-acid was extracted withether. It melted at 88-90°, was free from chlorine, and was lzevo-rotatory. I n ethyl-alcoholic solution :Z =4, c = 9-58, a, - 0*67', [a] - 1.7'.The action of phosphorus pentachloride (25 grams) ond-a-hydroxy-a-phenylpropionic acid (10 grams) was also studiedunder conditions similar to the preceding.The chlore-acid chloridewas in this case lzevorotatory. On decomposition with aqueousacetone it gave a mixture of Z- and r-a-chloro-a-phenylpropionicacids.Conuersion of 1-a-Chloro-a-phenylpropio?zyZ Chloride into Eth$1-a-ChZoro-a-ph enylpro pionat e.The lzvorotatory a-chlorcla-phenylpropionyl chloride, preparedfrom I-a-hydroxy-a-phenylpropionic acid (10 grams) and thionylchloride (28 grams), was added to ethyl alcohol and the productfractionated. The ester was a Zmuorotatory oil; it amounted to4 grams, boiled at 131-132°/18 mm., and gave the followingvalues :I = 1, a1,7 -- 6.30°, D:' 1.124, [a]: -5.6'.Found, C1= 16.8.We have no evidence that this ester was optically pure, and itis necessary to bear in mind that partial racemisation occurs veryfrequently when the alcoholic hydroxy-group of an optically activehydroxy-carboxylic acid is displaced by halogen.It appeared from the following experiment.that this ester corre-sponds in configuration with I-a-chlorcm-phenylpropionic acid. Theester (3 grams) was added to 25 C.C. of 1V-aqueous silver nitrate, andmaintained at the ordinary temperature for twenty-four hours. Thesilver chloride was removed, and the filtrate boiled with aqueouspotassium hydroxide until all the oil had disappeared. The result-ing a-hydroxy-a-phenylpropionic acid obtained by acidification andextraction with ether amounted to 2 grams, melted a t 84-89',and was dextrorotatory in ethyl-alcoholic solution :CllH,,O,C1 requires C1= 16.7 per cent.!= 2, c = 18.48, a, + 1'33O, [ a ] + 3'6OWALDEN INVERSION.PART VI. 2569Action of PhospJ~oi~us Pentachloride and of Thionyl Chloride on theOptically A ctive Ethyl a-Hydroxy-a-phenylpropionates.Ethyl l-a-hydroxy-a-phtnyZpro@onate, OH-CMePh-CO,Et, pre-pared by the esterification of I-a-hydroxy-a-phenylpropionic acid byethyl alcohol and sulphuric acid, is an oil boiling at 127O/12 mm. :0.1330 gave 0.3322 CO, and 0.0865 H,O.It has Did 1.097 and C Z ~ - 29.24O ( I = 1) ; whenceWhen this ester is acted on by phosphorus pentachloride, theresulting ethyl a-chloro-a-phenylpropionate is dextrorotatory, butit is impossible to prevent a large amount of racemisation takingplace in this change.Powdered phosphorus pentachloride(7 grams) was added gradually within an interval of one hour t o theI-hydroxy-ester (6 grams). After three hours a t the ordinary tem-perature the product was warmed at 30° for a few minutes, whenno further action was perceptible. It was then treated with etherand ice, and the ethyl a-chloro-a-phenylpropionate isolated as anoil, boiling at 138-139°/28 mm.:C = 68.1 ; H =7'3.- 26.7'.C,,H,,O, requires C = 68-0 ; H = 7.3 per cent.Found, C1= 16.5.The ester had a , + l * l O o in a 1-dcm tube.On decomposing it with a slight excess of 1.03iV-aqueous sodiumhydroxide, the displacement of the chlorine by the hydroxy-groupof course accompanied the saponification; the product of the actionwas r-a- h y dr oxy-a-p hen ylpr opionic acid.Although attempts to prepare ethyl dZ-a-chloro-a-phenylpropionatein a state of even approximate purity from ethyl dl-a-hydroxy-a-phenylpropionate (b.p. 124-125O/ 10 mm.) and thionyl chloridemet with no success, it was nevertheless decided to examine theaction of thionyl chloride on the optically active hydroxy-esters.The material used for this purpose was the dextrorotatory mixtureof d- and r-a-hydroxy-a-phenylpropionic acids obtained from themother liquors resulting from the morphine resolution of the r-acid.It was esterified by ethyl alcohol and sulphuric acid, and the esterobtained had a,+ 14O in a 1-dcm. tube. Twelve grams of thisproduct remained for seven days at the ordinary temperature afterhaving been mixed with 14 grams of thionyl chloride. The liquidwas then heated for twenty hours at 50-60°, and for five hourslonger a t 60-70°, but the action was apparently not quite completeeven under these conditions. The product was fractionated, and anoil boiling at 138-141°/25 mrn. was obtained; it was dextrorotatory,giving a,, + 1*50° in a 1-dcm. tube. It contained, however, only 11-7per cent. of chlorine. We were able to draw the conclusion,C,,H,,O,Cl requires C1= 16.7 per cent2570 FORSTER AND NEWMAN: THE TRIAZO-GROUP. PART xv.however, from the following experiment Chat d-a-chlorea-phenyl-propionate was actually present in this impure product. Thechlorine in it was first displaced by aqueous silver nitrate, and theproduct then saponified with aqueous potassium hydroxide. Theresulting potassium salt was Zaevorotutory in aqueous solution, andthe a-hydroxy-a-phenylpropionic acid obtained from it was alsoZaevorotatory. This result was confirmed by a second experiment.BIRKBECK COLLEGE,LONDON, E.C

ISSN:0368-1645    

DOI:10.1039/CT9109702564

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

2570 FORSTER AND NEWMAN: THE TRIAZO-GROUP. PART xv.CCLXI 11.-The Trinzo-group. P a r t X V. Triaxo-ethylene ( Vinylazoirnide) and the TriazoethylHalides.By MARTIN ONSLOW FORSTER and SIDNEY HERBERT NEWMAN.MANY cases have now been placed on record in which the atomscomposing a triazo-group in the neighbourhood of an unsaturatedlinking have lent themselves to the formation of a cycloid, owingto a change involving saturation of this linking by the membersof the azoimide nucleus. As recent examples of this principle maybe quoted the spontaneous transformation of allylazoimide into anisomeric diazoamino-compound (Trans., 1908, 93, 1174), whilst anattempt to prepare benzhydroximic azide by interaction of thechloride and sodium azide led t o 1-hydroxy-5-phenyltetrazole (Trans.,1909, 95, 183; compare also Wieland, Ber., 1909, 42, 4199).I n the cases mentioned above, and in others which might beindicated, the environment favourable to the display of additivefunctions on the part of the triazo-group is intramolecular.Whether it is necessarily so cannot be stated with confidence,because, although striking examples of apparently intermolecularaddition have been furnished quite recently by Palazzo and Oliveri-Mandal2 ( A t t i R.Accad. Lincei, 1910, [v], 19, i, 218, 228), whofound that hydrazoic acid converts fulminic acid and methyl-carbylamine into 1-hydroxytetrazole and 1-methyltetrazole respec-tively, whilst Dimroth and Fester (Ber., 1910,43,2219) showed thattetrazole itself is obtainable by the interaction of hydrazoic andprussic acids, it is nevertheless possible that these changes actuallydepend on preliminary addition of H and N, t o unsaturated atoms,and that it is the resulting triazo-compound which undergoes intra,molecular rearrangement, as follows FORSTER ANI) NEWhIBN : T H E TRIAZO-GROUP. PAKT XV.2571I n addition to the experiment just mentioned, Dimroth andPester caused hydrazoic acid to act on acetylene, and although1: 2 : 3-triazole was obtained therefrom, they do not classify thischange with the foregoing ones, as depending on the intermediateformation of vinylazoimide,N-YHCH:CH’ HCiCH+HN,=N,*CH:CH, -+ N<because phenylazoimide is converted into 1-phenyl-2 : 3-triazole bythe action of acetylene. As we have been engaged for some timein experiments lea,ding to the preparation of vinylazoimide, wethink it may be of interest to put forward a description of thissubstance, which was isolated with the object of studying itstendency to undergo the above reari angement.The first experiments in the direction indicated were begun morethan t’wo years ago in continuation of the work on allylazoimide.Attempts were made to bring vinyl bromide into double decom-position with sodium azide, but there was not any evidence of thechange having taken place; in spite of the readiness with whichusually the triazo-group may be substituted for halogen in aliphaticcompounds, the failure was not surprising, as it is well known thathalogen attached to unsaturated carbon takes part in such reactionswith the greatest difficulty.The preparation of triazoethyl alcohol(Trans., 1908, 93, 1865), however, suggested the possibility ofarriving at triazoethylene (vinylazoimide) by the withdrawal ofhalogen hydride from a triazoethyl halide. Accordingly, triazo-ethyl alcohol was converted into triazoethyl bromide by the actionof phosphorus tribromide, and then by double decomposition withsodium iodide, triazoethyl iodide was prepared from the bromide;on acting with alcoholic potassium hydroxide on these compounds,they were readily deprived of halogen hydride without affecting thetriazegroup.Triazoethylene is a pale yellow liquid, heavier than water, boilingat 26O, and having an odour suggesting that of ethylene itself.Itdecolorises bromine water without delay, forming a heavy, oilydibromide. At one time we entertained the hope that it might bepossible to withdraw the elements of hydrogen bromide from thissubstance in such a way as to produce triazoacetylene, the coppe25'72 FOKSTER ANL) NEWMAN: TliE TRIAZO-GROUP. PART XV.derivative of which would probably rank among violent explosives,but i t was soon found that the dibromide itself is a dangerousmaterial, and, moreover, breaks up in an interesting manner underthe influence of water. When suspended therein, the oil rapidlydisappears, hydrobromic and hydrazoic acids being set free, whilstbromoacetaldehyde remains dissolved :CH,Br*CHBr*N, + 2H,O = HBr + HN, + CH2Br-CH(OH), -3CH,Br*CH:O + H,O.So far as we know, the dibromide of triazoethylene is the firstcompound in which a triazo-group is attached to an atom of carbonwhich carries also a hdogen, and its peculiar susceptibility towardswater explains the subsidiary decomposition which has always beenobserved to accompany the production of a bistriazo-compound fromthe double decomposition of sodium azide and a.dihalogen derivativeof the aliphatic series in which both halogen atoms are attached tothe same atom of carbon (Trans., 1908, 93, 1070; also this vol.,pp. 126 and 1360). We have not att,empted to isolate and distilthe substance, because a brief experience of aa-bistriazwthane,which exploded with great violence at the laboratory temperature,apparently spontaneously, renders it most probable that ab-dibromo-a-triazoethane would behave in the same way.This seems the morelikely to take place in view of the possibility that the decompositionof triazoethylene dibromide might follow a different course inabsence of water, leading to bromoazoimide :CH2Br*CHBr*N3 -+ BrN3 + CH,Br*CH -+ CHBr:CH,.Since Raschig has shown (Ber., 1908, 41, 4194) that chloro-azoi.mide is frightfully explosive, the foregoing possibility is dis-couraging to a further investigation of aP-dibromo-a-triazoethane.The original purpose with which triazoethylene was prepared,namely, to illustrate its transformation into triazole :has not been fulfilled, the substance having shown itself to besurprisingly stable. After being heated with dilute alcohol underreflux during twelve hours, a considerable proportion was foundto have survived, and although the remainder had changed into adark brown substance, the presence of triazole could not beestablished. Furthermore, on heating an alcoholic solution in asealed tube during twelve hours at 100-llOo, there was produceda dark brown liquid having the odour of a carbylamine, and givinga precipitate with mercuric chloride, but again it was not foundpossible to recognise triazole.The pale yellow colour of triazoethylene is an interesting featureof the compound, and appears to be a genuine property, becausFORSTER AND NEWMAN : THE TRIAZO-GROUP.PART XV. 2573it has been noticed in every specimen, whether prepared from triazeethyl iodide or bromide. It is doubtless due to the concentrationof unsaturated atoms in a small molecule, and although not SOintense as that of diazomethane, it is nevertheless quite distinctive.The comparatively high boiling point was not expected, because therecorded boiling points of vinyl chloride and of vinyl bromide are- 1 5 O and + 1 6 O respectively, and without having made a study ofthe subject, we were under the impression that, whilst the boilingpoint of an aliphatic chlorederivative is unquestionably lower thanthat of the corresponding triazo-compound, the latter would bemore volatile than the brominated substance.As it is often amatter of considerable practical importance to be able to predict,roughly, the boiling point of a new triazo-compound from that ofits haloid parent, we have taken afresh the boiling point of severaltypical aliphatic azoimides described in previous papers, side byside with those of the corresponding bromclderivatives.The resultsshow conclusively that the triazo-group exerts an elevating effecton the boiling point greater than that of the bromine atom.Vinyl bromide .................Vin ylazoimide .....................Ethylene dibromide ............Triazoethyl bromide i.. ..........Ethyl a-bromopropionate ......,, a-triazopropionate ......,, a-bromoisobutyrate ......, , a- triazoisobutyrate ......,, a-bromoisovalerate ......, , a- triazoisoval era te ......B. p. Mni.CH,:CHP,r ..................... 16" 750CH,:CHN,, ................... 26 760CH,Br'CH,Rr ..................37 20CH,Br'CH,N, .................. 49 20CH,.CHBr.CO,Et ........... 61 16CH,*CHN;CO,Et ............ 70 16CBr(CH,);CO,Et ............ 62 16CH(CH,),*CHBr'CO,Et ...... 79 16CH(CH,),*CHN,'CO,Et ...... 82 16CN3(CH3);C0,Et ............ 71 16The relationship between the triazo-group and the chlorine atomby the as regards their effect on the boiling point is revealedfollowing data :B. p. Mm.Vinyl chloride .............................. CH,:CHCl .................... - 15" 760Vinylazoimide .......................... CH,:CHN,. .................. 26 7608-Chlorocthyl alcohol.. .................. CH,CI*CH;OH .............. 44 20B-Triazoethyl ,, ..................... CH,N;CH,'OH ............ 73 20Ethyl chloroformate .................... Cl'C0,Et .....................93 760,, triazoacetate ....................... CH,N,*CO,Et ............... 70 20Methyl a-chloromethylacetoacetate .. , CH;CO'CCl(CH,)*CO,Me . 76 13 ,, a-triazomethylacetoacetate ... CH;CO*CN,( CH,)*CO,Me . 76 0 '66We have not, as yet, been very successful in attempts to utilisetriazoethyl iodide as a triazo-ethylating agent. Triazoethyl chloridehas been obtained by heating the iodide with dry mercuric chloride,and in this connexion it is worth noting that the bromide remainsunchanged when treated with the mercury salt under similar con-ditions. isoNitrosocamphor was transformed into an oily triazo-,, triazoforamte ..................... N;CO,Et ..................... 114 769,, chloroacetatc ........................ CH,Cl'CO,Et ..................52 22574 FORSTER AND NEWMAN: THE TRIAZO-GROUP. PART XV.ethyl derivative when heated with triazoethyl iodide and silver oxidein dry ether, but an attempt to prepare bistriazoethyl ether byheating a mixture of triazoethyl alcohol and iodide with dry silveroxide on the water-bath led to the recovery of unaltered triazoethylalcohol after five days. This is the more curious because the actionof ethyl iodide on triazoethyl alcohol in presence of silver oxideleads without difficulty to triazoethyl ether, C,H,*O*CH,-CH,N,.Lastly, we have not been able to produce triazoethylcarbimide bythe action of triazoethyl iodide on lead o r silver cyanate, whilst theinteraction of triazoethyl iodide and silver cyanide, although pro-ducing an odour of carbylamine, was too far from complete toadmit of isolating any definite products.EXPERIMENTAL.Triasoethylene (Vinylaaoimide), C'H,:CHNs.The alcoholic potassium hydroxide used for withdrawing halogenhydride from the triazoethyl halides was a solution of 5 grams in20 grams of water, mixed with 25 grams of absolute alcohol.Thiswas heated on steam in a generating flask, into which was fitteda dropping-funnel and a reflux double-surface condenser ; from thelatter, connexion was made to a small, dry flask, thence to aU- tube filled with calcium chloride, and finally to a large test-tubesurrounded by a freezing-mixture. The temperature of the waterin the condenser having been adjusted to 30°, 5 grams of triazoethyliodide was admitted drop by drop into the alcoholic potassiumhydroxide at the temperature of boiling alcohol, when a pale yellowliquid gradually accumulated in the small flask between thegenerator and the U-tube.All the iodide having been added, theliquid was boiled during fifteen minutes, when i t was found thatthe cooled tube also contained some yellow liquid, and this, beingpresumably free from alcohol and water, was regarded as puretriazoethylene, and found to boil at 26O/760 mm. Although thisexperiment has been made several times, and triazoethyl bromidehas been substituted for the iodide, it has always been observedthat the liquid in both condensing vessels is pale yellow, and thatthe colour does not vary in depth; it therefore seems safe to concludethat this feature is not due to some impurity.Reference has beenmade to the absence of any conclusive evidence that triazoethylenechanges into triazole; in addition to the experiments towards thisend which have been already described, a solution of triazoethylenein petroleum was left in a, stoppered vessel exposed to light duringmany days without giving the faintest indication of triazole; onallowing the solvent to evaporate, the odour of a carbylamine wasnoticeableFORSTEH, AND NEWMAN: THE TRIAZO-GROUP. PART xv. 2575The dibrom,ide of triazoethylene was prepared by adding ice-coldbromine water to a well-cooled suspension of the substance in water,the colour of the halogen being immediately destroyed, whilst thelimpid vinylazoimide changed to a heavy, viscous oil.It is necessaryto be most cautious in adding the halogen, because on one occasiona drop of bromine was admitted by accident. to the vessel containingthe triazo-compound, and led to a violent explosion, although theamount of material involved could not have exceeded 1 gram, andthis was diluted with 20 C.C. of water. On allowing the dibromideto remain in contact with water, it rapidly disappeared, and theliquid was found t o contain hydrazoic and hydrobromic acids;moreover, it restored the colour to Schiff's reagent, and when mixedwith ammoniacal silver oxide and filtered, the liquid quicklydeposited silver on warming. In order to make sure that the decom-position of triazoethylene dibromide by water does not follow thepossible alternative course, that, namely, leading to bromoazoimideand vinyl bromide, a specimen of vinylazoimide was converted intothe dibromide with a deficit of bromine, and at once treated withdilute sodium hydroxide, in the expectation that if bromoazoimideis formed, it would behave towards alkali in the manner thatcharacterises chloroazoimide, and that alkali hypobromite would beproduced; we were able to show that hypobromite is not formed,and therefore conclude that the decomposition proceeds only in thedirection of hydrobromic and hydrazoic acids along with bromo-acetaldehyde.The interaction of triazoethylene and concentrated sulphuric acidis mild, gas being evolved slowly, but brisk effervescence occurs witha solution of stannous chloride in hydrochloric acid.The con-clusion that alcoholic potassium hydroxide is without action on thesubstance may be drawn from the fact that on evaporating todryness the liquid contained in the generating flask, no trace ofalkali wide was to be found.8-Chloro-a-triazo e t han e (Trbzo e t h yl Chloride), N,*C%, CH,Cl.The first attempt's to prepare this material were made by addingtriazoethyl alcohol dissolved in absolute ether to the calculatedamount of phosphorus pentachloride covered with the same solvent ;considerable action took place, and was increased by heating underreflux, but the yield of triazoethyl chloride, being only 2 gramsfrom 20 grams of the alcohol, was too disappointing to encouragethe adoption of this method.Thionyl chloride acts vigorously ontriazoethyl alcohol, but, as might be expected, gives a product whichappears to be triazoethyl sulphite, and triazoethyl chloride couldnot be detected, whilst the effect of passing dry hydrogen chlorid2576 FORYTER AND NEWMAN : THE THIAZO-GROUP. PART XV.into a suspension of anhydrous zinc chloride in triazoethyl alcoholwas to liberate hydrazoic acid. It was not until triazoethyl iodidebecame available that the preparation of the chloride was possible.Twenty grams of triazoethyl iodide, mixed with 32 grams ofdried mercuric chloride, were heated at looo during three hours ina small distilling flask, from which the product was then boiledunder 25 mm. pressure, 10 grams, or 90 per cent. of the theoreticalamount, being obtained ; on re-distillation under the same pressure,the substance boiled steadily at 45O:0.0874 gave 30.9 C.C.N, at 2 4 O and 751 mm.0.2709 ,, 0.3642 AgC1. C1=33.25.N = 39.16.C,H,N3C1 requires N = 39.81 ; C! = 33.65 per cent.The substance is limpid and colourless, having a pleasant odoursuggesting that of chloroform ; the density is 1.2885 / 24O. Theaction with a solution of stannous chloride in hydrochloric acid issluggish, gas being evolved only on warming the liquids; theeffervescence with concentrated sulphuric acid becomes brisk onstirring, but the triazo-group appears to be indifferent towardsalkalis, which only liberate triazoethylene. The chloride does notlose its halogen completely when heated with boiling alcoholic silvernitrate, as is the case with the other tqiazoethyl halides, and theabove estimation of chlorine was made by heating in alcohol with30 per cent.aqueous potassium hydroxide, followed by precipitationwith silver nitrate in the solution acidified by nitric acid.When thrown on a hot plate, the substance decrepitates, andburns with a violet flame.P-Bromo-a-t riasoet Tmne (T?.z'uzoe thy1 Bromide) , N3* CH,*CH2Br.Although triazoethyl bromide has been obtained by the action ofbromine on tria.zoethy1 alcohol in presence of amorphous phosphorus,this is not the most convenient method of preparation, the inter-action of phosphorus tribromide and the alcohol, when moderatedby a diluent such as ether or petroleum, leading to more satisfactoryresults.One hundred grams of triazoethyl alcoho,l, covered with100 C.C. of petroleurn (b. p. 40°) in a flask surrounded with meltingice, were treated slowly with 112 grams of phosphorus tribromidein 250 C.C. of the same petroleum, the mixture being shakenvigorously after each portion was added ; phosphorous acidseparated, and a heavy, pale brown, viscous oil, insoluble inpetroleum, constituted a large proportion of the product. Afterthree hours on the water-bath under reflnx, the less dense liquidwas decanted, and the viscous residue shaken several times withsmall quantities of petroleum, which were added to the decantedsolution of triazoethyl bromide ; any excess of phosphorus tribromidFORSTEK AND NEWMAN : THE TRIAZO-GROUP. PART.xv. 2577was destroyed by agitation with small quantities of water, and theliquid having been treated with ignited sodium sulphate, petroleumwas boiled fiway, and the residue distilled under diminishedpressure. The best yield obtained by this process was only 58 grams,representing about 34 per cent. of the amount anticipated :N=28*00. 0-0641 gave 15.9 C.C. N, at 24O and 765 mni.0.4942 ,, 0.6198 AgBr. Br =53*38.C,H,N3Br requires N= 28-02 ; Br = 53.33 per cent.Triazoethyl bromide is a colourless liquid, having the odour ofethylene dibromide, and rapidly becoming yellow when exposed tolight; i t boils at 49O/20 mm., and has the density 1.6675/19'.Action with concentrated sulphuric acid and with a solution ofstannous chloride in hydrochloric acid resembles that of the chloro-compound, but hot alcoholic silver nitrate leads more readily tothe elimination of halogen tha.n in the case of that substance, andthe above determination of bromine was carried out by this agent.The bromide does not become ignited when thrown on a hot plate,merely decrepitating mildly.Attempts have been made t o identify the viscous, brown oil whichaccompanies triazoethyl bromide when prepared by the foregoingmethod, so far without success.It is the production of this sub-stance which is responsible for the disappointing yield, and is par-ticularly inconvenient because triazoethyl bromide is the startingmaterial for the chloride and the iodide. The presence of phos-phorus, bromine, and the triazo-group suggested that the sub-stance might be the bromide of bistriazoethylphosphorous acid,(N3*CH2*CH2dO),PBr, but the bromine content was much too low;it may be a mixture of this substance with triazoethyl phosphite,(N3-CH2*C'H,*~O),P, but an attempt to recover triazoethyl alcoholfrom itl by hydrolysis was not successful.P-lodo-a-t?-iazoethane (Triuzoethyl Iodide), N,-CH,*CH,I.The method employed for this preparation was the one recentlydescribed by Finkelstein (Bey., 1910, 43, 1528), and was found tobe expeditious and economical.Fifty-eight grams of triazoethylbromide were added to a solution of 60 grams of sodium iodide in400 C.C. of dry acetone, sodium bromide being precipitated imme-diately; the mixture having remained at the ordinary temperatureduring the night, action mas completed by heating under reflux,when about two-thirds of the solvent mas distilled off, and theresidue poured into water contained in a separating funnel, fromwhich the heavy, dark brown liquid was then tapped.This wasmixed with the ether used for extracting the triazoethyl iodide fromthe aqueous acetone, and shaken vigorously with a little mercur2578 FORSTER AND NEWMAN: THE TRIAZO-GROUP. PART xv.in order to remove dissolved iodine, the residue from the driedether being then distilled under diminished pressure, yielding 43grams :0.0814 gave 15.5 C.C. N, a t 23O and 764 mm. N=21.58.0.4270 ,, 0.5063 AgI. 1=64*12.C&14N31 requires N = 21-32 ; I == 64.45 per cent.Triazoethyl iodide boils at 68O/20 mm., and when freshly distilledis colourless, but quickly becomes pale red; the odour resemblesexactly that of ethyl iodide.It has the density 1*9154/25O, andis able to dissolve mercuric iodide, a property brought to light bythe fact that a specimen which had been decolorised by agitationwith mercury left a considerable residue of the salt on redistillation.The action with stannous chloride in hydrochloric acid is morebrisk than in the case of the other triazoethyl halides, which theiodide resembles, however, in regard to interaction with concentratedsulphuric acid. Behaviour on the hot plate is similar to that oftriazoethyI chloride.It was hoped that a variety of interesting substances might beobtainable from typical compounds containing replaceable hydrogenby triazo-ethylation, but hitherto we have not been successful inthis direction. p-Nitrophenol, for instance, when heated in drybenzene with silver oxide and triazoethyl iodide, gave a brown oilwhich did not invite further examination. isoNitrosocamphor alsogave an oil, remaining liquid during four months, and containing22.35 per cent.of nitrogen (C,,H,,O,N, requires N = 22.4 per cent.).Silver and lead cyanates were heated in ether and in benzene atthe boiling points of these with triazoethyl iodide during manyhours, but triazoethylcarbimide could not be recognised, althoughin absence of a diluent, some action takes place at about looo, asindicated by a mild explosion which occurred. Silver cyanidedeveloped the carbylamine odour when heated with triazoethyliodide during two days on the water-bath, but the proportion ofmaterial remaining unchanged at the end of the experiment wastoo large to hold out any prospect of success.Bistriazoethyl sulphateappears to be formed when triazoethyl iodide is heated in drybenzene with silver sulphate, production of silver iodide beingclearly indicated; the residue left by the solvent on evaporationdid not distil at 140°/1 mm., but .when hydrolysed with 30 percent. potassium hydroxide, the liquid contained potassium sulphate,unmixed with iodide.An attempt was made to prepare bistriazoethyl ether by heating5 grams of triazoethyl alcohol and 11.3 grams of triazoethyl iodidewith 15 grams of dry silver oxide on the water-bath during fivedays, but the entire product distilled at 85O/35 mm., weigheCONDENSATION OF AROMATIC SULPHINIC ACIDS. 25795 grams, and contained 48.3 per cent. of nitrogen; this is theamount required by triazoethyl alcohol itself, whilst bistriazoethylether contains 53.8 per cent., from which it would appear that inthe above experiment the triazoethyl alcohol remained unchanged,whilst the triazoethyl iodide wils transformed into triazoethyleneand diffused out of the apparatus.P-Triaaoethyl Ether, N,*CH,*CH,*O*C2H,.Twenty grams of triazoethyl alcohol and 50 grams of ethyl iodidewere allowed to remain in darkness with 50 grams of dry silveroxide during two days, being then heated on the water-bath withoccasional addition of small quantities of ethyl iodide. After oneweek, the liquid was separated and distilled under diminishedpressure :0.1057 gave 33.5 C.C. N, at 2 l 0 and 763 mm.The substance is a colourless liquid, boiling at 49O/25 mm., andhaving the density 0-9744/24O. The odour resembles that of chloro-ether, and in steam is pungent and sweet. With concentratedsulphuric acid or a solution of stannous chloride in hydrochloricacid, there is a vigorous effervescence, but hot concentrated alcoholicpotassium hydroxide appears to be without action on triazoether,the azoimide nucleus remaining intact. Triazoethyl ether does notexplode when thrown on a hot iron plate. the vapour burning with aluminous, white flame.N=36*39.C,H,ON, requires N = 36.51 per cent.ROYAL COLLEGE OF SCIENCE, LONDON.SOUTH KENSINGTOE, S . W

ISSN:0368-1645    

DOI:10.1039/CT9109702570

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

CONDENSATION OF AROMATIC SULPHINIC ACIDS. 2579CCLXIV.-The lntewnolecula~* Condensatiorb o jAyomatic Sulphinic Acids. P a r t I.By THOMAS PERCY HILDITCH.THE well-known tendency of aromatic sulphinic acids to enter intocombination with other benzenoid residues through the eliminationof water is more than maintained in the corresponding acidchlorides, which, as was observed when the latter compounds wereoriginally obtained in a pure condition (Hilditch and Smiles, Ber.,1908, 41, 4113), are exceedingly reactive and unstable. In thecourse of some work on the reduction of these chlorides, it wasnoticed that, if too much heat was applied during their preparatio2580 I-IILDITCH : THE INTERMOLECULAR CONDENSATION OFor the subsequent treatment, decomposition set in, and white,crysta.lline, insoluble Compounds, sometimes accompanied by tarrymatter, were formed in considerable quantity.The present communication describes some experiments under-taken t o elucidate the nature of these by-products.It was foundthat by heating benzenesulphinyl chloride, C,H,*SOCl, or p-toluene-sulphinyl chloride, C6H4Me*SOC1, either alone at looo or in boilingchloroform, or in presence of a slight excess of thionyl chloridebeyond that needed for the preparation of the acid chlorides, asemi-solid, dark-coloured mass was obtained, from which the variouscompounds formed were separated by successive extraction withlight petroleum, alcohol, and toluene. Furthermore, in order toavoid the formation of tarry decomposition products when heat wasapplied, the condensing action of cold concentrated sulphuric acidon these two chlorides was investigated, and analogous productswere obtained, whilst, finally, it was established that the freesulphinic acid, when left for a sufficient length of time in solutionin cold concentrated sulphuric acid, underwent a similar change,and from experiments with a number of aromatic sulphinic acidsit appeared that the course of the reaction was conditioned largelyby the substituents present in the benzene nucleus.From a general point of view, it would appear that besides simpleoxidation to sulphonic acids there are the following possibilities tobe considered in this decomposition of sulphinic acids :(i) The usual formation of disulphoxides, with possible furtherdecomposition of the latter substances :(ii) (a) Intermolecular condensation of the sulphinic acids,possibly involving more than two molecules of the acid, but notproceeding beyond the sulphoxide stage ; for example :( b ) Further int,ermolecular condensation of the sulphoxides t ocomplex sulphonium bases (compare Smiles and Le Rossignol,Trans., 1906, 89,696; 1908,93, 745) :and so on.As a matter of fact, definite evidence of the production ofsulphonium derivatives has not been obtained, but both of theother reactxiom appear to take place, the one or the otherpredominating according to the manner of substitution in thesulphinic acid used.Thus, from the action of heat on benzeneAROMATIC SULPHINIC ACIDS. PART I.2581sulphinyl chloride, a quantity of diphenyl disulphide and the white,insoluble compound mentioned above was formed, whilst p-toluene-sulphinyl chloride yielded under similar conditions a mixture ofdi-p-tolyl disulphoxide and it small amount of di-p-tolyl-a-disulphone.On the other hand, benzenesulphinic, o-toluenesulphinic, anda-naphthalenesulphinic acids reacted in the presence of concentratedsulphuric acid to form varying amounts of the insoluble products,together with disulphoxides. As much as 50 per cent. yields of theinsoluble compound were obtained from benzenesulphinic acid, butonly about 20 per cent. of the two other acids was converted to thecorresponding insoluble derivative. Finally, ptoluenesulphinic,p-ethoxyphenylsulphinic, P-naphthalenesulphinic, and o-carboxy-benzenesulphinic acids gave no " insoluble " product whatever, butusually furnished sinall amounts of disulphoxides.Of these various compounds, the white, insoluble substances, whichin the first place attracted attention to this decomposition, areperhaps the most interesting.Since these were not a-disulph6nes,i t appeared probable that they had been formed by means of thecondensation (ii) (a) referred to above, but from their insolubilityin sodium hydroxide solutions it did not seem likely that any freesulphinic acid group was present in their molecules. Accordingly,the possibility of the remaining sulphinyl radicle having enteredinto the reaction had to be considered, and at first sight it appearedt,hat derivatives of diphenylene o-disulphide had been formed :HO*SO soIt soon became evident, however, from both physical and chemicalproperties of the products under investigation that they were notderived from ordinary diphenylene o-disulphide, and attention wasnext paid to a statement by Genvresse (Bull.SOC. chim., 1896, [iii],15, 421, 1038; 1898, [iii], 17,599) that in the usual preparation ofdiphenylene o-disulphide large quantities of insoluble by-productswere formed, and that under suitable conditions as much as 80 percent. yields of an insoluble compound isomeric with diphenyleneo-disulphide could be obtained from benzene, sulphur, andaluminium chloride. Genvresse suggested at the time that thesecompounds were par&condensation products, and that ordinarydiphenylene disulphides contained meta-disulphide ring systems.Recently, however, Deuss (Ber., 1908, 41, 2329) has establishedthe constitution of diphenylene disulphide as an ortho-ring systemby heating diphenylene disulphone, C6H4[ SO,],C,H,, with phosphorusVOL.XCVII. r g 2582 H~LDITCH : THE INTERMOLECULAR COXDENSATION OFpent,achloride, when a mixture of odichlorobenzene and benzene-o-disulphonyl chloride was obtained according to the equation :On trea.ting the insoluble product derived from benzenesulphinicacid according to Deuss’ directions, the author has obtained solidp-dichlorobenzene and benzene-p-disulphonyl chloride in sufficientamount for definit-e characterisation. It therefore appears that thecompounds now being described are analogous to diphenyleneo-disulphide, but are condensed into a ring system by means of theirpara-atoms :A close comparison of the properties of these compounds withthose described by Genvresse (Zoc.cit.) left no doubt that they wereidentical therewith ; for example, the colour of their solutions inconcentrated sulphuric acid is similar, bus differs from that of theortho-disulphides, whilst on oxidation a disulphone resulted identicalin properties with that, obtained by that author. Unfortunately,the compound from benzenesulphinic acid, which corresponds witha dioxide of Genvresse’s isomeric compound, could not be reducedto the latter substance, owing probably to a simultaneous ruptureof the ring system.The proof of the orientation of these substances is strikinglysupported by the fact that not a trace of the corresponding insolubleproduct could be obtained from either p-toluenesulphinic, p-ethoxy-phenylsulphinic, or P-naphthalenesulphinic acids, the positions para-to the sulphinyl group being occupied in these instances by otherradicles.The author has, however, not succeeded in deciding whether theseproducts are really analogous to diphenylene o-disulphide or whetherthey consist of an indefinitely prolonged series of *S*C,H,*S* groupsunited in para-positions.The latter alternative might be thought pos-sible in view of their insolubility in practically all organic solvents,of their high melting points, and of their not too well-defined crys-talline structure, but, on the other hand, para-substituted compoundsusually melt higher and are less soluble than the correspondingortho-derivatives, and, again, their general stability and theformation on oxidstion of disulphones similar to diphenylene diAROMATIC SULPHINIC ACIDS.sulphone lend colour to the opinion thatthe simple ring system:PART I.2583they are derived fromA determination of molecular weight, which would have definitelyestablished the point, was unfortunately quite out of the question,owing to the exceedingly slight solubility or volatility of any of thecompounds.There is, however, little reason to suppose that a par%ring systemas depicted above would be less stable, although less familiar, thanthe usual six-membered ring, for since it is generally conceded thatthe para-benzenoid atoms are almost as closely related in space asthe ortho-atoms, the above ring system will partake much morenearly of the nature of a six-membered than of the ten-memberedheterocyclic chain which at first sight it appears to be.Before describing the experimental part of this investigation, itwill be well to discuss the mechanism of the condensation.whichtake place in diphenylene disulphide syntheses, and especially thenon-appearance from sulphinic acids of any ortho-ring products.Speaking in general terms, the numerous syntheses of heterocyclicring systems which have been worked out do not permit of anychoice of orientation on the part of the molecules concerned. Thus,in the case of phenazine, the nitrogen atoms in which are situatedsimilarly to the sulphur in diphenylene disulphide, derivatives ofNby oxidation in presence of phenols (Ris, Ber., 1886, 19, 2207), orby condensation with catechol or derivatives of o-quinones (Hinsberg,‘4nnnZen, 1896, 292, 258), but the oxidation of aniline itself leadsnot to phenazine, but to the “aniline-black” dyes, in which anumber of benzene nuclei are united by means of nitrogen atomseach in a para-position with respect to the next.It seems probable that similar influences determine the course ofring formation from sulphinic acids and mercaptans ; moreover, thepreference for para-condensa.tion is emphasised in the case of sulphurcompounds by the fact that, cetem‘s paribus, in the condensation ofsulphinic acids or sulphoxides with phenolic ethers (Smiles and LeRossignol, Zoc.cit.) para-substituted products predominate overortho, the latter, indeed, being frequently not formed at all.Again, all the synthetic methods for the preparation of di-8 F 2584 HILDITCH : THE INTERMOLECULAR CONDENSATION OFphenylene o-disulphides involve much loss of product owing t o theformation of insoluble compounds, and it appears to the author thatin most of these syntheses the formation of the disulphide is due toa secondary reaction, and may be ascribed to the fact that thestarting materials are derivatives of phenyl mercaptan rather thanof the more oxidised benzenesulphinic acid. The condensation ofsulphinic acids is explained readily by the equation :and it is probable that the underlying cause of all the earlierdiphenylene disulphide syntheses is the production of temporaryhydroxylic sulphur derivatives of the type CBH,*S*OH, rather thanthe simultaneous removal of a hydrogen atom from a mercaptangroup and from a benzene nucleus by means of extraneous oxygen(compare Davis and Smiles, this vol., p.1292).Thus the chief methods extant for the synthesis of diphenyleneo-disulphides are as follows :( a ) Action of sulphur on benzene in presence of aluminiumchloride (Stenhouse, Annalen, 1869, 149, 250; Krafft and Lyons,Ber., 1896, 29, 436).( b ) Action of aluminium chloride on mercaptans or disulphides(Deuss, Rec. trav. chim., 1908, 27, 145; 1909,28, 136).( c ) Action of hot concentrated sulphuric acid on mercaptans,disulphides, or disulphoxides (Fries and Volk, BeT., 1909, 42, 1170).These reactions have been explained by the transitory formationof various oxidation and reduction products or by temporaryisomerisation of the compounds involved, but it is evident that asimpler and more comprehensive explanation of the whole seriesresults from the hypothesis that derivatives of sulphoxylic acids arefirst produced, as has been assumed by Davis and Smiles (Zoc.cit.) inthe formation of thioxanthones, and by Hinsberg (Ber., 1903, 36,109) in the formation of hydroxydiphenyl sulphide from benzene-sulphinic acid and phenol.The process is thus similar to the condensation of the sulphinicacids, and differs only in that, whilst in the latter case no ortho-condensation occurs, in the former instance derivatives of di-phenylene o-disulphide are f ormed in varying, but subsidiary, pro-portions.It should be mentioned here that phenyl mercaptan itself, onbeing kept for some hours in concentrated sulphuric acid at theordinary temperature, was converted to a mixture of a small amouuAROMATIC SULPHINIC ACIDS. PABT I.2585of diphenylene o-disulphide and about 70 or 80 per cent. ofdiphenylene pdisulphide.The decomposition of disulphoxides in cold concentrated sulphuricacid is at present under investigation.EX PE R I MENTAL.A ction of Heat on Benzene- and p-Toluene-sdphinyl Chlorides.( a ) Five grams of benzenesulphinic acid were converted to thechloride by solution in et>her and treatment with the theoreticalquantity of thionyl chloride.It is found that this method yields amuch cleaner product than the course formerly pursued of allowingexcess of thionyl chloride tlo act on the undissolved acid in the cold.The ether was subsequently evaporated, and the residue heated onthe water-bat.h for about an hour, when abundant evolution ofhydrogen chloride took place. A t the end of this period, the semi-solid product was extracted several times with boiling alcohol, afterwhich the colourless, insoluble residue, which could not be crys-tallised from even such high boiling solvents as nitrobenzene oraniline, was dried at 130° and then analysed:0.1023 gave 0.2186 CO, and 0.0321 H,O.C,,H,O,S, requires C = 58.07 ; H = 3-23 per cent.The alcoholic extract was found to contain a smaller quantity ofdiphenyl disulphide, melting at 59O, and identified with that sub-stance by the mixed melting-point method.( b ) Two equal portions of benzenesulphinic acid were taken; onewas converted into the acid chloride, and then heated with the otherfor some hours in boiling chloroform solution.As in the firstinstance, a large amount of diphenylene p-disulphoxide, togetherwith a smaller amount of diphenyl disulphide, was obtained.( c ) Equal weights of benzenesulphinyl chloride and ptoluene-sulphinic acid were heated in boiling chloroform for some time.After the evaporation of the chloroform, the product, which wasvery dark coloured, was first extracted with light petroleum, fromwhich on evaporation a pale yellow oil was obtained, which wasnot closely examined, but appeared to be phenyl-p-tolyl disulphide(Otto and Rossing, Ber., 1886, 19, 3133).The residue was boiledwith alcohol several times to remove tarry by-products, and aninsoluble powder was thus formed, which again gave anqlyticalnumbers corresponding with diphenylene p-disulphoxide.(d) Five grams of benzenesulphinic acid were heated for an hourwith an amount of thionyl chloride in slight excess of that necessaryfor complete conversion to the acid chloride. The usual evolution ofhydrogen chloride occurred, and the residue was extracted withC=58*26; H=3*492586 HILDITCH : THE INTERMOLECULAR CONDENSATION OFboiling light petroleum, which removed a small amount of diphenyldisulphide, and then with boiling toluene, from which thereseparated a quantity of a white, crystalline substance, melting anddecomposing at 180O. This proved to be a monoxide of diphenglenep-disulphid e, C6H4<y>C,H,.0.1161 gave 0.2673 CO, and 0-0398 H20.C=62-77; H =3-80.0.1192 ,, 0'2712 CO, ,, 0'0420 H20. C=62*04; H=3.91.C,,EsOS2 requires C = 62-07 ; H = 3-45 per cent.For comparison with this compound a sample of the monoxide ofdiphenylene o-disulphide was prepared from diphenylene o-disulphideby the method used by Fries and Volk (Zoc. cit.) in the preparationof the monoxide of ditolylene o-disulphide from ditolylene o-di-sulphide. Two grams of synthetic diphenylene o-disulphide, melt-ing a t 159O, were dissolved in glacial acetic acid, and dilute nitricacid (1: 5) was added until a turbidity appeared.The solutionmas set aside for twenty-four hours at the ordinary temperature,and then poured into water. The precipitate was collected andcrystallised from alcohol, when it formed colourless, glisteningprisms, readily soluble in glacial acetic acid, benzene, or toluene,more sparingly so in alcohol, and melting at 148O:0.1150 gave 0.2607 CO, and 0.0369 H,O.CI2,H,OS2 requires C = 62-07 ; H = 3-45 per cent.( e ) On similarly heating 5 grams of p-toluenesulphinyl chloridein boiling chloroform, much tarry matter was produced, and, afterevaporation of the chloroform, extraction with light petroleumyielded a white, crystalline substance, which melted at 74-76O, andappeared from its other properties to be di-p-tolyl disulphoxide.(Found, C = 61.06 ; H = 6.34. Calc., C = 60.43 ; H = 6-04 per cent.)The residue was decolorised by repeated boiling with alcohol,and was found to crystallise from boiling toluene in small prisms,which melted at 210-212O (di-p-tdyl a-disulphone melts at 212O :Kohler and MacDonald, Amer.Chem. J., 1899, 22, 219; 221O:Hilditch, Trans., 1908, 93, 1524). (Found, C =53'20; H =4.17;C = 54-22 ; H = 5-49.No t.race of diphenylene p-disulphide derivatives was observed,and it would appear that, the para-position being already occupiedby a methyl group, the reaction had taken the alternative course (i)referred to on p. 2580, in tahe presence of a certain amount of freesulphinic acid which must be assumed to have been regenerated :R-SQCl+ R.SO,H --+ R*SO*SO,*R (int'ermediate product)ZR*SO*SO,*R -+- R*SO*SO*R + R*SO,*SO,-R.C= 61.81 ; H=3-57.Calc., C = 54.20 ; H = 4-52 per cent.)AKOMATIC SULPHINIC ACIDS.PART I. 25S7Action of Cold Concendrated Szclphu& Acid om BenzenesulphinicAcid.( a ) Two grams of benzenesulphinic acid were converted to thechloride and poured into cold concentrated sulphuric acid.Hydrogen chloride was immediately disengaged in abundancethroughout the solution in the form of minute bubbles, and afterhalf an hour at the ordinary temperature, the reaction mixturewas poured on crushed ice. The solid product was separated andboiled with alcohol, thus removing a small amount of diphenyldisulphoxide, which melted at 45O.The residue (diphenylenep-disulphoxide) was dried at 130° and analysed. (Found, C = 58-22 ;H = 3-35.( b ) Ten grams of benzenesulphinic acid were left in solution inexcess of cold concentrated sulphuric acid. The mixture, whichwas at first colourless, gradually turned purple, and was eventuallyof an almost black hue. On pouring into a large bulk of coldwater, the colour entirely disappeared, and a granular, cream-coloured, solid product separated, and was collected and dried ona porous tile.The whole was then boiled with alcohol under reflux for a timeand again filtered; from the alcoholic filtrates about half a gramof diphenyl disulphoxide was obtained, which crystallised fromlight petroleum in characteristic, wax-like crystals, melting at 46O.(Found, C = 57-00 ; H = 4-20.The insoluble part of the product, when boiled for some time withalcohol, lost its cryst'alline appearance, and swelled up to a viscid,indiarubber-like mass.After removing the alcohol, however, thesubstance quickly became brittle again, and appeared gradually tobreak up into a microcrystalline powder on long keeping. Thisbehaviour was also noticed with all the previously-described pre-parations of diphenylene p-disulphoxide, and also with the sub-stituted derivatives subsequently mentioned.The substance, which was then almsst pure, was further sub-mitted to two different methods of purification.(i) A portion was boiled with toluene under reflux for some time,and was then collected and dried at 130° for some hours to removeadsorbed solvent and moisture, which was otherwise retained remark-ably firmly. Diphenylene p-disulphoxide, as thus prepared, is acream-coloured Eowder, practically insoluble in all the organicsolvents tried (even in boiling nitrobenzene or aniline), but dis-solving with a greenish-black# colour in concentrated sulphuric acid.It commenced to soften and decompose without actually melting at305O :Calc., C = 58.07 ; R = 3-23 per cent.)Calc., C = 57.60 ; H = 4.00 per cent.2588 HILDITOH : ‘I’HE INTERMOLECULAR CONDESSATION OF0.1035 gave 0.2194 CO, and 0.0298 H20.(ii) The remainder of the preparation was boiled with water for0.1353 gave 0.2685 CO, and 0.0485 H,O.C =54*12; H=3*98.0.1292 ,, 0’2540 CO, ,, 0.0401 H20. C=53.60; H=3*45.C,,H80,S,,H,0 requires C = 54.13 ; H = 3-76 per cent.An at,tempt was made to remove this molecule of water by pro-longed boiling with xylene, but a subsequent analysis showed thatthe composition of the product had not been altered. (Found,C = 53-34 ; H = 3.53.)Water thus firmly attached is inconsistent with the presence ofwater of crystallisation, and it can only be surmised that some suchhydrate formation as the following had taken place:C =57-81; H = 3-17.C,,H,O,S, requires C = 58-07 ; H = 3-23 per cent.two hours, and then collected and dried at 130° as above:,\so- /\ /Oxidation of DiphenyZene p-Disdphoxide.Two grams of diphenylene p-disulphoxide were boiled for eighthours with a slight excess of anhydrous chromic acid in glacial aceticacid; oxidation ensued, and the hot reaction mixture was filtered,and the residue washed with boiling water until all traces of greenchromium salts were removed, and then with boiling alcohol; anamorphous, white powder, which neither melted nor changed inappearance below 350°, was left.A sample dried in a vacuumdesiccator was analysed :0.0994 gave 0.1693 CO, and 0.0362 H,O. C = 46.45 ; H = 4.05.0.1380 ,, 0.2343 CO, ,, 0.0422 HiO. C=46*30; H=3*40.C,,H,0,S2,2H20 requires C = 45.57 ; H = 3-80 per cent.Redaction of Diphenylene p-Bisulphoxide.(a) Two grams of hydrated dioxide were heated for eight hourswith 5 grams of sulphur at 150O; this process reduces the orthedisulphoxide to the corresponding disulphide (Krafft and Lyons,Zoc.cit.), but on removal of excess of sulphur by means of carbondisulphide, the para-disulphoxide was found to have been un-attacked.( b ) Three grams of the dioxide were heated under pressure at160-180O with 1 gram of red phosphorus and 10 C.C. of hydriodicacid (D 1.7). Considerable pressure was generated, and the productwas poured into wat,er and extracted with benzene. A large proAROMATIC SULPHINIC ACIDS. PART I. 2589portion of insoluble matter was removed by filtration of the wholeof the liquid, and the benzene layer was then dried and evaporated.It yielded a small amount of an oil, which soon crystallised, and,when purified by light petroleum, melted at 61O; analysis confirmedthe supposition that this was diphenyl disulphide.(Found,C = 66-01 ; H = 5.01.An attempt made t o purify the insoluble product, which wasassumed to be diphenylene p-disulphide, by sublimation, led to theevolution of iodine vapotns, and further experiments showed thatthe substance contained chemically bound iodine in quantity.Analysis proved that one atlorn of iodine was present in eachdiphenylene pdisulphide residue, but as the compound was not thedesired parent substance it was not further studied; it is probablyeither an iododiphenylene p-disulphide or else a compound of thetype HS°C6H*oS*C6H,I, formed by rupture of the para-ring system :@12H7S21 requires C = 42.1 1 ; H = 2-05 per cent.Calc., C = 66-06 ; H ~ 4 ' 6 0 per cent.)0.1800 gave 0.2750 (20, and 0.0516 H,O.C=41.68; H=3.18.C&E&@,I ,, C=41.86; H=2*62 ,,Proof of the Constitution of Diphenylene p-Disulphoxide.Six grams of the disulphoxide were ground in a. mortar with 30grams of phosphorus pent>achloride, and heated in sealed tubes at220° for six hours. The contents of the tubes were poured on ice,and subsequently extracted with ether; this extract was dried, $heether evaporated, and the residue distilled in a current of steam.The aqueous distillate contained an oil which quickly solidified to amass of white needles, melting at 53O, and possessing the character-istic odour of pdichlorobenzene. (Found, C = 48-60 ; H = 2-25.Calc., C=48.98; H=2*71 per cent.)Since both 0- and rn-dichlorobenzene are liquids, the identity ofthe product was considered to be satisfactorily established.The non-volatile portion of the product was extracted with etherand shaken with di1ut.e sodium hydroxide; on evaporation of thedried ethereal solution, wax-like and not very well-defined crystalsseparated, melting at 131-1 33c ; benzene-o-disulphonyl chloridemelts at 1 0 5 O ; the mcompound at; 63O; and the p-compound at132O.Calc., C = 26.18 ; H = 1.46 percent.)The compound was further characterised by conversion into thesparingly soluble diamide, which formed small, hard prisms, andmelted at 295O. The ortho-compound melts at 233O, the meta at228O, and the para at 288O. (Found, C=29-92; H=3-89. Calc.,C = 30.51 ; H = 3.39 per cent,.)(Found, C = 26.70 ; H = 1.262590 HILDlTCH : THE INTERMOLECULAR CONDENSATION OFCondensation of Pheryl Mercaptan ilz Cold Concentrated SulphuricAcid.Five grams of phenyl mercaptan were dissolved in concentratedsulphuric acid st the ordinary temperature, and the mixturevigorously shaken to dissolve the crystalline cake of diphenyldisulphide, which rapidly formed.After twenty-four hours, thedeep purple-black reaction mixture was poured into a large bulk ofcold water, the precipitate collected, dried, and extracted suc-cessively with boiling light petroleum and with hot alcohol. Theabsence of any solid on evaporation of the former solvent provedthat no disulphide was left unattacked, whilst from the alcoholicfiltrates a quantity of colourless, crystalline material was recovered,which, after further purification from alcohol, melted at 156-159O.A sample mixed with some pure diphenylene o-disulphide possessedthe same melting point.About a gram of diphenylene o-disulphide,dissolving in concentrated sulphuric acid to a characteristic deeppurple solution, was thus obtained. (Found, C = 66.66 ; H = 4.54.Calc., C = 66.67 ; H = 3-70 per cent.)About 3 grams of a cream-coloured, amorphous powder, insolublein boiling alcohol, were left from the above extraction, and this wasboiled with acetic acid for an hour, collected, and dried at 130O.(Found, C = 67.04 ; H = 3.88.Genvresse (Zoc. cit.) states that diphenylene p-disulphide can bepurified by sublimation ; the sample under consideration was sub-mitted to purification by this means, but did not sublime sufficientlyreadily for any quantity of the purified substance to be so isolated;enough was obtained, however, in minute, white needles for adetermination of the melting point; the compound melted anddecomposed at 290-295' (295O, Genvresse).Its solution in con-cen trated sulphuric acid was of a greenish-black hue.Calc., C = 66.67 ; H = 3-70 per cent.)Condensation of Other Aromatic Sulphinic A cids in ColdConcentrated Sulphuric Acid.(a) p-ToZzcenesuZphkvk A &.-The sulphinyl chloride. on solutionin sulphuric acid, evolved hydrogen chloride copiously, and gave agreenish-brown solution, which ultimately became deep purple. Onpouring into cold water, no p-disulphide compound was obtained,and only a very small amount of disulphoxide, which melted at 76O.A similar result was obtained from the condensation of the freeacid.( b ) p-Phemetolesulphinic ,4 cid.-The acid was dissolved insulphuric acid in the usual manner, and the purple reaction mixturepoured into water after a considerable time. The only insolublAROMATIC SULPHINIC ACIDS.PART I. 2591product was a quantity of di-p-phenetole disulphoxide, which meltedat 139O (a sample of the disulphoxide prepared in the usual wayfrom p-phenetolesulphinic acid melted at the same temperature).( c ) P-Napht halenesulphinic A cid.-The condensation was con-ducted as usual ; the products of the reaction were all soluble in colddilute acid, the solution being very deeply coloured. Neitherderivatives of a p-disulphide nor any disulphoxide could be detected.(d) o-Toluenesulphinic ,4 cid.-On separation of the products ofcondensation in sulphuric acid of 5 grams of o-toluenesulphinicacid, it was found that rather more disulphoxide derivative hadbeen produced than in the other cases.The di-o-tolyl disulphoxidecrystallised from acetone in short, colourless prisms, melting at97--98O. (Found, C = 60.09 ; H = 5-06. Calc., C = 60.45 ; H = 6.04per cent.)On the other hand, only about 20 per cent. of the sulphinic acidwas converted into p-disulphide derivative in this instance ; theditolyl erne p-disulphozide was a soft, colourless, insoluble powder,which softened, without actually melting, at 280° :0.0909 gave 0.2004 CO, and 0.0375 H,O.C,,H,,O,S, requires C = 60.87 ; H = 4.35 per cent.(e) a-Naphthalenesulphinic A cid.-The amount of .di-a-naphthyldisulphoxide obtained from the condensation was very small; itmelted at 104O. A tolerably large proportion of insoluble matterresulted, but was contaminated by the presence of traces of dark-coloured products, even after prolonged boiling with various solvents.The probably still somewhat impure dinaphthylene p-disulphoxidefinally analysed softened at 275-280°, and commenced to char ata rather higher temperature :C = 60.12 ; H = 4.58.0.1902 gave 0.4760 CO, and 0.0730 H,O.C20H,,02S2 requires C = 68.98 ; H = 3.45 per cent.( f ) o-CarborcybenzenesuZpDh~nZc A cid.-A sample of this acid wasalso submitted to the condensation in concentrated sulphuric acid.The dried product of the reaction was completely soluble in hotalcohol, no pdisulphide compounds having therefore been produced.From the alcoholic solution, pa10 yellow crystals of di-o-car boxy-phenyl disulphoxide, melting at 228O, separated ; the total amountof this product corresponded with about 10 per cent. of the originalsulphinic acid employed :C = 68-26 ; H =4-26.0.1546 gave 0.2808 CO, and 0.0444 H,O. C =49.52 ; H =3*20.C,,H,,O,S, requires C = 49.71 ; H = 2.96 per cent.THE ORGANIC CHEMlSTRY LABORATORY,UNIVERSITY COLLECIE, UNIVERSITY OF LONDON

ISSN:0368-1645    

DOI:10.1039/CT9109702579

出版商:RSC    

年代:1910

数据来源: RSC