摘要:

WORLEY: THE SURFACE TENSION OF MIXTURES. PART 11. 273XXX.-The Surface Tension of Mixtures. Part 11.Mixtures of Perfectly Miscible Liquids and theRelation. between Their Surface Tensions andVapour Pressures.By RALPH PALLISER WORLEP.THERE is an obvious although not very simple relationship betweenthe vapour pressure and the surface tension of a pure liquid, andlikewise of a mixture of liquids. In the case of the latter theseproperties can be made to vary by altering the proportions ofthe constituent liquids, and it seemed to be of interest t o learnwhether in mixtures of liquids deviations from a general lawgoverning the vapour pressures were accompanied by correspondingdeviatiom in the case of surface tensions.I n spite of the fact that the surface tensions of a considerablenumber of mixtures have already been determined, the surfacetensions and the vapour pressures have not been investigated forthe same mixtures, and it was therefore impossible to draw anyconclusions from the work of others.Such being the case, it was decided to find the surface tensionsof mixtures of the following three pairs of liquids, since theirvapour-pressure curves, determined by Zawidski (Zeitsch.physikal.Chem., 1900, 35, 129), belong to three characteristic and verydifferent types.1. Benzene arbd Ethylene Dich1oride.-The vapour pressure-composition curve corresponds with the theoretical straight line.2. Acetoge and Carbon Disu1phide.-In this case the vapourpressure-composition curve lies above the theoretical straight line,and passes through a maximum value.3.Pyridine and Acetic Acid.-In this case the vapour pressure-composition curve lies below the theoretical straight line, andpasses through a minimum.Various formuh have been proposed to express the surfacetension of a mixture in terms of the surface tension of the com-ponents, but experiment has shown that none is of universalapplication. According to Volkmann (Ann. Phys. Chem., 1882,[iii], 16, 320), the surface tension of a binary mixture is repre-sented by the formula S= V,S, + V,S,, where V , and Vz are thevolumes of the liquids in the mixture expressed fractionally, andS , and 8, their surface tensions when unmixed.Whatmough (Zeitsch. phtysikal. Chem., 1902, 39, 158) modifiedthis formula to take into account the change in volume which takesVOL.cv. 274 WORLEY: THE SURFACE TENSION OF MIXTURES. PART 11.place on mixing, and proposed the following : S = R ( YIS, + V2S,),R being the ratio of the calculated to the observed density. It wasfound that the observed values of only a few mixtures agreed withthose calculated, the majority being too small, whilst in some casesthe curve passed through a minimum value. I n two or three caseslle attempted t o show that a relation existed between surfacetension and relative compressibility. I n the other cases no attemptwas made to account for the divergence between observed andcalculated results, nor were the surface tensions compared withother physical properties of the mixtures.It is to be noted that the admixture rule for finding the vapourpressure of a mixture deals with molecular proportions, whilst thatfor surface tension deals with volumes. The mixtures experimentedon were therefore made up by volume, and not either by weightor molecular proportions, either of which ways would seem a t firstglance to be superior.The surface tensions were determined in exactly the same manneras that employed in the previous paper, and the symbols in thetables have the same significance.The densities are referred t owater at 4O.1.-Benzene and Ethyleize Dichloride.The benzene was treated with concentrated sulphuric acid inthe cold and then distilled, the whole passing over between 7 9 Oand 80°, and the portion used between 7 9 O and 79.5O.The ethylene dichloride was treated with potassium hydroxide,and then with sulphuric acid, and the portion used distilled between84O and 84.5OThe surface tensions of the pure liquids were first determinedover a range of temperatures, and three mixtures were made upof different proportions, and the surf ace tensions likewise f ~ u n d .The results are contained in tsbular form below.t.14"4570TABLE I .S u r f a c e T e n s i o n of B e n z e n e .T (em.).tl. h (em.).0 -0 1528 0.8854 4.3110.01528 0.8545 3.8610 -01528 0.8300 3'474TABLE 11.Sqr face Tensiou of Ethyle?te DdcA lo r i d e .12.5" 0.01528 1'2579 3.38543 0-01528 1-2184 3.0555.28.60624 '72521 '60731.91427.88WORLEY: THE SURFACE TENSION OF MIXTURES.PART 11. 275TABLE 111.Benzene (30 c.c.) and Ethylene Dichloride (20 c.c.).14.5" 0.01528 1.0297 3.807 29.32245 0'01528 0.9975 3-428 25'62770 0'01528 0.9695 3.119 22 $25t. r (cm.). d. h (em.). s.TABLE IV.Benzene (20 c.c.) and Ethylene Dichloride (30 c.c.).15" 0 -01 528 1.1055 3.614 29'94441 0.01528 1.0730 3.324 26.73058 0-01528 1-0515 3'124 24.620TABLE V.Benzene (40 c.c.) and Ethylene Dichloride (10 c.c.).14" 0.01528 0'9605 4.030 28 '94250 0 *O 1528 0.9268 3'547 24.634The results contained in the above tables were first plottedgraphically, and from the curves formed the following table con-taining the data f o r surface tension and composition a t 20° and50° was compiled. The calculated results were obtained by meansof the admixture rule mentioned above.TABLE VI.Surface Tension of Mi.n:tures of Benzene and Ethylene Dichloride.Vol. per cent., c A 5 / \C,H,Cl,.Observed. Calculated. Observed. CaI cula ted.0 30.90 - 26'92 -40 29-30 29'68 25-73 25-7360 28'60 30.25 25-10 25-1480 28'1 8 28.42 24-60 24-60S a t 20". S a t 50".h100 27.80 I 24.00 -The curves obtained by plotting these numbers are shown inFig. 1. It will be seen that a t 50° the observed and the calculatedvalues agree very well, whilst a t 20° the observed values are slightlyless than those calculated. Now reference to Zawidski's paper(loc. cit.) shows that a t 50° the observed values of the vapourpressures of mixtures of these two liquids agree absolutely withthose calculated from the admixture rule.As far as can be judgedfrom these two liquids, therefore, there is close agreement in theproperties of surface tension and vapour pressure of mixtures, inthat the laws as regards each are obeyed.T 2'76 WORLEY: THE SURFACE TENSION OF MIXTURES. PART 11.2 . 4 a r b o n Ddsulphide and Acetone.The carbon disulphide was treated with concentrated sulphuricacid and then distilled, the whole passing over at 46'5O.The acetone was dried over calcium chloride and distilled, theportion used passing over between 5 6 O and 56.5O.The surface tensions of both the pure liquids and mixtures ofthe two in varying proportions a t different temperatures are con-tained in the tables followingto.14"28.544FIU. 1. 11 I I I0 20 40 60 so .- 10:Ethylene diddoride. 170l. p w cent. Benmze.TABLE VII.Surface Tension of Carbon Disulphide.r (cm.). d. h (cm.). S.0.01528 1.2716 3'358 332.0210'01528 1.2521 3.196 29.9710.01528 1 -2292 3-012 27.746TABLE VIII.Surface Tension of Acetone.14-4" 0 - 01 528 0.7988 3.92555 0.01528 0.7770 3 '63053 0.01528 0-7563 3'32523.46921-13918 -84WORLEY: THE SURFACE TLNSION O F MIXTURES. PART IJ. 2'7'7to.16"38TABLE I X .Carbon Disulphide (40 c.c.) and Acetone (10 c.c.).r (cm.). d. h (cm.). S.0'01528 1-1649 3.063 26.7380.01528 1.1320 2.826 24 *542TABLE X.Carbon Disulphide (35 c.c.) andl Acetone (29 c.c.).15" 0.01528 1.0419 3.195 24'94829.5 0.01528 1 *0230 3-033 23 -25439 0.01528 1'0124 2.905 22-039TABLE XI.Carbon, Disulphide (10 c.c.) and Acetone (40 c.c.).18" 0.01528 0-8760 3.558 23.35638 0.01528 0'84996 3-290 20.910As in the last case these results were plotted graphically, andthe following table, showing the surface tension and composition a tloo and 35O, was compiled from the curves plotted.TABLE XII.Mixtures of carbon Disulphide and Acetone.S at 35". S at 10".Vol.per cent., r h\Acetone. Observed. Calculated. Observed. Calculated.20 27'40 30-85 24-79 2'7.3540 25.50 28.64 22-65 25-3024.31 25'70 21 '28 22.52 80- 28-98 - 0 32.55- 100 24 '00 - 21 -00These results are shown graphically in Fig. 2. At both tem-peratures the observed values are considerably below those calculated(shown by dotted line in diagram). Now, according to Zawidski,the vapour pressures of mixtures of these two liquids are muchgreater than those calculated, the curve, instead of being a straightline, passing through a maximum.It appears therefore that whenthe vapour-pressure curve of a mixture diverges from the theoreticalstraight line in one direction, the surfacetension curve diverges inthe opposite direction.3.-Pyridine and Acetic Acid.The pyridine was obtained from commercial pyridine by frac-tional distillation, the portion kept for use passing over betwee278 WORLEY: THE SURFACE TENSION OF MIXTURES. PART 11.1 1 2 O and 1 1 8 O .that Zawidski stated the same of the sample used by him.It was therefore not pure, but it may be notedThe acetic acid distilled between 1 1 7 . 5 O and 1 1 8 O .TABLE XIII.Surface Tension of Pyrid,iue.13" 0.01528 0-9882 5.13249 0,01528 C-9545 4.60480 0.01528 0.9062 4.1720 T (em.).d. h (cm.).TABLE XIV.Surface Tension of Acetic Acid.14.5" 0 -0 1 528 1.0553 3'43952 0.01528 1.0162 3'10175 0-01528 0.9913 2.869S.38.00032.93528'33427.19523-61821-30WORLEY: THE SURFACE TENSION OF MIXTURES. PART 11. 2791".17"5276TABLE XV.1'ydin.e (37.5 c.c.) a d A c e t i c Acid (12.5 c.c.).r (em.). d. h (em.). S.0.01528 1.0175 4.765 36.3340-01528 0.9860 4 '332 32.0060 *O 1 528 0.9595 4.012 28.848TABLE XVI.P y r i d i n e (27 c.c.) alzd A c e t i c A c i d (23 c.c.).12" 0-01528 1 -0585 4-485 36'57747 0*01528 1 *0265 4.145 31.88675 0.01528 0.9975 3'850 28-780TABLE XVII.P y r i d i n e (15 c.c.) and A c e t i c A c i d (35 c.c.).14" 0.01528 1.0871 4.084 33.28149 0.01528 1.0537 3.779 29.82675 0-01525 1'0230 3.554 27 '247As in the previous cases these results were plotted graphically,and from the curves drawn the following table was compiled.TABLE XVIII.Mixtures of P y r i d i n e and A c e t i c *4cid.S at 40".S at 80".Vol. per cent., V- r A bC,H,02. Observed. Calculated. Observed. Calculated.0 34.30 - 28.32 -25 33'59 31.85 25-32 26'4546 32-65 29 *85 28-00 24-8230'63 27-40 26-79 23'00 70100 24'73 - 20 -80 -These results are plotted graphically in Fig. 3. I n this case theobserved values are much greater than those calculated, and thecurves tend to pass through a maximum value. Reference t o thepaper of Zawidski mentioned above shows that mixtures of pyridineand acetic acid form a minimum vapour-pressure curve a t 80'05O.This case is exactly the opposite of the previous one, and appearsto verify the contention that the properties of surface tension andvapour pressure of mixtures vary in opposite directions.As had been anticipated, the above results show that a markedrelationship does exist between the surface tensions and vapourpressures of mixed liquids.The relationship may be summarisedin the three following rules280 WORLEY: THE SURFACE TENSION OF MIXTUREF. PART 11.(i) I f a t any given temperature the vapour pressures of mixturesof two liquids agree with the values calculated by the rule ofadmixture in molecular proportions, then a t that temperature thesurface tensions of the mixtures agree with those calculated bythe formula S = V,S, + V2S2.(ii) If the vapour pressures are greater than those calculated,then the surface lensions are less than those calculated.1 I I I I I0 20 40 60 80 100Pyridbc.Yo,?. per ceibt. Acetic acid.(iii) I f the vapour pressures are less than those calculated, thenthe surface tensions are greater than those calculated.It had been intended to investigate mixtures of benzene andcarbon tetrachloride, since the vapour-pressure curve lies only alitt.le above the theoretical straight line (Zawidski), The surfacWORLEY: THE SURFACE TENSION OF MIXTURES. PART 11. 281tensions of mixtures of these two liquids were, i t was found, deter-mined by Ramsay and Aston (Zeitsch.physikal. Chem., 1894, 15,92), who showed that the observed values were a little below thecalculated values. It follows therefore that mixtures of these twoliquids behave in accordance with the above rules. So also domixtures of ether and carbon disulphide, which form a maximumvapour-pressure curve (Guthrie, Phil. Mag., 1883, [v], 18, 513),and tend to form a minimum surface-tension curve (Whatmough,The case of mixtures of the alcohols with water is very instruc-tive, and offers further proof of the validity of the foregoing rules.The vapour pressures of mixtures of these in all proportions werefound by Konovalov (Ann. Phys. Chem., 1881, [iii], 14, 34). Withincreasing molecular weight of the alcohol, the vapour-pressurecurves rise higher and higher above the straight line, and in thecase of both propyl and isobutyl alcohols the curves pass through amaximum value.The greatest differences between observed andcalculated values, a t the temperature when the vapour pressure ofeach pure alcohol is 400 mm., are roughly as follows :blethyl alcoliol and water.. ..................112 9 , Ethyl ,, ,) ....................Propyl ,, ,, .................... 203 ,,GoButyl ,, ,, 315 2 9loc. c i t . ) .43 m u ......................The surface tensions of mixtures of the same liquids and waterwere determined by Duclaux.With increasing molecular weight of the alcohol the surfacetension-composition curves fall more and more below the theoreticalstraight lines.The maximum differences are roughly :Me hyl alcohol and water ................... 14 degrees..................... Ethyl ,, 9 , 21 ,,iyoPropy1 ,, 3 , 26 , IisoButyl ,, , , ..................... 41 , I.....................These mixtures therefore show a striking agreement with therules laid down, and show, moreover, that the greater the divergenceof the vapour-pressure curve from the theoretical straight line, thegreater is the divergence of the surfacetension curve, but in theopposite direction.It may be noted in passing that no difference is to be drawnbetween mixtures the surface tensions of which diverge from thetheoretical straight line and those the surface tensions of whichform either a maximum or minimum as the case may be, these beingformed only when the surface tensions of the pure liquids happento be near together.This greatly simplifies the classification ofmixtures proposed by Whatmough. It Beema also, that mixturesVOL. cv. L282 CURTIS AND KENNER:may obey the admixture rule at one temperature, and not at others,as in the case of benzene and ethylene dichloride.Finally, it appears that the relationship between surf ace tensionsand vapour pressures of mixtures holds good also f o r solutions ofsolids in liquids. All salts increase the surface tension and decreasethe vapour pressure of liquids. An experiment made by the authorwith solutions of sulphur in carbon disulphide gave the followingresults. G is the number of grams of sulphur dissolved in 100 C.C.of the liquid, and S is the surface tension a t 31O:Q. S.0 29.60010 30 505G. S.20 31-18230 31.593The surface tension is noticeably increased. This fact points tothe relationship holding good for all mixtures.It may be remarked, also, that thc vapour pressures of solutionsof aniline, phenol, and isobutyl alcohol in water are considerablygreater than that of water, and therefore much above the theoreti-cal values, whilst their surface tensions were shown in a previouspaper to be greatly below the theoretical values. Moreover,Eonovalov (Zoc. cib.) found that the ratio between the observed andcalculated vapour pressures of a saturated solution of isobutylalcohol in water diminished but slightly between Oo and 80°, aresult in accordance with the rate of change of surface tension withtemperature of that solution. The vapour pressures of aqueoussolutions of aniline and phenol over a range of temperatures havenot yet been found, but from results from measurement of the fateof change of surface tension, i t is probable that the ratio of theobserved to the calculated vapour pressure would diminish rapidlywith rise of temperature.UNIVERSITY COLLEGE,AUCKLAND, N. Z

ISSN:0368-1645    

DOI:10.1039/CT9140500273

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

282 CURTIS AND KENNER:XXXI. -The Condensation of Ethyl Glutaeonate.By RAYMOND CURTIS and JAMES EENNER.THE formation of act- and of ay-dirnethyl glutaconates by the directmethylation of ethyl glutaconate (Henrich, Mormtsh., 1899, 20,539; Blaise, Compt. r e d . , 1903, 136, 639) suggested to us thepossibility that by the interaction of ethylene dibromide and ethylglutaconate in the presence of sodium ethoxide, either a cyclo-propane (I) or a cyclopentene (111) derivative, or both of thesemight be obtained. After our experiments in this direction hadbeen completed, we discovered that Fecht (Ber., 1907, 40, 3883THE COSDEKSATION OF ETHYL GLUTACONATE. 283had previously studied this reaction, and embodied his results in apaper, the title of which would not suggest that such experimentsmight be described in it.This author obtained evidence of theformation of the cyclopropane derivative (I) by isolating the esterof its reduction product (IT) :7H2 C0,Et + CH2>C<CH2*CH2*C02Et;(11.1CH,.QH*CO,EtCHq'C*CO,Et(111.)I EHNo other compound is mentioned, although i t is evident fromthe account given, as well as from a consideration of the experi-ments now described, and of those of Blaise (Zoc. c i t . ) on thealkylation of ethyl glutaconate, that only a very small amount ofcyclopropane derivative could have been formed; the fate of themajor portion of the ethyl glutaconate theref ore remained unknown.The experiments carried out in the present instance furnished awhite, crystalline solid, and some oily matter (10 per cent.of theyield). The latter, although formed in such small amount, wasprobably similar in its nature to the product obtained by Fecht,and has not yet been further investigated. The crystalline com-pound gave a blue colour with ferric chloride, and had acidicproperties (equivalent = 316). This, together with its composition,pointed to its production from two molecules of ethyl glutaconate(mol. wt. = 186) by the elimination of the elements of one moleculeof alcohol, the ethylene dibromide having taken no part in thereaction.It was then found that the properties of two condensationproducts of ethyl glutaconate, which had already been described,were in agreement with those of the compound isolated by us.On the one hand, Blaise (loc.cit., Bull. SOC. chim., 1903, [iv],29, lola), by heating an alcoholic solution of ethyl glutaconatewith sodium ethoxide a t looo, isolated it compound to which heassigned the constitution of ethyl glutaconylglutaconate (IV) :QH2*CH :CH*CO,Et ---+ SH,*CO,Et + CH:C H*C02Et C0,Et$?H,--CO---$!H*CH:CH*CO,EtCH :CH*CO,Et C0,Et(IV.)On the other hand, Pechmann, Bauer, and Obermiller (Ber.,1904, 37, 2113) showed that ethyl glutaconate undergoes con-u 284 CURTIS AND KENNER:densation when its ethereal solution is heated with sodium ethoxide.From analogy to Pechmann'~ work on the formation of ethyla-methyleneglutarate from ethyl acrylate under similar conditions,the reaction in the case of ethyl glutaconate was expressed in thefollowing manner :70,Et 70,EtQHz 70,Et 7H2 yO,EtGH + GH + FH-E +YH p a yHqo,I!:t ?O,Etp 2 7%CO-CH*CO, Et co-bH,C0,Et CH,*CO,Et c.'" CH,.C0,Et C0,Et$!H--E.CO,Et or 7H-q. C0,Etp 2 p EtO,C*QH CHVn.) (Vb. )This view as to the course of the reaction received confirmationfrom the oxidation of the compound with bromine and the ultimateconversion of the product into l-hydroxy-2 : 4-dicarboxyphenyl-acetic acid, but no decision could be reached as to which of thealternative formulae (Va and Vb) represented the original condensa-tion product.In spite of some discrepancies between the accounts given of thesetwo products, it appeared to us highly probable that they wereidentical with each other and with our product. A repetition ofthe experiments described by Blaise and by Pechmann, respectively,was therefore undertaken in order to decide this point, and toexamine the outstanding differences.It was found that all three substances were identical, for they(1) melted a t very approximately the same temperature,* and noneof the compounds depressed the melting points of the others;(2) were converted into the same benzene derivative by oxidationwith bromine; and (3) furnished the same condensation productwith phenylhydrazine.Further, the condensation takes place inaccordance with the view of Pechmann and his co-workers, and the* The slight differences in melting point are due t o traces of other products whichare difficult to remove. Thus, if a hydrogeii atom should migrate from eachmolecule of ethyl glutaconate to the other, in the manner represented byPechmann, a cyclobutane derivative would result, aud this appears to be the caseunder certain conditions (compare Pechmann, Ber., 1899, 32, 2301 ; Gutzeit, Ber.,1901, 34, 678).Further, Blaise showed that during the methylation of ethylglutaconate, a portion of the ethyl " glutaconylglutaconate " also underwentmethylationTHE CON DENSATlON OF ETHYL GLUTACONATE. 285compound in question was the chief product in the attemptedcondensation of ethyl glutaconate with ethylene dibromide.Of the two possible formule (Va and Vb), the latter, whichrepresents (in its enolic form) ethyl 2 : 6-dicarbethoxy-A2:~-cyclo-hexadien-5-oZ-luceta~te, appears to us the more probable, for thefollowing reason.The intermediate compound, being a derivativeof ethyl glutaconate, will form a sodium salt, from which theformation of a condensation product would be expected to takeplace in the following manner :yH,-CO,'Et 7 H,*CO,E tf: H-E*CO,E t $! H *$*CO,EtEtO,C*CH, YH --3 EtO,C*QH QHCO-CH, NaO (E t 0) C : C HAccepting this inference, the nomenclature and formule of thevarious derivatives prepared from the condensation product byPechmann and his workers (Zoc. cit.) require to be amended accord-ingly.Pechmann and his collaborztors were unable to prepare a con-densation product of the compound with phenylhydrazine, whilstBlaise was undecided as to whether the derivative isolated by himwas a hydrazone (VI) or a pyrazolone (VII).It has now beenfound that the latter formula is disproved by the inability of thecompound to enter into salt-formation, and that it is to be lookedon rather tics a hydrazide (VIII) than as a hydrazone, for it iseasily oxidised in alcoholic solution by mercuric oxide to a redazo-compound.?El2* CO,E 5CHyH,*CO,EtCH/\\/f! 0-YH g*CO,EtC'H,/\\/(TI.)EtO,C*yH G-CO,EtC,H,*NH*N:C CH C,H,*N-N:C CH(VII.)OH,$!H,*CO,EtCHEt02C*lc;( G*CO,Et/\vCH2C6FiZ,*NH*NH*C CR(VIII.)We found, however, that a pyrazokone derivative was a t onceproduced by the action of hydrazine hydrate on the condensatio286 CURTIS AND KENNER:product ; the carbethoxy-groups were also attacked, so that theresulting compound had the structure IX or X :$lH,*CO*NH*NH, YH,*CO*NH*NH,CH CH/\ /\ $lO--FH g*CO*NIF*NH, yO---E i;‘*CO*NH*NH,NH-N:C CH NH*NH*C CHBy hydrolysis with dilute mineral acid, as described by Blaise,the original condensation product furnished a monobasic acid,C8HI2O4, from which a lactone could be obtained.Although Blaisewas unable to ascribe a constitutional formula to the product, itis evident that its oxidisability by bromine and its easy lactonisationfind expression in the formula of a cyclohexanone derivative (XI) :~E€,-CO,E;t 7 H ,*CO,H FH2*C02HCH CH/\\/EtO,C*Yt-I R*C02Et --+ HO,C*$!H 5!(0€1)*CO,H -+- YH, YH*OHCO CH, I GH2 ; CH,/\\/CH,CO CHc H2(XI. 1From a coi~sideratiou of Pechmann’s explanation of the con-densation of ethyl glutaconate, it seemed probable that a similarcondensation could occur to ethyl a-ethyl glutaconate, but not toethyl ay-diethylglutaconate, whilst the view advocated by Blaisewould permit of both condensations. It was found, however, that,unlike ethyl glutaconate, its a-ethyl derivative did not undergocondensation under either of the conditions employed by Pechmannand by Blaise.An explanation of the difference between ethylglutaconate and its a-substituted derivative may be based on theviews expressed by Bischoff as a result of his researches on chainformation, for i t will be evident that if two molecules of ethyla-ethylglutaconate condense in the manner above suggested, therewill be a much larger number of groups in Bischoff’s critical 1 : 5-and 1 : 6-positions than in the case of ethyl glutaconate itself.Weprefer, however, to place another interpretation on this result;thus, ethyl glutaconate takes part in the initial polymerisation inthe form of its sodium salt, the constitution of which is expressedby the formula XI1 :CO,Et*CH:CH=CH:C(ONa)*OEt( S I I . )CO,Et*OEt:CH*CH:C(ONa)*OEt.(XI 11.THE CONDENSATIOK OF ETHYL GLUTACOKATE. 287I n this formula the hydrogen atom which migrates during theinitial polymeri6ation is shown in heavy type, and it appears prob-able that polymerisation would not take place if this atom werereplaced by an ethyl group, its shown in XIII. If, however, wetherefore adopt this formula for the sodium salt of the ethyla-ethylglutaconate in question, i t follows that the salt-formationtakes place in the carbethoxy-group of this ester remote from theethyl group, a deduction which is in harmony with the conclusionarrived a t by Thorpe and Wood (T., 1913, 103, 1754) on othergrounds.Nevertheless, it is worthy of note that the hydrogen atom, themobility of which is responsible for the polymerisation, is differentfrom the mobile hydrogen atom of ethyl glutaconate, with whichthe recent work of Thorpe and his collaborators has been con-cerned.Pechmann’s reaction is, however, exactly analogous to thereaction by which ethyl sodiocyanoacetate condenses with ab-un-saturated esters, as is evident from the equation representing thisreaction* (Thorpe, T., 1900, 77, 932):CO,Et*GH:CHR + CO,Et*CH:C(ONa)*OEt=CO,Et*CH,*CHR*C( C0,Et) :C( ONa) *OEt .It thus appears that a hydrogen atom attached to an ethyleniccarbon atom does possess a certain mobility if a negative group bealso attached t o this atom.This mobility is perhaps less marked inthe case of ethyl glutaconate than in the case of ethyl cyanoacetate,for whereas ethyl sodiomethylcyanoacetate takes part in the reactionjust mentioned, it has already been explained that ethyl aethyl-glutaconate does not polymerise.* It must be observed that this condensation differs essentially from the ordinaryMichael reaction, in which ethyl sodiomalonate is employed, for in the latter case itis the sodium atom, and not the hydrogen ntoin, that migrates. Thus ethyl sodio-methylmalonate nnd ethyl a-methylacrylate ultimately furnish ay-dimethglglutaricacid (hnwers arid Kobner, Ber., 1891, 24, 1927), whereas ethyl sodiomethylcyano-acetate and ethyl &l-dimethylacrylate yield ethyl y-cyano-413-trimethylbutyrate(Thorpe, Zoc. cit.).The contrast between the sodium salts.of ethyl malonate andethyl cyanoacetate thus illustrated is not confined to this reaction (compare Thorpe,Zoc. cit.), and suggests that they differ in constitution. It seems probably that ethyl,OEtsodiomalonate is more adequately represented by the formula CH(C0,Et):C\ON?....................................(compare Hantzsch’s formula for ethyl sodioacetoacetate, Bey., 1910, 43, 3053)288 CUKTlS AND KENNER:EXPERIMENTAL.Interaction of Ethyl Glutaconate, Ethylene Bihromi.de, and SodiumE t h oxid e.Ethylene dibromide (6.3 grams) was added to a mixture of ethylglutaconate* (6.2 grams) with a cold solution of sodium (0.8 gram)in alcohol (12 c.c.).The mixture remained at the ordinary tem-perature for- several hours, and was finally heated f o r four hourson the water-bath. The product, isolated in the usual manner,consisted of an oil, from which crystals quickly separated. Themixture decomposed when the attempt was made t o distil i t underdiminished pressure,? and the separation of the solid from the oilwas therefore accomplished by filtration. By repeated crystallisationfrom methyl alcohol, white needles were obtained, which melted at78'5O :0.1511 gave 0.3255 CO, and 0.0950 H,O. C=58.76; H=7-05.Equivalent = 317.0*1840 required 5.8 C.C. -W/lO-NaOH.C,,H,,O, requires C = 58.89 ; H = 6.7 per cent. Equivalent = 316.The compound was readily soluble in the nsual organic solvents,and in sodium carbonate solution, less so in sodium hydrogencarbonate solution. It gave a Seep blue colour with ferric chloride.The following table shows the results obtained by a comparison ofthe melting point of the compound with those of the productsprepared according to the directions respectively of Blaise and ofPechmann, Bausr, and Obermiller :(1) The above product ........Mixture of (1) and (3) ...............78.5"(2) Blaise's ,, ........ 80-80*5" (Rlaise found 78-79")(3) Pechmann's ,, ......... 78.5-79" (Pechmann found 81-82")76-79.5",, ,, (1) ,, (3) ...............76-77",, ,, (2) ,, (3) ............. 78-79".The three products are therefore identical, and are to be regardedas ethyl 2 : 6-dicarbethosyd2 :hyclohexadier5-ol-l-acetate (see theo-retical part).The copper salt was prepared by shaking an ethereal solution of* Ethyl glntaconate was obtained according to the diredions of Blaise (BztZl. Soc.d i m . , 1903, [iv], 29, 1012) by the elimination of the elements of water from ethyl/3-hydroxyglutarate, the reduction product of acetonedicarboxylic acid. Withregard to the preparation of the latter acid, i t may he of value to emphasise thenecessity of proceeding with its isolation immediately carbon dioxide can bedetected in the gases evolved from the jnteraction of fuming sulphuric acid andcitric acid.This was found to be the case a t a very early stage of the heatingrecommended by Pechmann (Bey., 1884,17, 2543) after the preliminary rcaction hastaken place without the application of external heat.-I This is in agreement with the experience of Fecht (Zoc. cit.)THE CONDENSATION OF ETHYL GLUTACONATE. 289the ester with aqueous copper acetate solution, and remained asa brown powder after the green ethereal solution thus obtainedhad been evaporated. It crystallised from alcohol in flat needles,melting at 145O. The salt was insoluble in water or cold alcohol,moderately so in hot alcohol, and readily so in ether, chloroform,or benzene :0.4668 gave 0.0502 CuO. Cu =8.97.(C?,,H2,0,),Cu requires Cu = 8-91 per cent.The phenylhydrazide resulted when the ester (5 grams) washeated a t looo for fifteen minutes with phenylhydrazine (2 g r a b )and glacial acetic acid (12 drops).The mixture solidified wheni t was stirred with alcohol, and after crystallisation from thissolvent, truncated hexagonal pyramids were obtained, which melteda t 130° (Blaise gives 126-127O).Blaise experienced difficulty in the analysis of this compoundowing to the formation of carbon monoxide, but we were unableto detect this gas by the use of palladium chloride solution in thecourse of the .analyses quoted below, and no diminution in thevolume of nitrogen obtained was observed when it was left incontact with cuprous chloride solution :0.1612 gave 0.3746 CO, and 0.1013 H,O.0.2859The compound was insoluble in alkali, and underwent oxidationwhen its alcoholic solution was warmed with yellow mercuric oxide,a red azo-compound being produced.This behaviour shows thecompound to be a hydrazide and not a hydrazone (compareDieckmann, AnnaZert, 1901, 317, 60).C = 63.37 ; H = 5-66.0.1540 ,, 0.3605 GO2 ,, 0.0924 H20. C=63*85; H=5.94.,, 17.2 C.C. N2 a t 17O and 735 mm. N=6*88.C22H280sN2 requires C = 63.46 ; H = 5.98 ; N T= 6-73 per cent.Tnteraction of Ethyl 2 : 6-Dicarbethoxy-h2 :6-cyclo.hexadie~5-ol-l-acetate and Nydratine Hydrate.The addition of hydrazine hydrate (5 grams) to an alcoholicsolution of the ester (5 grams) caused the gradual separation of awhite compound a t the ordinary temperature, and the reaction wascomplete after a very short time a t looo.After being dried onporous earthenware, the product melted sharply a t 205-206O :0.2049 gave 0.3020 CO, and 0.1143 H,O. C =40.30; H = 6.24.0.0868C10H1403N6,N2H4 requires C = 40.27 ; H = 6-04 ; N = 37.58 per cent.The product was therefore a hydrazine salt of a pyrazolonederivative, C,,H,,O,N,. It was insoluble in alcohol, benzene, or,, 29.2 C.C. N, a t 19O and 729 mm. N=37-79290 THE CONDENSATION OF ETHYL GLUTSCONATE.chloroform, but readily soluble in water, alkali, or dilute acid. Itlost hydrazine only slowly a t looo, being converted into the yellowpyrazolone derivative. A yellowish-white silver salt separated whensilver nitrate was added t o an aqueous solution of the compound,rendered just acid with nitric acid.It was, however, unstable,and gradually underwent decomposition and reduction to a violet,and ultimately t o a black mass.The copper salt, prepared in a similar manner by the use ofcopper acetate, was sufficiently stable t o permit of its analysis:0.3924 gave 0.1164 CuO. Cu=23*7.C,oH,,03N,Cu requires Cu = 23.9 per cent.Hydro1ysi.s of Ethyl 2 : 6-Dicarbethoxy-b2 ~~-cyclohemdien-5-oJ-l-acetate.(1) A specimen of the ester, prepared according to Blaise’sdirections, was treated with potassium hydroxide under the con-ditions described by him. The diethyl ester thus obtained melteda t 110-1 12O (Pechmann gives 11 2-1 1 3 O , Blaise 98-99O). Themonoethyl ester melted and decomposed a t 167O (Pechmann gives157O, Blaise 1 7 8 O ) .(2) A specimen of the ester, prepared according to Pechmann’sdirections, was hydrolysed with 10 per cent. sulphuric acid underthe conditions described by Blaise. The product melted a t 66O,and agreed in its properties with the account given by Blaise.Further, it was oxidised by bromine in chloroform solution.O x i h t i o n of Ethyl 2 ; 6-Dicar6 ethtoxy-A2 ~~-cyclohexudien-5-ol-l-acetate.The ester, prepared according to the directions of Blaise, wastreated with bromine in chloroform solution (Pechmann, Bauer,and Obermiller, Zoc. cit.), whereupon ethyl I-hydroxy-2 : 4-dicarb-ethoxyphenylacetate (m. p. !30-81°) was obtained. It furnished atribasic acid (m. p. 249-250O) on hydrolysis (Pechmann gives250-255O) (Found, C = 49-95 ; H = 3-40. C,,H,07 requires C = 50.00;H=3*33 per cent.).THE UNIVERSITY,SHKFFIELD

ISSN:0368-1645    

DOI:10.1039/CT9140500282

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

FIPU’DLAY AND HOWELL : THE 1NFLUEKCE OF COLLOIDS, ETC. 291XXXI1.-The Influence of Colloids and Fine Suspensionson the Solubility o f Gases in Water. Part I??Solubility of Niti-ous Oxide at Pressures Lowerthan Atmospheric.By ALEXANDER FINDLAY and OWEN RHYS HOWELL (UniversityStudent in Chemistry).IN previous communications have been given the values of thesolubility of carbon dioxide in water in presence of colloids atpremures varying from about 250 up to about 1400 mm. ofmercury; as also the solubility of nitrous oxide under pressuresvarying from 750 to 1400 mm. (T., 1910, 97, 536; 1912, 101,1459; 1913, 103, 636). I n the present communication we completethe series by giving the valaes of the solubility of nitrous oxideunder pressures lower Lhan atmospheric.I n order to be able tocombine these results more satisfactorily with those previouslyobtained by Findlay and Creighton (T., 1910, 97, 536), thesolubility determinations were extended up to pressures of about1000 mm.The apparatus employed and the general method of workingwere as described by Findlay and Williams (T., 1913, 103, 636).The nitrous oxide was prepared by heating carefully purifiedammonium nitrate, as described by Findlay and CreightonSolzc bil it y Bet ermina tions.(a) Water.(loc. c i t . ) .The following values were obtained for the solubility of thenitrous oxide :TABLE I.Solubility of Nitrous Oxide in V a t e r .Pressure ............. 282.5 396.1 562.9 664-5 789.3 1027.5Solubility ........... .0.585 0.585 0.584 0.585 0.585 0.585Pressure .............272.8 393.2 548.6 652.4 751.0 1021-7Solubility ..; ......... 0.585 0.585 0.585 0.585 0.585 0.586As mean value of the solubility, therefore, we obtain 0.585, anumber somewhat lower than that obtained by Geffcken (Zeitsch.physikal. Chem., 1904, 49, 298), namely, 0.5992, o r that obtainedby Findlay and Creighton (Zoc. cit.), 0.592292 FINDLAY AND HOWELL: INFLUENCE OF COLLOIDS, ETC.,(b) Ferric IXycEroxide Solution.The ferric hydroxide solution was prepared by the method ofA. A. Noyes (J. Arner. C?zJem. SOC., 1905, 37, 94). It was freedfrom salts by dialysis, and rendered air-free by boiling underdiminished pressure. The values of the solubility are contained intable I1 (compare Fig. 1).FIG. 1.0.6000,5900'5800.5700.560@ 0'550Y2 0'5400'5300.52005100 '5000'490106250 350 450 550 650 750 850 950 105Presszsre in mm.Hg.Nitrous oxide and ferric hydToxidc (- - -1.Nitrozu oxide and dextrin (-).TABLE 11.Solubility of Nztrous Oxide in Ferric Hydroxide Solutions.Concentration: 0.43 gram of Fe(OH), in 100 C.C. of solution.Density= 1.001.Pressure ............. 291-2 409-1 574.7 648.5 767.5 1029-8Solubility ............ 0-594 0,594 0.591 0.589 0.583 0.580Pressure ............. 279-4 402-1 561.4 668.9 785.9 1043.7Solubility ............ 0.594 0-592 0.591 0-588 0.553 0.580Concentration: 0.92 gram of Fe(OH), in 100 C.C. of solution.Density= 1.003.Pressure ............. 287.0 425.0 571.6 681.4 787-9 1054.6Solubility ............ 0.589 0.587 0.584 0.582 0.578 0.576Pressure .............283.0 408.5 564.6 646.5 776.0 1026-7Solubility ............ 0.590 0.586 0.584 0.582 0.579 0.57ON THE SOLUBILlTY OF GASES IN WATER. P,QRT IV. 293TABLE I1 (conthued).Concentration: 3.82 gram of Fe(OH)3 in 100 C.C. of solution.Density= 1.027.Pressure ............. 256.1 372.9 543.7 633-6 764-8 1014.3Solubility ............ 0-583 0-581 0.580 0.577 0.572 0.568Pressure ............. 247-9 363-3 524.4 646.4 747.9 987-3Solubility ............ 0-583 0.582 0.579 0.576 0.573 0.568(c) Dextm’a.The concentrationof the solutions WSLS determined by evaporating to dryness, andweighing the residue after drying in the steam-oven. The solu-bility values are given in table I11 (compare Fig.1).Kahlbaum’s purest dextrin was employed.TABLE 111.Solubility of Nitrous Oxide i7z Dextrin Solutions.Density= 1.019.Pressure ............. 281.5 407.1 565.1 673.1 819.1 1004-6Solubility ............ 0.557 0.550 0442 0.542 0.547 0.554Concentration: 6.82 grams of dextrin in 100 C.C. of solution.Concentration: 6.70 grams of dextrin in 100 C.C. of solution.Density= 1.019.Pressure ............. 284.3 407-8 560.7 664.7 773.1 980.6Solubility ............ 0.555 0.550 0.544 0.544 0-546 0.554Concentration: 12.41 grams of dextrin in 100 C.C. of solution.Density = 1.037.Pressure ............. 283.8 407.7 574.8 660.5 785.7 985.0Solubility ............ 0.537 0.532 0.526 0.527 0.526 0.534Concentration: 12.50 grams of dextrin in 100 C.C.of solution.Density= 1-037.Pressure ............. 281-6 416.3 577.1 671.7 774.0 971.4Solubility ............ 0.535 0.530 0.526 0.526 0.524 0.532Concentration: 13.24 grams of dextrin in 100 C.C. of solution.Density = 1.060.Pressure ............. 293.0 421.5 598.7 695.5 799-3 997.5Solubility ............ 0.515 0.510 0.504 0.501 0.500 0.50294 FINDLAY AND HOWELL: INFLUENCE OF COLLOIDS, ETC.,TABLE I11 (continued).Concentration: 19.31 grams of dextrin in 100 C.C. of solution.Density = 1.060.Pressure ............. 288.2 413.4 569.2 646.0 777.0 996.2Solubility ............ 0.516 0.510 0.504 0-502 0.500 0.506(d) Starch.Kahlbaum’s pure soluble starch employed for the determina-The solubility values are given in table IV (compare tions.Fig.2).FIG. 2.Nitrous oxide and egg albumen (- - -).Nitrous oxide and starch (-).TABLE IV.Solubility of Nitrous Oxide in. Stmch Solutiom.Concentration: 6-76 grams of starch in 100 C.C. of solution.Density = 1.023.Pressure ............. 285-2 415-0 566.7 657.5 770.3 1054.0Solubility ............ 0.565 0.563 0.560 0.560 0.553 0.550Concentration: 6-70 grams of starch in 100 C.C. of solution.Density = 1.023.Pressure ............. 263.6 370.5 524-7 646.6 750.6 997.5Solubility ............ 0.566 0.563 0.561 0.558 0-554 0.549Concentration: 9.58 grams of starch in 100 C.C. of solution.Density = 1.030.Pressure ............. 267.6 373.7 504.8 627.7 747.1 1024.0Solubility ............ 0.554 0.551 0.549 0.546 0.541 0.53ON THE SOLUBILITY OF GASES IN WATER.PART IV. 295TABLE IV (continued).Density = 1.029.Pressure ............. 290.5 416.5 576.8 659-0 775.8 1003.6Solubility ............ 0.551 0-550 0.548 0.543 0.540 0.537Concentration: 9-40 grams of starch In 100 C.C. of solution.Concentration: 13.62 grams of starch in 100 C.C. of solution.Density = 1.039.Pressure ............. 284-3 418.4 614.8 703.2 843-0Solubility ............ 0.541 0.537 0.535 0.532 0-528Concentration: 13.60 grams of starch in 100 C.C. of solution.Density = 1.039.Pressure ............. 263.8 378.6 496.9 624.0 756.1 973-5Solubility ............ 0-541 0-539 0.536 0-534 0.530 0.525(e) Gelatin.I n these experiments French gelatin, free from salts, wasemployed.TABLE V.Solubility of fiitroits Oxide in Solutions of Gelatin (seealso Fig.3).Density = 1.000.Pressure ............. 256.5 372-2 530.5 623.9 755.0 1009-6Solubility ............ 0.582 0.581 0.577 0.575 0.579 0.581Pressure ............. 260.9 379.4 542.5 646.5 763.4 1032-1Solubility ............ 0-581 0.582 0.575 0.577 0.579 0-579Concentration: 1-45 grams of gelatin in 100 C.C. of solution.Concentration: 3.12 grams of gelatin in 100 C.C. of solution.Density = 1.004.Pressure ............. 251-5 367.3 530.3 632.4 750.7 1000.0Solubility ............ 0.577 0.576 0.568 0.569 0.572 0.576Concentration: 3.16 grams of gelatin in 100 C.C. of solution.Density = 1.004.Pressure ............. 287.8 414.5 569.2 668.5 796.3 1054-0Solubility ............ 0.577 0.574 0.570 0.570 0.572 0.576Concentration: 6.10 grams of gelatin in 100 C.C.of solution.Density = 1.008.Pressure ............. 257.7 381.0 546.4 637-4 762-9 1029.9Solubility ............ 0.556 0.556 0.548 0-546 0.550 0.68296 FINDLAY AND HOWELL INFLUENCE OF COLLOIDS, ETC.,TABLE V (continued).Density = 1.008.Concentration: 6-14 grams of gelatin in 100 C.C. of solution.Pressure ............. 259.0 380.6 546.5 639-8 759.6Solubility ............ 0.556 0.655 0.548 0.646 0.650( f ) Egg-a1 b umen.Commercial egg-albumsn was employed. This was treated withwater, and the solution, after filtration, submitted to dialysis.FIQ. 3.Nilrous oxide and silicic acid (- - -).JVitrous oxide and gelatin (-).TABLE VI.Solubility of Nitrous Oxide in Solutions of Egg-albumen (seealso Fig.2).Concentration: 0.38 gram of egg-albumen in 100 C.C. of solution.Density = 0.998.Pressure ............. 248.7 361.3 530.7 633-7 755.7 996.2Pressure ............. 262-1 370-5 537-3 634.5 733.5 915.0Solubility ............ 0.572 0.573 0.573 0-572 0.571 0-568SOh1bility ............ 0.572 0.573 0.573 0.572 0.570 0.571Concentration: 0.62 gram of egg-albumen in 100 C.C. of solution.Density = 1.000.Pressure ............. 254.1 380.0 453-5 644.5 762.5 1020.5Solubility ............ 0.568 0.569 0.568 0-567 0.565 0.57ON THE SOLURILI'I'Y OF GASES IN WATER. PART IV. 297(9) Silicic a c i d .Pure silica was dissolved in potassium hydroxide solution, andthe, clear solution poured into excess of hydrochloric acid. Themixture was then submitted to dialysis until free from chloride.The concentration is expressed in terms of SiO,TABLE VII.Solubility of Nitrows Oxide in Solutions of Silicic Acid (seealso Fig.3).Concentration: 1.62 grams of SiO, in 100 C.C. of solution.Density = 1.000.Pressure ............. 254.9 369-1 536.8 664.0 764.8 1007.1Pressure ............. 255.1 370.4 537.6 676.0 765.4 1025.6Solubility ............ 0.594 0.591 0.589 0-588 0.588 0.591Solubility ............ 0.590 0.587 0.589 0-589 0.588 0.592Concentration: 3-50 grams of SiO, in 100 C.C. of solution.Density = 1.004.Pressure ............. 250-2 375.2 546.5 687.5 758.7 1033.7Solubility ............ 0.600 0-595 0.594 0-593 0.594 0.598Pressure ............. 250.1 376.6 557.2 653.6 757.6 1004.0Solubility ............0.596 0.595 0.593 0.594 0.595 0.598(h) Suspemions of Silica and of Charcoal.For these experiments finely-powdered silica and animal charcoalwere employed. The charcoal was boiled with water, and then,after being dried a t looo, was heated in a vacuum almost toredness.The solubilities obtained with suspensions of silica did not differappreciably from those in pure water. With charcoal the followingvalues were obtained (see also Fig. 4) :Concentration: 3.0 grams of charcoal in 100 C.C. of water.Pressure ............. 252.6 366.8 527.7 626.6 749-8 989.5Solubility ............ 0.580 0.586 0.587 0.588 0.588 0-609Pressure ............. 255.3 374.3 545.3 639.0 760-3 1001.3Solubility ............ 0.583 0.581 0.586 0.591 0.588 0.610Discussion of Results.The solubility values which have now been obtained fit inexceedingly well with the values obtained at higher pressures byFindlay and Ckeighton (Zoc.cit.) if one allows for the slightdifference in the value for the solubility in pure water. Since theVOL. cv. 298 FINDLAY AND HOWELL: THE INFLUENCE OF COLLOIDS, ETC.solubility values recorded here were carried out up to pressuresof about 1000 mm. of mercury, whilst the pressures under whichthe experiments of Findlay and Creighton were carried out variedfrom about 750 mm. upwards, the two sets of solubility curvesoverlap over a considerable range; and we have found that overthis range the two sets of curves are parallel with one another inthe case of any particular solution.The two sets of experiments,therefore, mutually confirm each other.Although it is hoped to discuss more generally at a later timethe general question of the solubility curves obtained in the caseof carbon dioxide and nitrous oxide, i t may be mentioned herethat an examination of the solubility curves for nitrous oxide asobtained by the present authors and, previously, by Findlay andCkeighton, reveals a remarkable uniformity in general behaviour.FIG. 4.0'6200.610d2 0.600 z2 0-5900-58@0.570&Is250 350 450 550 650 750 850 950 1050Pressure in mna. Hg.Nitroils oxide and charcoal (- - -).X i t ~ o u s oxide and silica (--.).On considering the solubility curve for pressures varying fromabout 250 to 1400 Him. of mercury, i t is found that in every casethe curve exhibits a minimum, which is rather shallow indeed inthe case of solutiona of silicic acid, but is very well marked inmost of the other cases, for example, in the citse of solutions ofgelatin, dextrin, and ferric hydroxide. Even in the case ofsolutions of starch we have found that the solubility of nitrousoxide passes through a quite distinct minimum value, although it isremarkable that no such behaviour was met with in the solubilityof carbon dioxide in starch solutions (Findlay and Williams,loc. cit.). Although we have no reason to doubt the accuracy ofany of the determinations, this somewhat exceptional behaviour,as it. appears, of carbon dioxide in starch solutions makes it neces-sary for us to study more fully that particular case.THE Er)wAm DAVIES CHEMICAL LABORA-I OKIEY,UNIVEEW~Y OF WALES,ABERYS'I'WPTII

ISSN:0368-1645    

DOI:10.1039/CT9140500291

出版商:RSC    

年代:1914

数据来源: RSC

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HYDROLYSIS OF MIXED SECONDARY AMIDES BY ALKALIS. 299XXXIII.-The Hydraolysis of Mixed Sccondary Amidcsby A lkalis.By ARTHUR WALSH TITHERLEY and LEONARD STUBBS.THE hydrolysis of mixed secondary amides of the typeR*CO-NH*COR’, which takes place readily under the influence ofalkalis, in the first stage may conceivably follow two courses, givingeither the acid, R-CO,H, and amide, R/*CO*NH2, or the acid,R’CO,H, and amide, R*CO*NH,. I n previous communications byone of the authors it has been noted that the hydrolysis of certainmixed secondary amides proceeds exclusively in one of the altermtivedirections. Thus, s-dibenzo-oxamide (Titherley, T., 1904, 85, 168 1)yieIds oxalic acid and benzamide, and not (as might be expectedfrom the stability of oxamide) benzoic acid and oxamide.Similarly,acetobenBamide yields only acetic acid and benzamide, if care istaken to avoid secondary hydrolysis of the latter, and it wouldappear likely that aliphatic-aromatic secondary amides in generaldecompose under the influence of alk.ali into the correspondingaliphatic acid .and aromatic amide exclusively, or virtually so. Thistype of hydrolysis is of interest as bearing on the ring-rupture ofcyclic secondary amides of the purine group, and on the positiontaken up by the mobile hydrogen atom in such pseudo-acids wheni t is repiaced by sodium. It is probable that the sodium compoundsof secondary amides contaic the unsaturated grouping CO-N:C*ONa,and that their more o r less ready hydrolysis in aqueous solution isto be referred t o the doubly linked C:N pair.I f this is so, thepreferential decomposition yielding aliphatic acid and aromaticamide, in mixed secondary amides of the type R-CO-NH-COR’(when R-CO. is an aliphatic acyl and R’*CO* is an aromatic acylgroup) could be explained by assuming that the sodium compoundsare derived from the tautomeric form R*C(OH):N*COR/ exclu-sively. On this assumption hydrolysis is preceded by water-additiona t the double link, as it probably is with amidines and all com-pounds containing the C:N-linking, and formation of the unstabledihydroxy-derivative, R*C(OH),*NH=COR’, which immediatelydecomposes into the aliphatic acid, R*CO,H*, and aromatic amide,R’*CO*NH,. The extreme ease with which most secondary amidessuffer hydrolysis by alkali, as compared with simple amides,R*CO*NH,, and their general similarity to amidines and imino-ethers in hydrolytic sensitivity, renders the above mechanism veryprobable.On the other hand, it is not clear why the mobilehydrogen atom in the tautomeric form should migrate exclusivelyto one of the two oxygen atoms, and it would appear that stericx 300 TITHERLEY AND STUBRS: THE HYDROLYSIS OFinfluence must also be a t work in favouring preferential fission.I f this is the case, i t would seem that the velocity of water-additiona t the double link in the form R-C(OH):N*COR/ must be so muchgreater than in the form R*CO*N:C(OH)R/ (where R/ is the largeraromatic group) that practically no hydrolysis of the latter formoccurs.This supposition is confirmed by the observation of theauthors (see curve, p. 306) that the velocity of alkaline hydrolysisof diacetamide, acetobenzamide, and acetylcarbamide is very muchgreater than that of dibenzamide and other purely aromatic amides;and further confirmation is fomd in the fact that benzo-o-toluamidesuffers fission in one direction exclusively, as described below(p. 301), whilst the para-isomeride decomposes in both possibledirections.It would seem therefore that whilst there are good reasons forbelieving that the mechanism of hydrolysis is one involving additionof water a t the unsaturated C:N pair, the fact that in the abovecases the hydrolysis follows ope course exclusively cannot be inter-preted as indicating the exclusive intermediate production of onetautomeric form.It is possible and probable that both sodiumcompounds, (I) R*C(ONa):N*COR/ and (11) R*CO.N:C(ONa)R’,are formed, in equilibrium, when the secondary amide,R*CO*NH*COR/, is treated with aqueous sodium hydroxide, butthat, owing to the vastly greater rate of hydrolysis of (I), theequilibrium is constantly disturbed as i t is decomposed into theacid R*CO,H and amide R’*CO*NH,; and the amount of acidR’-CO,H and amide R*CO*NH, formed would be thus too smallfor detection.I n order to obtain further evidence as t o the nature of thehydrolysis with mixed secondary aromatic amides, the case of benzo-o-toluamide and benzo-ptoluamide has been closely studied ; andsince each of the mixed secondary amides showed some evidence ofappearing in two desmotropic forms, attempts were also made toisolate the latter, but without success.The first, a modificationof the method of Titherley (T., 1904, 85, 1673), was by condensationof phenyl benzoate with the sodium derivatives of 0- and ptoluamiderespectively :C,H,Me*CO*NHNa + Ph*CO,Ph +Two methods of synthesis were adopted.C,H,Me*CO-NH*COPh + Ph-ONa.This method, however, gave poor results, owing to the occurrenceof secondary reactions leading (by a process analogous to doubledecomposition) t o the formation of dibenzamide and ditoluamide ;and it was found to be practically impossible to eliminate theseimpuritiesMIXED SECONDARY AMIDES BY ALKALIS. 301The second method, which was entirely satisfactory, was basedon the cautious hydrolysis of the acylamidines obtained in thecondensation between benzamidine and phenyl 0- and p-toluatesrespectively by the method of Titherley and Hughes (T., 1911,99, 1505), thus:(1) NH:CPh*NH, + C6H4Me*C02Ph +(2) NH:CPh*NH*CO*C,H,Me + H,O +NH:CPh*NH-CO*C6H4Me + Ph*OH.COPh*NH*CO*C6H4Me + NH,.Excellent yields of pure benzo-o- and -ptoluamides were obtainedin each case.I n studying the products of hydrolysis of benzo-o-toluamide andbenzo-p-toluamide, advantage was t-aken of the fact that in thepresence of aqueous sodium hydroxide the hydrolysis to amide andacid is complete within from three to four days at laboratory tem-peratures or within #a few minutes a t 90°; and under these con-ditions the further hydrolysis of amide was almost completelyavoided.No fundamental difference between the effect of coldand hot alkaline hydrolysis was observed, in the proportions ofthe resulting products. This important difference in the behaviourof the two isomerides was established, however, that whilst benzo-ptoluamide suffers fission under the influence of hot aqueous alkaliin both possible ways to a roughly equal extent (and in the coldt o a larger extent yielding ptoluamide and benzoic acid), benzo-o-toluamide suffers fission exclusively in one direction (at 1 5 O orgoo), yielding o-toluamide and benzoic acid. I n no case couldbenzamide be isol-ated from the products of hydrolysis. As therates of hydrolysis of benzo-o-toluamide and benzo-ptoluamide underthe same conditions are practically equal, and also the same as thatof dibenzamide (see curve, p.306), it. would seem- that sterichindmnce must be responsible for this preferential fission of theortho-derivative into o-toluamide and benzoic acid, since in theequilibrium :Ph*C( 0Na):N CO C,H,Me ZZ Ph CO N : C( ONa) C,H,Me(1.1 (11.)the rate of hydrolysis of I1 wpld be relatively very low, whilst thatof I, which is much higher and governs the entire decomposition,would be virtually the same as that of clibenzamide or of benzo-ptoluamide in its two forms (corresponding with I and 11).From a general consider,ation of the facts established withreference to the rate and direction of hydrolysis of secondary amidesby alkali, it would appear that two factors are a t work, namely,(1) the additive affinity (for water) of the tautomeric grouping*N:C(ONa)R, which is dependent on the nature of the group R 302 TITHERLEY AND STUBHS: THE HYDROLYSIS O Fas well as of that united to the nitrogen atom; and (2) the stericinfluence, more particularly of the group R, a.nd t o a less degreeof the other (acyl) group united t o the nitrogen atom.E XPER 1 MEN TA4L.Benzo-o-toZuaml.de, C,H,*CO*NH.CO*C,H,n/Ie.(1) Preparation from Benzamidine.-Phenyl o-toluate (requisitein the synthesis, and apparently not previously described) wasobtained by heating 13.6 grams of 0-toluic acid, 15 grams ofphosphoryl chloride, and 9 grams of phenol for four hours a t 75O.The resulting red oil, after cooling, was shaken with 10 per cent.sodium hydroxide, and the oil extr9acted by ether.A nearlytheoretical yield (20 grams) of phenyl o-toluate was obtained (dis-coloured), which distilled unchanged a t 306O/754 mm. as a faintlyyellow liquid, which did not solidify on cooling or long keeping.The product obtained by the action of o-toluoyl chloride on phenoland alkali had similar properties, and did not crystallise.o- ToZz~oy Zb e n zamidine, C,H,* C( :NH) *NH* CO C,H,Me.This compound was obtained readily by the condensation ofphenyl o-toluate (10 grams) and benzamidine (6 grams, freshly pre-pared from the hydrochloride) in alcoholic solution, the mixturebeing heated at 50° for five hours. Most of the alcohol was thenremoved by evaporation and the residue treated in the cold withwater and dilute hydrochloric acid.I n this way the o-toluoyl-benzamidine was brought into solution and removed from the smallquantity of unchanged phenyl o-toluate. The aqueous acid solutionwas then rendered alkaline, in the cold, with excess of aqueoussodium hydroxide, when the amidine derivative was precipitated asa colourless oil, which solidified after some time. The yield was5 grams (theory required 11.9 grams), and after recrystallisationfrom light petroleum the compound was obtained in long, trans-parent plates, melting a t 122':0.4646, by Kjeldahl's method, required 38.6 C.C. AT/ 10-HCl.N = 11-63,C,,H,,ON, requires N = 11.76 per cent.o-ToZuoyZ b enzamidine is readily soluble in alcohol, chloroform, oracetone, and insoluble in cold water.It is basic, and dissolves incold dilute hydrochloric acid without decompcsition, but, on heating,slow hydrolysis takes place with formation of ammonia and benzo-o-toluamide, which was obtained in quantity as follows.Ten grams of o-toluoylbenzamidine were dissolved in 850 C.C. offl/lO-hydrochloric acid (2 mols.), and the solution was heated a MIXED SECONDARY AMIDES BY ALKALIS. 30370°. After thirty minutes the solution became milky as thesecondary amide began t o separate, and after three and a-half hours,when the hydrolysis was complete, it had collected as a mass offine, colourless needles (10 grams), the yield being theoretical. Itwas practically pure, and after recrystallisation from 50 per cent.aqueous alcohol was obtained in long, silky needles, melting a t158-159O :0.4666, by Kjeldahi's method, required 19.9 C.C.N/10-HCl.N = 5.97.CI5Hl3O2N requires N = 5-86 per cent.Beizzo-o-tolmmide is moderately readily soluble in alcohol,sparingly so. in benzene, and practically insoluble in ether or lightpetroleum. It dissolves a t once in aqueous sodium hydroxide, andis precipitated unchanged by acids, but the alkaline solution isreadily decomposed on keeping or heating (p. 308).(2) Prepration from o-7'oluarriide.-An intimate mixture of 6.8grams of o-toluamide and 2 grams of sodamide, both previouslyfinely powdered, was moistened with benzene and heated in a refluxapparatus, in a bath the temperature of which was gradually raisedto 120O. After three hours, when no more ammonia was evolved,the resulting white solid (sodium o-toluamide) was covered withbenzene and treated with a solution of 10 grams of phenyl benzoate,dissolved in the least quantity of benzene. After heating themixture to boiling for two hours, the benzene was distilled off, thesolid residue treated with ice-cold water, and the last tr.aces ofbenzene removed by current of air.The discoloured mixturecontaining benzo-o-toluamide and its sodium compound, partlydissolved and partly in the solid state, was filtered, and the filtrateacidified a t Oo with 30 per cent. acetic acid. The solid residue wasrepeatedly extracted with ice-cold aqueous sodium hydroxide, andthe filtrates immediately acidified.The combined precipitates,obtained by acidification, which were oily a t first, solidified quicklya t OD, and after remaining for thirty minutes were collected ,andwashed (11 grams). The solid (crude benzo-o-toluamide) was puri-fied, first by dissolving in sodium hydroxide, and, after filtering,acidifying with acetic acid, and subsequently by repeated re-crystallisation from 50 per cent. alcohol. It was thus obtainedin colourless, silky needles, melting indefinitely a t 147O :0*4122, by Kjeldahl's method, required 17.6 C.C. N / 10-HCI.N = 5.98.C,5K&,N requires N = 5.86 per cent.The persistently low melting point a t first led tlie authors tosuppose that the product was an isomeride of that obtained by th304 TITHERLEY AND STUBBS : THE HYDROLYSIS OFamidine method (p.303), but since no differences in propertiescould be detected, and since the melting point was not depressed byadmixture with the pure substance (m. p. 1 5 8 O ) , there can be nodoubt that the product melting at 147O is benzo-o-koluamide witha little isomorphous impurity (probably dibenzamide), which cannotbe removed by recrystallisation.This compound has been described previously by Wheeler,Johnson, and McFarland ( J . Amer. Chem. SOC., 1903,25, 787), andTitherley and Holden (T,, 1912, 101, 1877, 1887). It was obtainedeasily by the following new method of synthesis.Preparation from Benzamidi?ie.-The phenyl ptoluate, requisitefor the synthesis, described by Kraut (Jahresber., 1858, 406) as asolid, melting a t 71-72O, was prepared from p-toluoyl chloride andphenol by the Schotten-Baumann method (m.p. 72O), but a bettermethod was as follows.13.6 Grams of p-toluic acid, 15 grams of pure phosphoryl chloride,and 9 grams of phenol were heated a t 75O for four hours. Theresulting red liquid, after cooling and digesting with aqueoussodium hydroxide, solidified, and the red colour was removed byfurther digesting. The ester (22 grams) separates from hot alcoholas a white, crystalline powder, melting a t 76O. After repeatedrecrystallisation from .alcohol the pure ester melts at 83O.p-Toho y l b eizzamidiize, C,H,* C( :NH)*NR*CO*C,H,Me.Benzamidine (3 grams), freshly prepared from its hydrochloride,and phenyl p-toluate (5 grams) in alcohol (10 c.c.) were heated forfive hours at 50°; the alcohol was then mostly evaporated off, andthe residual oil, after cooling, shaken with dilute hydrochloric acid.I n most cases the oil (crude ptoluoylbenzamidine) completely dis-solved, but sometimes a little unchanged phenyl p-toluate remainedand was filtered off.The acid solution was immediately renderedalkaline in the cold by sodium hydroxide, in order t o liberate thefree base, which separated QS a milky oil, and crystallised afterseveral hours (8.5 grams). From light petroleum i t separated as amass of fine, silky, white needles, melting a t lllo:0.4604, by Kjeldahl's method, required 38.8 C.C. N / 10-HC1.N = 11'80C,,H,,0N2 requires N = 11.76 per cent.p-Toluoylb e?izamidi?ze is fairly readily soluble in alcohol, ether,chloroform, or acetone. It dissolves a t once in concentrated hydro-chloric acid, and the solution, if containing excess of acid, quicklMIXED SECONDARY AMIDES BY ALKALIS. 305deposits a voluminous, microcrystalline precipitate of the hydro-chloride (m.p. 21S0), which is readily soluble in water, moderatelyso in alcohol or chloroform, but very sparingly so in acetone.On heating the hydrochloride with aqueous hydrochloric acid,slow hydrolysis takes place with the formation of ammonia andbenzo-ptoluamide, which was prepared thus. Four grams ofptoluoylbenzamide were dissolved in 370 C.C. of AT/ 10-hydrochloricwid (2 mols.), and the solution was heated a t 70° for two hours.After about thirty minutes, the solution became milky as thesecondary amide began to separate, and this finally collected as amass of colourless needles, weighing 3.5 grams (theoretical yield,4 grams).After recrystallisation from dilute alcohol, the benzo-p-toluamidemelted a t 1 1 8 O , and repeated recrystallisation only raised the meltingpoint to 119O (Found, N=5-88.C,,H,,O,N requires N=5.86 percent.). The product was identical with that obtained by Titherleyand Holden (m. p. 114O, loc. cit.), and by Wheeler, Johnson, andMcFarland (m. p. 112--113O, loc. cit.) by the converse method frombenzoyl-ptolylamidine, C,H,Me*C( :NH)*NH*COPh, by .acid hydro-'lysis. When prepared direct from sodium ptoluamide by the actionof phenyl benzoate, by a method similar to that (p. 303) used in thecorresponding synthesis of benzo-o-toluamide, a much lower yield(30 per cent.) was obtained, and in spite of repeated recrystallisationa pure product could not be obtained.The appearance of thecompound was different (pearly flakes), and the melting point higher(varying with different samples between 125O and 130O) than thatobtained by the amidine synthesis, but correct figures were obtainedon analysis. It was a t first believed t o be a definite isomericcompound, but from an exhaustive examination of its propertiesand the products it yields on hydrolysis by alkali, the authorsconclude that the substance is a solid solution consisting of benzo-ptoluamide, di-ptoluamide, and dibenzamide, which cannot beseparated by fractional crystallisation.Hydrolysis of Secondary Amides by Alkalis.The ,study of the initial products of hydrolysis of secondaryamides by aqueous alkali was rendered easy by the fact that thefirst stage leading t o acid and primary amide is very sharplydefined, and is complete before any appreciable further hydrolysisof amide oan occur.I n the cold the latter is completely prevented,and the decomposition to acid and primary amide is therefore, so faras could be measured, practically quantitative. The curves belowshow the comparative rdes in the cold a t which hydrolysis occursof diacetamide, acetobenzamid e and acetylcarbamide, on the on306 TITHERLEY AND STUBBS : THE HYDROLYSIS OFha.nd, and of dibenzamide, benzo-o-toluamide, and benzo-p-tolu-amide, on the other, using in each cme two molecular equivalentsFit..1.10090807060504030201002 4 6 8 10 12 14 Id 18 20 22 24 26 28 30 32Tirne in rniimtes.o Diacetnmirlc . + Acetobenzamide. x Acelylcnrbamide.Hydrolysis of dincetaatide, ncctobenznmidt, and amtyZcarbc;midc by alknZi at 15",vising 2 eqibiualents of N/lO-NaOI-T.of sodium hydroxide at N l 10-concentration. These curves areconstructed from the figures obtained by titrating the alkalineHydrolysis of dibenzamide, benzo-o-toluamide, and bcnzo- p-tolztamide b y alkaliat 15") t6sixg 2 epuivabnts of N/10-NaOH.solution with LT / 10-hydrochloric acid a t intervals in order toascertain the a"mount of alkali used, and thus the percentagenumber of molecules of secondary amide hydrolysedMIXED SECONDARY AMIDES BY ALKALIS.307From these curves it is apparent that whilst diacetamide, aceto-benzamide, and acetylcarbamide are completely hydrolysed by dilutealkali in the cold within forty minutes, wholly aromatic second-aryamides require about fifteen hours; but there is no sensible differencein the rates of hydrolysis between dibenzamide, benzo-o-toluamide,and benzo-ptoluamide. Contrary to expectation, it was observedthat whilst the hydrolysis of the two benzotoluamides is completein less than one deay, using two equivalents of iV/lO-sodiumhydroxide, three to four days were required for complete hydrolysisunder similar conditions with 2N-sodium hydroxide. That is,hydrolysis is inhibited, not accelerated, by increase in the con-centration of alkali, and this may be due to decreased concentrationof the ions R*C‘(O’):N*CO*R’, which are probably more sensitive tohydrolysis than the non-ionised sodium salts R-C(ONa):N-CO*R’,the concentration of which would relatively increase with decreasein the relative mass of water.I n comparing the curves (Fig.1) for diacetamide, acetobenzamide,and acetylcarbamide, it will be noticed that the rate of hydrolysisof the first is considerably greater than that of the other’two. I nall three cases acetic acid is eliminated almost quantitatively, pre-sumably by water addition a t the double link in the commongrouping, *N:C(ONa)*CH3, acetamide, benzamide, and carbamide,being respectively formed. Whilst with acetobenzamide there isreason to believe that the alternative tautomeric form,NaO*&h:N*CO*CH,is present in the alkaline solution, and that this form suffers noappreciable hydrolysis owing to the steric influence of the phenylgroup, in the case of acetylcarbamide probably the tautomericform, NH,*CO*N:C(ONa)*CH3, only, exi&s in alkaline solution.The higher rate of hydrolysis of diacetamide cannot well be referredto reduced steric effects (compare acetylcarbamidej, and must arisefrom inferior stability, and in general it may be concluded that theadditive affinity for water of the grouping *N:C(ONa)*CH, andconsequent rate of hydrolysis varies somewhat with the nature ofthe group united to the nitrogen atom.The products of decomposition of the two bsnzotoluamides wereinvestigated after hydrolysis with two equivalents of 2N-sodiumhydroxide (1) a t 15’ by keeping for four days,.and (2) a t 90° byheating for three t o four minutes, and immediately cooling. I nthe cold no secondary hydrolysis of the resulting primary amideoccurred, and a t 90° the extent of hydrolysis was only slight; thiswas evident from control experiments (using N-sodium hydroxidea t 90° for three minutes) with benzamide, of which 16 per cent. washydrolysed, o-toluamide, of which less than 1 per cent. was hydro308 HYDROLYSIS OF MIXED SECONDARY AMIDES BY ALKALIS.lysed, and ptoluamide, of which 3 per cent. was hydrolysed. Theamide (or mixture of amides), which separated after alkalinehydrolysis of the secondary amide, was removed, and the smallquantity dissolved in the alkaaline solution was extracted by meansof ether.From the residual alkaline solution the acid (or mixtureof acids) produced by the hydrolysis was precipitated by acidifying,the small amount remaining in solution being recovered by extract-ing with ether.A. Be?Ezo-o-toluurrLide.--(l) A t 15O with 2h7-NaOH for four days :1.2 Grams gave a total of 0.641 gram of pure o-toluamide (m. p.137-139O before recrystallisation : Found, N = 10.35. Calc.,N = 10.37 per cent.). This amounts to 96 per cent. of the theoreticalif o-toluamide is the only primary amide produced by hydrolysis.Benzamide was looked for carefully and repeatedly in differentexperiments, but never found.1.2 Grams gave a total of 0.528 gram of pure benzoic acid (m.p.119-120° before recrystallisation), o r 87 per cent. of theoreticalpossible. NO o-toluic acid was found.The following results were obtained:(2) A t 90° for three minutes:1.2 Gra.ms gave a total of 0.6234 gram of pure o-toluamide (m.p.136-137O), or 93 per cent. of theory (Found, N=10*32. Calc.,N=10*37 per cent.). NO benzamide was found. 1.2 Grams gave0.5324 gram of pure benzoic acid (m. p. 117-120° before recrys-tallisation), or 88 per cent. of the theoretical.No o-toluic acid was found, and it'is clear that, although, owingt'o experimental difficulties, 100 per cent. yields were not realised,nothing other than o-toluamide and benzoic acid is formed by thealkaline hydrolysis of benzo-o-toluamide in the hot or cold.B.Beuzo-p-toZuamide.-(1) A t 15O with 28-NaOH for four days.1.2 Grams gave a total of 0.596 gram of a mixture meIting between125O and 136O, containing 22 per cent. of benzamide and 78 percent. of p-toluamide. By fractionalcrystallisation, an imperfect separation of the two amides waseffected.1.2 Grams gave a total of 0.529 gram of a mixture of acidsmelting between l l O o and 153O, containng 11 per cent. of p-toluicacid and 89 per cent. of benzoic acid (mixed silver salts gaveAg = 46.88 per cent.). By fractional crystallisation, an imperfectseparation, only, of the two acids was possible.(Found, N = 10.63 per cent.)(2) A t 90° for three minutes:1-2 Grams gave a total of 0-554 gram of a mixture meltingbetween 125O acd 142O, contaiiiiiig 49 per cent.of benzamide and51 per cent. of y-toluamide. (Found, N= 10.96 per cent.) 1.2 Gramsgave a total of 0.573 gram of a mixture of acids melting betweeHARTLEY AND STUART: THE MISCIBILITY, RTC. 3091 1 6 O and 155O, containing 60 per cent. of p-toluic acid and 40 percent. of benzoic acid (mixed silver salts gave Ag=45*54 per cent.).The quantitative values are only very approximate, since theyare based on the nitrogen value of the mixed (uncrystallised) amides,and the silver value of the mixed silver salts obtained from themixture of acids. Slight errors due to differences in solubilitybecome greatly magnified in view of the fact that differences in thefigures for nitrogen and silver respectively are, of course, relativelysmall, between benzamide and ptoluamide and between silverbenzoate and silver ptoluate.I n the hydrolysis a t 90°, moreover, there is a further error arisingfrom the slight hydrolysis of the two primary amides found, andsince the extent of hydrolysis of benzamide is considerably greaterthan that of ptoluamide, the proportion of benzaniide actuallyproduced would be somewhat higher than 49 per cent.Whilst in general, owing to lack of accurate means of quantitativemeasurement, the above data can only be taken as a rough approxi-mation, the following facts are established.A . Benzo-o-toluamide by hydrolysis with alkali, whether at 90°or in the cold, yields exclusively o-toluamide and benzoic acid; thatis, decomposes in one only of the two possible directions.B. Benzo-ptoluamide, in similar circumstances, decomposes inboth possible ways, in. the cold mainly along the channel yieldingptoluamide and benzoic acid, and at 90° to a tolerably equal extentin both directions.ORGANIC LABOILATORY,UNIVERSITY OF LIVERPOOL

ISSN:0368-1645    

DOI:10.1039/CT9140500299

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

HARTLEY AND STUART: THE MISCIBILITY, RTC. 309XXXIV.- The Miscibility of Axobenzene and Axoxy-benzene in the Solid State and the SupposedExistence of a Stereoisomeride of Axobenzene.By HAROLD HARTLEY and JOHN MCARTHUR STUART.IN the preparation of azobenzenc by the electrolytic reduction ofnitrobenzene in aqueous alcohol containing sodium acetate witha nickel cathode a small quantity of a deep red liquid was occa-sionally obtained, which crystallised on keeping, giving radiatingmasses of orange, acicular crystals melting a t 25O. It appeared tobe identical with the substance obtained by C. V. and R. A.Gortner (J. Arne?*. Chem. SOC., 1910, 32, 1294) as a by-produc310 HARTLEY AND STUART: THE MISCIBILITY OFin the preparation of azobenzene by the distillation of azoxy-benzene with iron filings.The authors describe the by-product ofthis reaction as forming orange-red, stellate groups of needles,readily soluble in ether, light petroleum, alcohol, acetone, or methylalcohol, and melting a t 25O to a deep red liquid. Analysis gaveN = 15.35, azobenzene requiring N = 15.38 per cent. They say,further: ‘ I It will not crystallise when seeded with the 6 8 O substance(ordinary azobenzene), but in two instances we have succeeded inquantitatively transforrning the 25O substance into the 6 8 O sub-stance, once by boiling with dilute hydrochloric acid, and in theother instance the cause of conversion is unknown to us. We cangive no method which will always ensure conversion, nor havewe been able to trarsform the 6 8 O substance into the 2 5 O modifica-tion.According to Holleman, the syn-modifications are the leaststable, so it seems probable that the new compound is syn-azo-benzene. ”Attempts to discover the conditions which favoured the produc-tion of the substance of low melting point in place of ordinaryazobenzene by the electrolytic method failed, as little of it wasobtained. It was then found that carefully dried azoxybenzenewhen distilled with iron filings gave, as a rule, nothing butordinary azobenzene ; however, on moistening the azoxybenzsnewith alcohol, or, better still, with aniline, a considerable quantityof the product of low melting point was obtained. If aniline wasused, the solution of the distillate in light petroleum was wellwashed with dilute hydrochloric acid before crystallisation.Various specimens gave melting points varying from 25’2O to 26O,and two nitrogen estimations gave 14.95 and 14.84 per cent.respectively, showing that the substance is not pure azobenzene,which contains 15-38 per cent.of nitrogen. The resemblance ofthe crystalline form to that of azoxybenzene, and the fact thatthe drops of the supercooled liquid crystallised if seeded withcrystals of azoxybenzens, suggested that the orange crystals meltingat 25O might be a solid solution of azobenzene in azoxybenzene.The results of determinations of the freezing-point and melting-point curvm of mixtures of those two substances confirmed thisconjecture. The freezing-point curve was determined in a Beck-mann apparatus in the usual way, and the melting-point curve byallowing mixtures of known composition to crystallise slowly, andthen finding the temperature at which melting begins when a thin-walled tube containing the mixture is slowly heated.The melting-point curve determined in this way is necessarily rough, and givesonly an approximate estimate of the composition of the solid phase.The horizontal portion of the curve must pass through the eutectiAZOBENZENE AND AZOXYBENZENE IN THE SOLID STATE, ETC. 311point, but it will be noticed that the experimental points lie fromlo to 3 O above i t owing to the difficulty of deciding when meltinghas really begun to take place.The experimental results are given below :Molecular per-centage of azo-benzene.08.312.918.222.625.929.134.838.142.448.955.162.680.594.1100.0Freezing point.35.031.329.327.125.325.527.833.135.839.244.147.752.260.465-867.9Molecular per-centage of azo-benzene.02.93.66.913.525.234.847.356.964.075.091.5Melting point.35.330.929.627.825.626.726-427.726-834.648.062.1The form of the diagram shows that the substances give two setsof mixed crystals with an eutectic temperature of 24'5O; a t thistemperature crystals of azoxybenzene can dissolve about 10 percent.of azobenzene molecules, whilst those of the azobenzenedissolve about 45 per cent. of molecules of azoxybenzene.The crystalline form of azoxybenzene has not been fully investi-gated.Bodewig (Zeitsch. Kryst. &€in., 1879, 3, 411) measured theprism angle of the needles (87O32/), and from their optical proper-ties described them as orthorhombic. The crystalline form ofazobenzene has been examined by Calderon (Zeitsch. Kryst. Min.,1880, 4, 234), and by Boeris (ibid., 1901, 34, 301), who describesit as monoclinic with a prism angle of 55O3', and axial ratios:a : b : c = 2-1076 : 1 : 1.3312 ; /3 = 114O26'. The evidence is thus insuffi-cient to decide whether there is any relationship between the normalcrystalline structures of the two substances. Their miscibility inthe crystalline state is probably similar to a number of instancesnoticed by Jaeger (Zeitsch. Kryst. Min., 1907, 42, 236), where themiscibility seems to depend, not on a relationship of crystallineform, but cn the similar spacial structure of two molecules, forexample, the miscibility of azobenzene and benzylaniline (MissIsaac, Yroc.Roy. SOC., 1911, A , 84, 344). Crystals produced bythe crystallisation of mixtures of azobenzene and azoxybenzenefrom light petroleum appeared identical in every respect with theproduct of low melting point obtained by the electrolytic reductionof nitrobenzene or by distilling azoxybenzene with iron filings, an312 HARTLEY AND STUART : THE MISCIBILITY, ETC.i t seems certain that the substance obtained by C. V. and R. A.Gortner, and described by them as a new stereoisomeride ofazobenzene, was a mixed crystal of azobenzene and azoxybenzene.Their analysis gave N = 15.35, the theoretical content forazobenzene being N = 15.38 per cent.; the specimens analysedabove gave N=14*95 and 14.84; the eutectic mixture wouldcontain about 14.4 per cent. of nitrogen, so that the substanceanalysed probably contained some azobenzene.The production of the mixed crystals, owing to the contamina-tion of azoberzene by azoxybenzene, is easily explained in bothprocesses where they have been obtained. In the distillation of70603020Molecular perceningc of azobenxcnc.- G - Freezing-point curve. - _ + - - Jlelki?tg-point CZLTV~.azoxybenzene with iron filings the product of low melting pointwas only obtained in quantity when some volatile substance waspresent which carried over the azoxybenzene a t a. temperaturebelow that a t which it decomposes. I n the electrolytic reduction,since azoxybenzene is a product of the reduction of nitrobenzenein alkaline solution, some will be present if the current is passedfor an insufficient time to reduce it further. I n the unsuccessfulattempts t o prepare the substance of low melting point byelectrolytic reduction, on ;he assulnption that it wae a stereo-isomeride of azobenzene, the current was always continued untilreduction was complete.PHYSICAL CHEEMISTKY LASOKATUILY,BALLIOI, COLLEGE AND TlLlNITY COLLEGE, OXFOKD

ISSN:0368-1645    

DOI:10.1039/CT9140500309

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

EQUILlBRIUM OF DILUTE HYDROCHLORIC ACID AND GIELATIN. 313XXXV.-The Eyuilibrium o f Dilute Hydwclhi.icAcid and Gelatin.By HENRY RICHARDSON PROCTER.IN an earlier paper (Koll.-chern. Beihefte, 1911, 2, 243) it has beenshown that when gelatin jelly is immersed in a dilute acid, anequilibrium results which a t a given temperature is dependent onlyon the ionisation and concentration of the acid, which determinenot merely the volume of liquid absorbed, but the concentration ofthe anion in the jelly; and more or less empirical formulae weregiven connecting these with the concentration of the ionised acid.It was further pointed out that these formulae were consistent withthe view that a hydrolysable and ionising salt* of gelatin wasformed, and that the phenomena of swelling were simply dependenton the relation between the osmotic pressure of the ionising saltand that of the external acid solution.The object of the present paper is to indicate the precise natureof these relations, and to show that the formulEe there given, withsome slight modification, can be fully explained and justified onthe ordinary ionisation hypothesis. I f this is the case, there seeinsno reason f o r the assumption of more complicated and less verifiedtheories dependent on surf ace-tension and other forces, and involvingthe unproved an3 rather gratuitms assumption of a two-phasedstructure of the jelly.The discussion of the present paper hasbeen confined to the single case of gelatin and hydrochloric acid;but the theory proposed is quite general, and iE true in the particularcase, must also be true (with different constants) of any otheracid, and of other amphoteric proteins, so that its bearing, bothon colloid chemistry .and on physiological theory, is very wide.The theory assumes that the jelly is a molecular network, in whichthe water, the acid, and the protein are within the sphere of eachother’s molecular attractions, and theref ore homogeneous in thesame sense as any other solution; and it discards the Butschli-vanBemmelen idea of coarse microscopic pores, although it is not deniedthat such two-phased jellies exist, and can be produced, and thatthe pores observed by these investigators had a real existence,probably due t o the hardening agents with which their jellies weretreated.It has been shown by the author (loc.cit.) that when gelatin* I t is most probable that this salt is a “ hydrochloride,” in the same sense as“ aniline hydrochloride,” but as other constitutions are possible, it has been thoughtbetter to write “gelatin chloride ” simply.vor,. cv. 314 PROCTER : THE EQUILIBRIUM OFswollen with water is treated with a strong acid, such as hydrochloricor sulphuric, the swelling becomes much greater than with wateralone, but reaches a maximum at a very low concentration of theexternal acid, subsequently diminishing in a hyperbolic curve, asthe concentration of the acid is further increased. This con-traction is obviously due to the anion of the acid, since it can beincreased to almost complete dehydGation by the addition of itsneutral salt; but the exact mechanism of the osmotic pressure is noteasy to follow, since the jelly is in itself completely permeable bothto the acid and its neutral salt, and their ions, and the explanationgiven in the paper quoted seems an incomplete one.The fuller statement is that to satisfy the equation * of equality ofproducts (Donnan and Harris, T., 1911,99, 1575; Donnan, Zeitsch.Elektrochem., 1911, 17, 572), the concentration of the free acidcontained in the jelly must have a definite relation t o that of theionised anion of the jelly-salt; and as the latter cannot diffuse fromthe jelly owing to the colloid nature of its cation, the equilibriumcan only be reached by the absorption or expulsion of free acid andof water by the jelly.I n order to investigate these relations, itis necessary, not merely to determine the total chlorine contained inthe jelly, as had been done in the earlier experiments, but toascertain what were the relative proportions of ionised and of non-ionised chloride and of free acid in the jelly, and it became evidentfrom the mathematical investigation of the equilibrium that thetotal chlorine and one of these being known, the others could becalculated.The most obvious way of determining ionic concentrations is bymeans of concentration-cells, and much time was spent in unsuccess-ful efforts t o solve the problem in this way. The work, however,has not been fruitless, and the causes of failure may be brieflystated.First, it should have been obvious from the outset that theconcentration-cell method, marvellously accurate as it is in thedetermination of the order of quantity of minute ionic concentra-tions, was quite unfitted t o deal with the massive differences ofthe same order of quantity which were concerned in the presentproblem. Secondly, it was proved that the apparent ionic con-centration of amphoteric colloid solutions, as determined by the* This equation, which states that the product H' x C1' must be equal inboth phases, is, of course, in accordance with the mass-law, but the actual distributionof H' and C1' depeuds on the thermodynaniic equation :6n R T log H,/H, = 8ia R T log CI,/Cl,given by Donnan and Harris (T., 1911, 99, 1575) for the analogous case of sodiumchloride and Congo-red ; whence H, x C1, = H, x GI,.This equation relates to theionised portions only, and the non.ionised portions, if any, will be related to theionised according t o the ordinary mass-law equation, a x b=kcDILUTE HYDROCHLORIC ACID AND GEL.4TIN. 31 5concentration cell, was not the actual concentration of the solutionor jelly, but that of a non-colloid acid or salt solution with whichi t would be in equilibrium, since Donnan’s “ membrane-potential ”a t a real or virtual surface mathematically equals and compensatesany difference of potential between a colloid solution and itsequilibrium acid or salt solution. This is obviously a point offundamental importance with regard to the frequent use of theconcentration cell in physiological investigations, and demands morecomplete proof than space allows here. The author thereforeproposes to make this part of his work the subject of anotherpaper; but it may be noted that means were devised for theapproximate measurement of the membrane-potential, which,although only of a few millivolts, corresponded with large percentagedifferences in the present investigation.Efforts were also made to solve the problem by conductivitymeasurements, but the results, although of considergable interest,and possibly of importance to the theory of colloid salts, failed t ogive information either so comuleto or so accurate as wits subse-quently obtained by a much simpler and apparently ruder method;and this was also true of a modification of Veley’s colorimetricmethod with methyl-orange, which, within certain limits, gaveuseful results.The method finally adopted rests on the fact that the influenceof one salt on the ionisation of another depends solely on the con-centration of their (‘ common ” ion.Hydrolysis depends, therefore,on the hydrion concentratioin only, whilst the mutual ionisation ofa salt and i b acid is influenced only by the “ common ” anion. I ftherefore, sodium chloride is added to a jelly containing gelatinchloride and free hydrochloric acid, the ionisation is no doubtrepressed, but the hydrolysis of tha gelatin salt is not affected, andthe free acid is expelled with its associated water to almost com-plete dehydration by the osmotic pressure of the concentratedchlorine ion, and can be titrated in the expelled salt solution.The weight or volume of acid solution retained by the jelly can beeasily ascertained, and is so small that even if the assumption thatits concentration is the same as that of the solution expelled is notquite accurate, no serious error is introduced by adopting it.Theactual method of experiment was Bas follows. A quantity of care-fully purified thin bone-gelatin of known dry weight (usually 1gram) was soaked in 100 C.C. of acid solution of known concentrationin a stoppered bottle for forty-eight hours, a time which was shownto be sufficient for the attainment of practical equilibrium. Thecontents of the bottIe were then poured into a funnel provided witha finely perforated porcelain $ate, covered with a clock-glass, andY 316 PROCTER : THE EQUILTHRlUi\I O Fallowed to drain for two hours, the liquid being received in agraduated cylinder.The volume of the liquid, subtracted from 100c.c., gives the volume of acid absorbed by the gelatin, and this canbe further checked, if necessary, by the weight of the drained andswollen gelatin. By titration with alkali hydroxide and phenol-phthalein, the strength of the external acid is determined, and fromits concentration and volume, the total acid absorbed from thegelatin is calculated. The swollen jelly is now returned to thestoppered bottle, and dry salt added in the approximate quantitynecessary to produce a saturated solution.After repeated shaking,and standing f o r a t least twenty-f our hours, equilibrium is againestablished; the gelatin is shrunk to thin, horny plates, and afurther portion of acid liquid can be separated by the drainingfunnel, containing the whole of t-he free acid with the exception ofthat in the small volume of solution (usually about 1.5 c.c.) re-tained in the jelly. If the quantity of solution is determined byvolume, i t must not be forgotten that a saturated salt solutioncontains only 94 per cent. of its volume of water, but the effect onvolume of the small quantity of acid present may be safelyneglected. The acid salt solut,ion is titrated to determine its con-centration of acid, and the quantity is calculated t o the wholevolume of solution absorbed.We have thus the means of determining (a) the free acid unab-sorbed, which forms the " external solution " with which the jellyis in equilibrium; ( 6 ) the free acid absorbed by the jelly; and( c ) the chlorine, ionised and non-ionised, combined with the jellybase.The sum of b and c can be further controlled by the titrationof the dehydrated jelly with alkali hydroxide, which with phenol-phth.alein as indicator, completely decomposes the gelatin sait.*The following table gives a series of such determinations withvarying quantities of acid, and includes the whole of the resultsin the series of experiments t o which they refer, and are moreconcordant than would be expected from the comparative rough-ness of the method.Some of the results are given graphically onthe curves, t o allow the reader to form a judgment of the trust-worthiness of the experimental data; but in many cases there isnot room to insert the whole.* I n the actual experimental work the weight of solution absorbed was taken asthat of the volume, the increase of specific gravity by the acid being in most casenegligible as compared with other sources of error ; and the total chloiine in the jellyis the sum of the uncorrected titrations of the expelled acid and the residual jelly.The free acid of the jelly as given in col. 1 of the table of experimental results is,however, corrected to allow for the portion of solution still retained by the jelly-W O d dc 0.2SSZ2" ,o3 422 3 d 8 8%+-la0.3000.2500.2000.2000.2000.1750.1500.1500.1250.1000.1000.0750.0750,0500.0500-0250-0250.0200.0150.0150.0150.0100.0100.0100.0080.006 --wO H u It 2: 623.2zss 2 $36 2b0.29500-24500.19450.19400-19250.16850,14350.14340.11800.10520.0944049300.06800.06660.05760*04200.04050.01720.01700.01220.01200.00770.00730.00320,00280.00250*0018 o.oc11DILUTE HYDROCHLORIC ACID AND GELATIN.- o E .3*kh 3%;sz .3$$2 -C19.9820.2222.1022.6820.5923.4824.2424.0024.3629.7526.3823.0929.1227.8534.0131.0736.4248.1340.4451.7251.8952.2057.9153.6858.4359.9048.7044.11E_ti 5I. ja" 2I n 1 5-d18.018.621.121.519.323.023.023.023.829.025.622.027.527.834.630.236.548.539.052.552.753.660.054.559.062.050.044.6 -_EjB $5 2 25s",m$22322e4.4053.6803.2453.3252.9252.9902.5552.5502.3 252.3101.7401.4801.3801.3051.4100.8451.0250.4150-3400.3000.3050~0000.1230.0250.0240.0230.0190.019 -f2.2221.9911.7501.7701.7851.7051.6201.6051.4901.4901-4451.4271.3101.3401.2701.2551.2001.0901.1551.1001.1151.0651.0350.8800.8250-8550.7350.590 -e +f6.6275.6714.9955.0954.7104.6954.1754.1553.6153.8003.1852.9072,6902.6452.6802.1002.2251.5051.4951.4001.4201.1551-1580.9050.8490.8780.7540.609 -EEple 3sg8 .E!i G P15.2024.2553-6153.7313-3203.2472.8652.8302.3142.5211.9071.6521.5551.3911.4740.9251.0880.4380.3750-3140.3200.0930.1260.0260-0250.0240.0200.020 --z &z .% *=5.2gg0--M21.4251.4161.3801.3641.3901.4481.3101-3251.3101.2791.2781.2551-1351.2541.2061.1751.1371.0671.1201.0861.10014621.0320.8790.8240.8540.7340.589 -30.26030.21040.16360.16450.16120.13830.11820.11800.08970.08470.07230.07160.05340.04990.04330.02980-02990.00910-00930*00610.00620.00180.00220*00050.00040.00040.00040*0005 -40-3320.2810-2260.2250.2290.2000.1 720.1730.1480.1280.1210-1260.0920.0950.0790.0680.0610.0310.0370.0270.0270.0220.0200.0170.0150.0150.0150.014 --%5 *g .2Sa ik= .Bn.2 o n0 .250.3340-2850.2320.2280.2300.2050.1 740.1750.1470.1310.1230.1210.0870,0890.0770.0590.0550.0330.0310.0250.0230.0330.0240.0210.0200.0160.0080.003 -31'760.7330.7160.7650.6950.7460-7380,6970.7140.7400.6710.5'950.7600.7100.7900.7210.7950.7460.6770.8070.7690.7970.7530.7350.7330,6850.7280-6040-560 -The lettered columns in roman type are observations. The numbered columns initalics are calculated from the observations as follows :c x ed x 0'943 = 8cc x 0.94It is obvious that from these results two distinct series of curvescan be calculated: those of the actual quantity of each associatedwith 1 gram o r 1 mol.of gelatin, and those of relative concentra-tions of the different constituenb of the jelly and its equilibriumacid solution; and these two sets of curves are not necessarilyinterdependent.Taking first the question of quantities, the first problem is thatof the determination of molecular weight. By this must be under-stood, riot the weight of the associated group of molecules, which,if the molecular network theory be correct., may be co-extensivewith the jelly itself; but tlie smallest weight which could exist insome ideal non-associating solvent, retaining its chemical structur318 PROCTER : THE EQUILIBRIUM OFand reactive powers unaltered.It is obvious that the specialcharacteristic of the colloid state is the tendency t o form associatedgroups of molecules, often of quite indefinite size (as in the case ofsuspension sols), which, osmotically, act as a single molecule oras a single ion. If it were practicable to isolate the pure saturatedsalt, the equivalent weight would be that combined with one atomof chlorine, and i t would only remain t o determine the valency ofthe base. This is, however, impossible, since gelatin is a very weakbase, of which the salts hydrolyse readily, and, on account ofsecondary reactions, it is impossible so to concentrate the acid asto make hydrolysis negligible. All that we can obtain is a curve,of which the limit a t infinite concentration is the completelysaturated salt, and before this limit can be predicted, the mathe-matical expression of the curve must be known.For a weak mon-acidic base, such a curve is yiven by the Ostwald hydrolysisformula, which, as was shown by the author in the earlier paperalready quoted (Zoc. cit.), is conveniently transformed into thesimple expression y= where x is the molecular concentrationor normality of the equilibrium-acid, k is the ordinary hydrolysis-constant, and y is the proportion of unhydrolysed salt to the totalbase present. Such a, curve, if the k is small, ascends a t first almostvertically, curves sharply as it approaches unity, and thereafterproceeds almost horizontally, reaching unity only when x beCOm6sinfinite.I f the k be larger, the ascent is more gradual, and thecurve rounder and more prolonged, so that it may still be far fromunity within the limit of experiment, y having obviously a valueof 0.5 when k=x.The curve of gelatin chloride plotted from experiment, as willbe seen by reference to Fig. 1, rises vertically a t first, with all thecharacteristics of a small k, but after turning sharply, continues t orise throughout the limits of the experiment. Such a curve is thatof a diacidic base, or dibasic acid, and is the sum of two curves, oneof which is due t o the (usually small) k of the first valency, andthe other to the larger k of the second. The expression thereforeX + k ’X X becomes 9 = - + - and its limit is 2.* The experimentalX+k, x:+h9’curve is plotted Tor 1 &am of gelatin, whilst the expression is for1 mol., and must obviously be multiplied by ___- *Oo0 to make i tcomparable with experimental results. There are thus three un-inol.wt.* The curve of non-hydrolyecd gelatin given in n previous paper was calculatedon purely theoretical ground? and on the assumption that gelatin was monacid, andthe k then adopted of 0.005 was obviously a compromise between k, and k2DILU'L'E HYDROCHLORIC ACID AND GELATIN. 319knowns to be determined, the two k'sy and the molecular weight;and, although this might no doubt be done by three simultaneousequations from different points of the curve, I have preferred asmore satisfactory, to adopt a method of approximation whichapparently is identical in principle with one described by Lund6n(Meddcl.R. Vetensk. Nobelinstitut, 1, No. 11).FIG. 1.Curves of quantity : 1 gram.N.Where k, is small and k, large, the earlier part of the curve isalmost entirely dependent on the former, whilst the later part isapproximately 1 +-. If, therefore, the value of the curve a tx + k,z = O * O l be assumed to be equal to the reciprocal of the molecularweight, and this be subtracted from the value a t x=O-25, the320 YROCTER : THE EG&UILlBRIUM OFremainder, multiplied by the same reciprocal, will be the valuedue to the second term of the expression, and from these anapproximate k, and k, can be calculated. I f these are nowemployed to correct the first calculations, a closer approximationcan be obtained; and this can be repeated until the results arewithin the limits of experimental error.For each single term,k = - - x. With any approximate molecular weight, values for k,Yand k, can be calculated which will give a curve agreeing with theexperimental a t the two points taken, but unless the molecularweight is very nearly correct, the value of y will be noticeably wronga t a third point, which is most advantageously taken near that ofmaximum curvature.Since the molecular weight must be such as will give wholenumbers of atoms in accordance with ultimate analysis, i t becomeseasy to decide on the only possible weight within the limits ofexperimental error, and a (‘ rational ” formula is obtained.The experimental curve in the present case is very accuratelyXX 1000+ 1.05 * 839 ’ +-- and t o this the curve X represented byx + O 0013in Fig.1 has been calculated. This results in a probable ‘( rational ”formula for gelatin of C,,H,,O,,N,,, with a molecular weight of839, which agrees with Schutzenberger’s o~7n determinations quiteas well as his gener*ally accepted formula, C,,H.,,,O,,N,,, but isslightly higher in nitrogen than the average of published analyses,as is shown by the following table. It is probable that the differ-ence may be accounted for by the extreme difficulty of completelydrying gelatin without decomposition. The hydrogen is, of course,the most doubtful number.Formuls. Analyses.Procter.- Schutzenberger. I p t t e n d e nC3,H,70,3W,, C7,1-J,,0,N,, Schiitzenberger. Mulder. and Solly.C...... 50.06 49.7 50.0 50.1 49.4H .... 6.79 8.8 6.7 6.6 6.80.. .... 24-79 25.2 25.0 25.0 25.1N .... 18.36 18.3 18.3 18-3 18.0It may be noted that Paal obtained a molecular weight of about900 from freezing- and boiling-point methods (Ber., 1892, 25, 1202).It must not, however, be assumed that the molecular weight ofgelatin, from the physical point of view, is necesarily so compara-tively small. The weight calculGated from the previous experimentsis merely that of the smallest quantity which can act as a chemicalindividual, and i t is not incompatible with the association of thecolloid molecules in any way which does not affect their chemicalcombining powers; and, if the view of a molecular network iDILUTE HYDROCHLORIC ACID AND GELATIN.321correct, the whole jelly may be regarded in a physical sense asone enormous colloidal molecule dissociating a number of chlorineions; whilst it is impossible t o say what degree of association maystill exist after Iiquefaction.Since the hydrolysis-constant of a salt of a weak base is theionisation constant of water divided by that of the base, we cancalculate the two basic constants of gelatin as concerned in thereaction, although i t may be probable that the two affinities arein themselves equal, and that the second only takes its lower valuebec.ause of the previous saturation of the first.0.6 x 10-14 - Since Icw =0*6 x 10-14 and Ic, = 1.3 x 10-3, kbl= -1.3 x 10-30.5 x 10-l1, and Lund6n (loc.c i t . )gives for leucine 7ca=1*8 x 10-10, and kb=2*3 x 10-l2, and forglycine (aminoacetic acid), one of the principal constituents of thegelatin molecule, very similar figures, so that there is no interentimprobability in those calculated.Turning from the question of quantities to that of concentra-tions, if we represent on a curvediagram the hydrogen-ion con-centrations by the abscism and those of the chlorine-ion byordinates, the common concentrations of the external acid x, inwhich these are equal, will intersect on .a line passing through theorigin a t an angle of 45O, and this will be the axis of a series ofright-angled hyperbolas, corresponding with the different valuesof x, and of which x2 will be the generating square; and on which,for each value of x, all possible solutions of the equation x3 = H x C1will lie, and if the concentration of one of these constituents isgiven, the equilibrium will be definitely determined.At any suchpoint, the hydrogen and chlorine ordinates will enclose a rectangleequal in area t o x2, the chlorine being necessarily the greater fromthe ionisation of the gelatin chloride.It is obvious that on the concentration of this ionised chloridethe whole equilibrium depends, and if its relation to x can bedetermined, the problem is definitely solved. An experimentalsolution is given by the determination of the concentration of thefree acid of the jelly, which is equal to its hydrogen abscissa.Asthe jelly is completely permeable to the ions of the external acid,it must be in equilibrium with it both osmotically and thermo-dynamically, that is, both the total concentration of ions and theproduct of th6 hydrogen and chlorine ions must be the same ineach case, or any difference which exists between the two mustbe compensated by an electric potential a t the interface. Thereis no evidence, experimental or theoretical, that the colloid gelati322 PROCTER : THE EQUILIBRIUM OFion exerts any osmotic pressure, and, as an associated network,it should, theoretically, only act as a single molecule; but sincethe two sides of a rectangle are necessarily greater than those of asquare of equal area, some surface-potential must exist, opposedin sign t o that shown by Donnan (Zoc.cit.) to be caused by theunequal concentration of the hydrogen and chlorine ions. Sincethe ionised chlorine is confined to the jelly by the attraction of itsnon-diff usible colloid ion, the adjustment of equilibrium betweenthe jelly and the external acid can only take place by the passageinwards or outwards of hydrochloric acid and water, and if wesuppose the jelly divided into separate volumes, each containingone of the constituents a t the common osmotic pressure, that ofthe acid will be of the same concentration as the external acid x,and will have an osmotic pressure of 22, since both hydrogen ionand chlorine ion are of x concentration, and the ionised chlorine,to be at the same osmotic pressure, must also have a concentrationof 22, since the chlorine ion of the acid cannot be expelled withoutits attendant hydrogen ion.Thus the x2 of the external acid is in oemotic equilibrium withthe 2x of the jelly, and if we plot the concentration of the externalacid as x, we must also plot the osmotic concentration as 4% t omaintain the same relation.Experiment shows that, measuredin terms of x, the concentration of the ionised chloride isapproximately dyz, but is more accurately expressed by J 2x + 0.02,the explanation of the small correction being discussed later.Calling the concentration of the ionised gelatin chloride C1,tthe concentration of hydrogen ion in the jelly is algebraically-'I,+ ~c1,2+4xa and that of the expelled acid2but, graphically, all the concentrations are given by a simple con-struction, the proof of which is obvious.I f the C1' ordinate ofx be produced vertically to an additional length of CVg, and aline be drawn through this point parallel with the axis of thehyperbola (that is, a t 45O), it will cut the hyperbola a t the commonpoint of intersection of the IIC' and C1' ordinates of the jelly, theIT* ordinate of which, if produced, will cut the x vertical a t thetot.al Cl' concentration, and a horizontal line through the pointwhere the (31' ordinate of the jelly cuts the axis of the parabolawill cut the x vertical a t the hydrogen-chloride concentration ofthe jelly, whilst the difference between this and x will be the acidexpelled. If continuous curves are drawn through these pointsfor the different values of x, they will divide the diagram intDILUTE HYDROCELORIC ACID AND GELATIN.323regions of free hydrogen chloride or hydrogenion concentration,and of ionised chloride, respectively, below and above the straighbline axis of x. Experimentally, the concentration of the ionisedchlorine is obtained by dividing x2 by the concentration of freeacid in the jelly, and that of the total chlorine by direct titration.Both are plotted in Fig. 2, but, the ionised is marked 0 and theFIG. 2.0.05 0;lO 0.15 0.20 0.25 0.30 N.H'.Xtotal x . It will be seen that they practically coincide, and it maybe concluded that the gelatin salt is almost wholly ionised, or, a tleast, to an extent comparable with hydrogen chloride, for theincomplete ionisation of which no allowance has been made.With regard to the correction, approximately 0.02, added to 2xunder the squareroot sign, it may be noted that, putting x=O324 PROCTER : THE EQUILIBRIUM OFa value of chlorine-ion concentration still remains equal to J0.02.This ionisation of chlorine in absence of an appreciable hydrogen-ion concentration is also confirmed by experiment, a measurablechlorine-concentration being reached before any free acid is showneither by indicators like methyl-orange, or by the hydrogen con-centration cell.The probable explanation is that as gelatin isamphoteric, and, to some extent, ionises both H' and OH' in theneutral state, a small amount of neutral chloride can be forlr,edin absence of any other free acid than its own; or, perhaps, inother words, that it must be brought to a neutral condition ascompared with water before any hydrolytic production of hydrogenchloride can take place.This is in accordance with experimentsquoted by Pauli (KoZL-Zeitsch., 1913, 12, 222), which prove thatin neutral solution, gelatin and other proteins wander to the positivepole in elecikophoresis, and that a small amount of acid is necessaryto bring them to a neutral condition in which they are unaffectedby the current, whilst, with further additions of acid, their basiccharacter preponderates, and they wander to the negative pole(probably as basic ions). The correction may thus be regarded assimply indicating the .amount of hydrochloric acid required beforeneutrality is reached.It is obvious that, except for this small correction, the concen-trations are all purely mathematical functions of x, and thereforeindependent of the chemical properties of the protein, and .applic-able to all substances capable of similar equilibria.If the tem-perature is raised so that the jelly melts, it can be shown thatequilibrium still exists, although actual measurement, is complicatedby the necessity of a membmne, and the much longer time requiredt o attain equilibrium than with the thin sheets of the presentexperiments; but, in the case of gelatin, neither concentration cells,conductivity, nor the experiments of G. S. Walpole on refractiveindex (Roll.-Zeitsch., 1913, 13, 241) show any break in the curvesa t the melting point, .and, in all probability, the degree of associa-tion is still very large.Since such associated groups of ions muststill be in equilibrium with their surrounding solution, they mustalso be associated with acid and water in the terms of the jellyequilibrium, and the suggestion is obvious that, whilst the trueequilibrium-jelly is a homogeneous molecular solution, the .apparentaqueous solution is really a two-phased structure of associatedcolloid systems, surrounded by their equilibrium liquid. The samemay probably be true of jellies made up with arbitrary quantities ofwater and acid, and may serve to explain some of the results ofearlier investigators. Certainly, electrometric experiments madewith such jellies, both by conductivity and by the concentratioDILUTE HYDROCHLORIC ACID AND GELATIN.325cell, gave somewhat abnormal results; and it is clear that unlessby chance the exact equilibrium mixture has been made, they mustbe in unstable equilibrium, and must tend to separate into equi-librium-jelly and its corresponding acid, possibly developing theButschli sponge-structure.I n this connexion, it is well to refer to the work of Pauli (Zoc.cit.) on the viscosity of acid protein solutions, in which he obtainedcurves identical in type with the swelling curve of acid gelatin,which probably can be explained by the varying quantities ofwater and acid associated with the gelatin molecules.It was shown in the earlier paper (Zoc. cit.) that the volume of -swelling was nearly proportional to - X + J; or - J x or to theX + k x+k’theoretical quantity of non-hydrolysed gelatin divided by J 2.Obviously, if the quantity of ionised chloride a t any point be dividedby the corresponding concentration of the ionised Cl’, the quotientwill be the volume of the jelly, and it is found that by dividing thecalculated quantity of non-hydrolysed chloride which, it has beenshown, is almost wholly ionised, by d 2 x + 0.02, a curve is obtainedwhich agrees very closely with the smoothed curve of observedvolumes, both in type and quantity.It is worthy of note that theabove calculation takes no account of any solid rigidity or elasticityof the jelly, and it may therefore be presumed that these have noexistence apart from the osmotic pressures of the jelly, or, a t least,tihat they are of negligible amount.Finally, a large number of determinations were given in theearlier paper of what was called “ acid fixed ” ; that is, of the excessof acid in the jelly over that contained in an equal volume of theexternal solution.This is a well-defined quantity, rising rapidlywith the concentration of the external acid to about 0.8 milligram-molecule for 1 gram of dry gelatin, formrng a slight maximumat about s=0*015 and a still less marked minimum a t aboutx=O*15, and again increasing, but only very slowly. The value iseasily and accurately obtained by titration of the melted Jellyand of its equilibrium acid, but the curve is peculiar; and, a t thetime, w-as incapable of definite explanation. It is now obviouslythe quantity of gelatin chloride less that of the free acid expelled.Calling Q the value of the quantity of non-hydrolysed gelatinchloride, c the concentration of the ionised chloride, and a thatof the expelled acid, this is given by the (somewhat simplified)expression Qc2, This accurately reproduces the peculiarities ofthe experimental curve, but is very slightly too low in actualquantity, presumably because the theoretical expression assume326 PROCTER : THE EQUILIBRIUM OFtotal ionisation of the gelatin salt, and the consequent expulsionof a slightly larger quantity of free acid than actually takes place,All the curves described are plotted in Figs. 1 and 2, togetherwith the experimental results (so far as space allows), and thecorresponding algebraical expressions are annexed ; and to facilitateexperimental checking, the numerical calculated values f o r anumber of values of x are also given in the following table.Calculated Mathematical Curves for 1 gram of Gelatin.QuantityQuantity Quan- excess of Con-un- Quan- tity OF C1 centra-Nor- hydro- tity free in jelly Con- tion a tmahty lysed total acid over Volume Concentra- centra- H'of gelatin C1 HCI eq.vol. of Concen- tion, tion ex-eq.acid. chloride. of jelly. of jelly. solution. jelly. tration If'. C!, . total Cl'. pel!ed.2. a. b. C. a. e. f. 8. h. a.0.001 0.520 0.522 0.002 0.481 35.0 0*00007 0.0149 0.0149 0.00090.002 0.725 0.737 0-012 0.615 46.8 0.00025 0.0155 0.0157 0.00180-006 0.952 1.023 0.071 0.750 54.7 0.0013 0.0174 0.0187 0.00370.010 1.066 1.283 0.219 0.754 53.3 0.0041 0.0200 0.0241 0-00580.015 1.114 1.494 0.380 0.747 49.8 0.0075 0.0223 0-0298 0.00750.02 1.142 1.664 0.522 0.732 46.6 0.0112 0.0245 0.0357 0.00880.03 1.176 1.965 0.789 0.720 41.6 0.0190 0.0283 0.0473 0.01090.05 1.216 2.467 1.251 0.710 35.1 0.0356 0.0346 0.0702 0.01440.10 1.279 3.440 2-161 0.714 27.3 0.0793 0.0469 0.1262 0.02070.15 1.330 4.253 2.923 0.718 23.5 0.1244 0-0566 0.1810 0.02560.20 1.375 4.987 3.612 0.743 21-2 0.1702 0.0648 0.2350 0.02980.25 1.415 5.662 4-247 0-758 19.6 0.2165 0-0721 0.2886 0.03350.30 1.452 6.318 4.866 0.773 18.4 0.2632 0.0787 0.3419 0.0368The following are the forinuke used in calculation; the lettersrefer to the corresponding columns.X - C1, + JCJg2 + 4x22A = f + g = - 2 2fd = b - e x i = x - fa98 = -.The dehydrating effect of salts having a common ion with theacid has not been dealt with experimentally in the present paper,since it is obvious that if the anion of the acid diminishes swelling,by increasing osmotic pressure and concentration, additional quan-tities of the same ion introduced as neutral salt must have thesame effect.Even numerically, so long as the salt solutions aredilute, it is probably sufficient to take account of the common iononly, using the same mathematical formulai! as with the acid alone,but with more concentrated solutions, the effect on ionisation a tleast must be considered, and we can no longer assume that thecolloidal salt is totally i o n i d DILUTE HYDROCHLORIC ACID AND GELATIN.32 7It was shown in the earlier paper that when a salt with nocommon ion is introduced, as, for instance, sodium chloride intoa solution of gelatin formate, a quadruple equilibrium is produced,in which each anion is in equilibrium with its own gelatin salt.This has been shown rather strikingly by a recent experiment withthe substances just named, in which the gelatin was shown byanalysis to have combined with as much as 3 per cent. of .hydro-chloric acid derived from the sodium chloride. Similarly, inpresence of large excess of sodium formate, hydrochloric would bereplaced by formic in the gelatin salt, and this sort of reaction isnot without bearing on some physiological problems.The question whether the action of neutral salt solutions ongelatin falls under the aame theory still demands further study.It was shown in the previous paper (Zoc. cit.) that sodium chloridewas abaorbed by gelatin from neutral solution with increasedswelling, but was replaced and expelled by hydroch1o:ic acid, inpresence of which the absorption of salt was negative. Neutralsalta may combine with amphoteric proteins, either by the anionbecoming attached to the amino- and the cation to the carboxy-group, or the whole salt may be attached t o the amino-group, a,phydrogen chloride is to organic bases, by the nitrogen becomingquinquevalent; and the probable structure of the protein saltmust be left t o more purely organic chemists to decide, since eitherwould fulfil the requirements of the present theory.Conclusions.-The swelling of gelatin in dilute acid solutionsdepends on the osmotic pressures and equality of products of adiacid ionisable salt of gelatin as a base, and of the external acidwith which it is in equilibrium; and the ionisation-constants andmolecular weight being known, all the other quantities are deter-mined. The method is general and applicable to other proteinsand other acids.The ionic concentrations in the jelly are all mathematicalfunctiom of that of the equilibrium acid, and independent of thechemical nature of the gelatin or other protein.While gelatin jelly in equilibrium with an acid is believed t obe a molecular solution, jellies and colloid solutions, in which theconditions of equilibrium are not fulfilled, are probably two-phasedstructures, and may exhibit the pores described by Biitschli andvan Bemmelen.PROCTER INTERNATIONAL RESEARCH LABORATORY,UNIVERSITY OF LEEDS

ISSN:0368-1645    

DOI:10.1039/CT9140500313

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

328 LEFEBURE : ABSORPTION OF GASES BY CELLULOID.XXXVL-Absorption of Gases by Celluloid.By VICTOR LEFEBURE.THE discovery of the fact that celluloid films will take up gases wasmade in an indirect manner. It was proposed to use celluloidfilms as a basis on which to deposit plant pigments, in order t oexpose as large a surface as possible of the pigments to the actionof certain gases. Amongst these gases was carbon dioxide, and onattempting a control experiment, using simply celluloid film andcarbon dioxide, the film was found to take up a large quantityof gas.Considerable work has been carried out on the absorption ofgases by membranes. The object of most of it, however, has eitherbeen to demonstrate the specific nature of diffusion through themor to establish a parallel to some physiological process in livingorganisms (compare Hill and H.E. Ridewood, Proc. Physiol. SGC.,Few and more recent exp0riment.s have been concerned with theactual determination of the nature of the phenomenon by quanti-tative methods. Doubt still exists, however, on two essential points.First, the exact nature of the absorption in any particular case isnot clearly established. Secondly, it is not known whether thereis a general mechanism.We cannot experiment on the first point without throwing lighton the second.I n view of these facts, and knowing that celluloid offered certainadvantages for experimental work, the, experiments to be describedwere carried out. Both purely qualitative and actual quantitativeexperiments were commenced.Most of the latter are not yetcomplete.The apparatus and working method were common to all theabove so-called qualitative experiments, and were as follows :The absorbing material was placed in -4 (Fig. l), a tube con-nected by a mercury seal with the rest of the apparatus. T, ledto a mercury pump. All the taps wereopened except T3, leading t o the gas reservoir, and T4, leading tothe atmosphere. The whole apparatus was freed from all gas,using the mercury pump, in the circuit of which was a phosphoricoxide tube. That a vacuum could be obtained over celluloid wasfound by leaving the exhausted apparatus, containing that material,1899, 13-19).G was a mercury gaugeLEFEBURE: ABSORPTION OF GASES BY CELLULOID. 329overnight. After twenty-four hours the apparatus was stillvacuoiis.Gasentered up to 1', and into the tube B, and it was admitted to theactual apparatus by judicious use of T, and previous adjustmentof R until the gauge G indicated atmospheric pressure.The wholeoperation of entry of gas did not occupy more than ten seconds.Any absorpt>ion now occurring would cause a rise in the gaugeT I and T, were now closed, and T, and T, were opened.FIG. 1.R iarm y. This rise, measured at equilibrium, gave, for differentsamples in A , a comparativ'e measure of the absorption. Themeasure might be thought untrustworthy owing to gas being takenup during the few seconds of entry. This correction was foundt o be small, and, further, a small heat evolution accompanyingabsorption must have neutralised this initial error,It should first bO mentioned that all the gas taken up by thecelluloid could be pumped off in a few hours.The following tables give the results of the experiments :VOL.cv. 330 LEFEBURE : ABSORPTION OF GASES BY CELLULOID.Material.Kinema film ......Xylonite ..........Greenberg's Cel-luloid .........Viscose .............ArtXcial silk ....Gelatin ............." Precipitate . ' ...2a. {Refilmed film ....3. { Nitrocellulose ....Camphor ...................Celluloid ............Charcoal ..........Caoutchouc2b. [ ......Weightof film.Grams.1013.710101010106101010101010Pressure differenceTemperature. in cm. of mercury.18 36.723 38.718 37.150 44-518 2.6518 4.218 8.918 6.022.418.0< 1.0Volume Absorbed at N.T.P.40 C.C.approx.100 7 ) 7 )5-10 y y 9 7The conclusions to be drawn from these experiments may besummarised as follows :Series 1.-The effect is common t o all kinds of celluloidexamined.Series 2.-The effect is relatively specific for celluloid in so faras the materials examined were concerned (with the exception ofcaoutchouc and charcoal).Series 3.-The effect is not retained by the precipitated material(made by pouring the acetone solution into water). It is recoveredto a large extent by the refilmed film. A more complete accountof work on this " precipitate " is being prepared.Experiments made by substituting for carbon dioxide the gasesair and hydrogen showed the relative magnitudes of the effects tofollow the same order as that in which the gases are mentioned,hydrogen being the least absorbed.Finally, diffusion of carbon dioxide through celluloid films wasestablished.The quantitative experimenk, the chief object of which was todetermine the mechanism of the effect, were, and are, being carriedout along three distinct lines.The experiments include determinations of :I.Rates of absorption a t varying ( a ) temperature, ( b ) pressure,11. Equilibrium curves under varying conditions.111. Rntes of difficsion under varying conditions.Dispersivity is a term which has been used to express the ratioof tho total surface of a substance to its total volume.I n the aboveexperiments it is used in the sense of the ratio of total measurableexternal surface t o total voluine, unless otherwise stated.( c ) dispersivity (defined below)LEFEBURE : ABSORPTION OF GASES BY CELLULOID. 331Determinations of I and I1 have already been made, andalthough the data obtained are not yet complete enough t o yieldany definite conclu~ions, yet the curves will be given and theirfeatures indicated.I.-Bates of Absorption.The apparatus used will now be described, and a t the same timethe general experimental method given.FIG. 2.The experimental t.ube T, (Fig. 2) rested against a scale S etchedupon glass. I', was connected by means of the four-way piece F to(1) experimental bulb B through C, (2) mercury pump through P,and (3) gas reservoirs through R.From below T, was in connexion with another clean tube T,through a tap A of large bore (to ensure freedom of movementof mercury column).2 332 LEFEBURE : ABSORPTION OF GASES BY CELLULOID.For a determination the level, L, in T, was set a t a convenientheight a t the lower end of the scale.With Rclosed the whole cipparatus was completely exhausted. C and Pwere then closed, and gas was admitted from R at normal pressure.C was then opened, and the time taken. As soon as the desiredpressure was attained (seen by the gas reservoir), R was closed andA opened, and readings of time and absorption were taken withthe two levels adjusted. The gap between the first and second timereadings was usually about thirty seconds, and the amountabsorbed during that time was found by extrapolation.This wasmade possible by the close approximation of the initial part of therate curve t o a straight line.A was turned off.Prelimi?mry Rntc. Rendirigs witlb Vnrying Bispersiuity.Rate, curves were obtained for five samples of celluloid, comingfrom the same source, each weighing 5 grams and varying inthickness.Weight.Sample. Grams.1 52 53 54 55 56 5Thickness. Area.Mm. Sq. cm.1-32 -0.75 155.230.52 159-500.33 235.460.25 309.410.10 807.74The curves indicate that as the films become thinner, and withincreasing dispersivity, the effect becomes more like “ adsorption.”I n fact, curve 6 (Fig. 3) shows clearly the two features of aninitial rapid taking up of gas, followed by a very slow one, corre-sponding with adsorption, and later, solution attending slowdiffusion.Observations on Initial Rates.The actual readings of time and absorption reveal better thanthe curves of the last series that the initial rates are practicallystraight lines (Fig.4).A case of pure solution would yield the relationship: initialrate xi area of external surface, other factors remaining constant.The following figures are obtained, however :Sample. Initial rate. Area x.6 26.7 807.7 5-25 11.3 309.4 2.04 5-4 235.5 1.5159.5 1.0155-2 1.0 213 ‘;:;I- - -They indicate that no simple relationship exists, such as oneThe initial rate increases much would expect for tru0 solutionLEFEBURE: ABSORPTION OF GASES BY CELLULOID.333FIG. 3.0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2Time in hours.Broken Ziii c-No readings over this period, Temp. = 18".&FIG. 4.ITime in minutcs334 LEFEBURE : ABSORPTION OF GASES BY CELLULOID.more rapidly tlhan does the area. The initial rate will depend onSOMB factor which will probably be capable of expression a~ afunction of the surface, but is not directly proportional to thesurface. Such a factor might be variation in surface structureowing to conditions of formation of the film, such as evaporationafter rolling.A more definite view will be given when more comprehensiveevidence is acquired.Tlaria tion of Temperature.Just sufficient readings were taken to indicate the general natureof the influence of temperature change.Sample (4) was thoroughlydeprived of any gas held from the previous experiment. RatesFIG 5 .0 1 2 3 4 5 6 7 8 9 l O i l l 1 2 1 3 1 4Time in hours.were then measured a t the following temperatures: (a) 66O, usinga bath of methyl alcohol vapour; ( b ) room temperature, 18O, usinga cotton-wool covering; and ( c ) temperature of melting ice.The curves (Fig. 5) indicate that with rise of temperature thereoccurs small khange in rate of absorption but a decrease in totaleffect.It will be noticed that the initial rise in the curve, due presum-ably to adsorption on a rapidly attained surface, is not accentuatedin the case of the ice-temperature experiment. This may be takenas another indication of the fact that any truly external surfaceis small compared with internal adsorption and solution. Interest-ing results are expected with curves for the temperature of boilingcarbon dioxideLEFEBURE: ABSORPTION OF GASES BY CELLULOID.335E p ~ i l i b rium Curves.The burette used t o measure gas absorbed a t varying pressureswas similar to that used by Travers and Miss Homfray in theirinvestigations on gas absorption by charcoal. The author isindebted to Miss Homfray for the use of parts of her originalburette.The entire system, including gas generator, point burette, andgas burette, was, however, complete in itself. Carbon dioxide waegenerated in A (Fig. 6) by heating previously dried and pure mag-nesium carbonate. The gas passed through phosphoric oxide in B,and was collected by the pump C, which also served t o exhaust thepoint burette E.The collected gas was carried in gas jars overmercury to the gas burette D, whence a known volume of i twas passed through capillary tubing to E.Two isotherms were obtained for the temperatures Oo and 1 8 Oby using baths of ice and layers of cotton-wool respectively. TheFIG. 6 .A 3 <POINT BUR€TT€ - PUMP cErelationship between concentration in solid phase and concentra-tion in gas was plotted, and in both cases curves were obtainedintermediate in form between the true adsorption curve and thesolution straight line (Fig. 7). They tended, however, towardsthe straight line relationship, and in this connexion it is inter-esting to note the result of Reychler.This investigator, examin-ing the case of the absorption of sulphur dioxide by caoutchouc,drew the conclusion that it was probably a cast3 of solution. Thethree readings on which the conclusion was based, however, occurbetween the pressures 34 cm. and 59 cm. of mercury. Fromthe curves it is seen that three readings between these pressurelimits might have been interpreted in terms of solution in ourcase of celluloid. I f there is any analogy between the cases ofindiarubber and celluloid, one might imagine that a continuationof Reychler's readings would yield curves similar to those obtainedfor celluloid336 LEFEBURE: ABSORPTION OF GASES BY CELLULOID.General Summary.The wholes of the more preliminary work, both qualitative andquantitative, leads to the conclusion that the phenomenon isanother case of adsorption? or a combination of adsorption andsolution.We are then faced with the question as t o what is theadsorbing surface. There are three possibilities, namely, I. Actualexternal surface seen by the naked eye. 11. A surface of a similarnature, between celluloid and gas, presented by a porous structuredeveloped within the celluloid mass, and in view of the observationsbelow, probably near t o the external surface of the celluloid; andFIG. 7.0 10 20 30 40 50 60 70 80 90 100Pressure of c'wbon dioxidc in em. of mercury. Weight of film = 8 grams.111. A surface between two phases which are the remains of thedisperse and continuous phases of the colloidal system whichcelluloid admittedly possessed just previous to solidification byevaporation.These possibilities may be considered in turn, from the pointof view of data already obtained.It should be remembered thatany subsequent explanation is put forward with great reserve,subject t,o change when more data are acquired.I. I f this be the state of affairs, then it can be detected fromthe isotherms f o r equal weights of celluloid with different surfacLEFEBURE : ABSORPTION OF GASES BY CELLULOID. 337development. Considering the small variations of external surfaceexposed in the, rate and equilibrium experiments already made, itis highly improbable that mere external surface is the only factorin the adsorption.11. It should be noted, however, that in the rate experiment withthe thinnest film, where the rate curve indicated a true adsorption,the part of the curvy indicating adsorption accounted for morethan nine-tenths of the total gas taken in, and the time was lesstha.n one hour.Now this large initial effect must be concernedwith some part of the celluloid which can be attained withoutslow diffusion, for in the experiments with the thicker films, wherethe influence of diffusion is greatest, hours passed before one-thirdof the total ,gas had been taken in. We are thus led to concludethat the initial effect, which becomes so large with the thinnestfilm, is Concerned with some easily available surface between gasand celluloid. Such a surface might be caused by a developmentof porous structure within the mass, and near to the externalsurface of the celluloid.The experiments giving initial rates can now be appropriatelyconsidered.They indicated that a factor in absorption was somefunction of the actual external surface, increasing from film (1) tofilm (6) more rapidly than external surface. This factor, it wassaid, might be concerned with conditions of formation of the film,possibly some evaporative process. Porous structure would, nodoubt, be influenced by this process; thus the two lines of evidenceare capable of a similar explanation, that is, one in terms of adevelopment of porosity at the surface.111 The surface between disperse and continuous phases will,no doubt, play an important part in the phenomenon, but itsinfluence will not be discussed until more is known with regardto rates of diffusion through celluloid.The author desires to emphasise the tentative nature of theabove obseivations. The primary object of this paper is to presentthe general nature of the phenomenon, rather than to give i t acomplete explanation.The author wishes to express his gratitude t o Sir William Ramsayfor the active interet taken in ths early stages of this research,and his great indebtedness to Professor F. G. Donnan and Dr.Whytlaw-Gray for help received throughout the work. He alsowishes to acknowledge the kind assistance of Mr. R. S. Felgate inthe determinations of rates of absorption.UNIVERSITY COLLEGE,GOWER ST., W.C

ISSN:0368-1645    

DOI:10.1039/CT9140500328

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

338 WATSON : 6’-AMINOQUERCETIN.XXXVl I.-6’-Aminopuercetin.By EDWIN ROY WATSON.QUERCETIN is a natural hydroxy ketonic dye of considerable valueon account of its cheapness and the fastness of the shades obtainedwith it on suitable mordants. Other members of the flavone groupare also valuable for similar reasons. The chief limitation of thegroup seems to lie in the fact that the colour never goes beyondyellow, orange, or brown shades, It seemed, therefore, of interestand value to attempt to prepare derivatives which, whilst retainingthe fastness of the original dyes, would yield deeper shades, such asred, violet, or blue.The first method which suggested itself for fulfilling this objectwas the introduction of additional auxochrome groups. Thismethod has proved very useful in the alizarin group of dyes andthere #&re many cases where the addition of one or two more auxo-chromes causes a great deepening of colour (compare brazilein andhaematein, fluorescein and gallein). There were, certainly, reasonsfor not expecting too much from the addition of more auxochromesin this group.Myricetin and quercetin have not appreciablydeeper shades than luteolin, although they contain two and oneadditional hydroxyl groups respectively. It could be argued, how-ever, that much might depend on the positions of the auxochromes,thus, anthracene-blue, W.R., 1 : 2 : 4 : 5 : 6 : 8-hexahydroxyanthra-quinone, dyes blue shades on chrome and rufigallol, 1 : 2 : 3 : 5 : 6 : 7-hexahydroxyanthraquinone, gives only brown shades on the samemordant.A t any rate, it appeared worth while t o introduce anadditional auxochrome into quercetin and observe the effect onthe colour of the dye. The preparation of a hydroxyquercetinpossessed the further interest that i t might prove identical withmyricetin, gossypetin, o r quercetagetin, and thus confirm or helpin arriving a t the constitutional f ormulz of these substances.By the complete methylation of quercetin to protect the molecule,nitration, reduction, and subsequent demethylation, 6’-aminoquer-cetin was obtained. Attempts to convert the amino-group into ahydroxyl group by diazotisation and boiling .with water or diluteacid have not as yet been successful. 6/-Aminoquercetin dyesalmost the same shades as quercetin, and its preparation did notthus effect the primary object of this investigation. The subsequentinvestigation of quercetagetin and gossypetin (A.G . Perkin, T., 1913,103, 209, 650) seems t o show that the multiplication of auxochromegroups, whatever positions they may occupy, will not appreciablydeepen the colour in this group of dyesWATSON : 6’-AMINOQUERCETIN. 339Further work on somewhat different lines has been more suc-cessful and has resulted in the preparation of derivatives of quer-cetin which dye violet and blue shades. These will be describedin a subsequent communication.I n the courso of this investrigation, several oxonium salts ofquercetin pentamethyl ether were isolated, namely, the hydrochloride,C2,H2,O7,HC1, the hydro bromide, C,,H,,O,,HBr, the sulphate,C20H2007,H2S0,, and the nitrate, C,,H,,O,,HNO, ; also di bromo-pzcercetin pentamethyl ether hydro bromide, C2,H,807Br,,HBr.These compounds are all of a bright yellow colour a.nd easily pre-pared.Their formation wras rather unexpected, as, although quer-cetin itself readily gives such bright yellow oxonium salts, pro-gressive methylation seems to reduce the tendency to form com-pounds of this character. Rhamnetin and rhamnazin yieldsulphates with difficulty, but no compounds with the halogen acids(A. G. Perkin, T., 1896, 69, 1439) and quercetin tetramethyl etheronly forms a very unstable sulphate. Their bright yellow colourindicates tihat they should be assigned a quinonoid structuresuch as:0 0-CH,These compounds seem somewhat comparable with the hydro-chloride of fluorescein dietliyl ether which is of an intense yellowcolour and decomposed by water (Nietzki and Schrijter, Ber., 1895,28, SO), and most, if not all, become bright red on the surface ifleft exposed to the air, although, f o r the present, no explanationof this behaviour can be offered.EXPERIMENTAL.Preparation of Quercetin Pentamethyl Ether.-This was effectedby a modification of Valiaschko’s process (Arch.Pharm., 1904, 242,242; Ber., 1909, 42, 727). Herzig and Hofmann’s simpler process(Ber., 1909, 42, 155) was tried without success. I n preparingquercetin trimethyl ether from quercetin by treatment with potass-ium hydroxide and methyl sulphate in methyl-alcoholic solution,i t was found necessary to add the methyl sulphate and then thealcoholic potassium hydroxide as quickly as possible to the boilingsolution, instead of gradually, as recommended by Valiaschko.For the later stage of the process, namely, conversion of the tri-methyl ether into the pentamethyl ether through the potassiu340 WATSON : 6'-AMINOQUERCETIN.salt, i t was found necessary to leave a little excess of potassiumhydroxide in contact with the potassium salt.6f-Nitroyuercetin Pentamethyl Ether, C,,H,O,(OMe),*NO,.-Fivegrams of finely-powdered quercetin pentamethyl ether were addedgradually to 50 C.C.of cold nitric aGid (D 1.4 which had been boiledwith carbamide nitrate), in which it dissolved to a clear yellow-brown solution. This was poured slowly into 24 litres of coldwater, kept stirring, and the mixture was then boiled until thegelatinous precipitate changed into bright yellow, needle-shapedcrystals.After cooling, the crystals (5.15 grams) were collected,washed with water, and dried. The substance may be renderedpure by one or two recrystallisations from acetone, from whichsolvent i t is deposited in golden-yellow, needle-shaped crystalsmelting a t 202-204O. It can also be conveniently crystallisedfrom ethyl alcohol, methyl alcohol, ethyl acetate, or benzene; isvery soluble even in cold chloroform or acetic acid; and is insolublein ether, carbon disulphide, o r light petroleum. It dissolves incold sulphuric acid to a deep reddish-brown solution ,and is pre-cipitated unchanged on pouring this solution into water.0.1 134 gave 0.2405 CO, and 0.0463 H,O.0.1487 ,, 4.7 C.C.N, (moist) a t 14O and 769 mm. N=3*76.0.1516 ,, 0.4187 AgI. Me=17.61.C = 57.83 ; H = 4.53.C,,H,,09N requires C = 57.55 ; H = 4.55 ; N = 3.35 ;Me = 17.98 per cent.The above-described method of nitration is the only one by whicha good yield of the mononitro-compound has yet been obtained. I nsmall quantity (up to 10 per cent.), together with oxiaation pro-ducts, it was formed by the action of boiling dilute aqueous nitricacid on quercetin pentamethy1 ether or by nitrating this substancein the cold in glacial acetic acid solution.6'-Aminopuercetin Pentamethyl Ether, Cl,H402(OMe)5*NH2.-The preceding nitro-compound was readily reduced by tin andalcoholic hydrochloric acid, yielding the hydrochloride of 6/-amino-quercetin pentamethyl ethpr.Five grams of the finely-powderedmononitro-compound were mixed with 150 C.C. of alcohol, 15 C.C.of concentrated hydrochloric acid and 5 grams of finely granulatedtin, and the mixture kept nearly boiling. After some time, another15 C.C. of hydrochloric acid and 5 grams of tin were added. I nabout two hours, reduction was complete, and the fine, white, needle-shaped crystals produced were collected, dried, and dissolved in2 litres of boiling water to which a little dilute hydrochloric acidhad been added. The solution was filtered hot and treated at oncewith sodium carbonate solution until alkaline, which precipitatedthe free base as a sandy deposit of rhombic crystals.3.5 GramWATSON : 6'-AMINOQUERCETIN. 341were thus obtained, being a yield of 70 per cent. on the weight ofnitro-compound taken. No further quantity could be isolated byworking up the mother liquors.The substance can be purified by recrystallisation from benzene,from which solvent i t is deposited in white, stout, heavy prisms,melting a t 200-202O. It can also be conveniently crystallisedfrom hot ethyl or methyl alcohol, acetone, o r ethyl acetate. It isvery soluble even in cold chloroform, but practically insoluble inether, light petroleum, or carbon disulphide.0.1095 gave 0.2493 CO, and 0.0534 H,O.0.1353 ,, 4.7 C.C. N, (moist) a t 30° and 758 mm. N-3.7.0.1523 ,, 0.4553 AgI. Me=19'06.C,,H,,O,N requires C = 62.01 ; H = 5.42 ; N = 3-61 ;Me = 19.37 per cent.Cl,H40,(OMe),*NH2,HC1.-This substance was obtained in fine, white, needle-shaped crys-tals in the reduction of nitroquercetin pentamethyl ether.It w-asalso prepared by boiling the free base with dilute hydrochloricacid. On cooling the solution, fine, white, needle-shaped crystalswere deposited, which were collected and dried in a vacuum oversoda-lime, when they melted and decomposed at 245-247O. Thepure dry compound dissolves in cold water, owing to decompositionof the salt and the formation of a pseudo-solution of the base, but,after a short time, crystals of the free base are deposited.C = 62.09 ; 13 =5'41.6~-Aminopuercetin Pentamethyl Ether Hydrochloride,0.4886 was neutralised by 11.2 C.C.N/lO-KOH; HC1=8*37.6'- A mino qu erce tin Pe ntam e t hyl Ether Sulpha t e,C,,H,,O,N,HCl requires HC1= 8-61 per cent.C1,H402 (OMe) rj*NH,,H,S04-This salt was prepared by dissolving the free base in boilingdilute sulphuric acid ( 1 :20). On cooling the solution, white,needleshaped crystals separated, which melted and decomposed at245-247'.0.2020 was neutralised by 8.2 C.C. nT/lO-KOH; H,SO,= 19.89.C,,H2,O7N,H2SO4 requires H,SO, = 20.20 per cent.6I-Diace tylarnino pzsercetin Pentn me thy1 Ether,C,,H4O,(0Me),*NA~.-Aminoquercetin pentamethyl ether was boiled with excess ofacetic anhydride for several hours. The solution was then filteredhot and, after the addition of alcohol, evaporated on the water-bath. The residue, which almost immediately became solid, wasrecrystallised from alcohol.If necessary, the whole process wasrepeated. The substance crystallises in white prisms, melts a t 185O342 WATSON : 6’- AMINOQUERCETIN.is readily soluble in acetic acid, bu-t less so in alcohol. It has anexceedingly bitter taate, whilst neither pentacetylquercetin, hepbacetylaminoquercetin, nor quercetin pentamethyl ether possessesthis property.0.1249 gave 0.2809 CO, and 0.0596 H20.0.1990 ,, 5.8 C.C. N, (moist) a t 28O and 759 mm. N=3*19.0.2716 ,, 11.6 C.C. N/10-acetic acid; C2H40,=25*6.C = 61.34 ; H = 5.30.C24H2,OSN requires CT = 61.1 ; H = 5.3 ; N = 2.9 ;C2H402 = 25.5 per cent.Incomplete acetylation gave also another substance, less solublein alcohol and precipitated on adding alcohol to the acetylationmixture.This melts a t 223-226O (see P., 1911, 27, 163) and isprobably monoace t ylaminoquerce tin pentam e thy1 ether,C,,H40,(0Me),*NHAc.6/-A mino puerce tin Hydriodide, C,,H,02(0H j,*NH2,HI.-Thissubstance w.as isolated as the chief product in demethylating6/-aminoquercetin pentamethyl ether with hydriodic acid. Thesame reagent effected the simultaneous reduction and demethyla-tion of 6/-nitroquercetin pentamethyl ether and there was noadvantage in isolating the intermediate .aminopentamethyl ether.Five grams of 6/-nitroquercetin pentamethyl ether were gently boiledfor an hour with 150 C.C. of hydriodic acid (D 1.7). Then the mix-ture was boiled vigorously until most of the hydriodic acid wasdistilled off and only 10-15 C.C.remained. Water was added t othe residue, making the bulk up to 750 c.c., sulphur dioxide waspassed in until all free iodine was destroyed, the mixture was boiledand filtered hot to remove a little insoluble matter, and the brightorange-red filtrate was concentrated. On cooling, aminoquercetinhydriodide separated in orange-coloured nodules, was collected,washed with a little aqueous sulphur dioxide, and dried. Threegrams of the deep orange hydriodide were thus obtained. Attemptsto isolate a further quantity by concentrating the mother liquorwere unsuccessful, and i t was found advisable, in later preparations,to work up the mother liquor to give the remainder of the amino-quercetin as hydrochloride. 6’-Aminoquercetin hydriodide isfairly soluble in hot dilute hydrochloric acid, but much less so inthe cold.It is partly decomposed on boiling with water.6l-Amino qzt erc e tin Hydrochloride, C,,H,O,( OH) ,-NH,,HCI .--Forthe preparation of this salt; 6/-nitroquercetin pentamethyl etherwas boiled with hydriodic acid f o r an hour as described in the pre-ceding paragraph. The product w.as then poured into nine timesits bulk of water, freed from iodine by sulphur dioxide or a slightexcess of sodium hydrogen sulphite solution, filtered to remove acertain amount of insoluble matter, and treated with exceas of soliWATSON : 6’- AMINOQUERCETIN. 343sodium acetate. The sodium acetate produced a bulky, gelatinous,yellow precipitate of a sodium salt of aminoquercetin, and this wascollected and washed with cold water as rapidly as possible.Theprecipitate must not be allowed to remain in the air or it will bepartly oxidised to dark-coloured products. It was then dissolvedin boiling dilute hydrochloric acid (1 part of hydrochloric acid to12 parts of water) and the solution concentrated. On cooling,aminoquercetin hydrochloride was deposited in buff-yellow, fine,needle-shaped crystals in radiate aggregates, which were collected,washed two or three times with small quantities of cold dilutehydrochloric acid, and dried in the steam-oven, care being takennot to break up the cake or expose a larger surface than possibleto the air while moist. F o r purification, it was recrystallised fromdilute hydrochloric acid, avoiding any unnecessary oxidation.When free from oxidation products, aminoquercetin hydrochlorideis of a buff-yellow colour, and readily soluble in hot dilute hydro-chloric acid, but much less so in the cold.It does not melt even a t330O. On boiling the dry salt with water, it is partly decomposed.0.1150 gave 4.0 C.C. N, (moist) a t 18O and 755 mm.C,,H,,O,N,HCl requires N = 3-96 per cent.The most successful preparations gave 60 per cent. of amino-quercetin hydrochloride, reckoned on the weight of the nitro-penta-methyl ether taken.6’-Aminopurercetin Sulphate, C,,H,O,(OH),=NH,,H,SO,.-Onsubstituting dilute sulphuric acid for hydrochloric acid in the pre-ceding preparation, there was obtained aminoquercetin sulphate inbuff-yellow nodules or warts.A quantity of sulphate was alsoobtained from the hydrolysis of hepta-acetylaminoquercetin bysulphuric acid in alcohol and, on adding warm water and allowingto remain, the sulphate was deposited in aggregates of fine needles.It melts and decomposes a t 222-227O:N = 3-98.0.1314 gave 3.8 C.C. N2 (moist) at 30° and 756 mm.C,5H,,07N,H,S0, requires N = 3-37 per cent.6’-Aminopuercetin, C,5H402(OH)5*NH2.-Only the followingmethod was found successful for the liberation of the free base fromthe above-mentioned salts:-To one gram of the dry salt (hydro-chloride or hydriodide) were added 15 C.C. of pyridine and 30 C.C.of hot water and the mixture was kept just on the point of boiling.After a short time, crystals began to appear, chiefly a t the surfaceof the liquid and on the sides of the flask above the liquid, andthese, on keeping, increased in quantity.Forty-five C.C. of boilingabsolute alcohol were now added, the mixture once more broughtto the boiling point and allowed to cool, and the crystals whichN=3.12344 WATSON : 6'-AMINOQUERCETIN.separated were a t once collectecl, washed with absolute alcohol, anddried. From 1 gram of the hydriodide, only about 0.3 gram ofthe base was obtained. 6/-Aminoquercetin consists of buff-yellow,fine, needleshaped crystals, almost insoluble in alcohol, acetone,chloroform, ethyl acetate, phenol, or nitrobenzene. No suitablesolvent for its recrystallisation was discovered. It does not melt,but blackens and decomposes about 3 2 0 O .The following analyses were carried out with the substance driedat 150O:0.1171 gave 0.2434 CO, and 0.0401 H,O.C= 56.68 ; H = 3.80.0.1066 ,, 4.4 C.C. N, (moist) a t 24O and 760 mm. N=4.62.C,,H,,07N requires C = 56.78 ; I3 = 3.47 ; N = 4.41 per cent.Position of t h e ,4 ntiiio-group iu A r~ii~iozi'Prcetiti.-Tkis was de-termined, indirectly, by ascertaining the position of the nitro-groupin the nitroquercetin pentamethyl ether from which aminoquer-cetin is obtained. The nitro-pentamethyl ether was oxidised bypotassium permanganate and gave 6-nitroveratric acid,NO2\-/ CO,B/-\O Me,OMeas one of the products. Four grams of the nitro-pentamethyl etherwere dissolved in cold sulphuric acid and reprecipitated by pouringthe solution into a large volume of water.The substance was thusobtained in a finely-divided, amorphous condition. After washing,i t was rubbed into a paste with a cold aqueous solution of 10 gramsof potassium permanganate and allowed to remain over-night. Bythe next morning the pink colour of the permanganate had com-pletely disappeared. The precipitated manganese dioxide wasfiltered off, the filtrate acidified with hydrochloric acid, andextracted with ether. On spontaneous evaporation, the etherealextract left a yellow oil which quickly solidified. This was recrys-tallised from benzene and found to be 6-nitroveratric acid (Ber.,1876, 9, 938).Dyeing Properties of 61-9 mirzo~uerceti~z.-Full dyeings of thefollowing shades were obtained on wool with 4 per cent. of thedyestuff (reckoned on the weight of the wool): pure brown onchrome, yellowish-brown on alum, orange-red on tin, and brownish-black on iron.The shades on chrome and alum were browner, ontin redder and deeper, than those obtained by comparative testswith quercetin.Hepta-a~etyl-6~-arnii~o~uerceti,l., C,,H,O,(OAc),*NAc,. - Thischaracteristic derivative of aminoquercetin was obtained from thefree base or its salts by boiling with acetic anhydride for an hourWATSON : 6’-AMINOQUERCETIN. 345The acetyl derivative was precipitated in crystalline form byadding alcohol. For purification, it was again dissolved inacetic anhydride, boiled for half-an-hour, and precipitated byalcohol. The acetylation of the hydrochloride was effected byboiling together for one and a-half hours 1 gram of the well-driedhydrochloride, 1 gram of fused sodium acetate, and 5 C.C.of aceticanhydride. An equal volume of glacial acetic acid was then addedand the mixture poured into excess of water. The acetyl derivativewas precipitated as a white, amorphous powder, which was collected,dried, and purified by dissolving in acetic anhydride, boiling forhalf-an-hour, and precipitating by alcohol. By either method, itwas obtained in white, rhombic crystals, melting a t 151-153O,sparingly soluble in alcohol, readily so in glacial acetic acid oracetic anhydride. This derivative serves to characterise 6l-amino-quercetin :0.1275 gave 0,2671 CO, and 0*0510 H,O. C =57*12 ; H = 41-44.0.2033 ,, 4.5 C.C. N, (moist) a t 21° and 755 mm.N=2.50.0.4967 ,, 56.9 C.C. N / 10-acetic acid = 68.7.C2,H2,OI4N requires C = 56-96 ; H = 4.09 ; N =2*29 ;C2H40, = 68.7 per cent.If acetylation has not been complete, there is also formed anothersubstance melting above 200° which is probably the hexa-acetylderivative.Quercetin Pentamethyl Ether Diazonium Chloride,C,,H,02(0Me),*N,C1.One gram of finely-powdered 6/-aminoquercetin pentamethylether was treated with 10 C.C. of water and 2.8 C.C. of concentratedhydrochloric acid, warmed and mixed thoroughly to convert thebase entirely into hydrochloride. On adding 9 C.C. of a solution ofsodium nitrite (1 : 50) to the cooled mixture, the stiff, white pasteof hydrochloride became yellow and passed almost entirely intosolution. On scratching the sides of the tube, the diazoniumchloride was precipitated as yellow needles. After two hours, thesewere collected, washed with benzene and dried on a porous tile,and afterwards over soda-lime in a desiccator.This substance isreadily soluble in cold waeer or dilute hydrochloric acid and inalcohol. From solution in the latter medium, it can be precipi-tated in the crystalline form by ether. Its solution in water ordilute hydrochloric ,acid gives a t once a crimson precipitate with analkaline solution of &naphthol. The aqueous solution is fairlystable and gives the diazo-reaction, even after a few minutes’ boiling.VOL. cv. A 346 WATSON : 6'-AMINOQUELK!ErI'IN.The solid, on keeping in the air, becomes red on the surface. Whenheated in the steam-oven, itd loses most of its nitrogen:(1) 0.1376 gave 7.1 C.C.N, (moist) a t 19O and 749 mm. N=5*84.(2) 0.1520 ,, 8.2 C.C. N, (moist) a t 30° and 755 mm. N=5*81.[Sample (2) was purified by solution in alcohol and re-precipita-Querce tin Pen tame t hyl Ether Diazo nium Sulphat e,C2,Hl,0,N2C1 requires N = 6-44 per cent.tion with ether.]C,,H4O2(OMe),*N,HSO4.-This substance was gradually precipitated in short, needle-shapedcrystals on the addition of dilute sulphuric acid, (1 :4) to a coldsaturat.ed aqueous solution of the diazonium chloride :0.1520 gave 6.9 C.C. N, (moist) a t 30° and 756 mm.C2,H,,0,,N,S requires N = 5-64 per cent.6'-P-iVaph t holazo puerce tin Pentame thy? Ether,Cl,H,0,(OMe),*N2*C,oH,*OH.-One gram of 6/-aminoquercetin pentamethyl ether was diazotisedas described in the preparation or the diazonium chloride, water(about 100 c.c.) was then added until all the diazonium chloridehad dissolved, and this liquid was added gradually to a solutionof 0.4 gram of P-naphthol and 1.9 grams of potassium hydroxidein 50 C.C.of water. The gelatinous, crimson precipitate wascollected, washed, dried, and recrystallised from glacial aceticacid, from which solvent it was deposited in needle-shaped, crimsoncrystals, melting and decomposing a t 222-225O (compare P., loc.cit. It is fairlysoluble in alcohol, insoluble in aqueous alkalis, and dissolves insulphuric acid with an indigo-blue colour :N=4*90.The sample melting a t 211O was not pure).0.1521 gave 7.1 C.C.N, (moist) .at 29O and 758 mm. N=5.09.C3,H2608N2 requires N = 5.16 per cent.Triwitroquercetin Pentamethyl Ether ( ?), C,,H,0,(OMe)5(N0,)3.When quercetin pentamethyl ether was dissolved in cold fumingnitric acid and the solution poured into water, there wzs precipi-tated a canary-yellow substance which, on boiling the mixture,became granular. This substance, after filtering and washing, wastreated with dilute aqueous ammonia, when a considerable portiondissolved, forming a brownish-red solution. The residue, onanalysis, was found to contain a percentage of nitrogen correspondingnearly with trinitroquercetin pentamethyl ether. Attempts torecrystallise this compound were not successful. It was scarcelysoluble in alcohol, acetone, benzene, or acetic acid, but was readilyso in nitrobenzene, and melted a t 190-205°WATSON : 6'-AMINOQUERCETIN. 3470.0652 gave 4.9 C.C.N, (moist) a t 14O and 761 mm. N=8*86.C,,H,,Ol3N, requires N = 8.28 per cent.Dibromoquercetin Pentamethyl Ether Hydro b ro rnide,C15H302(OMe)5Br2,HBr.*This oxonium salt was obtained by brominating quercetin penta-methyl ether either in glacial acetic acid or in carbon disulphidesolution, for example, 2.5 grams of the pentamethyl ether weredissolved in 20 C.C. of glacial acetic acid and to this solution, whencold, were added, gradually, 2.2 grams of bromine (2 mols.) alsodissolved in about 20 C.C. of glacial acetic acid. A t once a deepcrimson liquid and precipitate were formed, which soon, however,became light yellow.When the whole of the bromine had beenadded, the mixture soon became a semi-solid, bright yellow massof fine, needle-shaped crystals. It w-as thoroughly stirred a t inter-vals and after keeping over-night the precipitate was collected andwashed with acetic acid.Dibroinoquercetin Pentamethyl Ether, C,,H,O,(OMe),Br,,EtOE.-The oxonium hydrobromide. prepared as above was, withoutdrying, treated with about 50 C.C. of alcohol which turned thesurface of the mass crimson. On warming, the whole dissolved,and, on cooling, the solution deposited about 1.5 grams of the newsubstaiice in almost colourlws crystals. It was puriGed by recrys-tallisation from benzene, which did not eliminate the molecule ofethyl alcohol, It is readily soluble in hot alcohol, still more soin hot benzene, and crystallism in prisms which, when depositedfrom benzene, are short, and arranged in sheaves.It melts a t0.1255 gave 0.2119 CO, and 0.0467 H,O ; C = 46.04 ; H = 4-13.0.2507 ,, 0.1640 AgBr. Br=27*84.C22H2408Br2 requires C = 45.84 ; H = 4-16 ; Br = 27.77 per cent.As quercetin was produced by the demethylation of this substancewith hydriodic acid, it could not be dibromoethoxyquercetin penta-methyl ether.Monobromopuercetin Pentarnethyl Ether, C15H402(OMe)5Br.-This was obtained by boiling dibromoquercetin pentamethyl etherhydrobromide with water. From each molecule of the oxoniumhydrobromide approximately two molecules of monobasic acid wereliberated, perhaps in accordance with the equation :C,,H30,(0Me),Br2,HBr + H20 = HBr + HBrO + C,,H,O,(OMe),Br.* This and the following bromo-derivatives were Ibreparecl with the idea thatthey might be more readily nitrated than quercetin pentamethyl ether ; thesuccessful preparation of nitroquercetin pentamethyl ether rendered their use,however, unnecessary.173-175' :A A 348 WATSON : 6'-AMINOQUERCETIN.A sample of the oxonium hydrobromide, oarefully washed withacetic acid, was dried on a porous tile and finally, for several days,over soda-lime in a vacuum desiccator, being removed from timeto time, finely powdered and replaced in the desiccator.Afterboiling with water, 0.3887 gram gave 11.2 C.C. N/lO-acid, whilstthe above equation requires 12.7 C.C.The insoluble product was recrystallised from benzene or alcoholand obtained in needles melting a t 215O.It was of a light creamcolour and was not readily soluble in either of the above-mentionedsolvents.The same substance was obtained directly by the bromination ofquercetin pentamethyl ether in acetic acid solution in the presenceof fused sodium acetate: 1 gram of the pentamethyl ether wasbrominated as in the preparation of the dibromo-oxonium hydro-bromide, excegt that 1.5 grams of fused sodium acetate were dis-solved with the pentamethyl ether in acetic acid before the brominewas added. A cream-coloured precipitate of apparently uniformneedles was a t once obtained. After remaining over-night, theprecipitate (0.65 gram) was collected, washed with acetic acid, andrecrystallised from benzene.0'1217 gave 0.2345 CO, and 0.0438 H20.C = 52.88 ; H = 4-08.0.2522 ,, 0.1054 AgBr. Br=17*80.C,,H,,O,Br requires C = 53.21 ; H = 4.21 ; Br = 17.75 per cent.Dibromonitroquercetin Yentamethyl Ether ( ?),C,,H,O2(01Me),Br2.NO,.One gram of dibromoquercetin pentamethyl ether was dissolvedin cold nitric acid (D 1.4) and the solution poured into water. Theprecipitate was collected, recrystallised from alcohol, and againfrom acetone, and was thus obtained in rhombic crystals of a paleyellow colour melting a t 173-175O :0.1072 gave 2.4 C.C. N, (moist) a t 14O and 773 mm.C,,H170,NBr2 requires N = 2.43 per cent.The peculiar behaviour of dibromoquercetin pentamethyl ethermakes it unwise, however, to definitely assign the above formulato this compound without further analysis.N=2*67.Quercetin Pen(tamethty1 Ether Oxonium Salts, C20H,,07,HCl ;C2,H,,07,HBr ; C,,H~O,H,SO, ; and C2,H2,07,HN0,.The first three of these oxonium salts were prepared by dissolvingthe pentamethyl ether in glacial acetic acid and adding the corre-sponding acids in a concentrated form, and separated in yellow,needle-shaped crystals. They were collected, washed with glaciaWATSON : 6’-AMINOQUERCETIN.349acetic acid, dried on a porous tile, and finally over soda-lime in avacuum, being once or twice finely powdered to expose a freshsurface. The sulphate could be dried in the steam-oven withoutdecomposition. These substances were analysed by boiling withwater, filtering, and titrating the filtrate :0.3471 hydrochloride gave 8.5 C.C.N / 10-acid ; HCl = 8.9.0.4240 hydrobromide (still containing a trace of acetic acid) gaveC,,H,,O,,HCl requires HCl = 8.9 per cent.10.6 C.C. N/lO-acid, and 0.1672 AgBr; HBr=17-41.C,,H,,O,,HBr requires HBr = 17.88 per cent.0.2904 sulphate gave 12.2 C.C. .Y/ 10-acid ; H,SO, =20*6.C,,H,,0,,H2S04 requires H,SO, = 20.85 per cent.All these salts showed a tendency to develop a red colour; thehydrochloride and hydrobromide became red on the surface whenleft on the tile, and the sulphate became salmon-coloured whenheated to looo.The nitrate was prepared by adding concentrated nitric acid inthe cold to a solution of quercetin pentamethyl ether in glacialacetic acid in the presence of carbamide nitrate, but, in this way,could not be freed from carbamide nitrate. It was also obtainedby adding concentrated nitric acid to a cold solution of quercetinpentamethyl ether in absolute alcohol and separated as a brightyellow precipitate of needle-shaped crystals. It was collected andE t once dried on a porous tile and over soda-lime in a vacuum.It could not be washed with alcphol without decomposition, norwith acetic acid as, in this medium, in the absence of carbamidenitrate, it is a t once attacked by the nitric acid with the liberationof nitrous fumes:0.2433 (dried without washing) gave 7.6 C.C. NIlO-acid;0.2541 (washed with alcohol) gave 5.1 C.C. N / 10-acid ; HNO, = 12.6.HNO, = 19 6.C~oH2007,HN03 requires HNO, = 14.4 per cent.I n conclusion, I wish to express my very great indebtedness toRfr. A. G. Perkin, F.R.S., who pointed out to me the advantagesof choosing quercetin as a starting point for researches such as Ihad in view, and who has, throughout the work here described,assisted me by continual advice and guidance.CLOTH WORKRRB’ RESEARCH LABORATORY,LEEDS UNIYERBITY

ISSN:0368-1645    

DOI:10.1039/CT9140500338

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

350 EWINS: T H E MUTUAL SOLURILITY O F FORMIC ACID ANDXXXVIIL-The Mutual Solubility of Formic Acid andBenxenp, and the System : Benxme-Formic Acid- Water.By ARTHUR JAMES EWINS.THE work which has hitherto been carried out on the mutual solu-bility of various pairs of liquids has been summarised by Rothmund( I ‘ Loslichkeit und Loslichkeitsbeeinflussung,” 1907, pp. 66-78).From the data there brought together i t appears that of about iortypairs of liquids studied, some twenty-five to thirty consist of pairsof liquids of which one component is water. This liquid, as is wellknown, possesses a very high dielectric constant. Methyl alcohol,which also has a high dielectric constant, is also a Component cftwo other systems. It seemed probable, therefore, that some otherliquid possessing a high dielectric constant might also be partlymiscible with certain organic liquids.A few preliminary experi-ments with formic acid * showed that this liquid was, indeed, partlymiscible with a number of liquids, among which were the following :Ethylene dibromideMethyl iodideEthyl iodideAcetylene tetrachlorideCarbon tetrachlorideAmylene (Trimeth ylethylene)%soAmy1 etherisoAmyl chlorideBenzeneBromobenzeneTolueneXyleneSafroleisosafrolePhenetoleAnisoleAll these mixtures showed maximal critical solution temperatawes.Further investigation would, in all probability, considerably acidto their number.Of these binary mixtures, that consisting of formic acid andbenzene was considered to be most advantageous for the purposeof a detailed investigation.The critical solution temperature iswell within the limits of experimental determination, but, a t thesame time, admits of the mutual solubility of the liquids beingdetermined over a fairly considerable range of temperature. Therewas no likelihood of any interaction between the two components,and both liquids are readily obtainable in a fairly pure condition.Additional interest attached t o the investigation, since the deter-mination of the critical solution temperature should afford the mostreliable method of ascertaining the purity of both liquids and, con-sequently, of establishing for these liquids such physical constantsas melting points, boiling points, density, etc., concerning which a* AccorJing to Thwiiig (Zcitsch.physikal. CILC~L, 1894, 14, 293), the Faluo ofthe dielectric coiistant of formic acid is 62’0, whilht Drude (ibid., 1897, 23, 308)gives 67’0BENZENE, AND THE SYSTEM : BENZENE-FORMIC ACID-WATER. 351considerable amount of uncertainty a t present exists, especiallywith regard to formic acid. The selection of benzene and formicacid was further influenced by the fact that the addition of waterto this binary system gives a tertiary system which is of interestowing to the peculiar character of the system so formed. Formicacid is completely miscible with water under all ordinary conditions.Benzene and water are, however, practically immiscible, their mutualsolubility being extremely small. These three liquids, theref ore,form an extreme case of a system of three components which canform two pairs of partly-miscible liquids.Systems of this classhave been previously studied by Schreinemakers (Zeitsch. physikal.Chern., 1898, 27, 95; 1899, 29, 577), the most closely analogoussystem being that of which the components are phenol, water, andaniline. It must be noted, however, that the analogy is representedthus :A phenol formic acidB water benzeneC aniline waterwhere A and A', and B and C are partly miscible liquids, A and Cbeing, in each case, completely miscible. Owing, however, to thevery slight mutual solubility of benzene and water, the region ofheterogeneous systems is very much more extended in the systemunder investigation, as is seen from the curve shown later (Fig.4).EXPERIMENTAL.The Preparation of Pure Formic Acid.Examination of the literature shows that there is a very con-siderable variation in the melting and boiling points which havebeen recorded for formic acid from time to time. This is seen fromthe following table :Melting Boilingpoint8*6O8.43'7.8'8.2"----7.0'5.6"8.35'point. -100.5"100.8"100.4'/759 mm101.0"/760 mm.101.3"/760 111111.100~5-100~8"/759 mm.100- 8 - 1 oi.00/760 -.101~O099.7'/741 mm.50.0°/120 mm. }Berthelot (Annalen, 1855, 98, 139)Pettersen and Eckstrand (Ber, 1880,13,1191)Zander (Annalen, 1884, 224, 59)Schmidt (Zeitsch. physikal. Chem., 1891, 7 ,Kahlbaum (Ber., 1883, 16, 2480)R,ichardson (T., 1886, 49, 763)Schiff (Annalen, 1885, 234.324)Kahlbaum (Zeitsch. physikal. Chem., 1898,Jones and Murray (Amer. Chem. J., 1903,Beckmann (Zeitsch. physikal. Chem., 1906,Garner, Saxton,'and Parker.(Amer. Chem. J . ,446)26, 591)30, 93)57, 129)1911, 46, 236352 EWINS: THE MUTUAL soLuBIrmy OF FORMIC ACID ANDThe preparation of the anhydrous acid is a matter of considerabledifficulty, owing t o the fact that the usual desiccating agents suchas phosphoric oxide, sulphuric acid, sodium, &c., all react with theacid. Further, the latter is itself extremely hygroscopic, so thatthe greatest care is necessary in manipulation in order to avoidreabsorption of water.The most recent attempt to prepare anhydrous formic acid wasmade by Garner, Saxton, and Parker (Zoc.cit.), who employed dis-tillation under diminished pressure from anhydrous copper sulphatefor the purpose. They obtained an acid melting a t 13.35~ andboiling a t 99*7O/741 mm., but it is probable, as will be seen later(p. 353), that this acid still contains a small amount of water.The following method of preparing the pure acid was adoptedand gave consistently good resul-ts.Kahlbaum ” formic acid was fractionally distilled through aYoung-Thomas stillhead (three compartments) to the outlet tubeof which was fused a small Liebig’s water-cooled condenser. Athermometer graduated in tenths of a degree was placed in positiona t the top of the fractionating column. I n order to prevent theacid from coming into contact with the cork through which thethermometer passed, the stem of the column above the outlet tubewas lengthened and surrounded by a glass jacket through whichwater was passed.The vapour of the acid was thus condensed justabove the sidc-tube and flowed back into the column. Formicacid “ Kahlbaum ” distilled in this way yielded an acid boiling, forthe most part, from 1 0 0 . 3 O to 100*8O, under a pressure of 760 mm.The lower and higher boiling portions of the acid were neglected.On refractionation, the main bulk of the acid was obtained boilinga t 100~4-100~6°/ 760 mm. Further fractional distillation wasfound to be useless as a means of purification, since no lowering ofthe critical solution temperature with pure benzene could be de-tected. The purified acid was next submitted to fractional re-crystallisation in the following manner.The acid was placed in awell-stoppered bottle and frozen solid in a cold room (temperaturebelow 0.). The bottle was then inverted over another bottle (at-mospheric moisture being carefully excluded) and the acid allowedt o thaw partly, at a temperature of not more than one or twodegrees above its melting point. When about one-eighth of theacid had slowly drained away, the remainder was liquefied a t asomewhat higher temperature, and it5 melting point determinedaccurately by means of a Beckmann thermometer. The process wasrepeated until, after three o r four recrystallisations, an acid wasobtained the melting point of which remained constant to 1/100thof a degree and gave a constant critical solution temperature witBENZENE, AND THE SYSTEM : BENZENE-FORMIC ACID-WATER,.353pure benzene. The amount of pure acid obtained in this mannerfrom 2 litres of Byfurther manipulation it was possible to obtain still more of the pureacid from the residual fraction.The course of the purification as indicated by the lowering of thecritical solution temperature * is shown by the following table :Kahlbaum " formic acid was about 300 C.C.Formic acid. M. p. R. p." Kahlbaum " 7.4"After fractionation . . . . - ( w ) 100*6-100- 7'/760After recrystallisationAfter recrystallisation99 > 9 - ( b ) 100~5-100~55"/760of purer fraction ( 6 ) - -until constant ...... 8.39" -Critical solutiontemperature (purebenzene).82"77"76"74.2'73.2"The Melting Point of Pure Formic Acid.The melting point was determined with a Beckmann apparatus.Since formic acid is very hygroscopic, the apparatus was fitted withthe sulphuric acid trap recommended by Beckmann for use in suchcases.That this arrangement was efficient was shown by the factthat three determinations of the melting point carried out on thesame sample of acid did not vary by more than O s 0 l o .The Beckmann thermometer was then immediately standardisedby comparison with a standard Kew thermometer and the freezingpoint of the acid so found to be 8 ' 3 9 O . with a probable error ofThe purity of the formic acid obtained was very strikingly shownby its behaviour on determining the melting point.With ordinarypreparations, as is well known, the amount of super-cooiing neces-sary to induce crystallisation is somewhat large, being, even withfairly pure preparations, fro= 2 O to 5 O . The acid obtained byGarner, Saxton, and Parker, for example, melting a t 8-35O and,therefore, of a high degree of purity, is stated by these authors tohave shown a super-cooling of 2 ' 5 5 O , even with vigorous stirring.I n the present instance, however, crystallisation commenced withan amount of super-cooling which was extremely small, the valuesactually obtained being 0'35O, 0'4O and 0 ' 1 5 O respectively in threeconsecutive determinations.& 0'02O.(b.) The Boiling Point of Pure Formic Acid.The boiling point of the acid cannot be taken as a criterion ofpurity, since very small amounts of water distil with the acid, the* For this method of controlling the purity of organic liqnids, compare Crismcr(Bull.A d , Boy. Belg., 1895, 30, 97), Flaschner (T., 1908, 93, 1000) andothers354 EWINS: THE MUTUAL SOLUBILITY O F FORMIC ACID ANDboiling points of the two liquids being very nearly the same a t theatmospheric pressure. The following values for the nearly anhydr-ous acid were obtained a t various times during the progress of thework :from which b. p./760 inrri.= 1 100-47O.100.3 -100*35O/ 754 mm.100.4 -100*45O/758 mm.100*55-100.6°/ 764 mm.Garner, Saxton, and Parker (Zoc. cit.) give 99'7O/741 mm., in goodagreement with the values tabulated above.The Density of Pure Formic Acid.The density of the pure acid obtained as described, was deter-mined by means of a Sprengel pattern pyknometer of nearly 30 C.C.capacity, the ends of which were provided with ground glassstoppers.As the result of three different determinations, the followingvalues were obtained for the density:D18 = (a) 1.2258( b ) 1.2260( c ) 1.2258the mean value being 1.2259 ( j- O*OOOl).This result is in good agreement with that obtained by Garner,Saxton, and Parker (Zoc.cit.), nameIy, 1.2260 a t 15O and 1.2200 a t26O, but is slightly higher, again pointing t o the probable presenceof traces of water in tke acid obtained by these authors.The Prepration of Pure Benzene.I n spite of the apparent ease with which benzene can be obtainedin the pure condition, no very good agreement has been reachedwith regard t o one of the most important crit'eria of purity-themelting point., as is shown by the following table of recorded values :5.17" R.Abegg (Zeitsch. physikal. Chem., 1894, 15, 213)5.44-5.445' E. Beckmann ( ,, 9 , ,, 1886, 2, 715)5.5" 9 9 ( ?9 1890, 6, 438)5-42" Lachowicz (Rer., 1 888,"21, 22dk)5.7" Schrvder (Zeitsch. physikal. Chem., 1893,11, 457)5.4" Lineberger (Amer. Chem. J., 1896,18, 437)5.54" Hansen (Zeitsch. physikal. Chem., 1904, 48, 595)The method of purification adopted in all cases is that of frac-tional crystallisation or distillation over sodium or a combinationof these two. The most recent determination, that of Hansen, wascarried out on a sample of benzene which had been purified, as faras possible, in the usual manner, and then, just previously to makingthe determination, had been boiled for a short time t o expel thBENZENE, AND THE SYSTEM : BENZENE-FORMIC ACID-WATER.355last traces of water. The melting point was, in this way, raisedfrom 5.470 to the value noted above, 5‘54O.The benzene employed in the present investigation was preparedfrom Kahlbaum’s benzene “ pure for analysis and molecularweight determination.” After one recrystallisation and subsequentdistillation from sodium in an all glass apparatus into a receiverfitted with a drying tube, benzene was obtained which gave a criticalsolution temperature with a sample of “ Kahlbaum ” formic acidof 81.9O. Further treatment of the benzene either by recrystal-lisation, distillation over phosph oric oxide, or metallic soliumfailed t o lower this critical solution temperature.The benzene was,therefore, considered to be as pure as could be obtained and em-ployed in the present investigation. The melting point of thebenzene was found to be (after careful standardisa-tion of the thermometer) 5.58O. This value is ingood agreement with that of Hansen (Zoc. cit.). Thevalue 5 ’ 7 O given by Schroder (Zoc. c i t . ) (whose methodof purification was simply recrystallisation) is probablytoo high.The Mutual Solubility of Formic Acid and Benzene.I n determining the mutual solubility of these twoliquids the synthetic method wae adopted.The actual procedure was as follows. A number ofbulb tubes of the shape shown (BC, Fig.1) were madefrom ordinary good quality glass tubing. The capacityof the bulb C was from 2 to 3 c.c., the length of thecapillary B about 3 cm., and the internal diameter ofthe capillary approximately 2 mm. The tubes werethoroughly cleaned by boiling with distilled water,and, after being compietely dried, were ready for use.I n order to fill the tube with known weighb of thetwo liquids the bulb tube was first weighed accurately to milligrams,The liquids were contained separately in two burettes, which wereprovided with drying tubes at the top so that excess of moisture wasprevented. The liquids were then run into the bulb by means offine capillary funnels ( A ) , which were so made that the wider por-tion of the funnel roughly fitted over the jet of the burette.Thecapillary stem of the funnel passed through the narrow portion ofthe bulb tube B projecting into the bulb C. On opening the tapof the burette the liquid passed directly into the bulb C withoutcontact with the surrounding atmosphere and without wetting thewalls of the narrow neck (Bj of the tube. By rapidly withdrhwingthe capillary A , wetting of the walls of the tube B was agai356 EWINS: THE MUTVAL SOLUBILITY OF FORMIC ACID ANDavoided. The composition of the mixture was accurately obtainedby weighing the tnbe after addition of each liquid, the amountsbeing roughly controlled by the readings on the burette. Owingto the hygroscopic nature of the pure formic acid and also in aless degree of benzene, i t was found necessary always to discardany liquid remaining in the jet of the burette after each filling,otherwise inaccurate results were obtained.For a similar reasonboth the bulb tube and capillary funnel were always carefullydried just before use. When both liquids had thus been introducedand weighed, the bulb tube was sealed off a t the top of the narrowportion. It was found that the possible loss of liquid during thisoperation, owing to vaporisation, was negligible. The amount ofliquid taken was so arranged that the bulb of the tube was abouttwo-thirds filled in order to allow of complete mixing of the liquidsby subsequent shaking.The temperature of complete miscibility of the mixture was thendetermined.The tube was immersed in water which was kept wellstirred by means of a mechanical stirrer, and the temperature wasrecorded by a standardised thermometer; this was graduated infifths of a degree, and was of such a range that, for all temperatures,the thread of mercury was completely immersed in the bath. Thetemperature was raised by passing steam into the water, a methodwhich was found t o be far more satisfactory, both in rapidity andin minimising the risk of breakage of the beaker, than the usualmethod of heating on a sand-bath by gas burners. The bulb tubewas placed as near t o the bulb of the thermometer as convenient,and the temperature of the bath gradually raised. The contentsof the tube (which was attached to a glass or wire holder) werefrequently shaken, until finally a temperature was reached at whichthe two layers disappeared and a perfectly clear homogeneous liquidwas obtained.This temperature was noted and the bath thenallowed to cool very slowly. The clear liquid gradually assumed thepeculiar blue fluorescent appearance characteristic of liquids nearthe critical solution temperature (see Konovalov, J . Russ. Phys.Chem. SOC., 1902, 34, 738; and Donnan, Chem. News, 1904, 90,139) ; this suddenly gives place to a true opalescence followedalmost immediately by a separation into two layers. The temper-ature a t which the opalescence appeared was noted and the tem-perature of tbe bath again slowly raised, and the point a t whichcomplete solution occurred again noted.By repeating theseobservations a few times the temperature of complete miscibilitywas easily obtained accurate t o 0.2O. The results obtained witha sel.ies of mixtures in which the concentrations of formic acidranged from 10 t o 90 per cent. are tabulated belowBENZENE, AND THE SYSTEM : BENZENE-FORMIC ACID-WATER. 357No. of Weight of Weight of Percentage of Solution1 0.082 0.814 9.2 21*0°2 0.250 1.862 12.8 39.13 0.191 1-152 14.2 44.24 0.248 1-165 17.5 51.45 0.210 0.855 19-7 56.C8 0.207 0.778 21-0 58.47 0.430 1.511 22.2 59.98 0-409 1.218 25.1 64.29 0.41 1 0.901 31.3 70.110 0.368 0.627 36.9 72.511 0.755 1.091 40.9 73.012 0.745 0.991 43.0 73.213 0.865 1.050 45.2 73.014 0.690 0.722 48.9 73-215 1.209 1.124 51.8 73.216 0-593 0.500 54.2 73-417 1.191 0.892 57.2 72.318 1.444 0.794 64.5 70.219 1.321 0-579 69.5 66.220 1.209 0.390 75.6 57.7(a) 0.794 0.177 81.8 41.20.546 81.9 41.0 * 22 (a) 1.211 0.201 85.8 25.2(b) 0.656 0.108 85.8 25.423 1.821 0.207 89.8 3.8* The second tube ( b ) iu each of these cases was made up with a different sampleof formic acid prepared separately at an interval of about twelve months, andaffords striking evidence of the trust to be placed in the method of purificationemployed.The curve obtained (Fig.2) from these experimentd data showsno marked variation from the type usually obtained from pairsof liquids showing maximal critical solution temperatures. Theportion of the curve in the neighbourhood of the critical solutiontemperature is very flat, a phenomenon which is, however, shownin many other cases (for example, in aniline and water).Theproportion of formic acid, therefore, in the mixtures which have asolution temperature corresponding with that of the critical tem-perature is seen to vary from about 40 to 53 per cent. From thepractical point of view this is an advantage, since in estimating thepurity of a sample of formic acid by this method, the mixture withbenzene can be made up volumetrically (having due regard to thedifferent densisies of the solutions) a t about 45 per cent. of formicacid without fear of falling beyond the limits of the temperatureof complete miscibility. On either side of the flat portion, thecurve falls very steeply, that is to say, the temperature-coefficient ofthe mutual solubility of the two liquids is comparatively small untilthe neighbourhood of the critical temperature is reached.This isseen experimentally on cooling a mixture containing from 40 to 50per cent. of formic acid, which has been heated above the criticalsolution temperature. On cooling, the clear liquid first becomestube. formic acid. benzene. formic acid. temperature*21 (b) 2.47358 EWINS: THE MTJTUAI, SOLUBILITY OF FORMIC ACID ANDfluorescent a t a little above the critical solution temperature, nextopalescent a t that temperature, and then almost immediately separ-ates into two well-defined layers almost equal in volume.As will be seen from Fig. 2 the generalisation first put forwardby Rothmund (Zoc. cit.) for this type of mixture of liquids holdsgood in this case also.The points bisecting the ordinates lyingbetween the arms of the curve lie on a straight line. The point a twhich this straight line cuts the mutual solubility curve determinesFIG. 2.Formic acid-Benzene mutual solubility curve.8 0"7060201010 20 30 40 50 60 70 80 90 100Percentage of formic acid.the true critical concentration of the system, which is thus seen t obe formic acid, 48 per cent., and benzene, 52 per cent.(1.) T h e Influence of Water on t h e Freezing Point of Formic Acidand on the Critical Solution Temperature with Beruene.The main difficulty in the preparation of pure formic acid un-doubtedly lies in the elimination of water from the extremelyhygroscopic acid.The effect of the presence of water in formicacid, both on the freezing point of the acid and on the formic acid-benzene critical solution temperature was, therefore, considered tobe of sufficient interest to warrant a quantitative study.Weighed quantities of pure formic acid were diluted by additionof weighed quantities of water. The melting points of the mixturesobtained were then determined by means of the Beckmann ap-paratus. The same care was taken in these experiments to avoidabsorption of moisture from the atmosphere as was exercised preBENZENE, AND THE SYSTEM : BENZENE-FORMIC ACID-WATER. 359viously. The melting points were determined one after anotherwithin a short space of time in order to avoid any error due t opossible change of zero of the Beckmann thermometer.The maxi-mal complete solution temperatures of these solutions with purebenzene were then determined as already described. The resultsobtained are tabulated below :Percentage ofwat,er.00.0530.0990.2240.5020.9842.04Depression of freezingpoint of formic acid. -0.07"0.16"0.305"0.70"1.35"2.67'Critical solution tempera-ture with pure benzene.73.2"74.9"75.8"76.7"79.3O84.2"92.8"From these results it follows that the effect of water on thefreezing point of the acid is additive. The values deduced for themolecular weight of water lie between 17 and 21, in good agreementwith the values obtained by Jones and Murray (Amer. Chem. J.,1903, 30, 193). The results tabulated above show also that, ex-cept in the case of very small amounts of water, where the effectappears to be somewhat greater, the rise in the critical solution tem-perature is proportional to the amount of water added.It is wellknown that the addition of small quantities of a third substanceto a binary system of partly miscible liquids has a very markedinfluence on the critical solution temperature which is either raisedor lowered according to the liquid added and the composition ofthe system. This is the case, for example, with methyl ethylketone and water, where the addition of a very small quantity ofethyl alcohol so altered the mutual solubility relations that a closedring was obtained (Bruni, Atti R. Accad. Lincei., 1899, [v], 8, ii,141).I n the latter case i t is to be noted that the third componentof the system is a liquid completely miscible with each of the twooriginal components. The addition of water t o the system formicacid-benzene as before indicated is different, for, in this case,whilst water is miscible in all proportions with formic acid, itssolubility in benzene is extremely small, so that practically t h e twoliquids may be considered to be immiscible. I n such a system,therefore, it would seem that the effect on the maximal solutiontemperature is proportional to the amount of the added thirdcomponent.Incidentally it will be seen how much more readily the presenceof water in formic acid can be detected by the critical solutiontemperature method.The rise in the critical solution temperatureoccasioned by the presence of 1 per cent. of water in the mixtureis some loo, whereas the fall in melting point produced by the sam360 EWINS: THE MUTUAL SOLUBILITY OF FORMIC! ACID ANDamount of water is only 1*3*, so that unless very special precautionsare taken in the determination of the melting point much greatertrust can be placed in the former method.The Ternary System, Formic Acid Benzewe-Water.As already explained, this system is of interest as being an ex-treme case of a type which has already been studied by Schreine-makers (Zeitsch. physikal. Chem., 1898, 27, 95; 1899, 29, 577),namely, a system of three components in which two pairs of partlymiscible liquids can be formed. Its strongly-marked character-FIG.3.The influence of water on the mutual solubiiily offomnic acid and hcnzene.120"1101 co60504010 20 30 40 50 60 70 80 90 100Percenlage of fomnic acid.istics are due t o the very small mutual solubility of water andbenzene.I n order t o depict graphically the complete conditions obtainingin the system, it is necessary t o obtain a series of isothermal curvesshowing the variations of composition of the system which can occurwhen the temperature (and pressure, which under the experimentalconditions is a negligible factor) remains constant. Such curveswere obtained experimentally as follows. A series of mixtures offormic acid and water containing different percentages of waterwas made up and the temperatures of complete miscibility of vary-ing proportions of these dilute formic acid solutions with benzenewere determined in the manner already described. A series oBENZENE, AND THE SYSTEM : BENZENE-FORMIC ACID-WATER.361curves (Fig. 3) or, more correctly, portions of curves, were thusobtained, showing the effect on the mutual solubility of benzeneand formic acid brought about by the presence of water, the pro-portion of water to formic acid being constant for each curve.The following are the experimental data from which these curveswere obtained. The percentage of water in the dilute formic acidmixture was varied from 5 to 40 per cent. by weight.Formic Acid containing 5 per cent. of Water.Dilute formic acidper cent.3.75.610.214.875.380.081.587.7Benzeneper cent.96.394-489-885.224.720.018.512.5T*.57.5"779511294.580.57851Formic Acid containing 10 per cent.of Water.3-65.17.979.681.485.596.494.992.120.418.614.570'82-5111105.59985Formic Acid containiny 15 per cent. of Water.2-53.44- 085-790.093-097.596.696.014.310.07.071"87101100.58146Formic Acid containing 25 per cent. of Water.88.091.594.012.08.56.0122"97.574Formic Acid containing 40 per cent. of Water.94- 0 6.0 105"96.2 3.8 8297.0 3.0 76* T=Temperature of complete miscibility.From the curves obtained, it will be seen that the addition ofwater t o mixtures containing a comparatively large proportion ofbenzene has the effect of very greatly raising the temperature ofcomplete miscibility, so much so that this portion of the curveVOL.cv. B 362 EWINS: THE MUTUAL SOLUBILITY OF FORMIC ACID ANDbecomes almost vertical. With mixtures containing a relativelylarge percentage of formic acid the effect is not so inconvenientlygreat, and the effect of relatively large differences of concentrationof water in the system as a whole can be more readily observed.This can only be due t o the fact that the presence of water in thesystem very greatly diminishes the solubility of benzene in formicacid. This is the reason also why the critical maximal solutiontemperature of formic acid and benzene is so greatly raised by thepresence of traces of water in either of the components.I n order to obtain the data for the required isothermal curvesmentioned above it is now only necessary to draw through thesecurves lines parallel to the horizontal axis from points on thevertical axis representing definite temperatures.At the points ofintersection of any one of these lines with the various curves wehave mixtures of definite composition showing complete miscibilitya t that temperature.I n this way the following figure8 were obtained:Formic acid.1.92.253-0416.079-383.182.178.970-968.21. Isothermal at 50°.Composition of System.Benzene97.897.696-884.020-712.68.87.26.53.02.2-133.154.131.663-079.460.177.970.768.0Isothermal at 70°.97.696.695.768.637.016.611 [8.46.83.32.76.473.1676.0676.069.267-47-83. Isothermal at 90°.96.894.091.823.016-211.87- 74.3Water.0.30.250-16004.49.113.923.638.80.40-360.2004.18.913.723.638-70-60.60.83.868.4613.223.138.BENZENE, AND THE SYSTEM : BENZENE-FORMIC ACID-WATER.363Formic acid.4.47.213.664-669-370.167.556.84. Zsothermal at llOo.Benzene.94.892.085.822.023.017.610.07.0Water.0-80.80.73.47-712422.637.2With the help of the figures thus obtained the system benzene-formic acid-water can be represented graphically by the methoddue t o Roozeboom (Zeitsch. physikal. Chem., 1894, 15, 147) andFIG.4.The terwrg system : benzeae-formic acid-water.Isothermals at SO", 70", go", and 110".employed by Schreinemakers (Zoc. cit.). This consists in plottingthe compositions of the various mixtures obtained as describedabove within an equilateral triangle. In the figure shown (Fig. a),the amounts of formic acid are measured in the direction B.F., andof benzene in the direction P.B. The series of isothermal curvesshown in the diagram is thus obtained. The areas enclosed bythese curves within the triangle represent the range within which,for the particular temperature for which the isothermal is drawn,heterogeneous mixtures will be formed. In other words, any mix-ture of the three components, benzene, formic acid, and water, thecomposition of which is represented by a point within such an araa,will separate into two layers. The figure obtained shows, in a veryB B 364 HEWITT, JOHNSON AND POPE: THE ABSORPTIONstriking manner, the extreme nature of the system under considera-tion. Even a t comparatively high temperatures heterogeneousmixtures are included in almost the whole area of the triangle. Itcan be seen a t once, for example, that below a temperature of 70°,only mixtures containing a relatively very small percentage ofbenzene are completely miscible’ with formic acid containing anappreciable amount of water. With comparatively large percent+ages of benzene the amount of water which can be present in thesystem is so very small as to be hardly capable of representationin the figure given.The influence of temperature on the system is seen to be asfollows :With mixtures containing a relatively large proportion of formicacid, increase of temperature permits of a somewhat wide variationin the amounts of benzene or water present in the homogeneousmixture. Where, however, a large proportion of benzene is con-tained in the mixture, the effect of temperature on the variationof the other two components is very small indeed.I n the analogous case already mentioned, of aniline, phenol, andwater, all three components are capable of variation over muchwider limits.The expenses of this investigation were, in part, defrayed by agrant from the Research Fund Committee of the Chemical Society,for which the author wishes to make grateful acknowledgment.The author’s t.hanks are due t o Dr. G. Barger for suggesting thesubject of this research and for his interest and advice throughoutthe work.THE GOLDSMITHS’ COLLEGE,NEW CROSS, S.E

ISSN:0368-1645    

DOI:10.1039/CT9140500350

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

364 HEWITT, JOHNSON AND POPE: THE ABSORPTIONXXX1X.-The Absorption 8pectq.a of Nitrated Phenyl-h ydrazones.Ry JOHN THEODORE HEWITT, RHODA MARIANNE JOHNSON, andFRANK GEORGE POPE.SOME few years ago Baly and Tuck (T., 1906, 89, 982) describedthe absorption spectra of a number of aldehydic and ketonic phenyl-hydrazones, and drew attention to the colour shown by several ofthe nitro-derivatives. It was suggested (Zoc. cit., p. 996) thaSPECTRA OF NITRATED PHENYLHYDRAZONES. 365possibly p-nitrobenzaldehydephenylhydrazone does not possess theformula I, but is to be represented with a quinonoid structure (11) :NO,*C,H,*CH:N*N H*C6H5 HO O>N:(>:C:N~NH-C,H,(1.1 (11.1Certain pnitrophenylhydrazones with which we were occupiedattracted our attention owing to the remarkable colour changesproduced when alkalis were added to their alcoholic solutibns; infact, some of these compounds possess distinctly acidic properties.The great difference in colour between the compounds themselvesand their salts led to the view that there was probably a con-stitutional difference.I f such difference actually exists, the quinonoid formula wouldprobably be assignable to the salt, and the conventional hydrazoneformula to the hydrogen compound; although for the latter anotherstructure is not impossible.The most promising way of obtaining evidence of the characterdesired is to compare the spectra of benzaldehyde-pnitrophenyl-hydrazone in neutral and in alkaline solution with that of pnitro-benzaldehydephenylhydrazone, and, further, to examine the extentto which colour changes are inhibited by replacement of thehydrogen atoms marked with an asterisk in the formulze: * * * *C,H,* CH *N*NH* C,H,-NO, NO,.C,H4* CHON -NH *C,H5when the solutions were rendered alkaline.phenylhydrazone would be represented by the formula :the diminution in oscillation frequency occurring on salt formation,accompanying the greater length of chain of conjugated doublelinkings.Comparison of Figs. 1 and 2 will show that, as might be expected,the p-nitrophenylhydrazones of benzaldehyde and of acetophenonegive practically identical absorption spectra, and further, thateach, when converted into a salt, shows practically the same shift inits absorption.According to our view, the sodium salt of benzaldehyde-p-nitroC6H5*CH:NoN: C6H4:NO$?a,I n fact, the pairs of formulae:andC6H5>C: N*N:C6H,:N0,Na.CH3',%>C:N*N :C6H,:NO2Naare .strictly comparable.Baly and Tuck showed that the absorption spectra of the phenyl-hydrazone and of the phenylmethylhydrazone of p-nitrobenz366 HEWITT, JOHNSON, AND POPE: THE ABSOBPTIONaldehyde were practically identical (Zoc. cit., p.996), and it isinteresting to note that the head of the band in the visible spectrumlies a t very much the same position as that of the band shown by thepnitrophenylhydrazones of benzaldehyde and of acetophenone.The addition of alkali hydroxidev to yellow alcoholic solutionsof the pnitrophenylhydrazones of benzaldehyde and acetophenonecauses the colour to change to red of very similar shade to magenta,Relative thicknesses in mm.of N/10,000-solulion.0mo m m a0 0 rl0 0 o m m e 4000 TI,0M ' gd G ga$% ;%%re.&& * g - s s'G 8 , c ; s f .s * ?.s e.4.Sei f g &$Q g 3" QQ.s 0 &X B . g x %SSS0 u g-4 h e 3 .p5I .3 0e b e b6 1 % ;a+000 *0' 02 , o Fr000 CJ? 7 9 900 407 P 9 4 0.~ozlnlos-0 00 '0 I INa a CJ m r( rl r( rl r( 040 'urn ue sassaulyqyp anzpqai so s z u y j y ~ b o ~and the maximum coloration is produced by a medium amount ofthe alkali. In the caw of the equally yellow solution of p-nitro-benzaldehydephenylhydrazone, as alkali is progressively added, nocolour change is a t first observed; a large excess produces adeepening of shade, but not a change of colour.These facts agreewith our view that the compounds contain the grouping *CH:Na,tor whilst the change of structure from the grouping represented bSPECTRA OF NITRATED PHENYLHYDRAZONES. 36'1NO,*C,H,-NH~ to KNO,:C,H,:N* seems to be fairly common, casesof such a change as N0,*C6H4*CUH: to KNO,:C,H,:C: orK",:C,H,:CH- are comparatively rare.The spectrum of pnitrobenzaldehydeplienylhydrazone is given inFig. 3; the curve differs slightly from that of Baly and Tuck, butthe head of the band in the visible spectrum will be found a t almostexactly the same persistence and oscillation frequency, namely,2350.Now, whilst Baly and Tuck show that both the phenylhydrazoneand the phenylmethylhydrazone of p-nitrobenzaldehyde givevirtually identical absorption spectra, it will be seen on referenceto Fig.3 that replacement of the hydrogen atom marked *NO,. C6&*cH:NmN&o C6H5,by acetyl instead of methyl shifts the absorption strongly towardsthe ultra-violet. One may compare this shift in the absorptionwith that accompanying the conversion of aniline into acetanilide.We have mentioned earlier that the hydrazones dealt with in thispaper are better represented by the conventional than by quinonoidformulae; a t the same time we remarked that a different constitutionwas not impossible. Thus, benzaldehyde-(pnitrophenylhydrazonemight possess an internal salt structure:C,H,*CH:N*NH:C,H,:N:OI .L - - O ,in fact, (pnitrophenylhydrazine itself might be :H,N* NH:C,H,:N:O1 6Baly and Tuck (Zoc. cit., p. 997) drew attention to the greatdifference in the absorption spectra of the pnitro- and pbromo-derivatives of phenylhydrazine ; further than this, Borsche(Annded, 1907, 357, 171) has shown that quinones of the benzeneseries react with o-nitro- and 2 : 4-dinitro-phenylhydrazines withformation of hydroxyazo-compounds, whereas phenylhydrazine itselfis oxidised in these circumstances. Borsche himself (lot. tit., 173,footnofe) suggests that o-nitrophenylhydrazine may possess thestructure :/='\:N-NH,, \JNO,HWhereby this behaviour would be accounted for. The wholequestion as to whether many nitroamino-derivatives may not possessan internal quinonoid d t structure requires further work368 DUNNINGHAM : THE SYSTEM : ETHYL ETHER-WATER-I n conclusion, we desire to express our thanks to the ResearchFund Committee of the East London College for a grant defrayingthe costs of the investigation.EAST LONI~ON COLLIWE.UNIVEKSI.I'Y OF LONDON

ISSN:0368-1645    

DOI:10.1039/CT9140500364

出版商:RSC    

年代:1914

数据来源: RSC