摘要:

2048 DAWSON AND WHEATLEY: REACTIVITY OF KETONES TOWARDSCCXV.--The Reactivity of Ketones towards Iodine andthe Relative Rates of Tautorneric Change.By HARRY MEDFORTH DAWSON and ROBERT WHEATLEY, B.Sc.IN a previous paper (Dawson and Leslie, Trans., 1909, 95, 1860) ithas been shown that iodine reacts readily with acetone at theordinary temperature, and that when aqueous solutions containingacetone and iodine are acidified by addition of a mineral acid, thereaction proceeds at a rate which is suitable for accurate quantitativemeasurements. These observations showed that when the acetoneis present in considerable excess, the rate of disappearance of theiodine is practically constant from the commencement until nearthe end of the reaction, the velocity being proportional to theconcentration of the acetone and of the added mineral acid.To account for these facts, the view was adopted that the reactionbetween acetone and iodine involves two stages.In the first ofthese, the acetone is converted from the ketone into the enolic form,and this is then acted on by the iodine at a relatively very rapidrate with the formation of iodoacetone. In consequence of the verygreat difference in the velocities of the consecutive reactions, therate of disappearance of the iodine is determined solely by the rateat which the acetone is transformed into the enolic form (compareLapworth, Trans., 1904, 85, 30).I f this is the correct interpretation of the facts, it is evident thatthe investigation of the velocity of reaction of iodine with otherketones should lead t o information respecting the rates at whichthe various ketones undergo tautomeric change.With this objectin view, experiments were made to compare the rates of dis-appearance of iodine in dilute acidified solutions of dimethyl, methylethyl, methyl propyl, methyl butyl, methyl hexyl, phenyl methyl,diethyl, and phenyl ethyl ketones. On account of the small solu-bility of certain of these ketones in water, the comparative measure-ments could not be made in aqueous solution, and instead of this, anaqueous alcoholic solution containing forty volumes per cent. of ethylalcohol was employed. In this connexion experiments were madeto ascertain the influence of the medium on t.he reaction betweenacetone and iodine in alcohol-water mixtures ranging from purewater to pure alcohol.The results of this investigation will becommunicated in a further paper. For the present it is sufficientt o state that the reaction between the two substances is of thesame character in alcoholic as in aqueous solution, and that, fora given concentration of acetone and acid, the rate of disappearanceof iodine is practically the same in alcohol-water mixtures as it iIODINE AND THE RELATIVE RATES OF TAUTOMERIC CHANGE. 2049in pure water, if the amount of alcohol present does not exceedsixty to seventy volumes per cent. The only difference to be notedis the displacement of the final equilibrium as the ratio of thetwo components in the solvent is gradually altered.This influenceof the medium is shown by the data in table I, which were obtainedin parallel experiments with solutions containing 0, 20, 40, 60, 80,and 100 volumes per cent. of alcohol. The temperature at whichthese measurements were made wits 25'1O.TABLE I.Initial iodine concentration = 0.0095 ; acetone = 0.272 * ;H,W, = 0.1 mol. per litre.alcohol . . . .. . . . . . . . 0 20 40 60 80 100concentration ... 0*000005 0'000015 0*00040 0.00100 0-00225 OvO0442changed iodine.. 0.05 0.15 4.2 10.5 23.7 46-5* This concentration corresponds with 20 C.C. of acetone per litre.These results show that the limit of the reaction is reached at aprogressively earlier stage as the proportion of alcohol in the solventincreases, and the range of the velocity measurements is corre-spondingly diminished.In presence of potassium iodide, thereaction takes place stJll less completely. I n the case of the firstthree solutions in the above table, the percentage of unchangediodine was found to be 0.8, 2.3, and 16.9 respectively whenpotassium iodide was present to the extent of 0.02 mol. per litre.This effect of the iodide is no doubt due to the removal of iodinein consequence of tshe formation of polyiodides. In choosing a40 per cent. alcoholic solution as the medium for the reactingsubstances, these circumstances were taken into consideration, andthe alcohol-water mixture in question represents the smallest pro-portion of alcohol which is necessary for the solution of the majorityof the ketones in the requisite concentration.The limit of the reaction in the aqueous-alcoholic solution varieswith the nature of the ketone.This is evident from a considerationof the data in table 11, which gives the results obtained for acetone,diethyl ketone, and acetophenone. In these and all other experi-ments the relative concent,rations of ketone and iodine were suchthat the active mass of the ketone could be regarded as constantduring the course of the reaction. Similarly, the concentration ofthe sulphuric acid was so large that no appreciable alteration inits value resulted from the formation of the hydriodic acid duringthe reaction.The ketone was weighed out into a graduated stoppered flaskVolumes per cent.Equilibrium iodinePercentage of un2050 DAWSON AND WHEATLEY: REACTIVITY OF KETONES TOWARDScontaining water and measured quantities of alcohol and standardsulphuric acid solution.The flask was placed in a thermostat at25'1°, and after'some time a known quantity of iodine was addedin the form of an aqueous potassium iodide solution, and the contentswere made up to the mark with water. After definite time intervals,portions of the solutions were removed, added to excess of a sodiumhydrogen carbonate solution, and titrated with a freshly preparedO'OlN-solution of sodium thiosulphate.In the following tables z1 is the observed iodine concentration inmols. per litre, and x2 the concentration calculated from the equationx z = x o - k t , in which xo is the first observed concentration (t=O),and k the velocity constant=dz/dt. The concentrations of theketone and the acid and the original concentration of the iodine aregiven in every case in mols.per litre.TABLE 11.Acetone.Acetone = 0-1886 ; H,SO, = 0.1 ; iodine = 0*0101.Time(minutes) 0 25 45 65 85 105 140&:,.lo4 91.8 77.8 67'4 57.2 46'9 37.9 27'5x2104 (91'8) 78.3 67'5 56.7 45.9 35'1 16'2k =0*000054.Diethtyl Ketone.Ketone = 0-2532 ; H,SO, = 0.1 ; iodine = 0.0102.Time (minutes) 0 30 60 80 105 120 135x,.lO4 90'4 72.7 54.7 43'0 28.5 20.4 12.9x,.lO4 (90.4) 72.7 55'0 43'2 28'4 19.6 10.8k=0*000059.A cetophenorce.Ketone= 0.1673; H,SO, = O * l ; iodine=0-0101.Time (minutes) 0 15 51 75 105 135 165 255x,.104 98.3 95.6 89,2 84.8 79.3 74.5 70.2 57.7%.lo4 (98'3) 95.6 89.1 84.8 79'4 74.0 68.6 52'4k=OmOOO018.24 hours20.324 hours2.2 -24 hour42.4-From a comparison of the equilibrium iodine concentrationsrecorded under t =24 hours, it is evident that the extent t o whichthe reaction proceeds is dependent on the nature of the ketone insolution.Although the above three experiments are not strictlycomparable because of the differences in the ketone concentrations,it is seen that in the acetone, diethyl ketone, and acetophenonesolutions the unchanged iodine amounts to about 20, 2, and 40 percent. respectively. Of the ketones examined, the reaction proceedIODINE AND THE RELATIVE RATES OF TAUTOMERIC CHANGE. 2051furthest in the case of diethyl ketone, and to the smallest extentin the case of acetophenone, and on this account data are recordedfor these two substances, as well as for acetone, which show theprogress of the reaction throughout the greater part of its course.On comparing the values of x1 and x2, it is seen that in the caseof acetone, the rate of disappearance of the iodine is constant untilabout 50 per cent.of the iodine originally present has reacted, andthat the velocity then diminishes as the equilibrium condition isapproached. For diethyl ketone the velocity remains constant untilabout 75 per cent. of the iodine has disappeared, whereas, in thecase of acetophenone, the velocity shows distinct evidence ofdiminution when about 30 per cent. of the iodine has reacted.The point at which the velocity begins to fall is obviously determinedby the proportion of the original iodine which remains when thecondition of equilibrium has been reached.The more complete thereaction, the greater is the range over which the reaction velocityremains constant.In the communication of further results this circumstance is takeninto consideration, and the measured velocities relate solely to thatpart of the total reaction in which the iodine disappears at aconstant rate. Table I11 contains the data obtained in experimentswith other ketones, the calculated iodine concentrations being placedalongside the observed values, as in table I1 :TLLBLE 111.Methyl Ethyl Ketone.Ketone = 0.174 ; H,S04 = 0'095 mol. per litre.854 12966.1 34-431 *257!i 52.9xp 104 (94.8) 79.8 66.3 52.5Time (minutes) 0 30i9.104 94.8 79 '4k=0*0000495.Methyl Prowl Ketone.Ketone = 0.1727 ; H2S04 = 0.1 mol.per litre.XI. 104 92.1 78.0 69.8 64.0 47'6q. 104 (92'1) 78.0 70.0 63'9 47-5k=O *0000453.Time (minutes) 0 30 47 60 95Methyl Bzltyl Ketone.Ketone = 0-1678 ; H,SO, = 0.1 mol. per litre.x,.104 89.5 76.3 66.2 58.1 45.5Time (minutes) 0 25 45 60 85x2. 104 (89 -5) 7 6 4 66 .O 58'1 45-1k= 0.00005232052 DAWSON AND WHEATLEY: REACTIVITY OF KETONES TOWARDSMethyl Hexyl Ketone.Ketone = 0.0814 ; H,SO,= 0.1 mol. per litre.Time (minutes) 0 30 70 100 130XI. 1 0 4 73 3 65'8 55.7 48 -3 41 '2x,. 104 ('13.3) 65-8 55.8 48'3 40.8k = 0.000025.Phenyl Et h8yl Ketone.Ketone = 0-0855 ; H,SO, =0*251 mol. per litre.Time (minutes) 0 120 235 350 4 $0 565XI.104 96.6 90.0 83 '6 78 *3 71.8 67 '4%. 104 (96.6) 90'4 84'4 78.4 71.6 67 '2I n addition to the above experiments others were made in whichthe concentrations of the various ketones and of the acid wereapproximately doubled or halved. These indicate that the variousreactions take place at a rate which is proportional to the ketoneand acid concentrations, as was found to be the case for the actionbetween iodine and acetone in aqueous solution. Apart from theconstancy of the reaction velocity, the fact that the influence ofketone and acid concentration is the same for all the ketonesexamined affords strong evidence in support of the view that thecause of the uniform speed of the reaction is the same in all cases,that is to say, a change in the ketone from the ketonic to the enolicform.On the basis of the observed proportionality between the velocityand the ketone and acid concentrations, the several values obtainedfor the speed of the reactions may be reduced to a uniform ketoneand acid concentration (ketone = 1 / 6 mol. per litre ; sulphuricacid=0.1 mol.per litre). I n this way the velocities of reactionrecorded in the second column of table IV are obtained. Thesenumbers may be taken as representing the relative rates at whichthe ketonic forms of the various members of the series are convertedinto the corresponding enolic forms. The velocit.ies with referenceto acetone as standard are given in the third volume.k=0'0000052.TABLE IV.k (niols. per litreAcetone .................................48 x I 0-6Methyl ethyl ketone ............... 50 xMethyl propyl ketone ............... 45 xMethyl butyl ketone ............... 53 xAcetophenone ........................ 18 x loF6Diethyl ketone ........................ 39.5 xPhenyl ethyl ketone ............... 4 *O xKetone. per minute).Methyl hexyl ketone ............... 51 xRe1 ativek values.11'040.941-101 '060 *370 '820.08IODINE AND THE RELATIVE HATES OF TAITTOMERIC CHAKUE. 2053From the above values of k, it is seen that the replacement ofone of the methyl groups in acetone by ethyl, propyl, butyl, orhexyl does not cause very much alteration in the rate at whichthe substance reacti9 with iodine. On the other hand, the reactivityis reduced to nearly one-third when the methyl group is replacedby phenyl.For diethyl ketone the velocity is only about 20 percent. smaller than in the case of acetone, and substitution of phenylfor one of the ethyl groups reduces the reactivity to about one-tenth.On the assumption that the measured velocities are determinedby the respective rates of tautomeric change, it is not surprisingthat the first five ketones should be found to react with iodine atapproximately the same rate, for in each case the transformationinvolved may be supposed to be that represented byOn the other hand, the fact that the reactivity of diethyl ketoneis nearly as great as that of the methyl ketones would seem toshow that the change represented byCH,*CH,*CO*R -3 CH,*CH:C(OH)*Emay take place almost as readily as the previous one.That thisapproximate equality of the rates of change of the groups CH,*CIO*and CH,*CH,*CO* is not general, however, is evident from a com-parison of the values for acetophenone and phenyl ethyl ketone.As shown by experiments with benzophenone, the phenyl groupdoes not react a t all with iodine under the conditions of the dynamicexperiments, and it might be expected that the ratio of thereactivities of these two substances would be the same as the ratiofound in the case of acetone and diethyl ketone. This is not thecase, the observed velocity of reaction in the case of acetophenonebeing about four and a-half times as great as that found for phenylethyl ketone.I n other words, the relative rates at which thegroups CH,*CO* and CH3*CH,*CO* undergo tautomeric change isdependent on the nature of the radicle with which the two groupsare combined. On the other hand, the approximate equality ofthe rates of reaction of dimethyl and diethyl ketone with iodineleads us to anticipate that methyl ethyl ketone will react with iodinein two ways, which are determined respectively by the tautomericchanges :CH,*CO*CH,*CH, -+ CH,:C(OH)*CH,*CH, andCH,*CO*R -+ CH,:C(OH)*R.CIJ ,*CO*CH,-CH, -+ CH,*C(OH):CH*CH,.The amounts of the corresponding iodo-substitution products willbe conditioned by the relative rates at which these two changestake place. On the basis of the results which have been obtainedwith the aliphatic ketones, it appears probable that aliphatic ketone2054 TUTIN : THE CONSTlTUTION OF ERIODICTP OL,will in general give rise to two substitution products, for thevelocities of the two possible tautomeric changes are apparently ofthe same order of magnitude.Preliminary experiments have been made which show that certainaldehydes react with iodine in a similar manner to that observedfor the various ketones investigated in this paper. This is the casefor propaldehyde, whereas the kinetic investigation of the reactionbetween acetaldehyde and iodine indicates that the mechanism ofthis change is of a different kind. This question is being furtherinvestigated.The chief results obtained in this inquiry are :1. Evidence is adduced to show that the mechanism involved inthe reaction of iodine on various ketones is of the same kind, theprogress of the change being determined by the rate at which theenolic form of the ketone is formed.2. From the measurement of the velocities with which the ketonesreact with iodine, the relatdve rates a t which the ketones undergotautomeric change have been obtained.PHYSICAL CHEMISTRY LABORATORY,THE UNIVERSITY,LEEDS

ISSN:0368-1645    

DOI:10.1039/CT9109702048

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

2054 TUTIN : THE CONSTITUTION OF ERIODICTYOL,CCXVI.--The Constitution of Eriodictyol, of Homoerio-dictyol, and of Hesperitin.By FRANK TUTIN.IN a paper communicated to the meeting of the AmericanPharmaceutical Association, held at Indianapolis, Ind., in Septem-ber, 1906, Dr. F. B. Power and the present author described theisolation of two crystalline substances of phenolic nature from theleaves of Eriodictyon Calif ornicum (Hooker and Amott), Greene(Proc. Amer. Pharm. Assoc., 1906, 54,352). These two compoundswere designated eriodictyol and homoeriodictyol respectively, theformer having been proved to possess the formula C15H1206, whilstthe composition of the latter was shown to be Cl6H,,O,.I n it subsequent communication (Trans., 1907, 91, 887) it witsnoted that there are certain similarities in the properties ofhomoeriodictyol and its isomeride, hesperitin, which suggested thatthese two compounds were structurally related.Experiments sup-ported this view, for, whilst hesperitin yields isoferulic acid(3-hydroxy-4-methoxycinnclmic acid) aad phloroglucinol on hydrolysis(Tiemann and Will, Ber., 1881, 14, 970), homoeriodictyol, wheOF HOMOERIODICTYOL, AND OF HESPERITIN. 2055similarly treated, gave the same phenol together with ferulic acid(4-hydroxy-3-methoxycinnamic acid).Tiemann and Will (Zoc. cit.) assigned to hesperitin the con-stitutional formula (I). This formula received support through theOHMeO(-)CH:CH*CO*O/-\ \-/HO- OH(1.1work of A. G. Perkin '(Trans., 1898, 73, 1037), who prepared acetyl-hesperitin, and recorded results which indicated that this compoundwas a triacetyl derivative.It appeared 'therefore from the results of the hydrolysis experi-ments mentioned above that homoeriodictyol differed fromhesperitin on5 in the relative positions of the hydroxyl and methoxylgroups in the catechol part of the molecule.When, however,acetylhomoeriodictyol was prepared, it was found to contain fouracetyl groups. It was therefore concluded that homoeriodictyolmust be represented by formula (11).HOHO/-\CH:CH -CO/-\OH \-/ \-/Me0 HO(11.)From this it would appear that homoeriodictyol was not 80similar to hesperitin in structure as had at first been concluded.Nevertheless, Dr. Power and the present author were so convincedof the near relationship of these two compounds that they venturedto suggest that the formula hitherto assigned to hesperitin isincorrect, notwithstanding the statement of Perkin (Zoc.cit.) thatthe latter yields only a triacetyl derivative. Formula (111) wastherefore put forward for hesperitin.HC)M~O/-\CH:CH .c.<-)oH.HO-\-/HO(111.)With regard to the constitution of eriodictyol, the amount ofmaterial which was at first available did not permit of many experi-ments being conducted with this substance, but the view wasexpressed that it was the parent compound of which hesperitin andhomoeriodictyol are monomethyl ethers (formula IV).HOHO<-)CH:CH~CO<-)OHHO- H 2056 TUTIN : THE CONSTl'IUTION OF BRIODIC'I'YOL,Shortly after the appearance of the first paper by Power andTutin on eriodictyon leaves (Zoc. cit.), a communication on the samesubject was published by G.Mossler (Annalen, 1907, 351, 233).This author recorded the isolation of a substance possessing theformula C,,H,,O,, designated " eriodictyonon," which was evidentlyidentical with homoeriodictyol. Mossler, however, did not succeedin isolating any eriodictyol.After having published the account of their work on the con-stitution of homoeriodictyol, Dr. Power and the present authorreceived from Dr. Mossler a reprint of a paper communicated byhim t>o the Academy of Sciences in Vienna (Sitzungsb er. K . A kad.Wiss. Wien, 1907, 116, ii, June, 1907). In this communicationMossler, who was unaware of the more recent work of the above-mentioned authors, admits that his '' eriodictyonon " is identicalwith homoeriodictyol, and sets forth the conclusion that this sub-stance is represented by one of the following formulae:orThis last publication by Mossler was replied t o by Dr.Powerand the present author (Proc., 1907, 23, 243), when it was pointedout that neither of the formulae proposed by Mossler could becorrect, since compounds possessing such a structure could not yieldphloroglucinol.One statement made by Mossler, however, was in direct conflictwith the views which the present author, in conjunction withDr. Power, had expressed regarding the constitution of homo-eriodictyol, namely, that the substance in question waa opticallyactive.The last-mentioned authors were unable to confirm this,and, since the correctness of their conclusions regarding homo-eriodictyol have now been fully proved, it is evident that the abovestatement of Mossler must have been based on an incorrectobservation.It appeared to the present author that there was one possiblealternative to the formula which had been suggested by him inconjunction with Dr. Power for homoeriodictyol, but which was notat all probable, namely, a structure related t o the second formulaproposed by Mossler, as follows OF HOMOERTODICTYOL, AND OF HESPERITIN. 2057A substance possessing such a formula might conceivably yield, onhydrolysis, phloroglucinol and ferulic acid by the addition of twomolecules of water, followed by the elimination of one such molecule,although such a change appeared highly improbable.It was con-sidered advisable, therefore, in order conclusively to prove theconstitution of homoeriodictyol and related compounds, to haverecourse to synthetical experiments.I f the formula suggested by Dr. Power and the present authorfor eriodictyol, homoeriodictyol, and hesperitin be correct, thenthese substances are 2 : 4 : 6-trihydroxyphenyl 3 : 4-dihydroxystyry.Zketone, 2 : 4 : 6-trihydroxyphenyl 4-hydroxy-3-methoxystyryl ketone,and 2 : 4 : 6-trihydroxyphenyl 3-hydroxy-4-met7toxystyryl ketonerespectively, It waa decided therefore to methylate the firstrmentioned three substances, and to compare the fully methylatedproducts with synthetically prepared 2 : 4 : 6-trimethoxyphenyl3 : 4-dimethoxystyryl ketone.The results of the methylation oferiodictyol, homoeriodictyol, and hesperitin are recorded in thepresent paper, and it is shown that each of them yields 2 : 4 : 6-tri-methoxyphenyl 3 : 4-dimethoxystyryl ketone and 2-hydroxy-4 : 6-di-methoxyphenyl 3 : 4-dimethoxystyryl ketone identical in all respectswith these substances as prepared synthetically (see the followingThe correctness of the formulx suggested by Power and Tutinfor eriodictyol, homoeriodictyol, and hesperitin is therefore provedbeyond question.Naringenin, a hydrolytic product of the glucoside, naringin, wasshown by Will (Ber., 1885, 18, 1311) to be related to hesperitin.On heating with aqueous potassium hydroxide, it undergoeshydrolysis in a manner similar to the latter compound, and yieldsphloroglucinol and p-hydroxycinnamic acid.Will therefore con-cluded (Bey., 1887,20, 297) that naringenin was the phloroglucinylester of the above-mentioned acid. I n view of t'he results recordedin the present paper concerning hesperitin, there can be no doubtthat naringenin is also a ketone, namely, 2 : 4 : 6-trihydroxyphenyl4-h ydroxys t yry 1 ketone.I n a previous communication (Power and Tutin, Trans., loc. cit.)a monomethyl ether of homoeriodictyol was described. A largerquantity of this substance has now been prepared, and it has beenproved to be 2 : 6-dihydroxy-4-methoxyphenyl 4-hydroxy-3-methoxy-styryl ketone. Similarly, when one methyl group is introduced intoeriodictyol, it takes up the 4-position in the phenyl radicle, theproduct being a new isomeride of homoeriodictyol and hesperitin,namely, 2 : 6-dihydroxy - 4 - methoxyphenyl 3 : 4 - dihydroxystyrylketone.paper).VOL. XCVII.6 2058 TUTIN : THE CONSTITUTION OF ERIODICTY OL,The observation of Perkin (Zoc. cit.) regarding the anomalouscharacter of the sodium derivative of hesperitin has been confirmed,this substance appearing to have the formula CI6H&Na,C,6H&.On the other hand, the statement made by Perkin that the productof the action of acetic anhydride on hesperitin is a triacetylderivative cannot be confirmed, it having been proved that thesubstance thus formed is tetra-acetylhesperitin.EXPERIMENTAL.Eriodictyol (2 : 4 ; 6-Trihydroxyphenyl 3 ; 4DihydroxystyrytKetone).A quantity (5 grams) of eriodictyol * was dissolved in alcohol, andan excess of methyl sulphate added, after which a concentratedalcoholic solution of potassium hydroxide was allowed to flow intothe hot liquid at such a rate that the mixture was kept gentlyboiling.The liquid at first showed a tendency to darken, owingto the absorption of oxygen, but this soon ceased as methylationproceeded. Finally, the mixture assumed a dark red colour onthe addition of the alkali, which only slowly disappeared. A furtherquantity of methyl sulphate was added, followed by more alkali,after which the mixture was kept for twenty minutes and thenpoured into water. The yellow product precipitated by this treat-ment was extracted by means of chloroform, the solution beingwashed, dried, and the solvent removed.The residue thus obtainedwas boiled with successive portions of dilute, aqueous potassiumhydroxide so long as the decanted alkaline liquid was yellow incolour, after which the material insoluble in the alkali was washedand dissolved in alcohol. On inoculating the solution thus obtainedwith synthetic 2 : 4 : 6-trimethoxyphenyl 3 : 4-dimethoxystyrylketone (see the following paper), crystallisation rapidly ensued.The product so obtained was identical in all respects with thesynthetical compound just mentioned. It crystallised in stout, paleyellow prisms, and, when dried in the air, melted at 85O, but inthe anhydrous state at 117'5O :0.1747 t gave 0.4279 CO, and 0.1046 H20.The potassium hydroxide extracts which had been decanted fromthe crude 2 : 4 : 6-trimethoxyphenyl 3 : 4-dimethoxystyryl ketonewere acidified, and the precipitated yellow product was crystallisedfrom alcohol, in which it was rather sparingly soluble.Deep yellow* For an inipioved method of isolating eriodictyol, homoeriodictyol, and otherphenolic substances fmm Eriodictyoa leaves, compare Tutin and Clewer, Trans.,1909, 95, 81.C = 66.8; H= 6.4.CmH2,06 requires C = 67.0 ; H = 6.1 per cent.t Anhydrous substanceOF HOMOERIODICTYOL, AND OF HESPERITIN. 2059leaflets were thus obtained, which melted a t 154O, and were identicalwith the 2-hydroxy-4 : 6-dimethoxyphenyl 3 : 4-dimethoxystyrylketone described in the following paper :0.1279 gave 0.3099 CO, and 0.0680 HiO.CISH,,O, requires 66.3; H =5*8 per cent.~OnornethyteTiodictyol (2 : 6-Dihydroxy-4-rnet?~oxyp?~enyl 3 : 4-di-hydroxystyryl ketone).-Four grams of eriodictyol were dissolvedin absolute alcohol, and to this solution was added one and a-halfmolecular proportions of methyl sulphate, which had just previouslybeen washed with aqueous sodium carbonate and dried.Slightlymore than the equivalent amount of sodium, dissolved in absolutealcohol, was then gradually introduced into the hot mixture. Afterremoving t'he al-cohol, the residue was dissolved in ether, washedwith water, and then fractionally extracted by shaking with suc-cessive portions of an aqueous solution of sodium carbonate. Thefirst few extractions removed only unchanged eriodictyol, whichformed the greater part of the product., but on acidifying thealkaline liquids subsequently obtained, a yellow product separated,which partly crystallised on keeping.This wits collected, wellwashed with alcohol, and then recrystallised from this solvent, inwhich it was but sparingly soluble. Almost colourless needles werethus obtained, which melted at 2 1 5 O :C = 66.1 ; H * 5.9.0.1284 gave 0.2995 CO, and 0'0583 H,O. C = 63.6 ; H = 5.0.Cl6HI4O6 requires C = 63'5 ; H = 4.6 per cent.This substance was therefore a, monomet?&yZeriodictyoE, and sinceit is not identical with either homoeriodictyol (2 : 4 : 6-trihydroxy-phenyl 4-hydroxy-3-methoxystyryl ketone) or hesperitin (2 : 4 : 6-tri-hydroxyphenyl 3-hydroxy-4-methoxystyryl ketone), and the hydroxylgroup in the 2(0r 6)-position is known to be difficult of methylation,it must be 2 : 6-dih~d~oxy-4-methoxyp?~enyl 3 : 4-dihydroxystyrylketone.Monomethyleriodictyol dissolves in aqueous alkali hydroxides,giving at first a practically colourless solution, but after aboutthirty seconds the liquid suddenly becomes totally bIack. Onscetylation, monomethyleriodictyol yields a tetra-acetyl derivative,which forms colourless needles, melting at 159O.Homoeriodictyol (2 : 4 : 6-T~ihydroxyphenyZ 4-HgcZroxg-3-rnet hoxy-.stpry$ Ifetone).The methylation of homoeriodictyo1 by means of methyl suIphateand potassium hydroxide proceeded analogously t o that oferiodictyol, with the exception that there was no tendency to absorboxygen, and consequently a cleaner product was obtained.The6 T 2060 TUTIN : THE CONSTITUTION OF ERIODICTYOLmethylated material wits examined as above-described, whea itreadily yielded 2 : 4 : 6-trimethoxyphenyl 3 : 4-dimethoxystyrylketone (m. p. 85O when air-dried; 117'5O when anhydrous), and2-hydroxy-4 : 6-dimethoxyphenyl 3 : 4-dimethoxystyryl ketone (m. p.154O).ik4onomethylhornoeriodictyol (2 : 6-DihycEroxy-4-methoxyphenyl4-hydroxy-3-met hoxystyryl ketone). - Monomethylhomoeriodictyol,prepared by the action of methyl iodide on the crystalline sodiumderivative of hoqmoeriodictyol, was previously described by Powerand Tutin (Trans., 1907,91,895). A larger amount of this producthas now been prepared by heating the above-mentioned sodiumderivative with methyl iodide and methyl alcohol.The productthus obtained was dissolved in ether and freed from unchangedhomoeriodictyol by extraction with dilute, aqueous sodiumcarbonate, after which the monomethylhomoeriodictyol was removedby shaking with a concentrated solution of this alkali. The productso obtained crystallised readily from alcohol in hard, yellow, wart-like masses, which melted at 142O.On boiling monomethylhomoeriodictyol for several hours with30 per cent. aqueous potassium hydroxide, hydrolysis occurred atthe double linking, after which vanillin was readily isolated fromthe reaction mixture. It is evident from this, and considerationapreviously given, that the ONa group in the sodium derivative ofhomoeriodictyol, which is converted into methoxyl on treatmentwith methyl iodide, must occupy the $-position in the phenyl groupof the molecule.Monomethylhomoeriodictyol is therefore 2 : 6-cti-hydroxy-4-methoxyphenyl 4-hydroxy-3-methoxystyryl ketone.Hesperitin ( 2 : 4 : 6-Trihydroxyphenyl 3-Hydroxy-4-methoxystyrylKetone.)Hesperitin, which is obtained by the hydrolysis of the glucoside,hesperidin, a constituent of the peel of the orange, lemon, and otherrelated fruits,, has been stated by Tiemann and Will (Ber., 1881,14, 970) to be the phloroglucinyl ester of isoferulic acid. As statedin the introductory portion of this paper, however, the accuracy ofthis conclusion was doubted by Power and Tutin, and the presentauthor has therefore further investigated the question.Hesperitin, as obtained from Schuchardt, was recrystallised fromethyl acetate, when it melted at 224O, but when mixed with homo-eriodictyol, fusion occurred a t 200O.The material so obtained,however, did not agree in its characters with t,he description ofhesperitin as given by A. G. Perkin (Trans., 1898, 73, 1037).Thus it formed pale yellow plates, which could not be distinguisheOF HOMOERIODICTYOL, AND OF HESPERITIX. 2061by inspection from crystals of homoeriodictyol, it was practicallytasteless,* and it dissolved in alkalis with a bright yellow colour.Perkin (Zoc. cit.), on the other hand, has described hesperitin ascrystallising in almost colourless needles, possessing an intenselysweet taste, and dissolving in alkalis with, a t the most, a faintlyyellow colour.Nevertheless, the identity of the material employedby the present author with hesperitin cannot be doubted, inasmuchas the melting points of the compound itself and its acetyl derivativeare in agreement with the corresponding constants given by Perkinfor hesperitin and its acetyl derivative. Moreover, the substanceyielded the abnormal sodium derivative, C,6H,306Na,Cl,Hl,0,,characteristic of hesperitin. (Found, Na= 3.8. Calc., Na= 3.8 percent.)Methylation of Hesperitbz.A quantity (1.5 grams) of hesperitin was methylated by means ofpotassium hydroxide and methyl sulphate in the manner previouslydescribed, when the reaction appeared to proceed precisely as inthe case of homoeriodictyol.A good yield of product was obtained,which was readily separated into the two compounds similarlyprepared from eriodictyol and its homologue, namely, 2-hydroxy-4 : 6-dimethoxyphenyl 3 : 4-dimethoxystyryl ketone (m. p. 154) and2 : 4 : 6-trimethoxyphenyl 3 : 4-dimethoxystyryl ketone (m. p. 8 5 Owhen air-dried.; 117’5O when anhydrous).Tetra-acetyZ~esperiti~.-Half a gram of hesperitin was boiled forthree hours with a considerable excess of acetic anhyaridc, afterwhich the greater part of the solvent was removed and the mixturediluted with ether. After several hours, a crystalline substanceseparated in tufts of colourless prisms, which melted at 120O. Afterrecrystallisation from alcohol, this substance melted at 1 2 7 O , andwas evidently identical with the compound similarly prepared byPerkin (Zoc. cit.), which he regarded as a triacetyl derivative. Thenumber of acetyl groups in the compound were estimated asfollows. A quantity of the substance was hydrolysed with dilutepotassium hydroxide, the mixture then acidified with sulphuric acid,and the acetic acid removed by a current of steam and titrated :0.2616 gave acetic acid equivalent to 0*0900 NaOH. CO-CH,= 36.9.Cl,Hl,0,(CO*CH3)1 requires CO*CH3 = 36.6 per cent.It is evident therefore t<hat this compound was tetra-acetyl-hesperitin, and not a triacetyl derivative. This conclusion is inharmony with the properties of the substance, for it was insoluble* Although hesperitin, when in the solid state, possesses no appreciable taste, itsalcoholic solution is distinctly sweet2062 TUTIN AND CATON : SYNTHESIS OF 2 : 4 : 6-TRIMETHOXY-in cold dilute sodium hydroxide, which would not have been the casehad it contained a hydroxyl group, all the groups of this naturepresent in hesperit,in having phenolic properties.THE WELLCOME CHEMICAL RESFARCH LABORATOR~ES,LONDON, E.C

ISSN:0368-1645    

DOI:10.1039/CT9109702054

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

2062 TUTIN AND CATON : SYNTHESIS OF 2 : 4 : 6-TRIMETROXY-CCXVIL-Tlze Synthesis of 2 : 4 : 6-TrimethoxyphenylA Methyl Derivative 3 : $-Dimethoxystyr,$ Ketone.of Eyiodictyol, Homoeiioclict yol, and Hesperitin.By FRANK TUTIN and FREDERIC WILLIAM CATON.SOME time ago Power and Tutin (Proc. Amer. Pharm. Assoc., 1906,54, 352) isolated from the leaves of Em’odictyon Californicurn(Hooker and Arnott), Greene, two crystalline substances of phenolicnature, which were designated eriodictyol and homoeriodictyolrespectively. Eriodictyol was shown to possess the formula,CI5Hl2O6, whilst homoeriodictyol was found to be isomeric withhesperitin, having the formula Cl,Hl,O,.I n a subsequent communication (Power and Tutin, Trans., 1907,9 1, 887) results were recorded which indicated that homoeriodictyolpossesse the following constitutional formula, :HOHO/-\CH: CH-CO/-\OH.\-/ \-/hleO HOThe amount of eriodictyol at that time available did not permitof many experiments being conducted with this substance, but theconclusion was drawn that it differed from its homologue only byhaving a hydroxyl in the place of the methoxyl group. It wasfurthermore suggested from certain similarities in the properties ofhomoeriodictyol and hesperitin t.hat these two substances differedonly in the relative positions of the hydroxyl and methoxyl groupsin the catechol part of the molecule, and that, consequently, theconstitutional formula, hitherto assigned to hesperitin was incorrect(Tiemann and Will, Ber., 1881, 14, 970; Perkin, Trans., 1898,73, 1037):HOHesperi tin(Power and Tntin)OHHesperitinThe above conclusions have now all been confirmed, inasmuchas, in the preceding paper, it is shown that eriodictyol, homeeriodictyol, and hesperit.in each yield the same product when fullymethylated.Final and conclusive proof of the structure of thesecompounds was, however, desirable, and it appeared that this couldbest be obtained by the synthesis of the fully methylated product.If the views previously expressed regarding the constitution oferiodictyol, homoeriodictyol, and hesperitin be correct (Power andTutin, Trans, Zoc. cit.), then these substances are 2 : 4 : 6-trihydroxy-phenyl 3 : 4-dihydroxystyryl ketone, 2 : 4 : 6-trihydroxyphenyl4-hydroxyl-3-methoxystyryl ketone, and 2 : 4 : 6-trihydroxyphenyl3-hydroxy-4-methoxystyryl ketone respectively. It was thereforesought to synthesise 2 : 4 : 6-trimethoxyphenyl 3 : 4-dimethoxystyrylketone in order that it might be compared with the compoundobtained on fully methylating the naturally occurring substancesunder consideration. This has been accomplished, and the syn-thetical compound has been found to be in all respects identicalwith the product obtained from the three substances occurring innature, thus affording conclusive proof of the constitution of thelatter compounds.2 : 4 : 6-Trimethoxyacetophenone was prepared by the interactionof acetyl chloride and phloroglucinol trimethyl ether in the presenceof anhydrous ferric chloride, and this ketone was condensed withvanillin methyl ether by means of I' molecular " sodium in a mannersimilar to that employed by Perkin and Weizmann (Trans., 1906,89, 1649), when 2 : 4 : 6-trimethoxyphenyl 3 : 4-dimethoxysty ytketone resulted in good yield:Me0(Tiernnnn and Will).Me0MeO<-)CH :CH-CO/-\OMe + H20.\-/MeO- Me0This substance gave, on heating with aluminium chloride, ahydroxytetramethoxy-compound, which melted at practically thesame temperature as 2-hydroxy-4 : 6-dimethoxyphenyl 3 : 4-di-methoxystyryl ketone described by Eostanecki (Ber., 1904, 37, 793)2064 YUTIN AND CATON : SYNTHESIS OF 2 : 4 : G-TRIMETHOXY-The present authors, however, were unable to obtain from thesubstance prepared by them the acetyl derivative described byKostanecki.Nevertheless, it is considered certain that the hydroxy-tetramethoxy-compound obtained by the present authors is identicalwith that prepared by Kostanecki, inasmuch as the latter authorbias shown that a methoxyl group in the phloroglucinol nucleussituated in the 2-position with respect to the side-chain is mosteasily hydrolysed by aluminium chloride.2 : 4 : 6-Trimethoxyacetophenone was prepared by Kostanecki(Ber., 1899, 32, 2262) in the manner already mentioned, but it hadpreviously been stated by Friedlander and Schnell (Ber., 1897,30, 2150) to result from the interaction of phloroglucinol trimethylether and acetyl chloride in the presence of aluminium chroride.The present authors, however, could succeed in preparing it onlyby Kostanecki's method, and, when employing that of theearlier investigators, obtained a hgdroxpdk ce t yldim e t hox y b enz ene,C18H1405-EXPERIMENTAL.Met hylation of Phloroglucinol.Will (Ber., 1888, 21, 603) obtained phloroglucinol trimethylether by the action of sodium and methyl iodide on the dimethylether, the latter being prepared by passing anhydrous hydrogenchloride into a methyl-alcoholic solution of phloroglucinol.Thepresent authors, with the endeavour to simplify this process, soughtto obtain the trimethyl ether by the direct methylation of phloro-glucinol with methyl sulphate and potassium hydroxide. Thismethod, however, did not give satisfactory yields of the desiredsubstance, a considerable part of the material being converted intoa neutral oily product.The latter distilled at 140--145O/13 mm.,or at 258-266O under the ordinary pressure. It was unchanged byfurther treatment with methyl sulphate and potassium hydroxide,but was not further investigated. The method employed by Will(Zoc. cit.) was therefore adopted, but with the employment ofmethyl sulphate instead of methyl iodide. I n this way satisfactoryyields of phloroglucinol trimethyl ether (m. p. 52O) were obtained.Action of Acetyl Chloride and Aluminium Chloride onPhloroglucinoi Trimethgt Ether.Friedllnder and Schnell (Zoc. cit.) treated phloroglucinol tri-methyl ether with acetyl chloride and aluminium chloride, andobtained thereby 2-hydroxy-4 : 6-dimethoxyacetophenone and thecorresponding trimethoxy-ketone.The present authors, however,when employing the method of these investigators, could isolatPHENYL 3 : 4-DIMETHOXYSTPRYL KErONE. 2065from the reaction mixture only a small amount of 2-hydroxy-4 : 6-di-me thoxyacet op henone, unchanged p hloroglucinol trimet h yl ether,and a htydroxydiacetyldimethoxybenzene, CI2Hl4O5, no matter howthe conditions of the experiment were varied.A quantity (11.5 grams) of phloroglucinol trimethyl ether wasdissolved in carbon disulphide, 6 grams of acetyl chloride added,and then 10 grams of powdered aluminium chloride graduallyintroduced. After heating the mixture f o r one hour the solventwas decanted, and the residue decomposed with ice and hydrochloricacid. The product so obtained was dissolved in ether and shakenwith a solution of potassium hydroxide, which removed the greaterpart of the material.The neutral product remaining in the etherconsisted almost entirely of unchanged phloroglucinol trimethylether. The alkaline extracts were acidified, and the precipitatedproduct was crystallised, first from ether, and then from alcohol,when it formed long, slender prisms, melting a t 127-128O :0.1090 gave 0.2407 (20, and 0.0583 H,O. C = 60.2 ; H = 5.9.0.1130 ,, 0.2491 CO, ,, 0.0595 H,O. G=60'1; H=5.9.0.1316 ,, 0.2924 CO, ,, 0'0714 H,O. C=60*6; H=6.0.OHo~6H2(O~e),(OO*CH3) requires c"= 61.2 ; H = 6.1 per cent.OH*C,H(OMe),(C'O*CH,), ,, C = 60.5 ; H = 5.9 ,,OH-@6(OMe)2(CO*CH3)3 ,, C = 60.0 ; H = 5.7 ,,These analyses indicate that the substance under considerationwas a hydroxydiacetyldimethoxy6 enaene, OH°C6H(OMe),(CO*CH3)2,and this conclusion was subsequently confirmed by the analysis ofits benzoyl derivative.No direct proof of the constitution of thediketone was obtained, but it would appear most probable that itis represented as follows:OH/\CO*CH,CO*CH,CH,*O\/ I O*CH, .This formula is preferred to the other possible one, as it is knownthat 2 : 4 : 6-trimethoxyacetophenone, which must first be formed,readily yields 2-hydroxy-4 : 6-dimethoxyacetophenone in the presenceof aluminium chloride, and a second acetyl group, when enteringthe nucleus of the latter ketone, would assuredly enter the par%position with respect to the hydroxyl group.Hydroxydiacetyldimethoxybenzene is sparingly soluble in ether,and moderately so in alcohol.It did not lose either of the methylgroups when treated with anhydrous ferric chloride or withaluminium chloride, and attempts to introduce a third acetyl groupinto the nucleus of it were unsuccessful2066 TUTIN AND CATON : SYNTEIESIS OF 2 : 4 : 6-TRIMETHOXY-Acetoxydiacetyldirnethoxybenzene, OAC-C~H(OM~)~(CO*CH~)~.-The acetyl derivative of the above-described compound was preparedby means of acetic anhydride. It crystallised from its concentratedsolution in this solvent, and was purified by recrystcallisation frombenzene. A cetoxydkcetyldimethoxy b enzene forms well-definedprisms, melting at 150-5O :0.1132 gave 0.2409 CO, and 0.0572 H,O.C14Hl606 requires C = 60.0 ; H = 5.7 per cent.This subst4ance cannot be crystallised from ordinary alcohol orother hydrous solvents, as it is rapidly hydrolysed when dissolvedin such liquids.Benzoyloxydkcetyldmethoxybenzene, OBz*C6H(OMe),(CO.CH3)z.-This compound was prepared by the Schotten-Baumann reaction.It crystallised from benzene in cubes, and from absolute alcohol inslender prisms, melting at 179O:C = 60.0 ; H = 5.6.0.1132 gave 0.2768 C'O, and 0.0551 H,O.C19H2206 requires C = 66.7 ; H = 5.3 per cent.The analysis of this compound conclusively confirms the resultsobtained by the analysis of the original hydroxy-diketone, inasmuchas the related compounds containing one and three acetyl groupswould require C= 65.6 and C = 68.0 per cent.respectively.Hydroxydiacet yldirne t hoxy b enz enephenylh ydrazone.- One gramof hydroxydiacetyldimethoxybenzene was dissolved in a smallamount of alcohol, and slightly more than two molecular proportionsof freshly distilled phenylhydrazine dissolved in acetic acid added.The mixture was heated on a water-bath for a quarter of an hour,when, after concentration, a crystalline product separated. Thiswas collected, and crystallised many times, first from acetic acid,and subsequently from a mixture of ethyl acetate and alcohol, whenthe melting point gradually rose from 215O to 230°, the productfinally obtained forming hexagonal prisms melting sharply at thelatter temperature :C=66*7; H=5*4.0.0927 gave 0-2248 CO, and 0.0529 H,O.0*1012 ,, 8.4 C.C. N, (moist) at 19O and 753 mm. N=9*4.Cl,H,,04N, requires C = 65.8 ; H = 6-1 ; N = 8.5 per cent.This compound was therefore a mowphenylhydrazone of hydroxy-diacetyldimethoxybenzene.The original ethereal mother liquors from the hydroxydiacetyl-dimethoxybenzene yielded a small amount of a substance which,when crystallised from alcohol, melted at 80°:0.0754 gave 0.1685 CO, and 0.0425 H20.C= 66.1 ; H = 6.3.C = 61.2 ; H = 6-3.CloH,,O, requires C = 61.2 ; H = 6.1 per centPHENYL 3 : 4-DIMETHOXYSTYRYL KETONE.2067This substance was evidently 2-hydroxy-4 : 6-dimethoxyaceto-phenone, described by FriedlSnder and Schnell (loc. cit.).Since no trimethoxyacetophenone could be obtained by means ofthe aluminium chloride reaction, recourse was had to the use ofsublimed ferric chloride (Eostanecki, Ber., 1899, 32, 2261).Bythis means it good yield of product was obtained, which consistedlargely of 2 : 4 : 6-t.rimethoxyacetophenone (m. p. 99-loo6), butcontained a little of the previously described hydroxydiacetyl-dimethoxybenzene.Condensation of 2 : 4 : 6-Trimethoxyacetophenone with VanillinMethyl Ether. Formation of 2 : 4 : 6-T~imethoxyphenyZ3 : 4-Dimethoxystyryl getone.Vanillin was methylated by means of methyl sulphate in themanner described by Perkin and Weizmann (Trans., 1906, 89,1649), when vanillin methyl ether was readily obtained. Onemolecular proportion of the latter compound was then heated in dryethereal solution with equivalent amounts of 2 : 4 : 6-trimethoxy-acetophenone and finely divided sodium.* Hydrogen was slowlyevolved, and, after six hours, a yellow solid commenced to separate.When the reaction was complete, which was after about twenty-fourhours heating, the ether was decanted, and the residue dissolved inbenzene and washed with water.Considerable difficulty wasoriginally experienced in causing the yellow, viscid residue obtainedon evaporating the benzene to crystallise, but this was eventuallyeffected from alcoholic solution, after which subsequent batches ofmaterial quickly crystallised on inoculating with the solid firstobtained. 2 : 4 : 6-Trimethoxyphenyl 3 : 4-dimethoxystyryt? ketoneforms stout, pale yellow prisms, which contain one molecule ofalcohol of crystallisation, and melt at 85O. The anhydrous substancemelts a t 117.5O :0.1158 t gave 0.2778 CO, and 0.1158 H20.C=65-4; H=7*1.0.1436 ,, 0.3512 CO, ,, 0'0796 H20. C = 66.7; H = 6'1.l*OOlO,t on heating at looo, lost 0.1140 EtOH- EtOH = 11.4.C2,H,0,,EtOH requires C = 65.3 ; H = 6.9 ; EtOH = 11.4 per cent.C,,HB0, requires C = 67.0 ; H = 6.1 per cent.2 : 4 : 6-Trimethoxyphenyl 3 : 4-dimethoxystyryl ketone is veryreadily soluble in benzene, xylene, chloroform, or acetic acid,moderately so in alcohol or carbon disulphide, and almost insolublein ether or petroleum. It also dissolves readily in moderatelyconcentrated hydrochloric or sulphuric acids, yielding deep red* Prepared by violently shaking molten sodium under xylene, the latter beingsubsequently removed by the addition of pure ether, and decantation.t Air-dried.$ Anhydrous substance2068 TRIMETHOXYPHENYL DIMETHOXYSTYRYL KETONE,solutions. It distils without decomposition at 325y 13 mm., solidify-ing to a yellow, vitreous mass.A quantity of the ketone was heated for five hours with a largeexcess of a concentrated alcoholic solution of potassium hydroxide.The greater part of the material was recovered unchanged afterthis treatment, but some veratric acid was isolated from the reactionmixture. It thus appears that, under the influence of potassiumhydroxide, the ketone in question is attacked at the double linking,just as has been shown, in the preceding paper, to be the case withmonomethylhomoeriodictyol. The first product of this change is,doubtless, vanillin methyl ether, whicb yields the veratric acid bythe further action of the alkali.Action of Aluminium Chloride on 2 : 4 : 6-Trimethoxyphenyl3 : 4-Dim.ethoxystyry2 Ketone.With the endeavour to remove methyl groups from the above-described ketone, in order to see if, in this way, homoeriodictyolcould be obtained, the effect of ferric and aluminium chlorides onthe pentamet.hoxy-compound was investigated.Ferric chloride wasquite without action on it, but when heated with aluminium chlorideit slowly lost one met-hyl group. The change was by no meanscomplete, even after many hours’ heating, but the hydrolysedproduct was readily separated from the unchanged material byboiling the mixture with successive portions of dilute aqueouspot,assium hydroxide. The alkaline liquids so obtained yielded, onacidification, a yellow compound, which crystallised very readilyfrom alcohol in deep golden-coloured plates, melting at 154O :0.1122 gave 0.2724 CO, and 0.0584 H20.C19H2006 requires C = 66.3 ; H = 5.8 per cent.This compound is doubtless identical with the 2-hydroxy-4 : 6-di-methoxyphenyl 3 : 4-dimethoxystyryl ketone (m. p. 157O) preparedin another way by Kostanecki (Ber., 1904, 37, 793), but the presentauthors were unable to obtain the crystalline acetyl derivativedescribed by him, although several attempts were made.C = 66.2 ; H = 5.8.THE \ITELLCOME CHEMICAL RESEARCH LABORATORIES,LONDON, E.C

ISSN:0368-1645    

DOI:10.1039/CT9109702062

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

MOLECULAR COMPLEXITY OF NITROGEN COMPOUNDS. 2069CCXVII1.-The Molecular Complexity, in the LiquidState, of Terlcalenh Niti-oyen Compounds.By WILLIAM ERNEST STEPHEN TURNER and ERNEST WYNDHAMMERRY.IN a review of the possible causes of association in the amides byDr. A. N. Meldrum and one of us (Trans., 1908, 93, 876), it wassuggested that the association observed might well be due to thepresence of the tervalent nitrogen atom or the oxygen atom of thegroup *CO*NH,, and the observations recorded in this com-munication were, in the main, carried out in order to test thissuggestion.Evidence bearing directly on the problem should be obta.inableby an examination of the molecular complexity of the amines, forin these substances the nitrogen atom can pass with great readinessfrom the ter- to the quinque-valent state.Such data as existed atthe beginning of the work were but meagre, consisting of deter-minations, either in solution or in the liquid state, of the molecularweight of aniline, two or three of its derivatives, and of thetoluidines (Auwers and Pelzer, Zeitsch. physilcal. Chem., 1897,23, 449; Auwers and Dohrn, ibid., 1899, 30, 542; Dutoit andFriderich, Compt. r e d . , 1900, 130, 327). It is well known, how-ever, and our research confirms the fact., that the molecularassociat.ion of an aromatic substance is either considerably less thanin the corresponding aliphatic compound, or is non-existent. Wedecided accordingly, whilst including a number of aromatic sub-stances, to make a study of the aliphatic amines.The research was extended, however, beyond a comparison of theamines and amides, and was made to include a survey of othernitrogen-containing compounds.Of these, some, notably acete,propie, butyrs, and benzo-nitrile, had already been examined byseveral investigators (Ramsay and Shields, Trans., 1893, 63, 1089 ;Dutoit and Friderich, Zoc. c i t . ; Guye and Baud, Arch. Sci. phys.nat., 1901, [iv], 11, 449; Renard and Guye, J. C'him. phys., 1907,5, 97), although their results do not in all cases agree as well asmight be expected. We have included in our work redeterminationswith these four substances, but have not given full results in eachcase.As regards the nitro-compounds, Ramsay and Shields (Zoc. c i t . )have proved, by a comparison of nitroethane and nitrobenzene, thataliphatic nitro-compounds are associated, whilst aromatic compoundsare non-associated.The observations on this class of substances wehave not extended, but the possibility of association connected wit2070 TURNER AND MERRY : THE MOLECULAR COMPLEXlTY, IN THEthe nitroscgroup, it5 revealed by the tendency of a few derivativesof hydrocarbons to form double molecules at low temperatures(Piloty, Ber., 1898, 31, 452; Bamberger and Rising, Ber., 1901,34, 3877), attracted us to examine-three nitrosoamines, of whichdimethylnitrosoarnine is of particular interest on account of its con-siderable conductivity, solvent power, and dielectric constant(Walden, Zeitsch. physikal. Chem., 1903, 46, 103).From the highvalue of the dielectric constant we expected to find association.The determination of the molecular complexities in the liquidstate, rather than in solution, was attended by certain advantages,for our results render it possible to make a comparison, in somecases, with the extent of association in solution; and we have alsobeen able to include a number of substances the solubilities of whichin benzene and similar solvents are very slight, the advantage ofbeing able to include formamide being considerable. As far aspossible, the experiments have been carried out over the same rangeof temperatures.Against these advantages, we have to set off the fact that thecalculation and interpretation of the results by the Ramsay andShields’ method, which has been used in its original form, is opento objection, and our own determinations support those of Dutoitand Friderich and of Guye and his pupils in demonstrating thatthe Ramsay and Shields’ formula can only be applied.within some-what circumscribed limits. We have not been able, owing to lackof data in most cases, to employ any of the alternative methods ofdetermining the molecular complexity, such as have been suggestedby Ramsay (Proc. Roy. Soc., 1894, 56, 175) and Walden (Zeitsch.physikal. C’hem., 1909, 65, 184).EXPERIMENTAL.The mea.surement of surface tension wm carried out inapparatus of the U-tube type, the capillaries used in the construc-tion being previously carefully tested and calibrated at differentpoints.I n form, the apparatus was very similar to that employedby Hewitt and Winmill (Trans., 1907, 91, 441)-reference to theirdiagram will serve to explain our arrangement-but differed fromit in two respects: the capillary tube was backed by enamel, and,more important still, the end of the capillary tube, to the extent ofabout one inch, was bent sharply downwards, and a piece of quilltubing of the same diameter fused on to it, this added tube beingbent sharply upwards so as to be parallel both with the Capillaryand with the wide limb of the U-tube. The object of this elbowof quill tubing was twofold. It served, in the first place, as it traLIQUID STATE, OF TERVALENT NITROGEN COMPOURDH. 2071for particles falling from the rubber connexions, and, in the secondplace, as a reservoir into which liquid could be t,ransferred from thecapillary.Constant temperatures were obtained by the use of large bathsand a carefully regulated flame. A t the higher temperatures weemployed a bath of paraffin wax (m.p. 60°), finding it muchpreferable to concentrated sulphuric acid, and we were able to useit at temperatures up to 2 1 0 O .In most of the experiments, the air was removed from theapparatus by exhaustion to a low pressure, although it has beenshown by Renaud and Guye (Zoc. cit.) that unless the substance iseasily oxidisable, measurements of the surface tension made both inpresence and in absence of air agree to within about4 per cent.A t each temperature, three readings of thecapillary rise were made by means of a readingmicrometer, the differences never amounting to morethan four hundredths of a millimetre. A freshsurface was obtained for each reading by t'ilting thetube and allowing liquid to run from the capillaryinto the elbow of quill tubing. The substances ofhigh melting point could not be treated in this way,and in these cases a fresh surface was obtained bytemporarily forcing the liquid from the capillaryinto the wide tube.Two independent series of deter-minations of the surface tension were made witheach substance, in many cases by employing two tubesand placing them side by side in the same bath.The density determinations were mainly made inspecific gravity bottles of 10 C.C. capacity, calibratedat five or six different temperatures between 20° and90°, so that the volumes at other temperatures couldbe deduced.A t the higher temperatures considerabledifficulty was experienced in using this form ofpyknometer, and the simple form shown in the diagram was devisedand employed, the narrow tubing being capillary of 1-1.5 mm.diameter of quill tubing of about the same bore. The cup wascharged with the solid, and the pyknometer transferred to theheating bath. The liquid level was adjusted by air pressure to themark b , excess above the level a removed by fine capillary tubes, andthe cup wiped out before weighing. All densities are comparedwith that of water at do.With the exception of benzamide and salicylamide, the materialswere obtained by purchase, mainly from Kahlbaum, and all wer2072 TURNER AND MERRY: THE MOLECULAR COMPLEXITY, IN THEaubjected to purification save a pure specimen of phenylhydrazineobtained from Kahlbaum.The liquid amines were treated with solid sodium or potassiumhydroxide, and afterwards distilled, benzyl-, dibenzyl-, and triamyl-amine under diminished pressure, the others under atmosphericpressure.Distillates of constant, or almost constant, boiling pointwere obtained and used throughout. Diphenylamine and tribenzyl-amine , were crystallised from alcohol until of constant meltingpoint,. Wherever possible, the densities obtained were comparedwith those of other investigators. The density of the anilineemployed agreed exactly with that found by Bruhl (Zeitsch.physikal.Chem., 1895, 16, 193) ; and those of propyl-, dipropyl-,and tripropyl-amine were in very close agreement with the numbersgiven by Perkin (Trans., 1889, 55, 693).The nitrosoamines (from Schuchardt) were treated as follows :phenylmethylnitrosoamine with freshly heated sodium sulphate,the two others with recently ignited potassium carbonate, and sub-sequently distilled under diminished pressure.Of the nitriles, acetonitrile, benzonitrile, phenylacetonitrile, andmtoluonitrile were treated with phosphoric oxide and afterwardsdistilled, the acetonitrile under atmospheric, the others underdiminished pressure. Propio-, butyro-, and isobutylaceto-nitrile werekept over sodium sulphate, and then distilled under atmosphericpressure. Lacto-, mandelo- and o-toluenitrile were merely distilledunder diminished pressure.The melting point of the p-toluonitrilewas 28*4O, and the substance was used without further purification.The densities at 20° of acetonitrile and benzonitrile agreed veryclosely with the values found by Bruhl (Zoc. cit.), but those ofpropio- and isobutylaceto-nitrile were a little higher, that of phenyl-acetonitrile a little lower, than Bruhl found.The formamide was well dried over sodium sulphate and after-wards distilled under diminished pressure. Its density at ZOOwas in good agreement with that given by Bruhl. Theother amides, the anjlides and urethanes were purified by methodsalready described (Meldrum and Turner, this vol., p. 1607).A t the conclusion of the surface-tension measurements, the meltingpoints of the salicylamide and phenylacetamide were tested, andfound to agree exactly with those of the original substances.I n addition to the amides on which we have been successful inmaking measurements, we endeavoured to bring into the scope ofthe work a number of diamides and ethyl oxamate, but found themall unstable.Carbamide decomposed at its melting point ; ammoniafrom malonamide could be detected even before melting; whilstethyl oxamate, when gradually heated, gave ammonia at 130OLIQUID STATE, OF TERVALEKT NITROGEN COMPOUNDS. 2073Neither could we find a suitable solvent for these substances. Theirinsolubility in benzene, ether, etc., is well known. Lachman(Zeitsch. physikal. Chern., 1897, 22, 170) found that ethyl oxamateis soluble in methyl oxalate, and, in this solvent, gave molecular-weight values indicative of decided association.We used methyloxalate, ethyl oxalate, diphenylamine, and phenylurethane inattempts to dissolve carbamide, oxamide, malonamide, and succin-amide, but found all these amides either insoluble or only slightlysoluble. We possess indirect evidence, however, showing that thesesubstances should be classed as associated.I n the following tables are recorded the molecular weight of thesubstance, the temperature ( t ) , the capillary rise in cm. (h), theradius of the tube in mm. ( T ) , the density (p), the surface tension(y), the values k1 and k, of the Ramsay and Shields' constantscalcula.ted from the separate experiments, k, the mean values, andthe degree of association (x).I n the case of formamide the mean values of k are derived fromfour sets of experiments.to.10"20304520"30456020"3045607520"30456020"30456075h .3.6463-5063.3683'1643.4623'3343'1522-9623.3423.2383.0792-9192.7603 '4623'3523.1843'0183-3093'3103.1723.0342-892VOL. XCVII.A mine 8 .n-PT-opgZa7ni71c (h1.W. = 59).T* P.7- k,.0.1779 0'7271 23.13 -0.1779 0.7185 21.98 1'830.1779 0 7081 20.81 1-830 1780 0'6894 19'04 1-82Dipyopylamine (M.W. = 101).0.1779 0 7390 22'32 -0 1799 0.7299 21.23 2.420.1780 0-7164 19-72 2-270.1780 0-7i25 18,17 2'37Tripropytanzine (31. W. = 143).0.1850 0.7571 22.96 -0.1851 0.7493 22.03 2-560.1851 0.7373 20'61 2-640.1851 0.7252 19'22 2'630.1851 0.7130 17.87 2.61isoAniylantine (M.W. = 87).0'1851 0'7506 23.59 -0 1851 0.7417 22-57 1-990.1851 0,7277 21.04 2.030.1851 0.7128 19-53 2 00Triamylanziae (KW. = 227).0.1851 0.7859 24-25 -0.1851 0.7790 23'41 3.090.1851 0.71376 22-11 3'180.1851 0.7568 20.85 3'140'1851 0'7461 19-59 3-20k2. -1.851 *841.86-2.142-312.33-2'432 $32 *652.65I1.922 '032.03-3 *123.113 *073-17k.1.841 '8351 -84--2-282'292-35-2.4952.6352'642.63-1.9552-032.0153'1053.1453'1153-185G Ux,-1.241.241.24-0 -900.890-86-0.780 '720.720.72-1-131 *071.08-0'560.550.560'52074to.60"759010520"3045607520"304560i 595"10512013520"30456020"3045607520"3045607520"3045607590TURNER AND MERRY: THE MOLECULAR COMPLEXITY, IN THEh.4'2684-1504'0233'8904,3884.2984 '1 554.0153.8724-3624.2804.1504.0263 8913.7073 6283-5043.3784'5i24 4804.3224'1794.2694'1734.0203.8583.6923.8383.7583.6283.4903.3504-3944.3104'1824.0483.9163'782A mines (continued.).Biphenylantine (M.W. = 169).r. P. Y- P I . k2.0.1777 1.0547 39-23 - -0.1778 1.0435 37.77 2'37 2.660.1778 1'0326 36.23 2.55 2'460.1778 1'0217 34.66 2.63 2.55Benzylamine (M. W. = 10i).0'1850 0'9813 39.07 - -0.1850 0.9727 37'94 2 09 2.070.1850 0.9597 36.17 2.19 2-050 1850 0'9463 34'49 2-12 2'050'1850 0.9338 32.81 2.28 2.17Dibenzyhnine (M.W. = 197).0.1850 1'0276 40'68 - -0.1850 1'0199 39'61 2.90 2.710'1850 1.0083 38'01 2.92 2-780.1880 0-9963 36 40 2.93 2-820-1850 0.9844 34.79 3'01 2.99TribencgZanzine (M.W. = 287).0.1850 0.9912 33'34 - -0-1850 0'9850 32'43 3-42 3-400.1850 0.9741 30.97 3-59 3'460.1851 0.9632 29'54 3.57 3'59Phenylhytbrazzne (M.W. = 108).0.1850 1.0978 45-55 - -0.1850 1.0899 44'31 2.18 2.160-1850 1.0777 42'27 2-47' 2-270.1850 1.0653 40'40 2.23 2.16DimetJbyZnitrosonminc (M. W. = 74).0-1850 0.9965 37'73 1-74 1.750'1850 0.9813 35'80 1.85 1'860'1850 0.9654 33'80 1-94 1'930.1850 0.9491 31.80 1.97 1'920.1850 1.0059 38.97 -Disthylnitrosoamine (M.W.= 102).0.1850 0.9422 32.81 - -0.1850 0'9331 31.82 1.79 1.770.1850 0.9197 30.28 1-90 1'890,1851 Om9061 28'71 1.97 2'000.1851 0.8919 27.13 2.01 2,02Phenylmethylnitrosoctmilac! ( B I . W. = 136).0.1850 1.1275 44.96 - -0.1850 1'1187 43.75 2.38 2-300.1850 1.1055 41'95 2.40 2'430.1850 1.0919 40'11 2-49 2-510-1850 1-0782 38-31 2-45 2'480.1850 1'0644 36-53 2-47 2-55k.2.5152-5052.59--2 -082.122.0852.225-2.8052-852.8753 *OO-3-413.5253.58-2-172 *372.195-1.7451 35.5 z .9351.945-1 *781'8951.9852.015I2 -342.4152 $02-4652-512.-0-770 7 80.74-1-031 -001 -030.97-0.660 '640 '630.59-0 '490'470'46-0.970-850.95-1 '341.221.151.14-1 '301'181-101.08-0-860-820 *780-800.7i?.20"30456020"30456020"30456020"30456020"30456020"30456020"3045607520"3045607530"456075LIQIJID STATE, OF TERVALENT NITROGEN COMPOUNDS.h.4.0593.9893.8793.7653.8923.7803,6083.4313.6373.5483.4103'2684.4074 3154'1764-0104.4884'4044.2764.1364.5154.4504.3464 -2344.1894.1003.9613.8093.6564.0894-0123.8903.7603.6244-1123.9783'8463-701iVitciles.Lactonitrile (M.W. = 71).r. P- Y. k,. k2.0'1850 0.9377 36.38 - -0.1850 0.9788 35-43 1.27 1.240.1850 0'9656 33-99 1-31 1'330-1850 0.9525 32-54 1-35 1.30Butyronitrile (M.W. =69).0.1780 0'7936 26.97 - -0-1780 0.7842 25-88 1.73 1-700.1779 0'7701 24.25 1.77 1.790.1579 0'7556 22.62 1-78 1.77is0 Butylacetonitrile (M. W. = 97).0.1850 0.8035 26.53 - -0-1850 0'7955 25 61 1-80 1-810.1851 0.7827 24-23 1.83 1.850-1851 0.7699 28-84 1.89 1.87Benaonitrile (M. W. = 103).0'1776 1*0051 38.59 - -0.1777 0.9974 37-61 1.93 1.950.1777 0.9831 35.78 2-03 2-080.1778 0.9692 33.89 2-32 2.25Phenylacetonitrile (M. W. = 117).0'1850 1,0157 41.36 - -0.1850 1'0076 40'27 2.09 2.070.1850 0-9939 38-56 2'14 2-130-1850 0'9792 36-75 2-32 2-29Mandelonitrile (M. W. = 133).0.1776 1.1165 43.91 - -0.1776 1.1086 42.98 1.78 1.870.1776 1'0966 41.52 1-87 1.890.1777 1'0844 40'02 1-96 1.93o-Toluoititrile (M. W, = 117).0.1850 0.9955 37'84 - -0.1850 0.9863 36'70 2-21 2-210.1850 0.9i37 35.00 2.25 2.330'1850 0.9596 33.17 2'45 2-270'1850 0-9481 31-46 2-39 2.32m- Toluonitrile (M.W. = 117).0'1778 1'0316 36.79 - -0.1778 1'0235 35'81 1'84 1-840.1778 1.0122 34.34 1-91 1.910-1778 0-9997 32'78 2.03 1'990.1779 0.9872 31-22 2.07 2.05p-Toluonitrile (M. W. = 117).0.1850 0.9785 36.51 - -0-1850 0'9640 34-80 2'22 2.210.1850 0 9512 33.20 2'13 2 2 20.1850 0'9390 31-54 2'29 2.178.1 -2551'321 -325--1.7151.781-775-1 *8051.841'88-1.942-0552-285-2.082.1352.315-1.8251.881'945-2.212-292 -362 *355-3. '841.912.012 -06-2.2152'1752 *232075X .2 '212 '042 03--1.381.301-31-1.271'241 -20-1.141-050'89-1 *030.990.88-1 -251.201'14-0.940.890.850.85-1'241-171.081'04-0 -940-960-086 u 2076to.20"3045607585"95105120aoo9010512080"903 05120130"140150160170160"170180140"15016017060"7590105120'130145160TURNER AND MERRY: THE MOLECULAR COMPLEXITY, IN THEh.5.8125'7705'7045'6345.5294.3004'2264-1474.0203-7963.7183,5993.4784.2724'2264.1524'0763.8863.8043.7563'7023.8463 -6443.5873'5223-7853.7463.7003.6483.8713'7903 *7003.5993.9383.8683-7623'6527..0-17720.17720.17730.17730.17730.18500 18500.18500*18500.17780 17790.17790.17790.18500.18500.18500.18500.18500.18500-18500.18500.1850Amides.Formnmide (M.W. = 45).P * Y- k,.1'1350 57'35 -1.1267 56-51 0.651'1142 65.27 0.641:1015 53.94 0.731.0892 52-36 0.93Acetamide (af.W.=59).0'9904 37.98 1-180'9822 36 96 1'240'9703 35-39 l . 3 1Propionamide (M. W. = 73).0 9517 30.88 1.2909395 29-50 1-350'9272 28 14 1.36Lnctanzule (M.W. = 89).1'1301 43'34 1.061'1181 42-13 1.121'1062 40 91 1'130.9986 33'96 -0'9597 31.77 -1.1381 44'12 -Bewzxamide (M. W. = 121).1.0792 88.06 -1.0717 37'40 1'111.0641 36.73 1-161.0565 36.01 1.291.0489 35-23 1'43k,.-0.610.650.730.941-141.171 -27-1.331-311'37-1.041 *131-15-1 *081-261-251'43PhengZncetmtide (M.W. = 135).0.1850 1,0179 33.66 - -0-1850 1-0105 32.89 1'58 1.510.1850 1'0029 32.05 1.77 1-70Sall'cylanaide (M.W.= 137).0.1850 1'1749 40'35 - -0.1850 1'1663 39'64 1'22 1.180.1850 1.1578 38.87 1'40 1'360.1850 1.1493 38'04 1-55 1-55Anitid es and Urethanes.E'ormanilide (M. W. = 121).0.1850 1'1115 39.04 - -0.1850 1.0971 37.73 1'49 1-480-1850 1'0866 36'48 1'55 1-550*1860 1'0743 35-08 1.75 1-70Acetanilide (M.W.=135).0'1778 1'0261 35-24 - -0.1778 1.0179 34'34 1-86 1.880.1778 1.0055 32.99 1-87 1.890.1779 0'9933 31.65 1.88 1-93k.0 %30.660-740.95--1-161 *2051 -29-1.311 -331.3651.051.1251-14-1.0951.211'271.43-1 -5451.735-1 *201 -381.55-1.4851 *561.725-1 '871 *881.9052. -6'185.764-853'34-2-472.332.11-2'062'011'9412 872 5 92-54-2.702.322.161.81-1-611 -35-2.351-901'59-1 -691 -601'36-1 -211-201.1LIQUID STATE, OF TERVALENT NITROGEN COMPOUNDS.207 7Anilides and Urethanes (continued).Methylacetanilide (M. W. = 149).to. h. T. P. Y. k,. k2. k. X.105" 3.524 0.1850 1.0036 32.09 - - I -115 3'448 0-1851 0'9951 31.15 2-14 2.22 2.18 0.96120 3.406 0-1851 0-9910 30.65 2-22 2.21 2'215 0'94130 3.330 0.1851 0.9528 29.71 2-24 2.24 2.24 0.92145 3.206 0.1851 0.9703 28.24 2 3 3 2'27 2'30 0'88The ranges of temperature for which the values of k are calculated are :-105-115" ; 105-60" 3,80075 3.68190 3'554105 3'42460" 3.31475 3'20590 3.095105 2.98060" 3.68075 3.57690 3.468105 3.384-120" ; 115-130" ; 130-145".Ethylacetanilide (1f.W.= 103).0.1850 0'9938 34.27 -0.1850 0'9798 32-73 2-460.1850 0 9657 31-15 2.580.1851 0.9516 29.58 2.59Ethylurethane (M. W. = 89).0.1851 1'0459 31.47 -0.1851 1.0313 30.01 1'510.1851 1'0162 28-56 1.530.1851 1.0005 27'07 1.58Phrnylzcrethane (M.W. =165).0.1850 1'0792 36-04 -0'1850 1.0677 34'65 2.180'1851 10538 33-18 2.250.1851 1.0399 31'67 2.39-2.462'492.60-1-481.511.56-2-152.192-41-2 '462.5352.595-1'4951-521-57-2-1652'222'40-0.800 *760.74-1.691'651.57-0-970-930.83The following results, which we do not consider it necessary togive in full, have also been obtained. Acetonitrile: 20-30°,x = 1.58, in good agreement with the values of Dutoit and Friderich(Zoc.cit.) and Renard and Guye (Zoc. cit.). Prop'onitrile: 20-30°,x = 1-44, agreeing substantially with the results of Ramsay andShields and Renard and Guye, but not with those of Dutoitand Friderich. Aniline : 20-45', k = 1.695, x = 1-40 ; 45-75',k = 2.005, x = 1.09, in agreement with Dutoit and Friderich.We have also confirmed the abnormal result obtained by Dutoitand Friderich for diphenylamine.In the case of ethylurethane, we have obtained values whichagree well with those of Guye and Baud, but entirely differentresults with phenylurethane. The authors mentioned found,between 63'8' and 108'8', k = l * 3 8 ; and 108*So and 152.8O, L=1*81,values indicative of pronounced association.In benzene solution,phenylurethane is but slightly associated, much less so than ethyl-urethane, which, at the lower range, Guye and Baud did not findassociated as much as phenylurethane.k = 1-47', x = 1.73 ; 3 0 4 5 O , k = 1.53, x = 1-63 ; 45-60', k = 1-56,Ic = 1-63, x = 1-48 ; 30-45', k = 1.63, x = 1.48 ; 45-60', k = 1.66,The general results are discussed in the sections below2078 TURNER AND MERRY: THE MOLECULAR COMPLEXLTY, IN THEn-Propylamine ..................... 1-84Dipropylamine.. ................... 2.29Tripropylamine .................. 2.635GoAmylaniine ..................... 2 03Benzylamine ............ 2.12Dibenzylamine ......... 2-85Tribenzylamine.. ...... 3.58 (120-135"LIQUlD STATE, OF TERVACENT NITROGEN COML'OUNDS.207 9isodmylamine (M.W. = 87'1).Solvent : 15'03 grams.zu (grams). A'. M.W. (0bs.j. 2.Longinescu's method ( J . Chirn. phys., 1903, 1, 296), and from thecryoscopic observations of Freundler (BUZZ. SOC. chirn., 1895, [iii],13, 1055).Other methods of testing the molecular complexity in the liquidstate are, however, not in favour of the idea that dissociation occurs.Walden (Zoc. cit.), using a formula which he had found to begenerally valid for non-associated liquids, showed that it number ofthe substances having high values of the Ramsay and Shields'constant did not differ from the well-recognised normal substances ;whilst Kurbatoff and Eliseeff ( J . Russ. Phys. Chem. SOC., 1909, 41,1422) have pointed out that the esters examined by Homfray andGuye are normal according to the values of Trouton's constantwhich they possess.Evidence of dissociation in the liquid state should be revealed,perhaps to a less extent, in solution, and the dissociation shouldincrease with the concentration. We have, accordingly, determinedthe molecular weights, in benzene solution, of the amyl- and benzyl-ITrianzyla?mhc (M.W.= 227-3).Solvent : 14.83 grams.w (grams'. Aa. M.W. (obs.). x.3l.W. (obs.)M. W. (calc.)'amines. In the tables, the association factor, x,=Benzylnmine (M. W. = 107.1).Solvent : 16.06 grams.0.5562 1.568 110.4 1-030.7489 2'055 113.5 1-061.348 3'485 122.4 1-141.497 3*7W 122'9 1-15Dibcnzylaminc (M.W. =197*1).Solvent : 14.88 grams.0'1395 0-253 185.3 0'940'4995 0,871 192.7 0.981.187 2.021 197.3 1-001-490 2,536 197'4 1.00ITribciazyZaminc (M.W. = 287.2).Solvent : 15.23 grams.0.3406 0.402 278.3 0-9703660 0.926 271.3 0.951-173 1'406 273 8 0 '951'534 1'861 270 7 0.94Our results afford further evidence that the primary amines areassociated, but there is no evidence of any dissociation of triamyl-amine or dibenzylamine. The results with tribenzylamine are low,but in no way commensurate with the apparent dissociation in thefused state.w (grams). AO. M.W. (obs.). z2080 TURNER AND MERRY: THE MOLECULAR COMPLEXITY, IN THEAs a final test, we plotted the values of molecular surface energyagainst the temperature for triamylamine, dibenzyl- and tribenzyl-amine, since Dutoit and Friderich (Zoc.c i t . ) found that thecoefficient of the molecular surface energy of the normal liquidswhich they examined was independent of the temperature. Thefollowing values were used :Triamylamine, 1060.7 ; 1029.8 ; 982.1 ; 935.0 ; 887.0.Dibenzylamine, 1353.0 ; 1324.0 ; 1280'2 ; 1257.7 ; 1190.5.Tribenzylamine, 1460.0 ; 1425.8 ; 1372.0 ; 1318.4.The temperatures are given in the tables (pp. 2073, 2074). Ineach case, the straight line joining the end-points passed, almostperfect'ly, through all the points.We must conclude therefore that the abnormal results underdiscussion are due to the non-validity of the Ramsay and Shields'formula.The Nitrosoamines and the Nitrites.As in the nitrclcompounds, so also in the nitroso-compounds hereexamined, association occurs only in the aliphatic series.The causeof association is to be connected with the nitrosegroup, since thesecondary and tertiary amines are non-associated.The tendency of the nitriles to associate is also only marked inthe aliphatic series. Benzonitrile has a slight tendency toassociation, and the property is exhibited distinctly by m-toluonitrile.The other aromatic nitriles, save mandelonitrile, which is associated,exhibit abnormally high values of k.It will not escape notice that the introduction of a hydroxylgroup into the substance considerably raises the association, as inlactonitrile and mandelonitrile (see also lactamide).The Arnides.The amides in the liquid state are very strongly associated, and,unlike the nitriles, nitro- and nitroso-compounds, this associationextends to the aromatic as well as to the aliphatic compounds.Indeed, the extent of association in benzamide and salicylamide isstriking.From the following table of association factors, it will be seenthat the extent of association is roughly of the same order as thatexisting in the hydroxyl-containing substances-the organic acidsand the alcohbls.The data for the acids, alcohols, water, andphenol are taken from the papers of Ramsay and Shields (Zoc. cit.)and Ramsay and Aston (Trans., 1894, 65, 168). Since data aLIQUID STATE, OF TERVALENT NITROGEN COMPOUNDS. 2081exactly comparable temperatures are not available, the actualtemperatures are quoted :H,O (20-30') 3-81C,H,*OH (16-46") 2-25 C,H,*CO,H (16-46") 1.77CH,*OH (16-46") 3-43 H*CO,H (16-46") 3-61C,H,*OH (16-46") 2-74 CH3'00,H (1 6-46") 3'62C,H,'OH (46-78") 1-43H*CO'WH2 ( 20- 30") 6.18CH3*CO*XH2 ( 85- 95") 2-47CzH5'CO~NHz( 80- 90") 2.08C,H,'CO*NH, (130-140") 2.70The outstanding feature of the results recorded is undoubtedlythe high associative power exhibited by f ormamide.Walden(Zeitsch. phpsikd. Chem., 1906, 54, 180) expressed the belief thatthis substance is strongly associated, but made no measurement ofits complexity save in aqueous solution, in which it possessed thenormal molecular weight. Again (Proc. Faraday Soc., 1910, 156),he states that "formamide appears to reproduce nearly all thevaluable qualities of water." Save certain fused salts and sulphuricacid, formamide is more strongly associated than any other liquidyet examined. Its molecular complexity, however, decreases rapidlywith rise of temperature. Between 20° and 75O, its complexity dropsfrom 6.18 to 3-34, whilst that of water falls only from 3-44 to 2.9.We suggested (Proc., 1910, 26, 128) that the solvent power offormamide for salts ig connected with its high molecular complexity.Acetamide has also been found a solvent for salts (Walker andJohnson, Trans., 1905, 88, 1597; Menschutkin, J .Russ. Phys.Cbem. SOC., 1908, 40, 1415). Formamide and acetamide can also,like water, produce hydrolysis of antimony trichloride (Bruni andManuelli, Zeitsch. Elektrochem., 1905, 11, 554).Paasing to the anilides and urethanes, we note that associationis diminished by substitution of hydrogen in the amidsgroup.Theresult with acetanilide was unexpected. The measurements ofAuwers, of Beckmann, and of Meldrum and Turner, made onsolutions of the anilides, show clearly that acetanilide is distinctlymore associated than formanilide. Quite a different result isobtained on comparing the two substances in the liquid state.The question whether the tervalent nitrogen atom is responsiblefor the association in the amides can, we believe, be regarded asanswered in the negative. Methyl- and ethyl-acetanilide are non-associated, as also are secondary and tertiary amines, in all of whicha tervalent nitrogen atom is still present. It is also obvious, fromthe results with methyl- and ethyl-acetanilide, that the oxygenatom does not bring about association (compare MeIdrum andTurner, 1910, 97, 1616), a conclusion in agreement with what isalready known concerning esters, acid anhydrides, and ether2082 MOLECULAR COMPLE Y l T Y OF NITROGEN COMPOUNDS.Whatever the properties of chemical combination possessed bythe nitrogen or oxygen atom, it appears clear that they cannot beheld to be the cause of molecular association, and, in most cases,perhaps in all, association only occurs when these elements arepresent in distinct electronegative groups.I n the case of the amides, it appears that association is onlypossible when hydrogen is still present in the amide group.Thepower of molecular association disappears only when the hydrogenis eliminated from this group. Formamide and acetamide, also,like the hydroxylic substances methyl and ethyl alcohols, ethyleneglycol, and glycerol, can combine with salts in the same way aswater enters into union as water of crystallisation (Titherley, Trans.,1901, 79, 413 ; Walker and Johnson, Zoc.cit. ; Menschutkin, J . Russ.Phys. C'hem. Soc., L906, 38, 1010; Grun and Bockisch, Ber., 1908,41, 3465 ; Rohler, Zeitsch. Elektrochem., 1910, 16, 419).Such facts as these might be used as evidence in favour of thehydroxylic constitution of the amides. But the arguments againstthis theory are very weighty (Meldrum and Turier, Trans., 1908,93, 890), and we have to remember that not only do water andf ormamide possess like properties, but liquid ammonia, an associatedliquid, closely resembles water, can produce hydrolysis (ammonolysis,Franklin, J .Amer. Cliem. SOC., 1905, 27, 820), and, like water, cancombine with salts.It is difficult to locate the exact cause of the association in theamides. The apparent connexion between association and powerof producing hydrolysis indicates another method by which thecause of association in the amides might conceivably be tested. I f ,in water, for example, the hydroxyl group is responsible both forthe association produced and also for the hydrolysing power ofwater, then we might assume that the grour, in the amides whichproduces hydrolysis is also the cause of association. Bruni andManuelli (Zoc. cit.) have found that when antimony trichloride ishydrolysed by formamide or acetamide, the entering group, whichis equivalent t o one chlorine atom, and therefore to the hydroxylgroup, is R*CO*NH.Evidence of the nature of the action, if any,of the anilides and urethanes is desirable in this connexion.Finally, our results bear out the general connexion between thedegree of association and the dielectric constant of a liquid. Quit8recently, Walden (Zeitsch. physikal. Chem., 1910, 70, 569) haspointed out that all substances with high dielectric constants possesscertain electronegative groups, as OH, NO,, CO, CN, NH,, etc.Such groups we know to be present in those carbon compoundswhich exhibit association, and we should expect to find the dielectricconstant and the degree of association run parallel. I n the paperDECOMPOSITION OF PEKSULPHURIC ACID, ETC. 2083already referred to, Walden has made comparison of the twoprope?ties. We quote the following values of the dielectric constant,in connexion with the fresh data brought forward in this com-munication : Formamide (20°), >84 ; acetamide (83O), 59.2 ; di-methylnitrosoarnine (20°), 53.3 ; lactonitrile (ZOO), 37.7 ; formanilide(liquid), 20.5 ; acetanilide (liquid), 19.5 ; phenylacetonitrile (21*5O),18-2.These numbers, and the more extensive comparisons by Walden,show that i t is generally true that associated substances have highdielectric constants. The converse is by no means true, although,as may be seen, the substances of highest dielectric constant arethose which have the highest association factors.As regards dimethylnitrosoamine, it is quite possible, bearing inmind the abnormal results obtained with secondary and tertiaryamines, that its degree of association is greater than our measure-ments reveal.The connexion between the dielectric constant and the degree ofassociation, although at best approximate, leads us, when taken inconjunction with the fact that the elements nitrogen and oxygenwith unsaturated valencies do not appear of themselves to causemolecular association, to the conclusion that association in liquidsis due to eIectrical rather than, as supposed by Guye and Baud(Compt. rend., 1901, 132, 1555), to chemical forces.The cost of the materiaIs used in this work was in part defrayedby a, grant from the Research Fund Committee of the ChemicalSociety, for which we desire to express our best thanks.CHEMISTRY DEPARTMENT,THE UNIVERSITY, SHEFFIELD

ISSN:0368-1645    

DOI:10.1039/CT9109702069

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

DECOMPOSITION OF PEKSULPHURIC ACID, ETC. 2083CCXIX.- The Dynamics of the Decomposition o f Per.-sulphuric Acid and its S d t s in Aqueous Solutiori,.By LEILA GREEN and ORME MASSON.LEVI AND MIGLIORINI (Gazzetta, 1906, 36, ii, 599) have shownthat potassium and sodium persulphates decompose in aqueoussolution unimolecularly, and that the action is much acceleratedby the addition of acids. Our own experiments confirm both ofthese results. It is, however, somewhat difficult to reconcile themwith one another, for the act,ion itself produces acid sulphate, andcan, indeed, be followed throughout its course by the increasin2084 GREEN AND MASSON : DYNAMICS OF THE DECOMPOSITION OFacidity, so that t’he curve should exhibit the features of an aut+accelerated, rather than those of an unmodified, unimolecular action.The difficulty, however, disappears if the acid sulphate product beassumed to ionise only into metal and HS04’, and to provide prac-tically no H’ ions, or if, in other words, sulphuric acid be regardedas a monobasic acid under the conditions of the experiments.Theaction may then be formulated by the equation:S20s” + H20 = 2HSO4’ + &02,which makes it strictly unimolecular in form. On general groundsthe assumption may be objected to, but it does not appear possibleto explain without it the behaviour of persulphuric acid and itssalts, and it will be shown that one can, by its aid, co-ordinate thevarious results obtained with the acid, its potassium and sodiumsalts, its barium salt, and mixtures of these with each other, withother salts, and with acids.One or two unexplained difficultiesremain, which will be dealt with in the sequel.The persulphate solutions employed by us were obtained fromsolutions of the barium salt, prepared from commercial ammoniumpersulphate by treatment with excess of barium hydroxide in itvacuum and subsequent neutralisation with dilute sulphuric acid.The initial strength of each persulphate solution was determinedby measuring the final acidity produced by boiling a measuredvolume, the titrations being carried out with standard sodiumhydroxide, using methyl-orange as indicator. Comparative testswere made in some cases by the ferrous sulphate and permanganatemethod, and also by gravimetric determinations of the metal assulphate.The results in all cases agreed fairly well, but theacidimetric method was found to be the most accurate, besideshaving the advantage of rapidity. The progress of the decom-posit.ion in each experiment was also followed by acidimetry. I nall cases the temperature of the thermostat was 80*0°, which wasfound to give a convenient rate of action, except in the experimentsconducted at 70° and 90° for the purpose of fixing a, temperature-coefficient. The solution was always divided at the outset into anumber of 5 C.C. samples, and these were heated in closed tubes,according to the method described in it previous research on cyanates(Masson and Masson, Zeksch. physikal. Chern., 1910, 70,290).The persulphates which we have examined may be divided, forthe present purpose, into three classes.The first contains those ofsodium, potassium, and ammonium, which are neutral salts con-vertible into soluble acid sulphates. The magnesium salt properlybelongs to this class, but differs somewhat in its behaviour fromthe other members. The second class contains pemulphuric aciditself, which doubles its acidity by conversion into sulphuric acidPERSULPHURIC ACID AND ITS SALTS IN AQUEOUS SOLUTION. 2085The third class contains barium persulphate, which, originallyneutral, produces persulphuric acid and insoluble barium sulphate.The course of the action is quite different in each of these classes,and they therefore require separate consideration.I n the sequel we have thought it desirable to economise space bysuppressing most of the numerical details of our work, and havetherefore given only the essential results, except where fuller treat-ment appeared necessary.Class I.-Neutral Persulpha.tes which form Soluble Acid Sulphates.These cases conform to the equation for simple unimolecularaction :1 A - x !@ = k,(A - x), 01' k, = -10&-1, cl t t, - t, A - x2where A is the initial concentration of persulphate, and A --z is itsvalue at any subsequent time, t .To avoid some slight uncertaintydue to the time required to raise the tubes to the bath temperature,the time at which the first sample was taken from the bath wasselected, rather than the moment of immersion, as t,. The valuesof k, given in table I are averages calculated in each case fromseveral points in a curve covering nearly the whole course of theaction. Separate values in any one experiment were found to agreewell.It is evident that li, is but slightly dependent on the initialconcentration, or even on the nature of the metallic radicle.I n this and subsequent tables, the concentrations are expressed ingram-molecules of persulphate per litre, and the times are measuredin minutes:TABLE I.Na,S,08 ............... 0 *226 0'00641Na 29208 ............... 0 '1 25 0.00577Na,S,08 ............... 0.127 0.00533(NH,),S,OB ............ 0 '229 0.0061The curve for the ammonium salt showed rather more irregularitythan the others, and its mean velocity-coefficient was, as shown,perceptibly higher.This is perhaps explained by the formation oftraces of nitric acid by oxidation, with consequent acceleration, butthe divergence from the normal course is only slight.Experiments with sodium persulphate solution containing addedsodium nitrate (selected as a typical neutral salt of the same metal)have proved that the only effect of such addition is to raise slightlythe unimolecular constant. Thus, in a test with 0'1283-sodium per-sulphate and 0'25-sodium nitrate solution, with twelve experimentalSalt. A . 4-K,S,08 ................. 0.108 0'00542086 GREEN AND MASSON : DYNAMICS OF THE DECOMPOSITION OFpoints covering a range of 85 per cent. decomposition, k, was foundto vary irregularly between the extreme values 0-0062 and 0.0068,with a mean value of 0.0065.On the ot'her hand, it will be shownthat acids largely accelerate the action, and the special influences ofadded sulphates will also be dealt with later.The magnesium salt, in contrast to those of the alkali metals,shows distinctly the effect of auto-acceleration, which, in this case,is probably to be explained by the formation of some non-ionisedmagnesium sulphate and free hydrogen ions, according to theequation :Thus, in an experiment in which the initial concentration ofmagnesium persulphate was 0.2414, the unimolecu1a.r coefficient,calculated in the usual way, was found t o increase steadily fromabout 0.0055 (appreciably equal to that of the sodium or potassiumsalt) at the start to 0.0066 when the action was half completed,and 0.0092 when less than 10 per cent.remained undecomposed.A similar, but much more pronounced, auto-acceleration will beshown to occur in the case of the barium salt, where the precipitationof the insoluble sulphate necessarily adds hydrogen ions to thesolution. But the case of persulphuric acid itself must be discussedfirst.ME" + HSO,' MgSO, + Ha.Class Zl.-Persulphum'c Acid.In this case the curves obtained are again of the simple uni-molecular form, with no sign of acceleration by increase of hydrogenions; but it differs in two respects from that of the persulphates ofthe alkali metals. In the first place, the velocity is considerablygreater, and, in the second place, the value of its coefficient isdependent on the initial concentration, so as t o vary in differentexperiments while constant in any one.These facts are inaccordance with the hypothesis already put forward, that the actionproceeds practically tccording to the equation :S20," + " H Z 0 =2HSO4' + 402,and that it 'is accelerated by the hydrogen ions which are initiallypresent and remain unchanged in concentration. Such a hypothesisleads to the differential equation := (k2 + kA)(A - x),dtwhere k,+ kA is necessarily a constant ( K ) in any given experiment,and1 A - x hr= k, + kA =----log,-----'.t, - t, A - x2A simple explanation suggests itself for this accelerative actioPERSIJLPHURIC ACID AND ITS SALTS IN AQUEOUS SOLUTION. 2087of hydrogen ions. It may be assumed that, at the dilutionsemployed, the great bulk of the persulphuric acid is completelyionised into 2H' and S2081', while a small proportion is convertedinto H' and HS,O,'.I f this proportion be small enough, thetotal H' concentration may be taken as constant and equal to 2A,whilst that of the S20,// is appreciably equal to A -5, and that ofthe HS,O,' itself is therefore proportional to A ( A - x). If, further,the HS,O,' has a sufficiently high rate of reaction as compared withthe S208//, it will make itself felt in spite of its small concentration,and the total velocity of the action will be the sum of two velocities,k,(A -x) and kA(A -z), in accordance with the equation alreadygiven.By comparison of experiments with different A values, it is easyto evaluate k , and k ; and it has been found in this way thatk,=0'010 and k=O*163. These figures are illustrated by a com-parison of the found and calculated velocity coefficients in table 11.The fact that k, is nearly twice as great as the k, of sodium orpotassium persulphate is difficult to explain on any hypothesis, f o rit implies some influence of the hydrogen ions other than thatrepresented by the term kA(A - x) and independent of their con-centration. It is a fact, however, that, whilst d x / d t = 0*0055(A - x)holds for the sodium and potassium salts, the equation for per-sulphuric acid is~=(0*010+0*1638)(A -x)=K(A -x).dtTABLE 11.Persulphuric A cid.0.2566 0-0527 0.051 80,1251 0'0304 0'03040.1237 0-0302 0'03020.0923 0'0258 0-02500'0644 0'0210 0.02050'0416 0.0184 0.0168A.K (found). K (calculated).The solutions used in the first, third, and fourth of these testswere prepared from barium persulphate by adding the calculatedquantity of sulphuric acid, and were filtered from the bariumsulphate; while those used in the second, fifth, and sixth wereobtained by allowing barium persulphab solution t o decomposeautomatically at 80°, and contained the precipitated sulphate insuspension. These cases will be discussed later2088 GREEN AND MASSON : DYNAMICS OF THE DECOMPOSITION OFPersdphum'c Acid with Added Nitric Acid.In this case there is a permanent increase of the hydrogen ions,and, if the initial concentrations of the two acids (both reckoned asdibasic, that is, as H2S2O, and H,N,O,) be respectively A and B,the course of the action should be expressed by the equation :e= (k2 + k ( A + B)}(A - z),dtwhere k, + k(A + B ) appears as a unimolecular constant in any givenexperiment, andThis w&s confirmed by the experiments summarised in table 111.The first of these tests was made with an original mixture ofpersulphuric acid and nitric acid, while the other three were thelat.er parts of experiments, in which barium persulphate, mixedwith nitric acid, was allowed to decompose at 80° until thereremained only persulphuric acid and nitric acid in solution, andthe subsequent decomposition was then studied.These tests will bereferred to later. The figures in the last column of the table showthe value which IK would have if the nitric acid were absent(compare table II), and are given to indicate clearly its effect.TABLE 111.Persu2phuric Acid with Added Nitria Acid.0.1248 0'1542 Om0500 0-0506 0.03040.0635 om15 0.0508 0 yo504 0.02040.0628 0.1255 0'0414 0.0407 0.02020,0630 0'0634 0.0315 0.0306 0.0203A.B. K (found). H (calculated). K (original).Mixed PersuZphuric Acid and Sodium Persulphate.The theory for such a case may be given on the assumption thatthe k, and k, constants are active approximately in proportion tothe unchanging relative quantities of Na' and H', and that the latteralso contributes its special accelerative effect. Thus, if the initialH,S206 be A , and the initial N+S@, be B, whilst x represents thetotal S,O, destroyed, A and B will also represent at any time ths(H')2 and the (Na')2 respectively, anPERStJLPHURlC ACID AND ITS SALTS IN AQt'EOVS SOLUTION, 2089In any given experiment therefore a unimolecular constantshould be obtained, andI n one test, in which A =0.1285 and B=0*1234, a mean valueof 0.0276 was found for K in place of the calculated value 0.0288.In another, in which A =0-0625 and B=0*1250, the found andcalculated values were respectively 0.0183 and 0.0172.The agree-ment is thus fairly satisfactory in both cases.Persulpliuric Acid with Added Sodium Nitrate.This case is similar to the last, except that, the permanent con-and (Na'), being respectively A and B, thatThe constantcentrations of theof the Sz08" at any time is A - x instead of A + B - x.is here thereforeA B + kA = -loge----4 1 A - xK = hAX + "Ax t2 - t , A - x2I n the only test carried out, A = 0.1377 and B =0.0625, givingthe calculated value of the constant as 0-0311.The mean experi-mental value was 0.0325, which is identical with that calculatedon the assumption that the sodium nitrate is quite without effect.The difference is in any case too small t o be significant, but itmay be pointed out that a similar discrepancy was exhibited bythe mixture of sodium persulphate and sodium nitrate, indicatingthat the latter has a small accelerative effect, not included in thetheory, which may, in the present case, compensate for the expectedsmall lowering of the E value.Class IZI.-Barium Persutphate.This case differs from the others in the precipitation of theproduct barium sulphate, and it differs also in the form of thecurve in which x is plotted against t ; for this, being at first concavetowards the x axis, at once points to strong auteacceleration.Thetotal change affecting the barium salt is represented by the equation :2BaS20s + H20 = H2S,0s + 2BaS0, + 302,and it must occur in two steps, nameIy:(1) S,O," + H,O = 2HS04' + BO,,( 2 ) 2Ba" + 2HS04' = 2BaS0, + 28'.The first of these is a relatively slow action, and the second keepspace with it.. Thus 2Ba" disappear from the solution for oneS208" destroyed; and if the latter be x, as in previous cases, it isevident that x also represents the persulphuric acid (or acidity)produced, and A - 2x represents the barium persulphate remaining.VOL. XCVII.6 2090 GREEN AND MASSON : DYNAMICS OF THE DECOMPOSITION OFThis holds until A - z = x = Q A , when the precipitation of thebarium is complete, and subsequent action is concerned only withpersulphuric acid. The whole action may thus be divided into twoconsecutive stages, the characters of which are shown in the follow-ing summary:First stage A --z A -- 2~ x AutocatalyticSecond stage A - x 0 A - x Simple unimolecularThree of the six experiments with persulphuric acid solutionssummarised in table I1 were, in fact, the second stages of experi-ments with barium persulphate, which will now be dealt with ingreater detail, Comparison of these with the others shows thatthe presence of precipitated barium sulphate (since there was noother real difference) does not appreciably affect the velocity ofpersulphate decomposition by any kind of contact catalysis.Asimilar conclusion may be drawn from the sodium persulphate solu-tions of table I, one of which (the third) was mixed with theprecipitate beforehand in order to test this question. It maytherefore be concluded safely that the formation of this producthas no such direct effect on the decomposition of barium persulphateitself in the first stage of the action.In table 11, which referred only to persulphuric acid, A and zwere given the corresponding significance, and were equal respec-tively to $A and x - ~ A , where the symbols are used in referenceto the original barium persulphate contents, as in the abovesummary.But they must now be used in this latter sense, andthe equation for the curve, after the complete precipitation of thebarium, must be written dx/dt = (A, -t k A / 2 ) ( A - x).Now, since the whole curve is continuous, it is evident that theequation for the first, or autocatalytic, stage must be such as tobecome identical with that just given at the half-way point, wherex=&A. But it has been shown already that the Ic, of persulphuricacid and the k1 of sodium or potassium persulphates have verydifferent values, so that it might fairly be expected that theconstant (k,) for barium persulphate should differ from k2, andperhaps also from k,. Such proves to be the case, forit can be shown by a graphic method that the initial velocityof the decomposition of the pure barium salt solution, whenit is as yet unmixed with persulphuric acid (when x=O),approximates to dx/dt = 0.0040A.We thus have k3 = 0.0040, whilstk, = 0.0055 and k2 = 0.010, and the catalytic constant k: = 0.163. Itmust therefore be assumed that, in any mixture of two of thesesalts, the appropriate constants will be operative in proportion toTotal S,OB. BaS,08. H,S,Oa. Form of curve.Half-way point x = 3 A = A - x 0 +A PgRSULPHURTC ACID AND ITS SALTS IN AQUEOUS SOLUTION. 2091the amounts present, and that, consequently, the equation for thefirst stage of the barium persulphate action is:dg- A - ~ x X dt - (k3 ~- + k2- + h)( A - w). A - x A - xThis conforms t o the requirements, for the contents of the firstbracket are equal to k, at the starting point, where z=O, and tok, + k A 12 at the half-way point, where x = A 12. It will be shown,also, tha.t it expresses the whole of the experimental results withconsiderable accuracy.It is, perhaps, not superfluous to pointout that, if hydrogen and barium persulphates had the same velocityconstant (if k,=k2), the equation would be the ordinary oneexpressing an autocatalysed unimolecular action, for it would thenbecome d x / d t = (k,+ k z ) ( A - x).By integration of the above differential equat,ion, we obtain anequation which may be writben :1 M(N+x) k( M + N ) = -log, --___t N(M- x)'where M and N are constants in any given experiment, but varywith the initial concentration, and have the values :Such an equation is of but little use for theoretical purposes unlessM and N can be evaluated by independent measurements of thefundamental constants from which they are derived; but we areable to do this in the present case, having'found already E , and kfrom the study of persulphuric acid, and k, from the initial velocityof pure barium persulphate solutions.We are thus enabled tocompare the results calculated from the integrated equation withthose obtained by experiment.The details of one complete experiment with initially neutralbarium persulphate solution are shown in table IV. The valuesof M and N , given at the head of the table, were calculated fromthose of A ; ic, k,, and k,; and the theory of the first stage of theaction may be tested by the constancy of at different 1t N ( h 1 - z )values of t , and also by its agreement with the calculatedvalue of Om4343k(M+N). Also the time is noted (as read fromthe curve) at which x = $ A , that is, the time of the complete pre-cipitation of the barium mlphate.The simple unimolecularcharacter of the decomposition of the persulphuric acid in the second6 x 2092 GREEN AND MASSON DYNAMICS OF THE DECOMPOSITION OPstage is shown by the pract.ica1 constancy of the normal logarithmicfunction, calculated from the observed values of x and t , and thetheory of its dependence on A by a comparison of its mean valuewith that of k,+ k A 12 (compare table 11).TABLE IV.Barium Persulphate. A = 0.2502,First Stage.M = 0.2840, N = 0.0216.t.10"253545505.0.01310.03980.06630.09740'1160M( N + x) l / t log,,-----N( M - x)'0.02260.02080 -02070 *02050.0206Mean constant found .................. = 0.021 0.Calculated value of 0'4343 k(M+N) = 0.0216.Second Stage, after complete precipitation of Ba a t t = 52.5O.t.60"70551001151351552.0.15580.17960.20680-22210.23360'24110-2441l f t - 60 l0g,~~?01558A - x * -0'01260.01350'01320 01370.01350.0125Mean constant found ..................... = 0.0132.Calculated value of 0'4343(rC, +kA/2) = 0-0132.The details of two tests with smaller concentrations of bariumpersulphate may be given more briefly. I n one of these tho valueof A was 0.1288, whence 0*4343k(M + N ) =0*0128 by calculation,and during the first stage of the action (sixty-five minutes) thevalues found for -loglo7 M ( N + 2 ) ranged from 0*0130 t o 0.0134(mean = 0'0132).During the second stage of the same experiment,tho mean uniinolecular constant found was 0*0091 in place of thecalculated value 0.0089. I n the other case, A was 0.0832, whence0*4343k(M + N ) = 0.0093, and the constant found during the firststage (seventy minutes) ranged from 0.0103 t o 0.0112 (mean,0.0109), while the calculated and found unimolecular constants ofthe second stage were 0.0073 and 0*0080. In this case thereforethe numerical agreement was not quite so goad its in those of thestronger solutions.It seems worth while to call attention here to a striking contrastt h(A4-xPERSULPHURIC ACID AND ITS SALTS IN AQIJEOUS SOLTTTION.2093between the persulphate case and that of the decomposition ofcyanates in aqueous solution, which in some respects is very similar(Masson and Masson, Zoc. cit.). Barium cyanate, which precipitatesbarium carbonate, gives a simple unimolecular curve, whilst thecyanates of sodium and potassium, which yield soluble ammoniumcarbonate, give strongly auto-accelerated unimolecular curves.Barium persulphate, which precipitates barium sulphate, givesstrongly auto-accelerated unimolecular curves, whilst the per-sulphates of sodium and potassium, which yield soluble acidsulphates, give simple unimolecular curves. In the former case, itwas proved that ammonium carbonate accelerates the action, whilstin the latter case soluble acid sulphates have no such influence, buttheir hydrogen ions have, when liberated by the precipitation ofinsoluble sulphate.Mixed Ba&m Persulphate and Barium Nitrate.If the latter be added in quantity equivalent to the former (ormore), the barium ions cannot become exhausted by precipitation asbarium sulphate so long as persulphate ions remain, and the wholeaction can be written:BaS,O, + BaN,O, + H,O = 2BaS0, + 2HN0, + SO,.The action therefore does not divide into two distinct stages as inthe case of initially pure barium persulphate, but is markedthroughout its course by continuous precipitation and increase ofhydrogen ion concentration. Hence the auto-catalytic charactermust be also continuous, and this is found to be the case.If A represent the initial concentration of the barium persulphateand B that of the barium nitrate, the composition of the solutionat any subsequent time is such that it contains barium and hydrogenpersulphates and nitrates with the following concentrations :S,O,”=A - x , (NO,’),=B, Ba”=A +B-2x, and (H*)2=z.Thetotal cations or anions (considered as bivalent) are thus alwaysequal to A + B - x.If, as in the case of initially pure barium persulphate, it beassumed that the barium and hydrogen ions are operative in p r sportion to their relative concentrations, while the latter also producetheir special catalytic effect, we have the following diff erentidequation to express the course of the action:+ kx}(A -x), dx- A + B - ~ x X --dt ‘k3 A + B - L& + k2 A + €3 - xwhich, by integration, gives :BIog,A(N+ -- X) M - A - B log,----N ( A - x ) M - d M ( A - 2 2094 GREEN AND MASSON : DYNAMICS OF THE DECOMPOSITION OFwhere M and N are constants in any given experiment, and havethe values:An obvious simplification of the formula results where, as in theactual experiment (table V), the barium persulphate and nitrate aregiven the same initial concent'ration, or B = A .The values ofM and N given a t the head of the table were calculated from thatof A and those of k,, k,, and k , as already determined. In the thirdcolumn are given the found values of the constant:which may be compared with each other as to constancy and alsowith the calculated value of 0*4343k(M+N), given at the end ofthe table.The agreement is fairly satisfactory.TABLE V.Barium Persulphat e and Barium Nitrate in Equimolecular Mixture.B = A =0*1253. M=0-2845. N=0*0217.t. X. K.10" 0 '0062 0.024020 0.0147 0.025530 I 0.0223 0.023945 0.0355 0.022860 0'0457 0.020870 0.0577 0'022975 0-0643 0-021990 0.0791 0.0220105 0,0926 0.0223120 0.101 9 0'0220135 0.1105 0'022.3160 0 -1 200 0.0238195 0,1236 0*0238Mean value of K found ... ... .. , ,. . ... = 0.0229.Calculated value of 0.4343k(V+N) = 0'0217.Barium Persulphate with Added Nitric Acid.Here, as in the case of pure barium persulphate, the action maybe expected to divide itself into two stages, since the barium must betotally precipitated when x = A - x = QA.If B stand for the addednitric acid (reckoned it9 dibasic) or for the initial (H*j2, thequantity of the latter must steadily increase by production ofpersulphuric acid during the first stage, where its vdue is B + x;but from the middle point onwards through the second stage iPERSULPEIURIC ACID AND ITS SALTS IN AQUEOUS SOLUTION. 2095must retain the value B + i A . As in the simple case, the Ba"must have the value A -2x until this becomes nil at the middlepoint, whilst the S,O,// must have the value A - x from first to last.The first stage should therefore show an autocatalytic curve merginginto the simple unimolecular one of the second stage, and therespective differential equations should be :(11.) !!? = {k, + k( B + &A)>( A - x),dtwhich are identical when x = IA.These equations, indeed, follow logically from those already con-firmed for the case of a mixture of barium persulphate and bariumnitrate, for it is obvious that such a mixture, if it initially containsexcess of the former ingredient, must, at a certain point in iBhistory, become converted into a solution of barium persulphate andnitric acid, and subsequently into one of persulphuric acid andnitric acid.There are thus three distinct stages in such an action,and i t seems an unavoidable conclusion that the theory which isquantitatively applicable to the mixtures of the first stage (table V)and also to those of the third (table 111) must apply equally wellto those of the second.Nevertheless, it has been found in a seriesof experiments with barium persulphate and nitric acid in differentproportions that the nitric acid produces initially only about halfthe acceleration indicated in equation I, although it graduallyincreases its effect its the action proceeds, and attains full value asan accelerator when the barium is completely precipitated, afterwhich equation I1 holds well. Without further investigation, itdoes not seem possible to reconcile these observations.The Zn@uence of Sulphates, Produced or Added.As already pointed out, sulphuric acid or acid sulphate is anecessary product of the decomposition of persulphuric acid orpersulphates of the sodium class of metals, and yet there is in thesecases an entire absence of that autocatalysis which is so marked afeature in t,he case of barium persulphate, where the growingacidity is due to persulphuric acid formed by the precipitation ofbarium sulphate.The explanation already suggested is that thenegative ions produced are in reality HSO,' (not SO,"), so thatthere is no appreciable increase in the concentration of H' ions(the true accelerator) unless the conditions are disturbed by pre-cipitation or, to a smaller extent, by the process mentioned in th2096 GREEN AND MASSON : DYNAMICS OF THE DECOMPOSITION OFcase of the magnesium salt,. Briefly, the hypothesis is thatsulphuric acid acts practically as a monobasic acid in these solutions,while persulphuric acid itself acts as a dibasic one.The most direct test of this view, apart from the evidence alreadygiven in support of it, is obtained by studying the velocity of thedecomposition of persulphuric acid and sodium persulphate solu-tions, to which have been added beforehand known quantities ofsulphuric acid, sodium hydrogen sulphate (that is, sodium sulphateand sulphuric acid), or sodium sulphate.According t,o thehypothesis, the velocity coefficient should not be affected by addingeither sodium sulphate or sodium hydrogen sulphate to sodium per-sulphate; sodium hydrogen sulphate should produce but a slightlowering of the coefficient of persulphuric acid by adding Na' ionsto the solution without altering the H' concentration; sodiumsulphate should largely reduce this coefficient by converting free H'into HSO,'; and added sulphuric acid should accelerate in bothcases, but only to the extent due to it as a monobasic acid, or halfas much as the equivalent quantity of nitric acid or of persulphuricacid itself.In all cases the numerical results predicted by thehypothesis can be calculated from a knowledge of the fundamentalcomtants already given, namely, kl = 0.0055 for (Na')2, k,= 0*010for (H'j2, and k = 0.163 forThe results of the experiments performed confirm theseexpectations, with one rather notable exception in the case of theaddition of sodium sulphate to sodium persulphate. Here the uni-molecular constant, although it has at first the normal and expectedvalue of about 0.0055, quickly diminishes until it reaches a steadyvalue, considerably smaller and dependent on the amount of addedneutral su1phat.e.Four tests were made with approximately4-molar-sodium persulphate, conta.ining respectively 0.060, 0.125,O"128, and 0.255 molecule of sodium sulphate. I n each case thecurve showed a similar retardation until about one-fifth of thepersulphate was decomposed, and thereafter, and reckoned fromthis point, a good unimolecular constant was obtained, the respectivevalues being 0-0035, 0.0025, 0.0025, and 0.0020. These resultspoint to some complication, which, as will be shown, is never metwith except in the presence of mixed neutral and acid sulphate, andwhich is perhaps due to a reverse action in which the dissolvedoxygen plays a part'; for this product is the only substance presentwhose quantity is initially nil, and tends, on account of its limitedsolubility, to increase quickly to a maximum.In all the other cases the curves showed steady unimolecularactions, and the found velocity coefficients agreed fairly well withthose calculated in accordance with the hypothesis.Although theaccelerationPERSULPHCTRIC ACID AND ITS SALTS IN AQUEOUS SOLUTION. 2097agreement is not quantitatively exact, it is noteworthy that theresults fully establish the following facts :(1) Addition of sodium hydrogen sulphate produces no markedacceleration, showing that i t does not add H' ions; (2) additionof sodium sulphate to persulphuric acid prodyces a large retardation,which points to a suppression of H' ions; (3) addition of sulphuricacid produces such acceleration as points to the ionisation of abouthalf its hydrogen.The results are summarised in table VI.I n the first columnare given the nature and concentration of the persulphate used. I nthe second, the added sulphate is similarly specified. I n the third,under K (found), is given the experimental unimolecular constant,this being, as in previous cases, the mean of several concordant valuesfound over a large range of action. In the fourth column, underR (calculated), is given the value of k -. + 7c-- + k(H'),,where the ionic symbols refer to the corresponding concentrationsafter allowance for the conversion of all SO, into HS04/ ions. I nthe fifth column, under K (original), is given, for comparison, thevalue the constant would have if the added sulphate produced noeffect whatever.TABLE VI.Tlbe Effects of Added Sulphates.N%' H*' N a + H Na'+H'Sulphate.0 *1338NaHSO,0*1332H,SO,0-3767H,SO40 *1 250Na2S0,0 '1366NaHS0,0 * 0 5 0 8 H,S 0,0 *1194H,SO,0 '1544H,SO,Kfound.C0'00600.01610.03720'01510.03040.03700 04210.0425K:alculated.0.00550.01790-03890'01600.02880'03430.04050-0435Koriginal.0-00550.00550 00550'02930-03030'03010'03080'0309The Effects of Added Alkali.Levi and Migliorini found that alkalis accelerate the persulphatedecomposition, but to a smaller extent than acids. Our experi-ments, however, with persulphates of the first class do not confirmthis.When sodium or potassium persulphate is mixed with thecorresponding alkali in equivalent, or greater, amount, a regularunimolecular curve is obt'ained with a constant which is almostidentical with that characteristic of the pure salt solution. It is,indeed, very slight,ly smaller, which is probably accounted for bythe physical effect of the extra dissolved substance, but there is noevidence of positive or negative acceleration by hydroxyl ions.These, of course, become destroyed as the action proceeds, for the2098 DECOMPOSITION OF PERSULPHURIC ACID, ET C.necessarily neutralise the acid sulphate product, and any suchcatalytic effect would thus continuously diminish, and the curvewould not be that of a simple unimolecular action. It is noteworthythat the normal sulphate which results from this neutralisationdoes not produce any such marked retardation as was observed whenthe same salt was added beforehand to sodium persulphate, so thatit may be concluded that the reaction responsible for that com-plication can occur only in the presence of both normal and acidsulphate, as already mentioned.The results of four experiments are summarised in table VII.The k, values here may be compared with those cited for the puresalts in table I.TABLE VII.Effects of Added AIkaZi.Persulphate.Alkali. k, found.0.1 192Na,S,08 0 -21 92NaOH 0.00510*1185Na,S,O, 0'2236NxOH 0.00510 '1214Na28,0, 0.3434NaOH 0-00490 -0797 K,S,08 0.2040KOH 0-0050The behaviour of barium persulphate when mixed with bariumhydroxide is quite different, and is difficult to reconcile with anygeneral theory. The autocatalytic curve of the pure salt solutionhas been fully explained by the production of persulphuric acid,but here it is evident that neutralisation must occur continuously,and that the precipitation of barium sulphate is accompanied by aprogressive diminution of alkali instead of an increase of acidity.Indeed, the course of the action is followed in practice by alkalimetryinstead of the usual acidimetry. Now, as it has been proved thakhydroxyl ions exert no appreciable catalytic effect in the case ofthe salts of the alkali metals, it seems inevitable that barium per-sulphate, when mixed with sufficient barium hydroxide, should givea continuous simple unimolecular curve with its own velocityconstant (k3). Nevertheless, the curves obtained show a muchhigher initial velocity than corresponds with k,, that is, an initialacceleration by the added alkali, and they also give evidence of afurther acceleration as the alkali subsequently diminishes. We areunable to explain these facts.The Temperature Effect.Experiments were made with sodium persulphate and with per-sulphuric acid a t 70° and 90° for comparison with those at 80°already described. The mean values of the unimolecular coefficientsare given in the following table. In the case of persulphuric acid,it must be remembered that this coefficient is largely dependent oA SIMPLE METHOD OF PREPARING TETRANITROMETHANE. 2099the initial concentration ( A ) , for it has been shown to be the sumof two terms, k,+ k A , whereas in the case of the salt it is a simpleconstant, k,. It appears, however, that the constants at 90° are allabout tenfold those at 70°.TABLE VIII.The Temperature Effect.UniriiolecularSalt. A. coefficients. Temperature.0.125 0*0016 70"0.126 0.0055 80 Na,S,08H2W* 0'124 0'0111 70H28208 0'124 0.0302 80Na2S2OsNa29,0s 0'130 OqOl6l 90H2S208 0'118 0'1035 90UNIVERSLTY OF NELBOURNE

ISSN:0368-1645    

DOI:10.1039/CT9109702083

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

A SIMPLE METHOD OF PREPARING TETRANITROMETHANE. 2099CCXX.-A Simple Method of Preparing Tetranit ro-waethane.By FREDERICK DANIEL CHATTAWAP.TETRANITROMETHANE can easily * be obtained without danger,and in almost theoretical amount, by allowing equal molecularamounts of nitric acid + and acetic anhydride to interact 1 at theordinary temperature for several days. Some heat is developed onmixing, and slight cooling is necessary during this part of theprocess, otherwise the action may become so vigorous that loss ofmaterial results, but, so far as the author’s experience goes, it neverbecomes explosive in character.IC The methods hitherto described for the preparation of tetraiiitromethane,namely, (1) nitrating nitroform (Schischkoff, Annalen, 1861,119, 247), (2) the actionof diacetylorthonitric acid on acetic anhydride (Pictet and Genequand, Bw., 1903,36, 2225), (3) distilling nitrobenzene with a large excess of a mixture of nitric andsulphuric acids containing sulphur trioxide (Claessen, D.R. -P. 184229), and (4)adding acetic anhydride to a mixture of nitrogen pentoxide and nitrogen peroxide(Schenck, D.R.-P. 211198, 211199), leave much to be desired in the way ofsimplicity.j- The use of more than the equiva ent amount of nitric acid is of noadvantage ; indeed, when an excess is added, the yield is seldom so good, as the acidordinarily employed always contains some small amount of water.$ On the 7th of July, since this paper was written, the Farbenfabriken vorm.F. Rayer & Go. published a method (D.R.-P.224057) of preparing tetranitromethnncexactly similar to that given above. As, however, this paper was read about a nionthearlier, namely, on June 16th (Proc., 1910, 26, 164), and as many details not to befound in the specification are given, it seems desirable that it should be publishedin full2100 CHATTAWAY: A SIMPLE METHOD OFThe action takes place almost quantitatively according to theequation :4CH3*C'O*O*C'O*CH3 + 4HN03 = C(NO,), + CO, + 7CH3*C02H.The tetranitromethane remains dissolved in the acetic acid, andseparates out as a heavy, oily layer on pouring the product intowater. Carbon dioxide is given off almost from the time of mixing,but the evolution is never rapid, and the tetranitromethane appearsonly to be formed gradually, as the yield is small unless themixture is kept for some days.When nitric acid attacks acetic anhydride, a mononitrederivativeis probably first produced, which is nitrated so much more readilythan the parent compound that action proceeds until the threehydrogen atoms of a methyl group have been replaced.Hydrolysisthen occurs, and the trinitroacetic acid formed slowly decomposesinto carbon dioxide and nitroform, which as soon as it is liberatedis converted by the remainder of the nitric acid into tetranitro-methane.The operations necessary in this method are so simple and so easilycarried out that the preparation is well adapted to take its placein any elementary course of practical organic chemistry to illustratethe ease with which aliphatic compounds can be nitrated, whilstthe materials employed are so cheap and the yield is so satisfactoryas to make tetranitromethane, which has hitherto been a somewhatunfamiliar substance, one of the most easily procurable of organiccompounds.Preparation of Tetranitromet hane.Thirty-one grams of nitric acid * (D*5 1-53) are placed in a 250 C.C.flask, and 50 grams of acetic anhydride are gradually added inquantities of about 2 C.C.at a time, the flask meanwhile beingcooled in water, as some little heat is developed. If the flask isnot cooled, action proceeds more and more vigorously as the tem-perature rises, and may, if unchecked, become violent. It isinadvisable therefore to allow the temperature to rise much aboveWhen all the anhydride has been added, the flask is coveredloosely by a watch-glass or inverted small beaker, and kept at theordinary temperature for about a week.As the reaction proceeds,carbon dioxide is continuously but very slowly evolved, and themixture, which at first is colourless, becomes brown, owing t o the* The anhydrous nitric acid required in the preparation is most ensily obtained byslowly distilling ordinary fuming nitric acid from its own bulk of concentratedsulphuric acid ; if ordinary concentrated nitric acid (D 1'41) is used, it is advisableto distil i t twice from sulphnric acid. It is not necessary, although advisable ifconvenient, to distil off the acid under diminished pressure.20-25OPREPARINU TETRANITROMETMAKG 2101formation, in small quantity, of oxides of nitrogen.After a week,the tetranitromethane which remains dissolved in the uetic acidmay be separated by pouring the mixture into about 150-200 C.C.of water. The bulk of the tetranitromethane subsides as a colour-less, heavy, oily layer, which can be removed by means of a separatingfunnel, whilst a small quantity still remaining dissolved in thedilute acetic acid may easily be separated by means of a current ofsteam. The tetranitromethane passes over with the first few C.C.of the distillate, and separates as a heavy globule.The tetranitromethane thus obtained may be freed from tracesof acid by washing with water, or even betker, although with slightloss, by distilling in a current of steam.* It is then separated anddried over fused calcium chloride.Tetranitromethane as thus prepared is a heavy, very fa.intlyyellow liquid.It can be distilled at 126O under the ordinarypressure, but the distillate is of a pale brown colour, due to oxidesof nitrogen formed by some slight decomposition which takes placeat this temperature, and still requires to be washed and dried toobtain it quite pure. If cooled a little below the ordinary tem-perature, it easily solidifies t o a mass of colourless crystals.The yield of tetranitromethane obtained is never quite thetheoretical one, although by careful working it cm be made toapproximate to it. The small loss cannot be entirely, or evenmainly, due to oxidation, as at no period of the action is there anyconsiderable liberation of nitrous fumes; it is probably caused bysome of the very heavy vapour being carried away in the escapingcarbon dioxide, and lost during the processes of separation.Using acid prepared as above, without removing the oxides ofnitrogen,? the yield is approximately 80 per cent.of the theoretical,about 18-20 grams of pure, dry tetranitromethane being obtainedfrom the weights of materials given.It is immaterial whether the acetic anhydride be added to thenitric acid, or the nitric acid to the anhydride, but the formerprocedure is preferable, as the evolution of heat then occurs mainlyduring the first few additions of anhydride, which can be addedmore rapidly afterwards.I n a set of experiments to ascertain the rate of formation, a* After distilling in a current of steam, the distillate containing the tetranitro-methane as well as the residue is always bright yellow in colour, owiiig to thepresence of dissolved nitroform, which is formed in small quantity when tetranitro-methane is allowed to come into contact with water or is heated with it.t There is no great advantage in freeing the anhydrous nitric acid from oxides ofnitrogen, as even if the acid is conipletely colourless on mixing aud the mixture iskept at 0" in a dry atmosphere it becomes coloured in a few days.The yield isslightly better if colourless anhydrous acid is employed, but the increased yielddoes not compensate for the extra labour involved in the preparatiou of the acid2102 CLAYTON : THE CONSTITUTION OF COUMARINIC ACID.number of similar mixtures of the above quantities were made, andthe amount of tetranitromethane formed was estimated afterdifferent intervals. After one day, 7.5 grams of tetranitromethanewere obtained; after t3wo days, 11.5 grams; after faur days, 14.5grams; after six days, 17 grams; and after eight days, 18.6 grams.After this, further keeping did not appreciably increase the yield.The process can be accelerated by heating the mixed liquidscautiously until the action becomes sufficiently rapid to cause thetemperature to rise even after removing the source of heat* andthen checking the action by cooling; when this has been doneseveral times, the liquid, which a t first cannot be heated with safetymuch above 30°, may be heated to 80-looo without any violentaction occurring, but on diluting the product the yield is not foundto be anyOhing like so good as when the mixture is simply allowedto remain at the ordinary temperature.OXFORD.UNIVERSITY CHEMICAL IAABORATORY

ISSN:0368-1645    

DOI:10.1039/CT9109702099

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

2102 CLAYTON : THE CONSTITUTION OF COUMARINIC ACID.CCXX1.-The Constitution of Coumarinic Acid.By ARTHUR CLAYTON.WHEN coumarin is dissolved in aqueous sodium hydroxide, thesodium salt of coumarinic acid is produced, whereas the prolongedaction of an alcoholic solution of the alkali results in the productionof an alkali o-coumarate. Coumarinic acid has not yet beenisolated, being resolved into coumarin and water at the moment ofliberation from its salts, but its alkyl esters are known, thesecompounds being isomeric with the corresponding derivatives ofo-coumaric acid. When the dialkyl esters of 3-nitrocoumarinic acidare boiled with aqueous alkalis, 3-nitrocoumarinic acid is producedfrom the acidified liquid, whereas the dimethyl ester of 3-nitro-o-coumaric acid under similar conditions yields the methyl etherof 3-nitro-o-coumaric acid (Miller and Kinkelin, Ber., 1889, 22,1708 e t sep.).This difference of behaviour towards alkalis hasbeen explained by Michael’s formula, (‘I) for coumarinic acid( J . p. Chem., 1888, [ii], 38, 27), which has also received supportfrom Perkin (Trans., 1881, 39, 560), Miller and Kinkelin (Ber.,If the mixture be heated until action becomes violent it is difficult t o condensthe productq, torrents of brown fumes are evolved, and the quantity of tetranitromethane obtained is very small.CLAYTON : THE CONSTITtJTION OF COUMARINIC ACID. 21031889, 22, 1713), Roser (Ber., 1882, 15, 2347), and Anschutz(Annalen, 1889, 254, 181) :0--0 8" 0(1.1 (11.1 (111). (W.On the other hand, the view has been held that coumarinic acidis the cis-isomeride (formula 11) of o-coumaric acid.A thirdpossible formula (111) is suggested by the constitution which Morganand Micklethwait (Trans., 1906, 89, 868) have proposed forcoumarin (formula IV).In order to confirm or exclude Michael's formula, the author ofthe present communication has investigated the alkyl derivatives of5-nitrocoumarinic acid, the nitro-group being introduced in orderto obtain solid compounds. It is obvious that if formula I repre-sents the constitution of coumarinic acid, only one methyl ethylester could be prepared, whereas formulae I1 and I11 indicate thepossibility of the existence of two such derivatives. For con-venience, the two hydroxyl groups will in this paper be distinguishedby the letters a and P.6-Nitrocoumarin dissolves in aqueous alkalis, and the solution,when treated with silver nitrate, yields silver 5-nitrocoumarimte.This salt, by interaction with methyl iodide, yields aS-dimethyl5-.nitrocoumarinate (V).The identity of this substance is estab-lished by boiling it with aqueous sodium hydroxide, 6-nitrocoumarinbeing readily regenerated. The ap-dimethyl 5-nitrocoumarinate isconverted by partial hydrolysis into a-methyl 5-nitrocoumnri7tate(VI). The silver salt of the latter compound, when treated withethyl iodide, yields a-methyl i3-ethyl 5-nitrocoumarinate (VII).By a similar series of operations, aP-diethyl 5-nitrocouma~inate,a-ethyl 5-nitrocoumarinate, and P-methyl a-ethpl 5-nitroco.umarinateare obtained as indicated by formulze VIII-X.All the compounds V-X (p.2104) are shown t o be derivatives of5-nitrocoumarinic acid by their exceedingly easy reversion to 6-nitro-coumarin when boiled with weak aqueous sodium hydroxide.a-Methyl P-ethyl 5-nitrocoumarinate and P-methyl a-ethyl 5-nitro-coumarinate proved to be distinctly different compounds, the formermelting a t 75-77O, and the latter at 111-113°, thus showingMichael's formula to be incorrect.In order that the foregoing proof should not be invalidated bythe possibility of one or both of the isomeric methyl ethyl ester2104 CLAYTON : THE CONSTITUTION OF COUMARINlC ACID.C,HSO,*NO,6 -Nitrocouwaarin.OEt.. . aC9H50<OEt ... p(VII I. )p H(X.1M. p. 111"--113".being derived from 5-nitrocoumaric acid by the rupture of thelactonic ring, an investigation of the ethers and esters of the latteracid was made as indicated by formulz XI-XIX./\OMe /\OH /\OEt ' 'CHO f- \/ ' ICHO -(,!CHO \/(XII.)IJ./\olgeNO,~,!CHO(XIII.)()OM.NO,\,CH: CH*CO,H(X1 V.)/\OMe I ICH:CH*CO,Et(XV. )3. Ag salt+ EtTM. p. 85".(XI. 1 (XVI.)IJ.O O E tNO,,,CHO(XVII.) 4/\OEt(XVII I. )/\OEtNO,?ICH:CH*Jbp salt + Me1NO,()CH :CH*CO,MeM. p. 163".(XIS.)The methyl ether of 5-nitrocoumaric acid (XIV) was preparedaccording to Schnell's directions (Ber., 1884, 17, 1382) as indicatedby formulae XI-XIV, and the silver salt of this acid heated withethyl iodide, thus yielding the methgl ether of etlhyl 5-nitroCLAYTON : THE CONSTITUTION OF COUMARINlC ACID.2 LO5coumarinate (XV). By a similar series of reactions the ethyl etherof 5-nitrosalicylaldehyde, the ethyl eth#er of 5-nitrocoumaric acid,and the ethyl ether of methyl 5-nitrocoumarate are obtainedThe two methyl ethyl derivatives of 5-nitrocoumaric acid thusobtained proved to be distinctly different from the methyl ethylderivatives of 5-nitrocoumarinic acid. The existence of these fourisomeric methyl ethyl derivatives permanently excludes the possi-bility of Michael's formula being correct.I n order to ascertain which of the two remaining formulaerepresents the constitution of coumarinic acid, UP-dimethylcoumarinate and the methyl ether of methyl 5-nitrocoumarute wereseparately treated with bromine.In each case methyl ufl-dibronzp-5-nitro-2-methoxy-P-phenylprop'onate was produced, thus excludingformula 111.Coumarinic acid is therefore proved to be the cis-isomeride ofo-coumaric acid.The positions occupied by the hydroxyl groups, which have beendistinguished by the letters a and P, are indicated by treating theethyl ether of m.ethyl 5-nitrocournarate, and. P-methyl a-ethyl5-nitrocoumarinate separately with bromine. Methyl ap-dibromo-5-nitro-2-ethoxy-P-phenylpropionat e (XX) is produced in each case,thus showing that the a-group is phenolic, and that the P-groupforms part of the carboxyl group (see formula XXI) :(XVII-XIX).(\OEt(XX). (XXI).Formula I1 being established, the chemical behaviour ofcoumarinic acid can easily be explained.If a representation ofthe molecule be built up with suitable models, the side-chain is seento follow approximately the sides of a regular hexagon, and thecarboxyl group is brought into close proximity with the phenolicgroup (formula XXI), thus indicating the ready elimination of theelements of water. I f , however, a nitro-group be introduced intoposition 3, the negative phenolic and nitregroups exert a combinedand powerfully repellent effect on the carboxyl group, which, beingrepelled from the immediate neighbourhood, no longer enters intochemical action with the phenolic group. This accounts for thefact that 3-nitrocoumarinic 'acid (XXII), 3 : 5-dinitrocoumarinicacid (XXIII), and 3-nitro-4-hydroxycoumarinic acid (XXIV) existin the free state (Miller and Kinkelin, Ber., 1889, 22, 1706;Clayton, this vol., p.1390 et sep.):VOL. XCVII. 2106 CLAYTON : THE CONSTITUTfOK OF COUMARINIC ACID.(XXII). (XXI 11). (XXIV).The ease with which the alkyl ether esters of the coumarinicacids undergo complete hydrolysis is unusual, since phenyl ethersare generally not affected by aqueous alkalis. I n all probability,however, after the removal of the alkyl from the carboxyl group,two causes operate in the second stage of the hydrolysis, namely,(l), the usual hydrolytic action of aqueous alkalis, and (2), thatcause which effects the elimination of the elements of water fromcoumarinic acid itself. These two influences, acting concurrently,bring about the hydrolysis of the phenyl ether which aqueousalkalis alone are generally unable to effect.SzC??WlUq.1.The two methyl ethyl ether-esters of 5-nitrocoumarinic acidand the two corresponding isomeric ether-esters of 5-nitrocoumaricacid have been prepared.2. The two methyl ethers of methyl 5-nitrocoumarate and methyl5-nitrocoumarinate yield the same bromine additive product whentreated with bromine.3. The above facts show that coumarinic acid is the cis-isomerideof o-coumaric acid. This view of the constitution of coumarinicacid affords a ready explanation of its chemical reactions.EXPERIMENTAL.The Ethers and Esters of 5-iVitrocou~marirtic Acid.6-Nitrocoumarin was found t o be best prepared by dissolvingcoumarin in sulphuric acid (10 parts), and treating the solutionwith one molecular proportion of nitric acid (D 1.4) mixed withthree times its volume of sulphuric acid, the temperature being keptbelow 20°.After one hour the solution is poured on crushed ice,and the precipitated solid crystallised from acetic acid.Silver 5-)zztrocoumarimte was obtained by dissolving 6-nitro-coumarin (10 grams) in an aqueous solution of sodium hydroxide(4.2 grams), and then adding a solution of silver nitrate (19 grams).The orange-red precipitate was washed with a little water and dried.When treated with dilute acids, the salt yields 6-nitrocoumarin :0.2813 gave 0.1908 AgCl. Ag=51*04.C,H,03N(OAg)2 requires Ag = 51.06 per centCLAY'I'ON : THE CONSTlTUTION OF COUMARINIC ACID. 2107The Methyl Ether of Methyl 5-Nitrocoumarinate.-Siltrer 5-nitro-coumarinate (6 grams) wits mixed with about 30 C.C.of ether, andthen shaken with a mixture of methyl iodide (1.5 grams) and ether(10 c.c.) for one hour, the temperature rising during this operittion.When cold, the contents were extracted with alcohol, from whichsolvent colourless needles, melting at 124-1 25O, were obtained :0-1375 gave0.2790 CO, and 0.0610 H,O. C=55.34; H=4.92.0.2146CllHl,O,N requires C = 55-70 ; H=4.64 ; N = 5-91 per cent.T7be Ethyl Ether of Ethyl 5-Nitrocoumarimte.-Silver &nitro-coumarinate (10 grams) was treated with ethyl iodide (4 gra.ms) inethereal solution in the manner described in the preceding experi-ment, and the product extracted with alcohol. Colourless needles,melting at 104-105°, were obtained :,, 11.3 C.C.N, at 24O and 770 mm. N=5.99.0.1404 gave 0.3020 CO, and 0.0740 H,O. C = 58.66 ; H = 5.85.0.2376C13H,,0,N requires C = 58.87 ; H = 5-66 ; N = 5.28 per cent.The MetKyl Ether of 5-Nitrocoumarinic AcS.--The methyl etherof methyl 5-nitrocoumarinate (6 grams) was dissolved in dilutealcohol, and heated to 100° with aqueous sodium hydroxide (1 gram)for about thirty minutes, when a portion of the liquid produced noturbidity on dilution with water. The mixture was then acidifiedwith dilute hydrochloric acid, and the voluminous precipitatecrystallised from alcohol or dilute acetic acid. Colourless needleswere obtained, melting at 202-203° :,, 11.7 C.C. N, at 25O and 750 mm. N=5.41.0.1647 gave 0.3230 CO, and 0.0650 H,O.C = 53.48 ; H = 4*3,9.0.1706C,,H9b5N requires C = 53-81 ; H = 4.04 ; N = 6.28 per cent.The Ethyl Ether of 5-Nitrocoumarinic Acid.-This substance wasobtained by the interaction of the ethyl ether of ethyl 5-nitro-coumarinate (6.5 grams) and sodium hydroxide (1 gram) in weakalcoholic solution, in the manner described in the preceding experi-ment.,, 10.1 C.C. N, at 26O and 754 mm. N=6-52.Colourless needles were produced, melting at 171-17Z0 :C = 56.07 ; H = 4.94.CiiH,iO,fJ requires C = 55.70 ; H = 4.64 ; N = 5.91 per cent.0.1498 gave 0.3080 CO, and 0-0662 H,O.0.1442 ,, 8.0 C.C. N, at 25O and 754 mm. N=6.14.The Methyl Ether of Silver 5-1\Titrocoumari~ate.--The methylether of 5-nitrocoumarinic acid (10 grams) was dissolved in anaqueous solution of sodium hydroxide (1.8 grams), and the yellowsolution treated with aqueous silver nitrate (8 grams), when thesilver salt was precipitated as an almost colourless powder:0*3100 gave 0.1004 Ag.Ag = 32.39.C,,H,O,NAg requires Ag = 32-73 per cent.6 ~ 2108 CLAYTON : THE CONSTITUTION OF COUMARINIC ACID.The Ethyl Ether of Silver 5-Nitrocoumum’nate.--The ethyl etherof 5-nitrocoumarinic acid (10 grams) was dissolved in an aqueoussolution of sodium hydroxide (1.7 grams). An aqueous solution ofsilver nitrate (8 grams) was then added. The salt forms an almostcolourless powder :0-3116 gave 0*0980 Ag. Ag=31.45.C,,H,,05NAg requires Ag = 31-40 per cent.The Methyl Ether of Ethyl 5-Nitrocoumarinate.--The methylether of silver 5-nitrocoumarinate (10 grams) was heated with ethyliodide (5 grams) and a little ether for one hour at looo.Theproduct, when extracted with alcohol, yielded colourless needles,melt’ing at 75-77O:0.1178 gave 0.2462 CO, and 0.0580 H,O. C = 57.00 ; H = 5.47.0.1092 ,, 5.7 C.C. N, at 24O and 756 mm. N=5.82.C12H130,N requires C = 57.37 ; H = 5-18 ; N = 5.58 per cent.The Ethyl Ether of Methyl 5-Nitrocoumarinate.-The ethyl etherof silver 5-nitrocoumarinate (10 grams) was mixed with ether andmethyl iodide (5 grams), and subjected to the treatment describedin the preceding experiment. The alcoholic extract yielded colour-less needles, melting at 11 1-1 13O :0.1594 gave 0.3328 CO, and 0.0744 H,O.0.1192 ,, 6.4 C.C. N, at 24O and 756 mm.N=5*98.C = 57.00 ; H = 5.19.Cl2H1,O,N requires C=57*37; H=5.18; N=5*58 per cent.The Ethers and Esters of 5-Nitrocoumaric Acid.The Methyl Ether of Silver 5-Nitrocoumarate.-The methyl etherof 5-nitrocoumaric acid (1.6 grams), prepared according to Schnell’sdirections (Bw., 1884, 17, 1382), was dissolved in a solution ofsodium hydroxide (0.29 gram). To this solution silver nitrate(1.3 grams), dissolved in water, was added, when an almost colour-less, gelatinous precipitate was produced :0.2868 gave 0.0936 Ag. Ag=32*63.C,,H805NAg requires Ag = 32.73 per cent.The Methyl Ether of Ethyl 5-Nitrocoumarate.-The methyl etherof silver 5-nitrocoumarate (1 gram), ethyl iodide (0.5 gram), and a,little ether were heated together for three hours at looo.Afterevaporating off the ether, the mixture wits extracted with alcohol,from which solvent colourless needles, melting at 85O, were obtained :0.1398 gave 0.2942 CO, and 0-0666 H,O. C=57.38; H=5*29.0.1716 ,, 9.0 C.C. N, at 25O and 764 mm. N=5*88.C,,H130,N requires C= 57.37 ; H = 5.18 ; N = 5-58 per cent.TA e Methyl Ether of Nethpl 5-Nitrocoumarate.-The methyl etherof silver 5-nitrocoumarate (1 gram) wits mixed with methyl iodidCLATTON : THE CONSTITUTION OF COUMARINIC ACID. 2109(0.5 gram) and a little ether, and heated to 100° for three hours.After evaporating off the ether, the residue was extracted withalcohol, when colourless needles, melting at 163O, were obtained :0.1050 gave 0-2150 CO, and 0-0454 HiO. C = 55-84 ; H= 4-80.0.1812 ,, 9.9 C.C.N, at 764 mm. and 25O. N=6.07.C,,H,,O,N requires C = 55.70 ; H = 4.64 ; N = 5-91 per cent.5-N~tro-2-et~~oxyZ,enzaZde7~yde.-2-Ethoxybenzaldehyde was slowlyadded to nitric acid (D 1.5), the temperature being kept below loo.After fifteen minutes the liquid was poured on crushed ice, and theprecipitate crystallised from dilute alcohol. The substance crys-tallises in pale yellow needles, melting at 71-72O:0.2910 gave 19.3 C.C. N, at 25O and 77.0 mm.C,H,O,N requires N=7.65 per cent.The Ethyl Ether of 5-Nitrocoumam'c Acid.-5-Nitro-2-ethoxybenz-aldehyde (5 grams), anhydrous sodium acetate (5 grams), and aceticanhydride (15 grams) were boiled together for six hours. Thecooled product was ground with water and extracted several timeswith ether.The ethereal extract was shaken with a solution ofsodium carbonate, and the aqueous solution so obtained treatedwith an excess of hydrochloric acid, when a white precipitate wasformed, which crystallised from dilute alcohol in colourless needles,melting at 194-195O :N=7*54.0.1766 gave 0.3622 CO, and 0.0780 H,O. C = 55.94 ; H = 4.91.0.2288CllH,,O,N requires C = 55.70 ; H = 4.64 ; N = 5-91 per cent.The Ethyl Ether of Silvcr 5-Nitrocoumnrate.-The ethyl ether of5-nitrocoumaric acid (10 grams) was dissolved in an aqueous solutionof sodium hydroxide (1.7 grams)? and a solution of silver nitrate(7.2 grams) then added, when the silver salt was precipitated as analmoat colourless, gelatinous mass :,, 12.0 C.C. N, at 25O and 762 mm.N=5-87.0.3620 gave 0.1132 Ag. Ag=31*27.C,,H,oO,NAg requires Ag = 31.40 per cent.The Ethyl Ether of Methyl 5-Nitrocoumarate.-The ethyl etherof silver 5-nitrocoumarate (1 gram), methyl iodide (0.5 gram), anda little ether were heated together at looo for three hours. Afterevaporating the ether from the product, the residue was extractedwith alcohol, from which solvent colourless needles, melting at141-14Z0, were obtained :0-1174 gave 0-2458 CO, and 0.0536 H,O.0.1624 ,, 8.4 C.C. N, at 25O and 764 mm. N=5*80.C=57*10; H=5*07.CI2Hl30,N requires C = 57.37 ; H = 5.18 ; N = 5.58 per cent2110 PATTEltSON AND STEVENSON : INFLUENCE OF SOLVENTSThe Bromine Additive Products.Methyl a~-Dib~~omo-5-nitro-2-met?~oxy-~-phercylln.opite, - Themethyl ether of methyl 5-nitrocoumarate (1 molecule) was dissolvedin carbon disulphide, and treated with bromine (2.5 molecules).After twelve hours the liquid was evaporated, and the residuecrystallised from alcohol. Colourless needles, melting at 126O, wereobtained. The same product resulted when the methyl ether ofmethyl 5-nitrocoumarinate was treated in a similar manner :0.1498 gave 0.1834 CO, and 0.0400 H,O.0.38060.1460 ?, 0.1380 AgBr. Br=40*22.C= 33.39 ; H = 2.97.,, 11-5 C.C. N2 at 25O and 770 mm. N23.44.C,,H,,0,NBr2 requires C = 33-25 ; A = 2.87 ; N = 3.53 ;B r = 40.30 per cent.Methyl a/3-Bibromo-5-nitro-2-ethoxy-/3-phenyZpropiomte. - Thiscompound was prepared from the ethyl ether of methyl 5-nitrecoumarate and bromine by the method described in the precedingexperiment, and also by a similar treatment of the ethyl ether ofmethyl 5-nitrocoumarinate. The substance crystallises from alcoholin colourless needles, melting at 125O:0*3010 gave 0-2760 AgBr. Br = 39.02.0-4020 ,, 12-5 C.C. N, at 25O and 770 mm. N=3*53.CI2Hl30,NBr2 requires N = 3-41 ; Br = 38.93.The author desires to express his thanks to the Research FundCommittee of the Chemical Society for a, grant which has in partdefrayed the expense incurred during this research.ROYAL COLLEGE OF SCIENCE, IJONDON.SOUTH KENSINGTON, S. W

ISSN:0368-1645    

DOI:10.1039/CT9109702102

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

2110 PATTEltSON AND STEVENSON : INFLUENCE O F SOLVENTSCCXXI1.-The Influence o f Solvents on the Rotation o fOptically Active Compounds. Part X VI.* TheRelationship bet ween the Chemical Constitution andthe Injuence ofa Solvent.By THOMAS STECWART PATTERSON and ELIZABETH FINDLAYSTEVENSON, M.A., B.Sc., Robert Donaldson Scholar of GlasgowUniversity.THE results which have been presented in former papers have madeit clear that the rotation of ethyl tartrate, and doubtless also ofmany other active substances, responds in a remarkable manner to* Part XV., Trans., 1909, 95, 1128ON THE ROTATION OF OPTICALLY AC'I'IVE COMPOUNDS. 2111differences in the constitution of the solvents in which the activecompound may be dissolved. Thus, in p = 5 solution in benzaldehyde,ethyl tartrate has a specific rotation of about + 4 5 O (Trans., 1909,95,3221, whilst in benzantialdoxime at about the same concentrationits specific rotation is approximately - 1 2 O , a difference of 57O.Not only can actual differences.of composition produce suchvariations in rotation, but even the subtle difference of constitutionin the syrzr and anti-oximes can readily be detected in this way,whilst other methods of investigation, absorption spectroscopy, forexample (Hartley and Dobbie, Trans., 1900, 77,509), fail to indicateany dissimilarity.It seems therefore possible that when a sufficient amount oforienting work has been done, an examination of the solvent effectof a given substance on the rotation of ethyl tartrate or others u h b l e active compound may throw valuable light on the con-stitution of the substance in question.I n our opinion the mechanism of this process is of a secondarycharacter;* that is to say, the arrangement and relationship of theatoms of the solvent molecules produce a liquid which, in the mass,has at play within it certain characteristic forces, and an activecompound dissolved in this liquid, coming under the influence ofthese forces, has its configuration and consequently its rotationaltered as the result.The change of rotation is thus only anindirect effect of the chemical constitution of the solvent. I n thefirst paper of this series the suggestion was made (Trans., 1901,79, 188) that the proximate cause of solvent influence on rotationwas that property of liquids known as internal pressure, and thatvariation of internal pressure from solvent to solvent might beindicated by variation of the solution-volume of the dissolved sub-If i t be thecase, as seems generally to be held, that absorption bands arc caused by vibrationsinside the niolecule which absorb light energy, then snch an effect wonld be of aprimary character, sincc it is directly transmitted to the medium in which it isobserved. I n regard to a iwimary effect, no two chemical compounds are likely t o beabsolutely identical, in much tlie same way that no two elements appear to 1i:ivespectral lines in commoii, but substances of analogous composition will probablyproduce closely similar effects.On thc other hand, however, two siibstances en tirelydissimilar might quite well prodnce exactly the same secondary effect, just as agiven strength of pull might be exerted either by n spring or by a system ofgyrostats, that is, in two very different ways.The boiling point of a liquidis a constitutive property of, a t least, the second ordrr, so that thc sameboiling point may be common to liquids having no chemical similarity. Themelting point of a componnd is a constitutive property of a higher order than thesecond. It is easy to see that the higher the order the more difficult it will be tointerpret the effect, and this acconnts for the striking failure to declucc anyrelationship between the simplest of physical properties, like boiling point, andespecially melting point, and chemical constitution.* As an instance of n prinia~y offect we may citc absorption spectra2112 PATTERSON AND STEVEh’SOh’ : INFLUENCE OF SOLVENTSstance. It was also suggested that, since in solutions of finiteconcentration the total volume change is doubtless shared in byboth constituents of the solution, it might be possible to correlatewith rotation values, values of molecular solution-volume calculatedfor infinite dilution, the assumption being made, as a firstapproximation, that in very dilute solution the change of volumedue to solution might be ascribed entirely to the solute.It is clearto us now, however, that this is an untenable assumption, although,of course, in some cases it may closely represent the truth, and thusaccount for certain regularities which were observed ; in general,it could only be substantiated by a strict correspondence betweenexperiment and theory, a correspondence which does not exist.Adefinite decision as to the existence of a relationship between rotationand solution-volume must be deferred until some method has beenfound of determining the true volume of the different constituentsof a solution.Some papers have recently appeared in which questions regardinginternal pressure are discussed. Winther, in a number of valuablepapers (Zeitsch. physikal. Chem., 1907, 60, 594, 651, 685), hasattempted to carry the relationship between rotation and internalpressure much further than Patterson. Dawson (this vol., p. 1041)draws the conclusion that there is no connexion between internalpressure and solution-volume, but that, nevertheless, internalpressure and rotation may be correlative.His experiments point,he considers, to the existence in solutions of compound molecules ofsolvent and solute. On the other hand, Scheuer (Zeitsch. physikal.Chem., 1910, 72, 513), setting out wit.h the view that the existenceof such compounds is highly probable, was unable to find anyevidence of their formation after a very complete and interestingexamination of the melting-point curves, the volume relationships,the viscosity, the rotation, and the dispersion of mixtures of diethyldiacetyltartrate and of menthol with various inactive solvents.Amongst other less probable hypotheses, Scheuer therefore alsosuggests, like Patterson and Winther, that rotation changes onsolution may be due to variation of internal pressure from solventto solvent.It may be added that Grossmann (Zeitsch. physikal.Chem., 1910, 73, 148), using light of various wave-lengths, hasexamined the rotation of ethyl tartrate in a number of solvents,almost all of which had already been investigated by Pattersonfor yellow light. Grossmann is of opinion that his and otherexperiments render extremely probable the existence of compoundmolecules of solute and solvent, but no effort whatever is made toshow how this conception would explain the results obtained.Other attempts to establish the existence of compound moleculeON THE ROTATION OF OP’I’ICALLY ACTIVE COMPOUNDS.2113of solvent and solute in solutions have been no more successftd.Armstrong and his students have attacked the problem in variousingenious ways (Proc. Roy. SOC., 1906, A , 78, 272; 1907, A , 79,564, etc.), as has also Philip (Trans., 1907, 91, 711), but furtherinvestigation by Usher (this vol., p. 66), and in a less degree byFindlay and Creighton (this vol., p. 536), has shown, at least, thatthe assumptions made in the particular method of attack areunwarranted.In the absence of satisfactory proof of either view, it appearsto us that the purely physical conception has the advantage ofsimplicity, and ought in the meantime to be adopted. I n seeking,therefore, to correlate the chemical constitution of a given substancewith its solvent influence, it should be carefully borne in mind thatsolvent influence being probably at least of a secondary character,any attempt to interpret it ought to be made with particular care.I n a recent paper of the present series (Trans., 1908, 03, 1838),a commencement was made in the direction indicated, when it wasshown by one of us that the solvent influence, on the rotation ofethyl tartrate, of disubstituted benzenes appeared to be governedby the general law that two substituting groups, similar or dis-similar, when in the ortho-position cause the greatest, and when inthe par&position the least, rotation in the dissolved active ester.This behaviour was observed in regard to (1) 0-, m-, and p-xylene;(2) 0-, m-, and pnitrotoluene; (3) 0- and m-dinitrobenzene; (4)a- and S-nitronaphthalene; (5) 2 : 6- and 2 : 4-dinitrotoluene.We have now examined, more or less completely, according t ocircumstances, the following solvents : phenol, anisole, phenetole,diphenyl ether ; o-nitrophenol, o-nitroanisole, o-nitrophenetole ;ncnitrophenol ; p-nitrophenol, pnitroanisole, p-nitrophenetole ;catechol, resorcinol, quinol ; pyrogallol, phloroglucinol ; a-naphthol,P-naphthol ; p-benzoquinone ; and also 0-, m-, and p-chloronitro-benzene.A considerable number of these solvents are solids, in some casesof moderately high melting point., and it was therefore occasionallyimpossible either to examine dilute * solutions at all, or to examineeven fairly concentrated solutions satisfactorily a t a low tem-perature, which renders it difficult to institute wide comparisonsbetween the data obtained for different solvents.So far as possible,however, we have extrapolated from our data to 20°, a standardtemperature adopted in previous communications, even althoughmany of the solutions could not possibly be examined in thepolarimeter at that temperature, and in spite of the fact t h a t therequisite extrapolation entails some loss of accuracy. I n other cases* With reference to ethyl tartrate2114 PATTERSON AND STEVENSON. INFLUENCE OF SOLVENTScomparison has been made at such temperatures as seemed mostconvenient.Of the solvents mentioned above, but little need be said regard-ing the three last, and we may therefore commence with them.Only one solution in each, of approximately p=25, was made upand examined in the polarimeter at several different temperatures.As in this case it is only the relative effect of the o-, m-, andp-positions that comes in question, it is unnecessary to extrapolateto 20° j numbers are given below for the interpolated temperaturegoo.Ethyl Tartrate in o-, M-, and p-Chloromitrob emzeme.Solvent. M.p. p. cc? (100 mm.). A",""."nc-Chloronitrobenzeae ..,.,..., 44'4 28-43 6'19 21 *8p-Chloronitrobenzene . . . . . , . . . 83 '0 24'26 3 '8 15'7* R,= 100 aD/p ; it does not differ much from specific rotation.It is clear that in this set of compounds, also, a,s in the othersalready mentioned, the presence of the two substituents in theo-position brings about a much more powerful solvent influencethan in either of the other two positions.A general idea of the behaviour of most of the remaining solventsexamined will be obtained from the diagram, which represents theeffect of diluting ethyl tartrate with the various inactive compoundsmentioned at a temperature of 20°, subject to the limitationsreferred to above.Phenol (m.p. 42*5°).-Solution in phenol very greatly modifiesthe specific rotation of ethyl tartrate. The value rises from +7*S0in the pure ester to +48.5O at infinite dilution in phenol, anincrease of 40.8O. Since benzene itself has but little effect (Trans.,1902, 81, 1098), it is clear that the introduction of the hydroxylgroup must profoundly modify the interatomic forces of themolecule.Anisole.-The replacement of the hydroxylic hydrogen by amethyl group brings with it a very great change in solvent influence.The specific rotation of the ethyl tartrate drops to +6*8O in ap=25 solut'ion, that is, to a somewhat lower value than in thehomogeneous ester.It will be noticed, too, that the shape of theconcentration-rotation curve is of the opposite type to that of phenol,being concave to the point of origin of the diagram, in such a waythat, starting from the value for the pure ester, the rotationincreases slight.$ on dilution with anisole to reach a maximumvalue of about + 8*2O between p=50 and 60, and then diminishesagain fairly rapidly to about +2*5O at infinite dilution.€'henetole.-In comparison with the difference between phenoland anisole, that between anisole and phenetole is slight.Foro-Chloronitrobenzene .. . . . . ... 32'5" 25.733 + 7-26 + 28 '2ON THE ROTATION OF OPTICALLY ACTIVE COMPOUNDS. 2115p = 25 solutions the rotation values are much alike (anisole, + 6.8O ;phenetole, + 7 - 3 2 O ) , but it will be noticed that in regard t o the formFIG. 1.Coilcentration-rotat~on CUTVCS for ethyl tartrate i n various solvents.+ 50"45403530 s ' 25*@ ulaG .@&2015105I ---+--- 3---20 40 60 80 100Concentration (p).of the concentration-rotation curve these two solvents differ, andat infinite dilution the values for the rotation of the dissolvedester are much more divergent (+ 2 ' 5 O and + 7-3O respectively)2116 PATTERSON AND STEVENSON : INFLUENCE OF SOLVENTSThe curve for phenetole is of the same type as that for phenol;there is a minimum rotation of + 7O at p=50, after which therotation rises to reach the value +8O at infinite dilution.Biphenyl Ether (m.p. 28O).-Only one solution was examined indiphenyl ether, of p=24*58. Its observed rotation at 20° was1-95', which, assuming a density of unity, gives a specific rotationof + 7 * 9 3 O , about one degree higher than that in anisole andphenetole at the same temperature and concentration.These results seem to make clear the fact that the powerfulinfluence of phenol in this direction is t o be attributed neither tothe oxygen atom of the molecule nor to the phenyl group or-inthe case of diphenyl ether-groups, but rather to the presence ofthe hydrogen atom of the hydroxyl group.o-Nitrophenol (m.p. 45O).--Since an o-nitro-group in toluene andother monosubstituted benzenes produces a much greater increaseof solvent influence than a m- or a pnitro-group, we had expectedthat o-nitrophenol would have a greater influence than phenol. Onthe contrary, however, the rotation at infinite dilution (+ 1 7 O ) ,although considerably higher than that of homogeneous ethyltartrate, is much below the rotation in phenol. The effect ofo-nitrophenol in this respect is in no way the mean of the effectsof nitrobenzene and phenol, which are both above +40°. Theinfluence of the substituents is thus certainly not sdditive.The concentration-rotation curve for o-nitrophenol is a straightline or nearly so.o-Nitroanisole.-The exchange of the hydroxylic hydrogen atomof o-nitrophenol for a methyl group brings about, a t infinite dilution,a considerable in~rease-l9*5~-in the rotation of the dissolvedester, namely, from + 1 F to + 3 6 * 5 O .o-flitrophene t ote .-In o-nitrop henetole the concentration-rotationcurve is very similar to that for the corresponding methyl ether,but lies wholly below it.A t infinite dilution the rotation wouldbe +27O.There is thus between phenol and its ethers, on the one hand,and o-nitrophenol and its ethers on the other, a relationship of aninverse character when the solvent effects at infinite dilution areconsidered. I n the former, the high rotation brought about byphenol gives place to a low rotation in anisole, and rises againsomewhat in phenetole, whilst in the latter compounds the com-paratively low value in o-nitrophenol rises to a fairly high value ino-nitroanisole, t o fall again considerably in o-nitrophenetole.p-Nitrophenol (m.p. 114°).-Owing to the higher melting pointsof the paraderivatives of phenol, observations could not be made,in this series, in so complete a fashion as in others, but sufficienON THE ROThTlON OF OPTICALLY ACTIVE COMPOUNDS. 2117data have been obtained to elucidate the general behaviour of thecompounds concerned. In pnitrophenol, two solutions wereexamined in regard to rotation, density determinations, however,being omitted. In a solution of p=47*86 by interpolation from theobserved data, IZl,”” = 34*6O,* whilst for p = 24.98, R1,G’’ = 46O, whenceat infinite dilution, also f o r looo, the value of R , would beapproximately = 60°.These are very high values, and they increaseas the temperature falls, so that a t ZOO the specific rotation, whichin this case would have a slightly lower value than R,, of aninfinitely dilute solution of ethyl tartrate in p-nitrophenol wouldprobably lie a t about + 75O. p-Nitrophenol is thus considerablymore powerful even than a-nitronaphthalene or o-dinitrobenzene,the most powerful of the solvents hitherto exa.mined. But owingto the extensive extrapolation requisite in this case, the concentration-rotation curve for pnitrophenol can only be regarded as a somewhatrough approximation, for which reason it is shown as a broken linein the diagram.p-Nitroanisole (m.p. 54O).-This solvent on mixture with ethyltartrate causes a, gradual and comparatively slight increase ofspecific rotation. For a solution of p = 53.84, CUE = + 12.5O. Byextrapolation of the observed readings for a, p=26*08 solution, thevalue a2,o (100 mm.)= +5-lo is fonnd. Assuming a density of1.2, which would certainly not be far from the truth, the specificrotation at infinite dilution would have it value of, approximately,+ 2 1 O .p-Nitrophenetole (m. p. 60°).-Solutions of p = 49.66 andp=24*37 were examined in this solvent. The specific rotations ofthese at 20°, assuming a density of 1.2 in each case, would benearly + So and + loo. With increasing dilution, therefore, therotation of the dissolved ethyl tartrate increases, although onlyslowly, to reach a value of about + 1 3 O at infinite dilution.m-Nitrophenol (m.p. 96O).-Only one solution-p = 49.76-wasexamined. Its behaviour is referred to below.2 : 4-Dinitrophenol (m. p. 114*5O).-We also examined one solu-tion (p= 75.15) in this substance. Its rotation was somewhat lowerthan that of an equally concentrated solution in o-nitrophenol.General Discussion of the Foregoing Results.1. We may examine first the solvent influence of phenol and itsthree nitrederivatives, which will be best accomplished by con-sidering the observed rotations for p=50 solutions at a temperatureof 70°:* See note on p. 21132118 PATTERSON AND STEVENSON : 1NFLUENCE OF SOLVENTSa j+; B d BuzPhenol + 45.5"Anisole + 2.5Solvent.P. a'," (100 mm. ). Difference.......... 2 *5"3 52 -4o-Nitrophenol 51 '13 + 9.3" .................. Phenol 48 '2 11 *8nt-Nitrophenol 49'76 15.3y-Nitrophenol ......... 47-86 17.7.........The influence of phenol is diminished 2 ' 6 O by the introductionof a nitro-group in the o-position; it is raised 3 . 5 O by a nitro-groupin the m-position and by a further 2*4* if the nitro-group be in thep-position, a behaviour which is thus just the opposite of thatobserved in other cases of ortho-, meta-, and para-isomerism.2. Comparing the behaviour of phenol, o-nitrophenol, and p-nitro-phenol with that of their respective ethers, it is to be noticed thatthe very great solvent influence of phenol disappears almost entirelyin anisole, phenetole, and diphenyl ether, and that in a similarmanner the very powerful effect of p-nitrophenol is greatlydiminished in its methyl and ethyl ethers, and by an approximatelyequal amount in the two cases, some 50°.On the contrary, how-ever, the comparatively feeble effect of o-nitrophenol is quite con-siderably raised in its ethers. Thus phenol and p-nitrophenolappear t o behave in an analogous manner, and to differ fromo-nitrophenol, as is shown in the table below.4i dG $4 2 *- Z d B aa*a.2 : 9 Ba'Z .P 2PH P T 4 2 0u1 u1 HG 6 Ap-Nitropherol + 75"p-Nitroanisole +21 +54" 1 o-Nitroanisde +36'5 - '"'" o-Nitrophenol + 17"3. As shown in the following table, o-nitroanisole has a greatersolvent influence than pnitroanisole, and o-nitrophenetole a greatereffect than p-nitrophenetole, and by almost the same amount.Rotation of Ethyl Tartrate.[aIF [slyInfinite I n fi 11 it eSolvent.dilution. Difference. Solvent. Dilution. Difference.o-Nitroanisole ,., 1-36-8" 15.80 I o-Nitrophenetole ... + 27" 140p-Nitroanisole ... 21 *O p-Nitrophenetole ... 13Although, theref ore, the behaviour of the nitrophenols is unusual,inasmuch it9 the two substituting groups produce the greatestsolvent effect when in the pposition, and least when in the o-position,this exceptional behaviour does' not extend to their ethers, whichexhibit the regularity previously described for the chloronitro-benzenes and a number of other substancesON THE ROTATION OF OPTICALLY ACTIVE COMPOUNDS.21194. It is of interest to compare, so far as is possible, our presentresults with some obtained by other methods having a similar aim.E. C. C. Baly and Miss Ewbank (Trans., 1905, 87, 1315) havedescribed the absorption curves for phenol, anisole, and phenetole.They point out that the curves for the ethers are identical, andthat they differ in one particular * from that of phenol itself.This agrees roughly with what we have found, for, although theconcentration-rotation curves for anisole, phenetole, and diphenylether are certainly not identical, still, in respect to the magnitudeof their effect when compared with phenol, they are much alike.That for phenol differs very markedly.We had also, during the course of this research, compared ourresults with the absorption curves given by Baly, Edwards, andStewart (Trans., 1906, 89, 512) for the nitrophenols and theirethers, but in a more recent paper Baly, Tuck and Marsden (thisvol., p.571) have explained the anomalous character of one earlierexperimental result -f as being due to solvent influence, and haveconsiderably altered the theoretical views formerly held. They haverejected the idea of the existence of a quinonoid structure, not onlyin the free nitrophenols, but also in their alkali salts, and theydraw the conclusion that o-nitrophenol and o-nitroanisole aresimilarly constituted, the same holding for the met& and para-compounds.It may be pointed out that our results, if it be legitimate tocompare them with those of Baly, are not in agreement wit,h thisconclusion, since, as stated above, phenol and p-nitrophenol arerelated to their ethers in a similar manner, the solvent influence oftho phenols being much greater than that of the ethers, whereasthe opposite is the case for o-nitrophenol and its ethers.Theethers of phenol, o-nitrophenol, and p-nitrophenol, however, behavenormally amongst themselves. It might therefore be concludedthat phenol and pnitrophenol are similar in structure and differentfrom o-nitrophenol, but that the ethers are all of analogousconstitution.The data which we have obtained in the examination of a numberof polyhydroxy-benzenes and of p-benzoquinone may be dealt withvery briefly. I n the table below, there are quoted interpolatedvalues for the observed rotation at looo of solutions all of aboutthe same concentration.this difference.* We are not aware what degree of importance Professor Baly would attribute tof That the spectrum of o-nitroanisole differed from that of o-nitrophenol2 120 PATTERSON AND STEVENSON : INFLUENCE OF SOLVENTSRotation of Ethyl Tartrate.Benzene ..................75.199 + 10*9=*Phenol ..................... 74-39 13.82Catechol .................. 74'81 13.45Resorcinol., ................ 74 -10 16 *55Quinol ..................... 74.47 17.60Pyrogallol.. ................ 74 '93 13.25Phloroglucinol ............ 74 *33 17 '20p-Benzoquinone ......... 74 -98 10.90Solvent. P. a;''''' (1 00 mm.).* By extrapolation from figures given in Trans., 1902, 81, 116.On account of the rather high melting points of these substances,only one concentrated solution in each was examined.Cat ec hol, Resorcinol, Quino1.-The first hydroxyl group intro-duced into the benzene ring produces a considerable increase ofsolvent influence.A second, however, in the o-position t o the first,instead of causing a further increase, brings about a slightdiminution of less than half a degree. I n the m-position, on theother hand, an increase of nearly three degrees results, whilst inthe p-position the increase is almost four degrees.Pyrogallol, Phloroglucino1.-The behaviour of these two solventsis in remarkably close accordance with what might now beexpected. The three hydroxyl groups in the vicinal position inpyrogallol bring about a small diminution its compared with catechol,whilst in the mposition in phloroglucinol there is a considerableincrease as compared with resorcinol. It is thus quite clear thattwo hydroxyl groups have least effect in the o-position and mostin the p-position, a behaviour which is thus similar to that shownby a nitregroup and a hydroxyl group when present together inthe benzene ring, but opposite to that which is characteristic of twonitro-groups, two methyl groups, or a methyl group and a nitro-group.p-Benzopuinone (m.p. 166°).-p-Benzoquinone, in a solution ofapproximately the same strength as for the polyhydroxy-benzenes,caused for u1,Ooc the value + 1 0 * 9 O , a considerably lower rotationthan is produced by phenol or catechol.It might therefore beargued that a quinonoid structure of the solvent causes, in ethyltartrate, it lower rotation than a simple phenolic constitution, andthat therefore the low rotation produced by o-nitrophenol as com-pared with phenol and p-nitrophenol may be due to it quinonoidstructure for the o-nitrophenol. We would not venture, of course,on this slight evidence, to draw any definite conclusion, but thefact is worthy of consideration along with others bearing on thequestion.a- and &Naphthol (m. p. 94O and 122O).-We also examined onON THE ROTATION OF OPTICALLY ACTIVE COMPOUNDS. 2121solution each in a- and &naphthol. In the former, REoo (p=25*24) =+ 2 9 . 7 O , and in the latter, &Eoo ( p = 29-01> = + 43'8O.The differenceis thus very considerable, and since the a-compound may be regardedas an o-hydroxy- and the &compound as a m-hydroxy-derivativeof benzene, the behaviour of these two solvents is strictly inaccordance with that of the other phenols dealt with above.Influence of Change of Temperature.With regard to t,he influence of change of temperature on therotation of these solutions, but little need be said, since the behaviourFIG. 2.Ternperchre-rotation cwrz'es for ethyl tartmle in various solvents( p = approximately 75 in each case).II I20" 40" 60" 80" 100" 120" 140"Ten iperature.observed has been entirely in agreement with what has been dis-covered in other cases. The effect of rise or fall of temperature isa function of the value of the rotation at the temperature chosen.I f the rotation at To be above a certain critical value for thattemperature, a, value which can be fairly definitely stated,* thenheating above TO will cause fall of rotation, whereas if the rotationbe below the critical value, further heating will bring about increaseof rotation. The temperature-rotation curves in Fig.2 illustrate* For 20°, for example, this critical value for specific rotation lies about3.18" to +20°.VOL. XCVII. 6 2122 PATTERSON AND STEVENSON : INFLUENCE OF SOLVENT3this point. The rate at which the rotation increases with rise oftemperature in pyrogallol (j = 74.93) is greater than that in catecholsolution of about the same concentration, in agreemeht with thefact that the rotation in the former solution is less than in thelatter.In phenol, with its greater solvent influence, the rate ofincrease of rotation is less than in catechol. I n resorcinol there isat first an increase of rotation and then a diminution, a maximumrotation occurring at a temperature of about 60°. This maximumrotation is therefore the critical value at 60°. Our data forphloroglucinol are rather scanty, but it is practically certain thatFIU. 3.Temperature-rotation cwves for ethyl tartrate in various solvents.-1--3-20" 40" 60" 80" 100" 120" 140"Temperalure.this solvent would show a similar behaviour, and therefore that amaximum rotation probably occurs at a lower temperature than60°.I n quinol only a fall of rotation was observed, but there isdoubtless a, maximum rotation somewhere about the temperature40°, which would have a greater value than the maximum inphloroglucinol or in resorcinol. The critical value of the rotationis higher the lower the temperature at which it occurs.The above remarks apply equally to the behaviour of a- and&naphthol and the nitrophenols. In phenol itself it may be notedthat whilst the temperature-rotation curves for solutions of highconcentration are concave to the point of origin of the diagramON THE ROTATION OF OPTICALLY ACTIVE COMPOUNDS. 2123that for a p=50 solution is almost a straight line but with a slightconvexity, which, as the solutions are diluted, becomes graduallymore pronounced.This resembles the behaviour of quinoline(Trans., 1909, 95, 323), and it is, of course, possible that others ofthe solvents we have dealt with would show the same behaviour insolutions more dilute than those we have investigated.The experiments recorded in this paper seem, we think, to justifythe conclusion that the chemical constitution of a solvent is notmerely reflected-which, of course, it must be-but is reflected in acomparatively simple manner, in the influence of that solvent onthe rotation of dissolved ethyl tartrate, and that, conversely, thismethod might be used for the investigation of chemical constitution.The method differs from that of refractive index and of magneticrotation, inasmuch as it does not seem possible to calculate anyconstant increment or decrement for a given group of atoms, for asingle atom or for a difference in the linking of an atom in themolecule, but these are certainly indicated qualitatively.There isperhaps a closer connexion between the phenomena we havedescribed and those of absorption spectroscopy. So far as we areable to judge, knowing only one of these methods intimately, thesolvent-influence of a compound on the rotation of ethyl tartrateaffords a more delicate criterion of chemical constitution thaneither of the others, as witness, for example, the effect of orthe,meta-, and para-isomerism, the difference between phenol andanisole, and especially the difference between the syn- and anti-oximes. We hope to describe the further study of the subject infuture papers.EXPERIMENTAL.Ethyl Tartrate in Various Solvents.dhloronitrob enzene.p=25'73:t ..................24.7" 30.55" 40.55" 49.2" 58" 82.9Oa: (100 mm.) ... 7.7 7'654 7'638 7.61 7.5 7'33m-Ciiloronitro b enzene.t .................. 36.9" 62'2" 77.4" 89.7" 1062"aD (100 mm.) ... 5.754 5.9 6.125 6'046 6,236p = 28.43 :p-Chloronitrobcnzene.t .................. 82.1" 105-2" 117" 128.2" 147'1"qt (100 mm.) ... 3.i35 3.885 4.098 4.106 4.12p = 24-26 :6 2 2124 PATTERSON AND STEVENSON : INFLUENCE OF SOLVENTEthyl Tartrate in Various Solvents (continued).Ph enot,t 20" ao.75" 62-30 69'5" 92.4"a: (100 mm.) ... - +5%95 +4.885 +4*525 4 *085[a]: ............... +385 +35*47 +80'96 -:-29'10 26-86I. p=14*79:..................11.p=23*85 :t .................. 18.8" 20" 32.4" 41.9" 53.5" 65.5 96.9" 130.4'a2(100 mm.) ... +9-039 - 8.445 8.031 7.586 7'23 6.345 5.666[a]: ............... 34-25 $34.2 32.32 30.98 29-55 28'42 25.7 23-65111. ~'48.2:t .................. 19" 20" 39" 65-2" 92.3" 140.6"a: (100 mm.) ... +13*124 - 12.64 11-95 11.27 10.15[a]: ............... 23.99 23.94 23'44 22.62 21.83 20.54IV. p=64.78:t .....................a: (100 mm.) ......[UJE, ..................v. p = 74-39 :E .....................a: (100 mm.) ......,a]; ..................VI. p = 79.24 :t .....................u: (100 mm.) ......[a]; ..................I. +-t. d.45'4 1.072566.4 1 -053978.8 1.043138.5" 1.0787I v.&t. d.14'6" 1-166535'5 1.145165 8 1'126183'4 1,099720" 20.9" 64.9" 100*3" 126"- 12,853 13.309 13.058 12.717.05 17'10 18.38 18'78 18'5218-75" 20" 53.5" 76.5" 89.7"11.99 - 13.225 13.62 135'7513'78 13.82 15,60 16.38 16.7619.95" 20" 55.5" 87'1" 117'2"11.485 11.534 13'248 14'018 14.20912.30 12.37 14'62 15-90 16.62Densities Determined.IJ.- t. d.21.4" 1.105037-9 1.090368.2 1.072178.1 1.053899.8 1.0332v.&t. d.16.1" 1-1 75528.7 1 -163542.0 1-149964.7 1.1284111. - t. d.11 '9" 1.14041'1252 33.546.5 1.113374.6 1.087899.2 1.0640v I.w.t. d.13.5" 1.183738 '4 1-160658.4 1.141282 1 1.117ON THE ROTATION OF OPTICALLY ACTIVE COMPOUNDS. 2125Ethyl Tartrate in Various Solvents (continued).A niso l e.I. p=9*99:t ........................18.2" 20" 27 *3" 35.2"at (100 m.) ...... + 0'432 - + 0.536 + 0.622[a]; .................. + 4'27 +4'5 + 5.34 + 6-2511. p=24-62 :t ................... 14.6" 20" 33.2" 46.8" 52-9" 68.9" 72-8"............... + 6'24 6.8 8'20 9.75 10.15 12.11 12.41aE, (100mm.) ... + 1'602 -- 2.068 2.428 2.512 2.952 3.012111. p = 49.85 :t ....................... 19" 20"- a; (100 mm.) ...... 4'324[a]:. .................... 7 '96 8-1I.-7 t. d.17.5" 1.014225.4 1.0064I. p=9.99:t... ...................a: (100 mm.) ......[a];. .................11. p=24'96:t .....................[a]:. ................. a: (100 mm.) ...111. p = 51-73 :Densities Determined.11. * t. d.14.9" 1.042432.5 1.026145.5 1'013055.5 1.0033Phenetole.195" 20": 22-1" + 0.76 - 0.786 + 7.72 7.75 8.0019.2" 20" 31.6 + 1'832 - 2.202 + 7-23 7'32 a*f9t........................ 1 a -20 20"[a]: .................. + 6-72 + 6'86- a; (LOO mm.) ...... + 3.742Densities Determined.11. - t. d.17.9" 1.016128'1 1.007138.3 0.996948.4 o m 6 930.6"4.9049 *12111. - t. d.15.8" 1'093325'6 1.0835- -43.5 50'510.14 10'922-51 2.68631-0"4.4328.02126 PATTERSON AND STEVENSON : INFLUENCE OF SOLVENTSEthyl Tartrate dn Various Solvents (continued).Diphenyl Ether.t. ..................... 18.7" 20" 51.8" 66.0" 76.3" ...... 3 2 8 8 a4, (100 mm.) + 1.824 1.95 2-68 2-92p = 24-58 :*Nitro pheno 1.t . ........................ 60.1" 81.4" 112.2"I. p=23.89 :......... a: (100 mm.) + 4.82 4-972 5-007[a]: +16*20 16.98 17.66 .....................11. p=51*12 :t ......................... 56.8" 78'2" 97.3"a: (100 mm.) ......... + 9-015 9.486 9.766[a]; ..................... -t14*31 15'35 16.08111. p = 74.95 :t ........................ 16" 43.4" 87.3' 115.1"[a]: + 9.74 12.14 14.38 14.21u4, (100 mm.) ...... f9'142 11.119 12-66 13.056.....................Densities Determined.I. IJ.* 111.+7 7-y - t. d. t. d. t. d.47.7" 1.2603 56.8" 1.2323 12.5" 1.255865.9 1.2416 78.2 1.2086 27.1 1.238578.1 1.2295 97.3 i m 7 8 49'4 1-2164 - - 72.5 1.1910* By interpolation from the determinations for the other two solutions.-o-Nitroanisole.t ................... 17.9" 20" 345" 43.3" 53.2" 62.8"I. p=9*79 :aE, (100mm.) ... + 3.748 - 3.548 3-490 3.354 3'26[a]; ...............+ 3 0 9 30.6 29'5 29.2 28 3 27.711. p=21*17:t. .........."...... 17.4" 20" 29.1" 39'3" 50" 55'8"at (100 nim.) ... 6.666 - 6.604 6-472 5.442 '324[a]: ............... 25.35 25'3 25'4 25.1 25'2 24.8Densities Determhed.I. 11.& &t. d. t. d.17.7" 1.2471 14.9" 1'244233 1 -231 9 35 1 *223742'9 1'2219 53'2 1.205359.7 1 '2050 66-4 1'191ON THE ROTATION OF OPTICALLY ACTIVE COMPOUNDS. 2127a; (100 mm.) + 11262 10.646Ethyl Tartrate in Various Solvents (continued),o-Nitro phene t ole.t. ................. 18-4" 20" 30*6" 53.3" 65.5"uk (100 mm.) ... + 5-698 - 5.812 5'906 5'896[a]; ............... +19*11 19.2 19.7 20.41 20'6I. p=25'09 :11. p=39-43:t ................... 15.9" 20" 25.1" 29.1" 42"aI, (100 mm.) ... + 7'252 - 7'544 7'57 7'848[a]: ............. + 15 '41 15 '75 26-16 16.27 17.06+ 17'624 16.878 16'274Densities Determined.I. 11. - - t. d. t. d.17.1" 1.1896 14'6" 1.194833'4 1,1734 25'9 1'183340'4 1.1659 33.3 1.175754'3 1.1524 41 1'1680p-Nitroanisote.aE, (100 mm.) ...... + 6,082 6.25 6.515 6,075 6 078p = 26.08 :t. ..................... 52.0" 55.8" 64.8" 73.6" 77"p = 53-84 :t :....... .......... 20" 35'1" 44'4" 51.3" 57'6"[a]: ............... +12'5 +13'63 14.23 14.58 14.91a; (100 mm.) ... - +8.876 9'198 9'376 9.54Densities Determined.t 35'1" 4 1 -4" 48" 57.2"d 1'2101 1.2038 1'1974 1.1883p-Nitrophenetole.t 50.1" 57'3" 67.3" 82'5" 49'4" 54-4" 66'6" 69.7"a; (100 mm.) ... +3'88 3'995 4-21 4'345 1-6.475 6.73 7-175 7.28p =49*66 : I ..................p = 2 4 * 3 7 :m-ATitropherroZ.t .................... 35.4" 41'4" 50.3" 57.7"a; (100 mm.) ...... +I53 15.68 15.665 15 55p =49*76 21 28 ROTATION OF OPTICALLY ACTIVE COMPOUNDS.Ethyl Tartrate in Various Solvents (continued),2 : 4-Dinitroyhenol (m. p. 114*5O).t ........................ 84.5" 107" 121.5"at' (100 mm.) ...... + 10'696 11'2i2 11.564p = 75.15 :Cat echol.p = 74.81 :t ..................... 41.4" 68.9"aE, (100 mm.) ..... +12.12 13.04PE eso r cino 1.t ..................... 15.9" 479"a; (100 mm.) ...... +16'25 16-86p = 74.12 :Quin ot.p = 74.47 :t ........................ 70.3"a; (100 mm.) ......... -t.18'1Pyrogallot.p = 74.93 :t ........................ 49.5"a: (100 mm.) ......... 11.88494.3" 103.7"13'40 13.5374.3"16-89105"17.578 '9"12.868Phloroglucinot.p = 74-33 :t ........................ 69.5" 93.6"(100 mm.) ......... +17.48 17.43a-iVap7hthol.p = 25.24 :t ........................ 105%"aI, (100 mm.) ......... +7*276P-ATaphthol.p = 29.01 :t ........................ 132.7"a: (100 mm.) ......... + 10'92p-Benzo puinone.p=74*98:t ........................ 87-5" 115"a', (100 mm.) ......... + 10-804 10'968TEE UNIVEILSITY,-~ GLASGOW.104.2"16'644136.5"16-53108.6"13.344104*1"17-10121 -5"6.732150" + 9 988122'9"13'12

ISSN:0368-1645    

DOI:10.1039/CT9109702110

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

EXPERIMENTS ON THE SYNTHESIS OF THE TERPENEY. 21%CCXXI~I.-Expei.i~ne.nts O I L the Sy.lzthesis o f the Twpenes.Part XIV. synthesis of d- am! 1- A 5 - m - ~ e ~ ~ t h e n o l ( 8 ) ,cll-A4-nl-Ment~~eiLo1(8) and their Derivatives.By WILLIAM HENIUY PZRKIN, jun-OF the six possible menthenols of t.he meta-series,* the followingfour have, so far, been synthesised :CMe CHMe/\ /\y*2 yH p 2 p\/ \/CH2 CH,CH, CH*C Me2*OH CH2 C*Cble2*OH(A2. 1 Al-( Dihydrocarvestrenol)(Trans., 1907, 91, 498.) (Trans., 1905, 87, 1101.)CHMe CMe(A3) (Trans., 1905, 87, 1099 ;coinpare this vol., p. 1029.)A6-( Dihydroisocarvestren 01).(Trans., 1908, 93, 1887.)The present communication containsof the remaining two, namely:CHMe/\ p F"2CH CH*CMe,*OH andOf the former, the d- and Z- andan account of the synthesisCHMe/\QH2 7%CH CH*CMen*OH.\/ YCH(A4.)dl-modifications have beenprepared, whereas of the latter only the dl-modification wasobtained, and that in very small quantity.A short time since (Trans., 1909, 95, lSS9), Meldrum and Perkinshowed that 5-hydroxy-m-toluic acid is reduced by sodium andisoamyl alcohol to l-methylcycZohexan-5-ol-3-carboxylic acid + :C0,HCHMe<CH2*CH(Co2H)Me/,-> -+ CH2--CH(OH)>cH29OHCOnH* Menthenols of the type of terpineol are here referred to.t In the paper referred to, this acid was called " l-methyIcycZohexan-3-01-5-carboxylic acid," but the alternativd ntiiiibering is more suitable2130 PERKIN : EXPERTMENTS ON THEand, in the present communication, it is shown that this reductionmay also be effected in alcoholic solution, provided that the alcoholhas been completely dehydrated by distillation over calcium.When 1-methylcyclohexan-5-01-3-carboxylic acid is treated withhydrobromic acid, it is readily converted into 5-bromcll-methyl-c~~Zohexane-3-carhoxylic acid, and the ester of this acid, whendigested with diethylaniline, yields a mixture of the esters of theacids :1 -Met hyl-A5-cyclohexene- 3 -carboxylic acid.1 -Methyl - A4-cyclohexene - 3 -carboxylic acid.and these acids, of which the former is produced in by far thelarger quantity," were separated by the fractional crystallisationof their calcium salts.The constitution of the former of theseacids (A5) was demonstrated by the examination of the products ofthe oxidation of h~--m-menthenol(8) obtained from its ester by theaction of magnesium methyl iodide (p.2132). The constitution ofthe other acid (A*) was proved by the fact that, when boiled withconcentrated aqueous potassium hydroxide, it is converted into1-methyl-A3-cycZohexene-3-carboxylic acid :the fly-unsaturated acid becoming a/3- in the usual manner.Ethyl dl-1-methyl-AS-cyclohexene-3-carboxylate reacts readily withmagnesium methyl iodide with the formation of dld6-m-mert-thenoZ(8) (b. p. 115-117°/30 mm.), and this, when boiled withaqueous oxalic acid, yields &-A5 :8(9)-m-menthadiene (b. p.175-176') :CH,*CH(CMe2*OH )CHMe<CH (;cH>CH, andCHMe<CH2*CH(CMe:CH ) CH (-l&>CH2.Under similar conditions, ethyl dZ-1-methyl-A%ycZohexenecarb-oxylate yields A4-mmenthenol(8) (b. p.115-117°/30 mm.) andA4:8(g)-mmenthadiene (b. p. 175-177O) :* It has often been observed, in cases where two isomeric unsaturated acids areformed by the elimination of hydrogen bromide from a bronio-acid, that veryslight changes in the conditions of experiment often effect in a remarkable mannerthe proportions of the isomerides produced. Two experiments were made on theelimination of hydrogen bromide from ethyl 5-bromo-1-me thylcyclohexane-3-carboxylate by means of diethylaniline. In the one the yield of l-methyl-a4-cyclo-hexene-3-carboxylic acid obtained on hydrolysis was 5 per cent., in the other,apparently under tho same couditions, the yield was less than 1 per centSYNTHESIS OF THE TERPENES.PART X1V. 2131CH,*CH( C0,Et) cH>CH yieldsCHMe<CH2---Besolution of dl-l-MetTlyl-h~-cyclohexene-3-carbo~lic A cia? andPreparation of the d- and LModifications of A6-m-Mentheno1(8).As the amount of pure dZ-l-~ethyl-A5-cycZohexene-3-carboxylicacid which had accumulated during these experiments amountedto more than 160 grams, it was thought that it would be interestingto attempt its resolution, and then to convert the active acids intothe corresponding menthenols and menthadienes. This wasultimately accomplished with the aid of either Z-menthylamine orquinine, the salt produced in b0t.h cases being the salt of the dextro-acid.The 1-ment.hylamine salt, after repeated recrystallisation, had[a],, -1.7O, and from this salt the acid was regenerated and con-verted into its ester and the corresponding menthenol and terpeneby processes already described in the case of the dl-acid. Theobserved rotations of these substances may be conveniently tabulatedthus :rain.cl-l-Methyl-A5-cycZohexene-3-carboxylic acid .........-I- 33.1"Ethyl d-1-methylcycZohexenecarboxglate ............... + 30.5&A5 8(9)-m-Menthadiene ................................... + 29'6d-A5-m-Nenthenol(8) ...................................... + 36 7After the d-acid had been removed, as far as practicable, bytreatment with Z-menthylamine and quinine, the Z-l-methyl-A5-c~clohexene-3-carboxylic acid, contained in the mother liquor ofthese salts, was nearly pure, since its rotation was [a], -30*9O, ascompared with the rotation [a], + 33'1O of the correspondingd-acid.From this Z-acid the same derivatives were prepared as in thecase of the d-acid, and these and their rotations may again betabulated :ta3D.E-l-Methyl-A5-cyc~ohexene-3-carboxylic acid .........- 30.9"Ethyl E-l-methylcycclohexenecarboxylate ............... - 27 -4Z-As--?)a-Menthenol( 8) ...................................... - 32-6Z-A5:8(9).-m,-~enthadiene .................................... - 25.3The constitutions assigned to these active menthenola andmenthadienes, and indirectly therefore those of the correspondin21 32 PERKIN: EXPERIMENTS ON THEinactive substances and also that of l-methyl-A5-cyc2ohexene-3-carboxylic acid, were proved in the following manner.Pure d-A5-m-menthenol(8) was oxidised with permanganate andthen with dichromate under the conditions described on p.2143,and the resulting acid converted into the ethyl ester, which waspurified by fractional distillation under diminished pressure. Theester, C;2H2004, thus obtained distilled at 188-190°/20 mm., andhad [a]= -18*7*.When this ester was hydrolysed, it yielded a mixture of twoisomeric lactonic acids, CI0Hl6O4, which melt at 102O and 136Orespectively, and are obviously the cis- and trans-lactones ofa-methyl-y-hydroxyisoprop yladipic acid :C02H*CHMe*C?H2-CH(CMe2*OH)*CH,*C0,H.The formation of this acid by the oxidation of A5-m-menthenol(8)may be expressed in the following manner:CHMe CHMe/ \\ /CH2C0,H FH2/\\/CH,RH FH,CH CH*CMe,*OH ---+ CO,H CH*CMe,*OHand its easy conversion into the lactone:CHMe/ \C0,H FH2CHGMe,/ >oCH2--GOproves that the menthenol from which it is derived must have thedouble linking in the A5-position, since the dibasic acid which mightresult from the oxidation of the menthenol of the other alternativeconstitution (A4) :CHMe CHMewould hardly be expected to pass into a lactone.The oxidation of d-A5-m-menthenol(8) is very similar to thatof ordinary terpineol, which, with chromic acid, yields methoethyl-heptanonolide (I), and then, with hypobromite, homoterpenylic aciSYNTHESIS OF THE TERPENES. PART Xlv.2133(11) (Wallach, Ber., 1895, 28, 1773; Tiemann and Semmler, ibid.,2141) :CMe COMe C0,H>o $ H-CMe,CH,-CO\$!H*CMe 2>0 CH2-CO(1.1 (11.)A similar series of oxidations carried out with Z-A5-m-menthenol(S)gave again the ester, C12H2004, of the mixed lactonic acids.Thishad [aID +17*4O, and yielded, on hydrolysis, the cis- and trans-lactones of melting points 1 0 2 O and 1 3 6 O , which had been obtainedfrom the &modification. Moreover, it is curious that, whilst theester, C12H2004, was, in both cases, optically active, the lactonesobtained on hydrolysis, although they still contain two asymmetriccarbon atoms, should prove to be inactive.These oxidation experiments show conclusively not onlythat the two active series tabulated on p. 2131 represent d- andI-modifications of the same substances, but also that these sub-stances have t,he constitutions which have been assigned to them.In connexion with this series of researches on the synthesis ofthe terpenes, there is one point of importance which should be madequite clear.When a menthenol is synthesised from the ester ofthe corresponding acid by the action of magnesium methyl iodide,for example :CMe,*OH C0,Etthe menthenol which is obtained is quite pure and homogeneous.When, however, water is eliminated from such a, menthenol, theresulting menthadiene is probably, as a rule, not a homogeneoussubstance, but may consist of a mixture, in varying proportions,of the isomerides:CMe:CH, CMe,Me/-\ and\=/ \=/and possibly, owing to intramolecirlar change, the third isomerideof the type:may also be present.It is well known, especially from th2134 PERKIN : EXPERIMENTS ON THEresearches of Wallach, that ordinary terpineol, on treatment withdehydrating agents, yields not only dipentene, but also terpinoleneand a-terpinene :Terpineol. Dipentene.Terpinnlene. a -Te r pin en e ,The conversion of terpineol into terpinolene appears to takeplace most readily when dilute acids are used as the dehydratingagent. Thus, Baeyer (Bey., 1894, 27, 447) recommends 30 percent. oxalic acid as the best reagent for converting terpineol intoterpinolene.I n the present communication it is stated that the reagent whichwas found most suitable for the elimination of water from A*- andAbn-menthenol(8) was 6 per cent. oxalic acid, and it seems thereforevery probable that the products obtained in each case may bemixtures of a t least two menthadienes:A4-?a-Menthenol(8).A4:8(9)-m,. A4:3(8).1)72-,CMe,*OH CMe:CH, CMe,aIe/2\a5-m-Menthenol(8). A5: 8(9).pn.. A5 : 3(8)-m-.\=/Me/-\ \=/ Me/-\ \=/It would be difficult to separate and identify such isomericproducts of the elimination of water even if large quantities ofthe menthenols were available, and, in the present case, where thepreparation of even small quantities of material is very laborious,this problem cannot, in the meantime, be solved. It has thereforebeen decided to retain for the present t'he names A4:8(9)- andAS :g(Q)-m-menthadiene for the hydrocarbons, and the determinationaf the exact nature of these products of dehydration must be leftuntil a better method for their preparation has been discovered.When larger quantities of material are available, an effort willalso be made accurately to determine the physical constants of allthe substances mentioned in this paper.The probability that substances of the terpinolene type arefrequently produced during the elimination of water from thementhenols according to the process :>CH*CMe,*OH -+ >C:CMe,suggests an explanation for some of the remarkable results whicSYNTHESIS OF THE TERPENES.PART XIV. 2135have been obtained, more particularly during the course of theinvestigation of optically active menthenols and menthadienes. Inthe first place, it is important to note that the above process cannottake place when the >CMe,*OH group is attached t o a doublylinked carbon atom, as in :>C-CMe,*OH. Apart from fund*mental intramolecular change, which both chemical properties andphysical measurements show t o be most improbable, menthenolscontaining this grouping can only yield conjugated menthadienescontaining the grouping >C*CMe:CH,, and there can be littledoubt that the several synthetical menthadienes of this type whichhave already been described (compare this vol., p.2154) are pureindividuals.Some time since, Kay and Perkin (Trans., 1906, 89,840) resolveddl-1-methyl-A3-cycZohexene-4-carboxylic acid :into its active constituents, and prepared from the d- and 2-acids,05 and I-pmenthenol(8) and d- and LA3 :8(g)-pmenthadiene :in the usual manner.Taking the d-series as the example, theopticd activity of these substances may be conveniently tabulated :1.b.d-l-Methyl-Aa-cycZohexene-4-carboxylic acid ......... -I- 101 *loEthyl d-1-methylcycZohexenecarboxglate ............ -i- 86.5d-A3-p-Menthonol(8) ...................................... +67*0d-~~:~@)-p-Methadiene .................................... + 98.2It will be observed that, in this case, the menthadiene has a muchhigher rotation than the menthenol from which it is produced bythe elimination of water. Subsequently Fisher and Perkin (Trans.,1908, 93, 1872) resolved dZ-l-methyl-A1-cycZohexene-4-carboxylicacid :and prepared from the active acids, the menthenols (terpineols) andmenthadienes (limonenes) :in the same way.values were observed as the rotations of these substances :Taking, t19 the example, the &series, the following[.ID* Z-l-Methyl-~1-cycZohexene-4-carboxylic acid ..,...:..Ethyl I-methylcyclohexenecarboxylate .................. - 5 2I-A'-p-Menthenol(8) ...................................... - 46'6E-A1:8(D)-p-Menthadiene .................................... - 5'0- 582136 PERKIN : EXPERIMENTS ON THEIt is clear that the relationship between the values for thedifferent substances given in this table are very similar to thoseshown in the preceding table, with the exception of the strikingdifferences in the rotations of the menthadienes. It is well knownthat the active limonenes are somewhat easily racemised withformation of dipentene, and for this reason we were careful toconduct the elimination of water at the ordinary temperature withthe aid of magnesium methyl iodide, and we were surprised to findthat, instead of obtaining a hydrocarbon of higher rotation thanthe menthenol (terpineol) (Llimonene has [a], - 120°), the rotationhad decreased to -5O.No doubt this result was partly due toracemisation, because we were able to show that the substancecontained considerable quantities of dipentene." But it is veryprobable that the low rotation is also due to the hydrocarboncontaining considerable quantities of terpinolene :which is of necessity inactive.shown that, when &A5-m-menthenol(8) ([a]D + 36'7O) :I n the present communication it isis digested with 6 per cent.oxalic acid, the resulting d-A5:8(9)-rn-menthadiene ([a],, + 29.6O) :has a, lower rotation than the menthenol instead of a higher one,as might have been expected from the experiments of Kay andPerkin just referred to. This would seem t o indicate thatthis terpene may contain A5:3(8)-m-rnenthadiene :and the rather high numbers obtained for the refractive power as theresult of preliminary physical measurements seem to support thisview. I f this is the case, one of the asymmetrical carbon atoms ofthe menthenol will have disappeared during the formation of thissubstance by the elimination of water, and this may be theexplanation of the drop in the rotation.* As the presence of dipentene was only proved qualitatively, the statement (Zoc.cit., p.1873: that the hydrocarbon of [u],-5" consisted essentially of dipenteneahould not have been made, and is probably incorrectSYNTHESIS OF THE TERPENES. PART XIV. 2137EXPERIMENTAL.Preparation of I-Methyl-h5-cyclohexene-3-carboxylic A cid andl-Met 12. yl-b4-cycloh exene-Scar6 oxylic A cid.I n the first experiments (Trans., 1909, 95, 1897), the reductionof 5-hydroxy-m-toluic acid was carried out in isoamyl-alcoholicsolution with sodium, but it was subsequently found that the acidis also reduced, although with some difficulty, when its solution inabsolute alcohol* is treated with sodium. The pure acid, inquantities of 50 grams, dissolved in alcohol (1250 grams) wasreduced by the rapid addition of sodium (180 grams) substantiallyin the manner described in detail in the case of the reduction of4-hydroxy-o-toluic acid (Trans., 1909, 95, 1876).After extractingin the usual way, the acid was reduced it second time under thesame conditions, and in all about 1 kilogram of the hydroxy-acidwas worked up, and yielded about 840 grams of reduction product.This acid (which consists for the most part of trans-l-methylcyclo-hexan-5-ol-3-carboxylic acid, compare Zoc. cit., p. l89l), in quantitiesof 50 grams, was mixed with three volumes of fuming hydrobromicacid (sat%urated at Oo), and, after remaining for two days a t theordinary temperature, the liquid was heated on the water-bath fortwo hours, when it separated into two layers. The product wasmixed with water, extracted twice with ether, and, after drying andevaporating, the crude bromo-acid was digested with alcohol (200c.c.) and sulphuric acid (20 c.c.) for four hours on the water-bath,and then left for twenty-four hours.On adding water, the heavybromo-ester was precipitated, and was extracted with ether, theethereal solution was thoroughly washed with water and dilutesodium carbonate, carefully dried, evaporated, and the crudc esterheated to boiling with three volumes of diethylaniline for eighthours. Excess of dilute hydrochloric acid was then added, theunsaturated ester extracted with ether, the ethereal solution washedfirst with dilute hydrochloric acid, and then with sodium carbonate,and distilled in steam.tThe volatile ester was extracted with ether, dried, and distilled,when almost the whole quantity passed over a t 140-150°/100 mm.,and weighed 710 grams.I n order to avoid any possibility of intr%molecular change (compare,p. 2146), the hydrolysis of this ester was* Distillcd over calcium, see footnote, Trans., 1909, 95, 1876.t When all the unsaturated ester had passed over, a considerable amount of aviscid, brown rcsidue remained in the distilling flask. This was extracted withether, and yielded 011 treatment with hydrogen bromide, diethylaniline, etc., exactlyas described above, a further quantity of unsaturated ester, which was added to thatobtained as the result of the first operation.VOL. XCVII. 7 2138 PERKIN: EXPERIMENTS ON THEvery carefully carried out. The ester was gradually mixed withexactly the quantity of alcoholic potassium hydroxide required forhydrolysis, the addition extending over about a week, and afterremaining for ten days in all, at the ordinary temperature, waterwas added, and any non-hydrolysed ester extracted with ether.Theaqueous solution was nearly neutralised with hydrochloric acid,saturated with carbon dioxide, evaporated until quite free fromalcohol, acidified, and the unsaturated acids were extracted withether and distilled, when almost the whole quantity passed over at140-142°/20 mm. It has already been mentioned (p. 2130) thatthis acid is a mixture of l-methyl-A~-cycZohexene-3-carboxylic acidand 1-rnethyl-A4-cycZohexene-3-carboxylic acid, and, in order toseparate these, the oil was digested with much water and excessof freshly precipitated calcium carbonate on the water-bath forseveral hours.After filtering and concentrating considerably, thecalcium salt of the A5-acid separated as a voluminous mass of ballsof needles, and the mother liquor, on concentration, depositedfurther crops of this same salt.After a certain concentration had been reached, the brownmother liquors yielded a crop of calcium salt quite different inappearance from the calcium salt of the A5-acid. This salt wasdecomposed by hydrochloric acid, and the acid extracted, distilledunder diminished pressure, and again made into calcium salt, andby repeating the process of fractional crystallisation, the twocalcium salts were, as far as could be seen, completely separated.dl- 1 -Met h yZ-A5-cyclo h exen e-3-car b ox ylZc A cia?.I n preparing this acid, the pure calcium salt, obtained in theway described in the last section, was decomposed by dilute hydrochloric acid, the oily acid extracted wit.h ether, the ethereal solutionwashed, dried, and evaporated, and the acid distilled underdiminished pressure :0.1957 gave 0.4897 CO, and 0.1561 H,O.C8H1,02 requires C = 68.5 ; H = 8.6 per cent.dl-l-MethyZ-A5-cyclohexene-3-carbozyl~c acid is a rather viscidoil, which distils at 145O/20 mm.or 177-180°/100 mm., and,especially when warm, has a very unpleasant odour. The highlycharacteristic catcium salt appears to have the formula(C,H,lO,)&a,5 H2O :0.1908 of the air-dried salt lost 0.0411 at looo, and yieldedH20 = 21.54 ; Ca= 9.67.0.1332 lost 0.0287 at looo.0.1128 gave 0.0370 CaSO,.Ca=9.65.C=68.2; H=8-8.0.0627 CaSO,.HiO=21-64.(CBH,,02)2Ca,5H20 requires H20 = 22.06 ; C a r 9.8 per centSYNTHESIS OF THE TERPENES. PART XIV. 2139These analyses, for which I am indebted to Dr. A. N. Meldrum,were carried out with three different preparations of the salt,Ethyl dl-l-MethyZ-A5-cyclohexene-3-carboxyZate.-Thk ester wasprepared by warming the acid (15 grams) with alcohol (100 c.c.)and sulphuric acid (6 c.c.) for three hours on the water-bath.Water was then added, the ester extracted with ether, the etherealsolution washed with water and sodium carbonate, dried, evaporated,and the oil distilled under diminished pressure :0.1117 gave 0-2914 CO, and 0-0984 H20.This ester distils a t 141-143°/100 mm., and possesses aC=71.2; H=9-8.CloH,,O2 requires C= 71.4 ; H = 9.5 per cent.penetrating and most unpleasant odour.dl-A5-m-iZfent7~enoZ( 8) and dl-As : 8(9)-m-iWenthadierce.I n preparing dZ-A5-m-menthenol(8), ethyl dZ-l-methyl-A6-cycZo-hexene-3-carboxylate (10 grams) was added to an ethereal solutionof magnesium methyl iodide containing 4 grams of magnesium, allrise of temperature above 25O being checked by cooling with water.After twenty-four hours, the product was decomposed by theaddition of water and then dilute hydrochloric acid, the etherealsolution washed well, dried, and eva.porated, and the residue mixedwith a solution of 2 grams of potassium hydroxide in methyl alcohol,and left for two days in order that any trace of unchanged estermight be removed.The neutral oil was then precipitated by water,extracted, and distilled under diminished pressure :0.1515 gave 0.4319 CO, and 0.1604 H,O.CloHIBO requires C = 77.9 ; H = 11.7 per cent.dl-h5-m-NenthenoZ(8) distils at 115-117O/ 30 mm., and is a viscid,colourless oil, possessing a strong and pleasant odour of terpineoland peppermint. I n order to convert this tertiary alcohol intothe corresponding hydroca,rbon, it was boiled with 6 per cent.aqueous oxalic acid in a reflux apparatus for three hours, thendistilled in steam, and the distillate extracted with ether. Aftercarefully drying over potassium carbonate and removing the etherby evaporation, the residual oil distilled almost completely at172-180°, and two distillations over sodium yielded the pureterpene :C=77-7; H=11*8.0.1192 gave 0.3834 CO, and 0.1282 H,O.CloHl, requires C = 88.2 ; H = 11.8 per cent.dl-A5 :8(g)-ni-Menthndiene distils a t 175-176O/ 765 mm., and hasa pronounced odour of lemons, which, however, is quite distinctfrom that of limonene.C = 87.9 ; H = 11.92140 PERKIN : EXPERIMENTS ON THEResoldon of dl-l-MethyZ-b~-oyclohexene-3-carboxyt?~c Acid.The resolution of this acid into its active modifications may beaccomplished with the aid either of l-menthylamine or of quinine.I.Experiments with 1-Nenthy1amine.-The acid available for thispurpose weighed rather more than 160 grams, and wans dividedinto two parts. The oil (80 grams) was dissolved in 570 C.C.ofN / 10-sodium carbonate, heated to boiling, and mixed with a solutionof pure I-menthylamine hydrochloride (120 grams), when a viscidsyrup separated which soon began to crystallise. After remainingovernight, the aqueous liquid was decanted* from the semi-solidcake; the latter was then washed, and left in contact with porousporcelain until quite hard and dry; it then weighed 105 grams.The crude salt was rubbed with a little pure acetone in a mortar,quickly filtered, and the colourless residue crystallised from acetone,from which it separated in long, slender needles:0-9028, made up to 20 C.C. with alcohol, gave a, -0'48O in a2-dcm. tube at 16O, whence [a], -5'3O.After two more crystallisations, the salt had [a],, - 2 * 8 O , andafter two further crystallisations, [a], - 1*7O, and it thereforeconsists of the Z-menthylamine salt of d-l-methyl-A5-cycZohexene-3-carboxylic acid :0-1108 gave 5.1 C.C.N, at 18O and 760 mm. N=5.3.C,,H3,O2N requires N = 4.7 per cent.By extracting the porous plates which had been employed inpurifying the crude I-menthylamine salt as explained above, andcarefully working up all mother. liquors, about 120 grams of thepure I-menthylamine salt of rotation [a], - 1'7O were ultimatelyobtained, and this was decomposed by dilute sodium hydroxide, andafter the I-menthylamine had been extracted with ether, thealkaline solution was acidified, the active acid extracted with ether,and distilled under diminished pressure :0.1931 gav9 0.4819 CO, and 0.1532 H,O.d-1 -Me t hyZ-A~-cyclohexene-3-car b ox ylic acid boils at 14 5 O / 20 mm.,and has the following rotation :1-0088, made up to 20 C.C.with ethyl acetate, gave a, +3.34O ina 2-dcm. tube at 16O, whence [aJD +33*l0.Ethyl d-l-NethyLA~-cyclohexene-3-carboxyEate was prepared bymixing the acid (40 grams) with alcohol (200 grams) and sulphuricacid (15 c.c.), and, after remaining at the ordinary temperature for* These aqueous liquors yield, on acidifying and extracting with ether, nearlyC=68*1; H=8.8.C8HI2O2 requires C = 68.5 ; H =8*6 per cent.10 grams of acid, which was used in another experimentSYNTHESlS OF THE TERPENES. PART X1V. 2141a week, water was added, and the oily ester extracted with ether.The ethereal solution W;L~ well washed with sodium carbonate,dried, and evaporated.The ester distilled at 140-141°/100 mm.its a mobile liquid with it penetrating and very unpleasant odour:Cl0H1,O2 requires C = 71.4 ; H = 9.5 per cent.0.1856 gave 0.4849 CO, and 0.1626 H,O.0-9520, made up to 20 C.C. with ethyl acetate, gave a, +2*9l0 ina 2-dcm. tube at 16'5O, whence [ulD + 30.5O.11. Experiment with Q&nine.-This met'hod of resolution, whichappears to give good results, was carried out subsequent to theexperiments with Z-menthylamine, just described, and with a com-paratively smail quantity of the dZ-acid. The acid (45 grams) wasdigested in ethyl acetate solution with quinine (125 grams), andthe clear solution left in the ice-chest for eight days, when a con-siderable quantity of a crystalfine crust had separated.This wascollected, twice recrystallised from ethyl acetate, and then decom-posed in the usual manner, when it yielded an acid which distilledat 142O/20 mm., which had the following high rotation:1.0052, made up to 20 C.C. with ethyl acetate, gave a,, + 3'31O ina 2-dcm. tube at 16O, whence [uID + 32'9O.It would have been interesting again to have converted the activeacid into the quinine salt in order to determine whether a higherrotation would have resulted than the +33*Io obtained in the caseof the resolution with 2-menthylamine, but unfortunately the acidwas accidentally lost.C=71*2; H=9*8.d-h5-m-Nenthenol(8) and d-A5 :8(9)-m-Menthadiene.The conversion of ethyl d-1-methyl-A5-cyclohexene-3-carboxylateinto d-A5-m-menthenol(8) was brought about by adding the ester(15 grams) to an ethereal magnesium methyl iodide solution con-taining 6 grams of magnesium, the temperature being kept below2 5 O during mixing and subsequently. After twenty-four hours, theproduct was decomposed by water and hydrochloric acid in theusual manner, the ethereal solution washed well, dried, andevaporated.The residual oil distilled remarkably constantly at115O/30 mm.:0.1438 gave 0.4120 CO, and 0.1551 H,O.0.8810, made up to 20 C.C. with alcohol, gave a, +3.25O in a2-dcm. tube at 16O, whence [a]= +36-7O.d-A5-m-MenthenoZ(8) is a colourless, rather viscid oil, possessing astrong odour of terpineol and ment.hol; even when kept for severalmonths, it showed no signs of crystallising, and an attempt toprepare a crystalline phenylurethane was also unsuccessful.C=78.1; H=12.0.CloH180 requires C = 77.9 ; H = 11.7 per cant2142 PElZKIN : EXPERIMENTS ON THEWhen a drop of sulphuric acid is added to the so1uti.m of thismenthenol in acetic anhydride, a faint pink colour, like dilutepermanganate, is produced, and, on keeping, this gradually becomesmore violet and then fades.The menthenol (5 c.c.) was shakenwith dilute sulphuric acid (350 C.C. of 5 per cent.) for seven dayson the machine, the product distilled in a current of steam, andthe volatile oil extracted and distilled under the ordinary pressure,when almost the whole quantity passed over at about 203*, andevidently consisted of the unchanged menthenol, only traces atmost of the corresponding terpene having been produced.Tliesolution in the steam distillation flask yielded, after saturation withammonium sulphate and extraction with ether, about 0-5 gram ofa syrup, which gradually crystallised and evidently consisted of thecorresponding terpin, but the quantity was too small for purification.When the menthenol was mixed with three volumes of fuminghydrobromic acid (saturated a t Oo), it did not appear to dissolve,and, even after several weeks, no solid additive product had beenformed.d-A5 :*(g)-m-Menthadiene.-This terpene is formed when d-As-m-menthenol(8) (10 grams) is digested with aqueous oxalic acid(100 C.C. of 6 per cent.) in a reflux apparatus for six hours, andthe product distilled in a current of steam.The volatile oil was extracted with ether, the ethereal solutiondried very carefully, evaporated, and the residue distilled, whenalmost the whole passed over below 180°, and, after twice frac-tionating over sodium, the terpene distilled constantly at 175-176O :C,,H,, requires C = 88.2 ; H = 11.8 per cent.0-1142 gave 0.3706 CO, and 0.1248 H,O.0.9124, made up to 20 C.C.with ethyl acetate, gave a, +2*7l0 inC=88.5; H=12.1.a 2-dcm. tube at 17O, whence [aID +29*6O.l-l-Met hyZ-A5-cyclohexene-3-carbosylic A cid, l-A5-m-MenthenoZ(8),and l-A5 :g@)-m-Menthadiene.The mother liquors from the separation of the Z-menthylamineand quinine salts of d-l-methylcydohexene-3-carboxylic acid weredecomposed in the usual manner, and the acid (60 grams), whichdistilled at 142-146O and had [a], -21*4O, was systematicallytreated with Z-menthylamine and quinine, with the result that anacid was ultimately obtained which distilled at 142O/20 mm.andhad the following rotation :1'1009, made up to 20 C.C. in ethyl acetate, gave % -3-41O ina 2-dcm. tube at 15O, whence [a]! -30.9O.It follows therefore that this acid is nearly pure l-l-methyl-A5-cyclohexene-3-carboxylic acid, since the rotation of the correSYNTHESIS OF THE TERPENES. PART XIV. 2143sponding d-acid was found to be + 33*1°. Unfortunately no suitablecrystalline salt of the I-acid was discovered, although experimentswere made with d-bornylamine, d-isomenthylamine, and most ofthe usual alkaloids, and therefore complete separation could notbe carried out.Ethyl 1-1-2ClethyI-A5-cyclo~exene-3-carboxykate, prepared from theacid by means of alcoholic sulphuric acid in the usual manner,distilled at 140-14Z0/ 100 mm.:1.0090, made up to 20 C.C. with ethyl acetate, gave a, -2'78O ina 2-dcm. tube at 15O, whence [aID -27'4O.This ester (27 grams) was added to an ethereal solution ofma.gnesium methyl iodide containing 10 grams of magnesium, and,after remaining overnight, the product was decomposed by dilutehydrochloric acid in the usual manner, and yielded 22 grams ofl-A5-m-menthenoZ(8), which distilled at 104-105°/ 20 mm. :0.1429 gave 0.4083 CO, and 0.1521 H,O.0.9986, made up to 20 C.C. with ethyl acetate, gave a, -32'5O ina 2-dcm. tube at 17O, whence [a], -32'6O.The whole of this menthenol was boiled with dilute oxalic acid(6 per cent.) for three hours, the product distilled in a current ofsteam, and fractionated, first under ordinary conditions, and thentwice over sodium ; the l-A5:8(9)1m-mlenthcGdiene thus obtained dis-tilled at 175-176O, and had a strong odour of lemons :C =77.7 ; H = 11.8.C,,H,,O requires C = 77.9 ; H = 11.7 per cent.0.1056 gave 0.3414 CO, and 0.1135 H,Q.1.0021, made up to 20 C.C.with ethyl acetate, gave a, -2.58O inC=88.1; H=11-9.requires C = 88.2 ; H = 11.8 per cent.a, 2-dcm. tube at 16O, whence [a], -25'3O.Formation of the cis- and trans-lactones of a-Methyl-y-hydroxy-isopropyladipjc Acid by the Oxidation of d- and LA5-m-Men-thenol(8).In carrying out this oxidation, dA5-m-menthenol(8) (5 grams)was suspended in water and powdered ice (1 litre), and then a1 per cent.solution of permanganate (13 grams) added in severalportions, the whole being mechanically shaken after each addition.The slight excess of permanganate was removed by sodium sulphite,and, after heating on the water-bath and filtering, the filtrate andwashings of the manganese precipitate were evaporated to it smallbulk. The brown liquid was then rendered acid wit.h dilutesulphuric acid, and further oxidised on the water-bath withpotassium dichromate and sulphuric acid until action ceased. Theproduct was saturated with ammonium sulphate and repeatedl2144 PERMIN : EXPERIMENTS ON THEextracted with ether on the machine, the ethereal solution was driedand evaporated, and the syrupy residue esterified by boiling with10 per cent.alcoholic sulphuric acid for twelve hours.The ester was extracted with ether, the ethereal solutionthoroughly washed with sodium carbonate, dried and evaporated,and the residue fractionated, when about twethirds distilled at188-190°/20 mm. :0.1228 gave 0.2811 CO, and 0.0975 H,O.1.0021, made up to 20 C.C. with alcohol, gave aD -1-88O in a2-dcm. tube at 1 7 O , whence [a], -18.7O.This ester was digested with dilute hydrochloric acid (3 per cent.)for several hours, evaporated to a small bulk, and the filteredliquid left over solid potassium hydroxide in a vacuum desiccatorfor some weeks, when the gummy mass gradually became semi-solid.It was placed in contact wit>h porous porcelain until quitecolourless, and then several times crystallised from water, when aglistening mass of plates was obtained, which consisted of the Eactoneof trans-a-methyZ-y-hydroxyisopropgZadi+c acid * (compare p.2132) :0.0907 gave 0.1999 CO, and 0.0657 H20.CloH160, requires C = 60.0 ; H = 8.0 per cent.0.1888, dissolved in water and titrated with Y/lO-NaOH,neutralised 9.5 c.c., whereas this amount of a monobasic acid,C,,HI6O4, should neutralise 9-4 C.C. A further 20.5 C.C. of N/10-NaOH (making 30 C.C. in all) were then added, the solution heatedto boiling, and titrated back, when it was found that the totalneutralised was 19.2 C.C. The amount required for neutralisationon the assumption that the lactone-acid, C,,H,,04, had becomedibasic by hydrolysis is 18.8 C.C.The solution was concentrated, acidified, heated to boiling for afew seconds, and allowed to cool; it then rapidly deposited glisteningplates of’the tram-lactone.This lactone melts at 136O, and isreadily soluble in warm water, but rather sparingly so in the cold;the hot saturated solution clouds on cooling, but rapidly crystallisesif the sides of the vessel are rubbed with a gIass rod.It is remarkable that, although obtained from a strongly activeester simply by boiling with dilute hydrochloric acid, this lactune,as also the corresponding cis-lactone (see below), should be quiteinactive.The cis-lactone.-The porous plates, used in the purification ofthe crude mixed lactones, were extracted with ether, the ethereal* This snbstance has been provisionally named tram- in order to distinguish i tfrom the more readily soluble modification of lower melting point which has beencalled cis-.C=62.6; H=8*8.CI2H,,O, requires C = 63-2 ; H = 8.8 per cent.C=60*1; H=7.9SYNTHESIS OF THE TERPENES.PART XIV. 2 14sextract mixed with water and the aqueous mother liquors of thetrans-lactone, and digested with carefully purified animal charcoal.After filtering and evaporating to a small bulk, the solutionwas left over sulphuric acid, when it gradually deposited a massof crystals, which were drained on porous porcelain and fractionallycrystallised from water. I n this way, a separation of the trans-and .cis-lacton es was ultimately accomplished.The cis-Zactone melts at about 102O, is readily soluble in warmwater, and the concentrated solution clouds on cooling, as does thatof the tmns-lactone, and then deposits the lactone in glisteningplates.On one occasion an aqueous solution, which had graduallyconcentrated in the air, deposited the cis-lactone in the form of athick, glistening, prismatic crystal like a crystal of sugar. Theanalysis and titration of this lactone gave the following results :C=60*2; H=8.0. 0.1117 gave 0.2471 CO, and 0*0800 H,O.CIoH,,O4 requires C = 60.0 ; H = 8.0 per cent.0.2090, dissolved in water, neutralised 10.4 C.C. of N / 10-NaOH,whereas this amount of a monobasic acid, C1,,HI6O4, shouldneutralise 10.45 C.C.On boiling with an excess of sodium hydroxide and titratingback, it was found that 20.9 C.C.had been neutralised, which isexactly the amount the lactonic acid, after hydrolysis, shouldiieutralise. The solution was concentrated, acidified, and boiled,when, on cooling, the lactone of melting point 102O crystallised out.An exactly similar series of experiments were made on theoxidation of Z-A5-m-menthenol(8), and as they yielded a similar ester,C,,H,,04, of rotation [aID + 17'4O, which, on hydrolysis, was con-verted into the inactive cis- and trans-lactones of melting points102O and 1 3 6 O respectively, it is hardly necessary to give the detailsof these experiments.dl-l-2llethyZ-A4-cyclohexene-3-carboxyZ~c Acid, dl-A4-m-MenthenoZ(8),and dl-A4 :g@)-m-Menthadiene.The calcium salt of 1-rnethyl-A4-m-cycZohexenecarboxylic acid,obtained as explained on p.2138, was decomposed with dilute hydro-chloric acid, the oily acid extracted with ether, the ethereal solutiondried and evaporated, and the residual viscid oil distilled underdiminished pressure, when the whole quantity passed over at143--146O/20 mm. :0.1256 gave 0-3159 C 0 2 and 0.0991 H20.C8H,,02 requires C=68*6; H=8*6 per cent.The constitution of this acid was proved by its conversion into1-methyl-A3-cycZohexene-3-carboxylic acid when boiled with alkalis,C=68*5; H=8-72146 SYNTHESIS OF THE TERPENEB. PART XIV.an isomeric change which was brought asbout under the followingconditions. The acid (8 grams) w w digested with aqueous potassiumhydroxide (50 C.C.of 30 per cent.) for four hours in a Jena-glassreflux apparatus, the solution was acidified, the acid extracted,dried, and left in contact with 30 C.C. of 8 per cent. alcoholicsulphuric acid at the ordinary temperature for fifteen hours. Waterwas then added, the oil extracted with ether, the ethereal solutionwashed with water, and then shaken with sodium carbonate inorder to dissolve unesterified acid.* When the aqueous extract wasacidified, an oily acid was deposited, which gradually crystallised,and this was collected and left in contact with porous porcelainuntil quite free from oil. The ester which had been producedyielded, on boiling with 30 per cent. potassium hydroxide andsubsequent fractional esterification, a further quantity of the aamesolid (AS) acid, and, when the operation was repeated a third time,a small quantity of solid acid was again obtained.Apparently acondition of equilibrium is established between the A4- and A3-acidsduring this process.The solid acid was dissoIved in sodium carbonate, digested withanimal charcoal, again precipitated, and the colourless, crystallinemass, after remaining in contact with porous porcelain until quitedry, was analysed. Found, C=68.6; H=8.7. Calc., C=68*6;H=8*6 per 'cent.)That this acid is l-methyl-A3-cycZohexene-3-carboxylic acid wasproved by the melting point, 58-60°, and by the fact that, whenmixed with some of this acid, which had been prepared by Perkinand Tattersall (Trans., 1905, 87, 1094) by another process, themixture melted at the same temperature as the components.Theidentity was further proved by converting the acid into the di-bromide (m. p. 165O) and hydrobromide (m. p. 108-109°; comparethis vol., p. 2152).Ethyl l-MethyZ-A4-cycl ohexeme-3-curb oxytat e.-This ester wasprepared by digesting the acid (10 grams) with 6 per cent. alcoholicsulphuric acid (50 c.c.) for three hours, and, after the addition ofwater, extracting with ether in the usual way. It distilled at142-144°/100 mm., and had a most unpleasant and penetratingodour.This ester (10 grams) was added to an ethereal solution ofmagnesium methyl iodide, containing 4 grams of magnesium, and,after remaining for twenty-four hours, water was added and the* This method of separation depends on the fact that l-methyl-A3-cyclohexene-carboxylic acid is an a@-unsaturated acid, and is esterified with greater difficulty than1-methyl-~4-cyclohexenecarboxylic acid, which contains the ethylene linking in the&-position. The value of this process of separation will be discussed in detail ina subsequent communicationSYNTHESIS OF TEIE TERPENES. PART XV. 2147product distilled in a current of steam. The distillate wasextracted with ether, the ethereal solution dried and evaporated,and the A4-m-nzenthenoZ(8) didilled under diminished pressure,when it passed over at 115--117°/30 mm. as a viscid oil which hada strong odour of terpineol and menthol :0.1145 gave 0.3267 CO, and 0-1224 H,O.Cl,-,H,,O requires C = 77.9 ; H = 11.7 per cent.A4 :a(s)-rn-nlenthn~~ene was obtained from A4-m-menthenol(8) byboiling with 6 per cent. aqueous oxalic acid exactly as describedin the preparation of A5:8(9)-m-menthadiene (p. 2139). It waspurified by distillation in a current of steam and then twice oversodium, and boiled at 175--177"/757 mm.:0.1347 gave 0.3358 CO, and 0.1452 R,O.C,,H,, requires C=88.2; H=11.8 per cent.The amount of these substances available was very small, and anattempt will be made to find a more satisfactory method for thepreparation of l-methyl-A4-cycZohexene-3-carboxylic acid in order, ifpossible, to prepare the active menthenols and menthadienes derivedfrom it..C=77*8; H=11.3.C=88-2; H=11*9.The author is indebted to Dr. A. N. Meldrum and Mr. L. Bensonfor preparing the l-methylcycZohexan-5-ol--3-carboxylic acid requiredfor this investigation, and to Miss B. Dobson for carrying out mostof the analyses and determinations of refractive power.The author also wishes to state that much of the heavy expenseof this research was met by a grant from the Research Fund ofthe Royal Society.THE UNIVERSITY,M ANCHESTER

ISSN:0368-1645    

DOI:10.1039/CT9109702129

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

SYNTHESIS OF TEIE TERPENES. PART XV. 2147By BERNARD DUNSTAN WILKINSON LUFF (1851 Exhibition Scholar)and WILLIAM HENRY PERKIN, jun.IN a previous communication (Trans., 1905, 87, loss), it wasshown that 1 -met,hylcy clohexan-3-c arboxylic acid (hexahydro-m- toluicacid) is readily converted by bromination and subsequen2148 LUFF AND PERKIN: EXPERIMENTS ON THEelimination of hydrogen bromide into a mixture of 1-methyl-A3- and-A2-cy clohexene-3-carboxylic acids :-+ C H M e < ~ ~ ~ ~ ~ ~ ~ ~ > C H and CHMe<CH, CH:C(CO,H)\ CH,,4H,.A3- A2-The separation of acids of such similar constitution proved to bea matter of much difficulty, and, as a result, only small quantitiesof the pure isomerides were available for subsequent investigation.l-Methyl-A3-cycZohexene-3-carboxylic acid (ni.p. 58-60°) wasconverted into its ester, and this, by the action of magnesium methyliodide, into A3-m-menthenol(8), a substance which, when left iiicontact with a large excess of magnesium methyl iodide, loses waterwith formation of A3 :8(Q)-m-menthadiene :I n a similar manner, A2-mmenthenol(8) and Az:8(g)-m-menthadienewere prepared from ethyl l-methyl-A2-cycZohexene-3-carboxylate :CH:C(CMe,*OH)C'H M e < ~ ~ ~ c ( " o ~ ~ ~ > C H 2 -+ CHMe< CH,--- C*,>CH2It will be observed that A3 :8(9)- and AZ:8(9)-m-menthadiene containconjugated double linkings, and investigation showed that theseterpenes do, in fact, show the characteristic behaviour of substanceswhich contain such groupings; they are, for example, only able tocombine with two atoms of bromine or with one molecule of hydrogenchloride (compare Trans., 1905, 87, 641, 667, and 1068).A short time since (this vol., p.1428), Perkin and Wallach madea special study of another synthetical terpene which contains con-jugated double linkings, namely, A3 :8(9)-pmethadiene :and observed that this terpene had a higher boiling point, density,and refractive index than terpenes, such it5 limonene, which do notcontain conjugated double linkings (compare p. 2154), and it seemeddesirable to investigate the physical constants of other terpenes ofsimilar structure in order to determine whether this behaviour isa general one. The difficulty in preparing the m-menthadienesalready mentioned in amount sufficient for accurate physicalmeasurement is due to the difficulty in obtaining the l-methylSYNTHESIS OF THE TERPENES.PART SV. 2149cy clohexene-3-carboxylic acids in any considerable quantity by theprocess described at the beginning of this paper. An attempt wastherefore made to devise a new method for the preparation of theseacids, and this has been successful in the case of the A3-acid (m. p.Quite recently (this vol., p. 1760), it was pointed out that 1-methyl-cyclohexan-4-one reacts readily with sodamide and carbon dioxide,with the formation of l-methylcycZohexan-4-one-3-carboxylic acid :58-60').and w0 have found that, under the conditions described in thepresent communication (p. 2150), the yield directly obtained is 50per cent.of that theoretically possible.* When this acid isreduced with sodium amalgam, it yields 1-methylcycZohexan4-01-3-carboxylic acid, and this, on distillation, is almost quantitativelyconverted into l-methyl-A~-cycZohexene-3-carboxylic acid (m. p.58-60') :This method of preparation is still laborious, but it is much lessso than the original method, and it has now been found possiblet o prepare nearly 200 grams of the pure acid, of which parthas been used in the present research, and the remainder isbeing resolved into its active constituents with the object ofpreparing and carefully investigating the corresponding activementhenols and menthadienes. I n possession of sufficientmaterial, we have now very carefully determined the physicalproperties of h3-m-menthenol(8) and A3:8(9)-m-menthadiene (seepp.2153, 2154).We find that the values of A3-m-menthenol(8) show a remarkablesimilarity to those of A3-pinenthenol(S), and, when these numbersare compared with those of terpineol, it is seen that the proximity ofthe double linking to the *CMe,-OH group causes a fall of boilingpoint, density, and refractive index. Similarly, the values forA3 :8(9)-m-menthadiene are very like those of A3 :8(g)-p-menthadiene,but, when these values are compared with those of limonene, it isseen that the presence of conjugated linkings causes a considerablerise in boiling point, density, and refractive index.A similar study of A2-m-menthenol(8) and of A2 :*(g)-m-menthadieneis in progress, and the results will shortly be ready for publication.* It is actually considerably more, because a good deal of ketone is recovered un-changed and may be employed in a subsequent preparation2150 LUFF AND PERKIN: EXPERIMENTS ON THEEXPERIMENTAL.Preparation of 1-Methylcyclohexan-4-one-3-carbozyZic Acid and1 -Met hyZcyclohexalz-4-ol-3-car~ oxylic A cid.I n order to obtain the large quantities of the above ketonic acidwhich we required for this research, we decided, as the result of along series of comparative experiments, to modify the method ofpreparation originally employed (this vol., p.1766) in the followingway.1-MethylcycZohexan-4-one (100 grams) is dissolved in dry ether(1 litre) in a three-necked flask fitted with a reflux condenser andmechanical stirrer, powdered sodamide (40 grams) is then addedin lots of 10 grams, and the stirrer set in motion, when a rapidevolution of ammonia takes place.After the reaction has subsided,the mixture is heated on the steam-bath for an hour, allowed tocool, and then a stream of dry carbon dioxide passed through a widetube so as to avoid stoppage, the whole being vigorously stirredduring the operation. This causes a rise of temperature, and thepassage of the gas is continued until the whole has cooled downto that of the atmosphere. The contents of the flask are thenwashed into a separating funnel with ice water, well agitated, theaqueous layer run off, and the ethereal solution kept in order torecover the unchanged ketone which it contains. The aqueoussolution is acidified, extracted with ether, the ethereal solutionshaken with sodium carbonate, and, after separating, the alkalineextract is cautiously treated with hydrochloric acid until the oilyimpurity has been completely precipitated and the crystalline acidcommences to separate.After filtering, the filtrate is acidifiedwith hydrochloric acid, and the colourless, crystalline precipitate ofnearly pure l-methylcycZohexan-4-one3-carboxylic acid collected,washed, and drained on porous porcelain. The yield is 45-50grams. The ethereal layer, containing the unchanged ketone, iswashed, evaporated, and the residue distilled in a current of steamin order to separate it from a quantity of the bicyclic condensationproduct described on p.2155. The ketone is extracted from thedistillate, and, after one fractionation, is sufficiently pure for afurther operation.I n preparing l-methylcycZohexan-4-ol-3-carboxylic acid, 1-methyl-c~cZohexan4-one3-carboxylic acid, in quantities of 10 grams, isdissolved in sodium carbonate, the solution made up to 600 C.C. withwater, and treated, in a bottle fitted with a mechanical stirrer,with freshly prepared sodium amalgam (500 grams), which is addedin three lots. Reduction takes place very slowly at the ordinarytemperature, and the most suitable temperature appears to bSYNTHESlS OF THE TERPENES. PART XV. 215150-60°, which is maintained during the whole operation by placingthe bottle in a trough of hot water ; it is also necessary to neutralisethe alkali produced by hydrochloric acid, which is dropped in insuch a way that the liquid is always faintly alkaline.The product is acidified with hydrochloric acid, saturated withsalt, and extracted at least five times with much ether; the etherealextract is dried over anhydrous sodium sulphate, and evaporated,when a syrup remains which soon becomes semi-solid, and thepurification and properties of which have already been described(this vol., p.1770).l-Methyl-A3-cyclohexene-3-carboxy~~c Acid.This acid has been prepared in large quantities in the followingmanner. Crude l-methylcycZohexan-4-ol-3-carboxylic acid, obtainedas described in the last section, is transferred to a distilling flaskwith a rather long neck, and heated in a metal-bath, wheneffervescence soon occurs, due to the decomposition of some unchangedketonic acid.In a short time, water commences to be eliminated,and as soon as this and the ketone have ceased to pass over, theresidue is distilled under diminished pressure, when almost thewhole passes over at 155-160°/25 mm., and solidifies on cooling.The mass is left in contact with porous porcelain until free fromtraces of oily impurity; it then melts at about 57-58O, and isalmost pure 1-methyl-A3-cycZohexene3-carboxylic acid. The yield isapproximately 10 grams from 50 grams of the crude hydroxy-acid.For analysis, the substance was crystallised from formic acid, fromwhich it separates in pearly plates, melting at 60°. (Found, C = 68.4 ;H=8.6.Careful comparison has shown that this acid is identicalwith the " Al-tetrahydro-m-toluic acid " obtained by Perkin andTattersall (Trans., 1905, 87, 1092) by quite a different process.Ethyl 1-methyl-A3-cycZohexene-3-carboxylate, which has already beendescribed (Zoc.cit., p. 1094), wm prepared in quantity by leavingthe pure acid (50 grams) in contact with alcohol (300 c.c.) andsulphuric acid (30 c.c.) at the ordinary temperature for two days,and then heating on the water-bath for two hours.After extracting in the usual way, it distilled at 146--148O/100 mm.It was noticed that the aS-unsaturated acid is esterified withsome difficulty at the ordinary temperature. Thus, for example,the mixture just mentioned, after being kept for twenty-four hours,contained a large amount of acid, and, even after forty-eight hours,a considerable quantity of unesterified acid was still present.Thisbehaviour has been utilised for separating the acid from 'theCalc., C=68*6; H=8*6 per cent.21 52 LUFF AND PERKIN: EXPERIMENTS ON THEisomeric By-acid by a process of fractional esterification (comparethis vol., p. 2146).ethulcvclohexarte-3-curb oxulic A cid.I n order to prepare this characteristic derivative, pure I-methyl-A3-cyclohexene-3-carboxylic acid, dissolved in a little dry chloroform,is cooled to -5O, and mixed with a few drops of dry bromine. Atthis low temperature, no action seems to take place, but, if allowedto rise to 15O, the colour of the bromine suddenly disappears, andthen the addition of the theoretical amount takes place rapidly at Oo.During the operation a good deal of the dibromo-acid crystallisesout, and the remainder is obtained by allowing the chloroform toevaporate.It is sparingly soluble in cold formic acid, and not veryreadily so on boiling, and separates in colourless, glistening leaflets :C8H,,0,Br2 requires Br = 53.3 per cent.0.3166 gave 0-3945 AgBr. Br=53-0.When rapidly heated, 3 : 4-dibromo-1-methylcyclohexane-3-carb-oxylic acid melts at 165O.It dissolves readily in sodium carbonate, and the solution, onboiling, does not cloud with separation of the bromohydrocarbon,aa sometimes happens in the case of afi-dibromo-acids of similarconstitution. After boiling for ten minutes with a large excess ofsodium carbonate, the solution deposited, on acidifying, a solidacid, which crystallised well from formic acid, melted at 148-150°,and appears to be a bromohydroxy-acid of the formulaC,H,,Br(OH)*C02H (Found, Br = 32.7.Calc., Br = 33*2), but itwas not further investigated.The aqueous filtrate from this acid contains a considerablequantity of a syrupy acid which may be extracted with ether, andis probably the corresponding dihydroxy-acid.4-Bromo-1 -m e t hylc yclohexane-3-curb ox ylic A cid,1-Methyl-A3-cyclohexene-3-carboxylic acid dissolves readily infuming hydrobromic acid (saturated at Oo), and, on keeping, butmore rapidly if slowly warmed to 70°, a syrup separates, whichgradually crystallises. After washing with water and draining onporous porcelain, the substance was dissolved in a little warm formicacid, in which it is very readily soluble, and from which it separatesin needles, melting at 107-109°SYNTHESIS OF THE TERPENES. PART XV, 21530.1544 gave 0.1314 AgBr.Br=36-2.C8H,,0,Br requires Br = 36.2 per cent.This bromo-acid is decomposed by boiling with sodium carbonate,and the solution, on acidifying, deposits a crystalline precipitateof 1-methyl-A3-cycZohexene-3-carboxylic acid.A3-m-Nenthenol(8) and A3 :8(9)-m-Menthadiene.The conversion of ethyl 1-methyl-A~-cycZohexen-3-carboxylate intoA3-mmenthenol(8) was carried out by adding the ester (13 grams)to an ethereal solution of magnesium methyl iodide, containing6.5 grams of magnesium. After fifty hours, the product was decom-posed by water (compare footnote, p. 2154), distilled in a current ofsteam, the distillate extracted with ether, and the ethereal solutiondried, evaporated, and the residue distilled under diminishedpressure.The whole quantity passed over a t 114--117O/35 mm.,and, after redistillation at 115O/35 mm., as a colourless, pleasantsmelling, rather viscid liquid, and the yield of this pure A3-m-men-thenol(8) was almost quantitative. The first time this substancewas prepared (Trans., 1905, 87, llOO), it was noticed that much ofthe ethyl ester remained unattacked; this was due to the fact thatthe amount of magnesium (2.9 grams to 10 grams of ester) wastoo small, and the length of contact (twenty-four hours) was also notsufficient. Under the conditions mentioned above, only a trace ofethyl ester remained unchanged, and this was removed, beforefractionation, by hydrolysis with a little methyl-alcoholic potassiumhydroxide in the usual manner.The phenylurethane of A3-m-menthenol(8) was prepared by leavingthe menthenol with an equal volume of phenylcarbimide for threedays.The mass was drained on porous porcelain, and thencrystallised from 80 per cent. methyl alcohol, from which itseparated in colourless needles, melting at 130° :0.1057 gave 5.0 C.C. N, at 21° and 758 mm.C&H,,O,,N requires N = 5.1 per cent.The physical properties of A3-m-menthenol(8) have been carefullydetermined, and found to be very similar to those of A3-p-men-thenol(8) (compare Perkin and Wallach, this vol., p. 1435), as thefollowing comparison shows :N=5.3.B p.............................. 102"/14 nim. 11 5"/35 iiim.d. 20"/20" ........................ 0.9268 0'9'210M ................................. 47.10 (calc. 47-16} 47'23M. p. of the phenylurethane 13U' 128"VOL. XCVII. 7 B?tu ................................. 1'4ii)S 1'4762154 LUFF AND PERKIN : EXPERIMENTS ON THEA3-m-Menthenol(8) has, so far, not crystallised, whereasA3-p-menthenol(8) is solid, and melts at 39O.A3:*(9)-m-Menthadiene has been prepared in two different ways,namely, (1) by the direct action of magnesium methyl iodide onethyl l-methyl-A3-cycZohexene-3-carboxylate, and (2) by the action ofaqueous oxalic acid on A3-mmenthenol(8).1. Ethyl l-methyl-A3-cycZohexene-3-carboxylate (25 grams) wasadded to an ethereal solution of magnesium methyl iodide (10 gramsof magnesium), and, after forty-eight hours, the product was decom-posed by dilute hydyochloric acid* and distilled in it current ofsteam.The ethereal extract of the distillate was dried, evaporated,and the product fractionated, when almost the whole passed over at178-183O/ 750 mm., the amount of As-m-menthenol remaining beingvery small.The A3:8(9)-nzrmenthadiene was then distilled three times oversodium, when it boiled constantly at 181-182°/760 mm.2. A3-m-Menthenol(8) was boiled for three hours with 6 percent. aqueous oxalic acid, and the product distilled in a current ofsteam. After extracting in the usual manner, it was found thatthe conversion into A3 : *@)-m-menthadiene had been almostquantitative, and that this terpene again distilled at 181-18Z0/760 mm.The physical properties of both the specimens of thisterpene were carefully determined, and found to be practicallyidentical, and it is interesting to tabulate these (I) with those ofthe two following terpenes :CH2*C(CMe: CH2)>cH,CH2 c=, I. A3 : s(g)-m-Menthadiene, CHMe<11. A3 's(g)-p-Mcnthadiene, C H 2 - C H > ~ e ~ ~ e : ~ ~ , .111. Limonene, CMeqCH2. CH-CH2>CH*CMe:CH2. CH,I. 11. ur.B. p. ............... 1 8 1-1 82" 184-185" 175-1 76"d. 20"/20" ......... 0-8609 0'8580 0'8460no .................. 1 *4975 1 '4924 1.4746M. .................. 46'3 46'02 45'28(C1,,H1&*= 45'24.)* The curious observation (conipare p. 2163) has been made in this and in othercases, that the product of the action of maplnzsium methyl iodide on the ester of amethylcyclohexenecarboxylic acid, containing the double linking in the afi-position,yields the menthenol when it is treated with water, but the conjugated menthadienewhen i t is decomposed by dilute hydyochloric acid.In cases where the doubleliuking is in any other position, this difference has not been observed, and theproduct has always been the menthenol whether the decomposition has beon carriedout simply by water or by the addition of liyclrochloric acidSYNTHESIS OF THE TERPENES. PART XV. 2155Cases 1 and I1 prove again that the effect of conjugation is toraise the boiling point,, density, and refractive index above thoseof limonene.I n possession of considerable quantities of pureA3: *(g)-m-menthadiene, the authors have again investigated itsbehaviour with bromine and with hydrogen chloride (compareTrans., 1905, 87, 1101). The freshly distilled terpene (3.3588grams) was dissolved in twice its volume of chloroform, cooled to- 15*, and titrated with a solution of bromine in chloroform (1 in 3),when 12.6 C.C. were decolorised, the end-point being quite sharp,but a little hydrogen bromide was produced. This amount ofterpene had therefore decolorised 4.2 grams of bromine, whereasthe amount required for the formation of the tetrabromide,C10H16Br4, is 8.0, and for the dibromide, C10H16Br2, 4.0 grams. Itis clear therefore, as had previously been pointed out, that this andother conjugated terpenes are only capable of combining with twoatoms of bromine.I n investigating the action of hydrogen chloride, about 5 C.C.ofthe terpene were cooled to -15O, and a, current of dry hydrogenchloride passed for one hour; the almost colourless product was leftfor two days, then placed over potassium hydroxide in a, vacuumdesiccator for several hours, and analysed :0.1773 gave 0.1390 AgCl. C1= 19-4.CloH,,,HC1 requires C1= 20.6 per cent.It is therefore obvious that this conjugated menthadiene is onlycapable of combining with one molecule of hydrogen chloride.1 : 4~-Dim~ethyl-3-cyclohexy~~denecyclohexan-4-one,Considerable quantities of this ketone, as well as higher con-densation products of l-methyIcyc7ohexan-4-one, are produced duringt.he action of sodamide and carbon dioxide (p.2150). After extract-ing the sodium salt of l-met~hylcycZohexan-4-one-3-carboxylic acidwith water, the ethereal solution is evaporated, and the residuedistilled in a current of steam, when unchanged methylcyclo-hexanone passes over, and the condensation products remain in thedistilling flask. The dark brown oil is extracted with ether, theethereal solution dried and evaporated, and the residue fractionatedunder diminished pressure, when a quantity of a pale yellow oilis obtained, which distils at 173--174O/25 mm., and has a pronouncedfruity odour :0-1971 gave 0.5862 CO, and 0.1924 H,O. C =81.1; H = 10.8.Cl,H,O requires C = 81.5 ; H = 10.7 per cent.d 20°/200=0*9728; n=1'4986; M=62.1 (calc., 62.4)'7 ~ 2156 FORSTER AND ZJMMERLI !This condensation product is very similar to the (‘ bicyclic ketone,’’C,,HzzO, which Wallach (Ber., 1896, 29, 1595) obtained by thoaction of hydrogen chloride on 1-methylcyclohexan-3-one.When a drop of sulphuric acid is added to the solution of theketone in acetic anhydride, an intense crimson coloration is produced,which persists for a, long time. The oxime was obtained by addingan aqueous solution of hydroxylamine hydrochloride to an alcoholicsolution of the ketone, when, almost immediately, a, crystallineprecipitate began to form, which, after crystallisation from alcohol,was obtained in glistening needles, melting at 160O:0.463 gave 26.4 C.C. N, at 18O and 758 mm. N=6*7.C14Hz,0N requires N = 6.3 per cent.THE UNIVERSITY,MANOHESTER

ISSN:0368-1645    

DOI:10.1039/CT9109702147

出版商:RSC    

年代:1910

数据来源: RSC