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Proceedings of the Chemical Society, Vol. 13, No. 181 |
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Proceedings of the Chemical Society, London,
Volume 13,
Issue 181,
1897,
Page 129-140
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摘要:
bsued 16/6/1897. PROCEEDINGS OF THE CHEMICAL SOCIETY. XDITZB BY THE SECRETARIES. No. 181. Session 1896-7. June 3rd, 1897. Professor Dewnr, F.R.S., President, in the Chair, Messrs. Thomas Tickle and Thomas Girtin wero formally admitted Fellows of the Society. Certificates were read for the first time in favour of Messrs. John Ball, Ph.D., lS, Redshaw Street, Derby ; Alec Alfred Beadle, Beadon- well, Belvedere, Kent ; James Walter Horseman, 5, South Parade, Chelsea, S.W. ; Charles John Jodrell Mansford, B.A., Lady Manners Grammar School, Bakewell, Notts. ; Thomas Southern, jun., 2, Cherry Mount, The Cliff, Higher Broughton, Manchester ; Francis Samuel Young, M.A., Mill Hill School, N.W. Of the following papers, those marked * were read :-“67. “On the thermal phenomena attending the change of rotatory power of freshly-prepared solutions of certain carbohydrates ; with some remarks on the cause of multirotation.” By Horace T.Brown, F.R.S.,and Spencer Pickering, F.R.S. During an investigation of the thermal changes attending hydrolysis iinder enzyme action, whose results are described in t,he next paper, it became necessary to enquire whether the change in the multi-rotrt- tion of certain sugars is attended with any heat disturbance, as it is now well known that, at any rate, dextrose and maltose are liberated by hydrolysis in the ‘‘ birotatory ” state. The authors find that the changes of rotation experienced by dextrose, lzvulose, and milk-sugar in passing from the optically unstable a-to the optically stable p-form, are accompanied by distinct thermal effects which, although taking place .;lowly iiz the solutions under ordinar7 conditions, can be pro- diwed, like optical stability, almost) instantaneously by the addition of trwes of an alkali.A full account is given of the apparatus employed, of the method of experiment, and the natnre of the corrections to be applied. In the cases of dextrose and milk-sugar, there is a liberation of heat accompanying the change of rotatory power ;wit.h lzevulose there is a very decided absorption ; and with maltose no thermal dis- tiwlmnce is recognisable. The following are tlie values-obtained. Per gram of PCYgram. sngar. ino1ec.nlc. Dextrose ........ +O*%S8cd. + 106 cal.Lzvnlose ......... -4.64 cd. -835 cal. Milk-sugRr.. ....... +0.19 cal. + 34 cal. Maltose ............ 0 0 The authors discuss the various explanations which have been given from time to time to account for multipot%tion, and consider that their experiments favour the view that it is conditioned by chemical rather than physical causes, and that Fischer is probably correct in his sug- gestion that dextrose, for instance, in passing from the optically unstable to the optically stable modification in solution, passes from the aldehyde, C,H,,O,, to the heptahydric alcohol, C,H,,07. They believe, however, that the analogy which Fischer suggested, of the change of a 1act.oiie into its acid, is less close than that afforded by the gradual change of acetic aldehyde, in contact with water, into ethyl- iclene glycol where the CHO group becomes CH(HO),.*68. i‘On the thermo-chemistry of carbohydrate-hydrolysis: (I) The hydrolysis of starch by vegetable and animal diastase. (11) The hydrolysis of cane-sugar by invertase.” By Horace T. Brown, F.R.S., and Spencer Pickering, F.R.S, The attempts made to determine the thermal effects of hydrolysis have hitherto beenconfined to indirect methods, based on the heats of coni-bustion of the hydrolysable substance and its products. Such methods, it is shown, cannot give results of any real value, as the thermal changes to be measured are considerably within the experimental errors of the combustion values. The paper describes the results obtained by direct measurement of the heats of hydrolysis of starch and of cane-sugar.Lintner’s soluble- starch was for the most part used, as there are certain mechanical difficulties in employing starch-paste in the calorimeter, owing to its viscidity. The hydrolytic agents used for starch were (1) malt diastase, (2) pancreatic-diastase, (3) Taka-diastase, and (4)saliva. With malt diastase, the heat of hydrolysis was found to be + 2.60 calories per gram of amylin converted into maltose. The amount of heat is proportional to the water fixed, and is independent of the molecular compIexity of the amylin attacked. The breaking down of the starch-molecule prior to hydrolysis does not appear to be attended with any thermal disturbance.With pancreatic-diastase, the heat liberated per gram of amylin hydrolysed amounts to + 1.8 cal., a value sensibly less than that deduced from the action of the malt-diastase. With Taka-diastase, the heat disturbance is still less than with the other two agents. The possible causes of these differences are discussed. Cane-sugar was hydrolysed with invertase, and was found to give i~ thermal effect of + 11.21 cal. per gram of cane-sugar inverted when the products were in the optically stable /3-form, and 13.34 cal. per gram at the moment of liberation of the products, i.e., when they are in their ‘‘ birotatory ” or optically unstable form. It is the larger number which correctly represents the heat of hydrolysis of cane-sugar. DISCUSSION.Mr. PICKERINGmade a statement as to some additional work which had been done in connection with the subject since the paper had been sent in to the Society. The nature of the change produced by water on the sugars has been suggested to be the conversion of the aldehyde groups present into aldehydrol groups, an action which there is every reason to believe occurs in the case of acetic aldehyde itself, and experi- ments were, therefore, made to ascertain whether the action in the case of aldehyde exhibits the same peculiarity as in the case of the sugars, of being greatly accelerated by the addition of alkali. This was found to be the case, and the analogy of the two actions is, therefore, greatly strengthened. In both cases, also, the ammonia combines directly with the substance-the sugar or the aldehyde-with evolution of heat, but the results with aldehyde show that the formation of these coin- pounds is not the cause of the hydrating effect of the alkali, for, nlthough the alkali renders the hydration instantaneons, the formation of the aldehyde ammonia proceeds gradually, and with the quantities used is complete only after seven or eight minutes, the action evidently being independent of, and posterior to, the hydration.The accelerative action of the alkali on the hydration is probably due to its increasing the number of free molecules of water present in the liquid, by forming continually dissociating compounds such as NH,OH, NaOHzH,O, kc., and :t free molecule of water would be a far more active hydrating agent than the average water aggregate constituting the bulk of liquid.Mr. A. R. LINGsaid he was under the impression that BQchamp, and subsequently Tollens, were the first to point out that the multirotation of carbohydrates was correlated with thermic phenomena, but neither had made the exact measurements now presented. He wished to know if the authors had observed any change in the density of the solutions before and after the transition from the abnormal to the normal rotatory power. Dr. KIPPINGsaid that although it seems to be generally understood that the phenomenon of birotation is not the result of a purely physical change, the assumption that it is due to the mere hydration of the aldehyde group might be objected to as involving the apparent contra-diction that a very considerable change in specific rotation is brought about, not by increasing or diminishing the number of asymmetric carbon atoms in the molecule, but by merely altering to a comparatively slight extent the asymmetry of the groups already present,.Important data in support of the chemical or hydration explanation of birotation were afforded, however, by some experiments made at the suggestion of Emil Fischer, as it had been found (Jacobi, Ann,, 1892, 272, 170) that the rapidity of the fornlation of a hydrazone from a sugar which showed birotation varied with the time which had elapsed since the sugar had been dissolved. Mr, HORACE in reply, siiicl that he believed Mr.Ling was BROWN, mistaken in his statement that Bechamp or Tollens had done anything to correlate multirotation with thermic phenomena. So far as he knew, the only previous work on this subject was that of Berthelot, who had indirectly determined, for the solid state, the heats of transforma- tion of a-and y-dextrose into the /3 form. Up to the present time, the authors had been unable to discover any change of density in solutions of multirotatory sugars. Whilst fully admitting the force of Dr. Kipping’s objections, it must be remembered that, so fiw as our knowledge goes at present, we are not justified in denying that coniparatively small changes in the asymmetry of groups may be attended with a considerable change in rotatory power.The experiments of Jacobi are fully described in the paper, and we regarded by the authors as strongly confirmatory of their views. %9. (( Optical inversion of camphor.” By Frederic Stanley Kipping Ph,D., D.Sc., and William Jackson Pope. It was shown some time ago (Trans.,1893,63, 548) that two optically active isomeric sulphonic chlorides of the composition C‘l,H,,O*SO,C1 could be obtained from the procluct of tho action of ariliydrosulphuric acid on ordinary d-camphor; these two compounds differed only in 133 optical and crystallographic properties, and it was therefore concluded that they must be regarded as optical antipodes. This conclusion has been fully borne out by some recent work, inthe course of which the properties of a coiisiderable number of inactive compounds, prepared from inactive cainphorsulphonic chloride, have been examined; it has thus been proved beyond doubt that these inactive compounds are composed of equal quantities of two enantio- mvrphous camphor derivatives, and that, consequently, either before or during sulphonation, the original d-camphor must be partly converted into its optical antipodes, I-camphor.In the present paper, particular attention is drawn to this interesting case of optical inversion, as the intramolecular changes which take place appear to be entirely different from those which occur in the case of substances which contain asymmetric carbon atoms as constituents of an open chain. Although the constitution of camphor is still a matter for further investigation, it is now almost universally admitted that the skeleton of this substance consists of two closed carbon chains having two or more carbon atoms in common; further, a study of the chemical and optical properties of the various modifications of camphoric acid leads to the conclusion that each of the carboxyl groups in cam- phoric acid is united to an asymmetric carbon atom (Aschan, Actcc Xoc.Scient., 21, [ 5 1, 1-227). Admitting these two apparently well-founded assumptions, t.he conversion of d-into I-camphor requires that part of one of the closed chains, for example, the group --UH,-PO-, should change places with the two atoms a and b as shown in the following scheme. As this view is brtsecl upoii tho two assuiuptions already stated, the insttcr is discassed from other standpoints, and it is finally concluded that the changes which occur in the optical inversion of C;L~I~~J~OL'arc: of the nature already suggested."70. '' Derivatives of camphoric acid. Bart If. Optically inactive derivatives." By F. Stanley Kipping, Ph.D,, B.Sc,, and William Jackson Pope. The optically inactive, extermally compensated derivatives of cam-phoric acid described in this paper were prepared hitially from ordinary 134 J-camphor by first converting this substance into the approximately inactive caniphorsulphonic chloride (Trans., 1893, 63,547) or camphor- sulphonic bromide (Trans., 1895, 6'7, 354), from which inactive rr-chlorocamphor and racemic a-bromocamphor were then obtained by the method previously employed (Trans., 1895, 67, 371).Inccctive a-c~Zo~*occcinp?~oi.ic c~cicl, Cl,H1,U104, prepared by oxidising inactive r-chlorocamphor with nitric acid, crystallises in flat plates or in prisms, and melts at about 194-195' ; its aiahydvicle, C,,H,,ClO,, melts at 193-194". Inccctiue rr-b~omo~unap?~oP.iC c~cicl, C,,H~,,BrO,, obtained in a similar manner from racemic .rr-bromocamphor, is a crystalline powder melting at about 203-204' ; its c~~zlqcliide,Ul,H1,BrO,, melts at 155-156". These four externally compensated substances resemble the corre- sponding active compounds (Kipping, Trans., 1896,69, 9 13 ; Lapworth and Kipping, Trans., 1897, 71,1) very closely in general properties, but the inactive anhydrides are not easily obtainable in large crystals, active tr-bromocamphoric anhydride forms large, monosymmetric crystals, measurements of which are given.Inactive trans-a-camphanic acid, C,,H,,O,, is obtained by the deconr- position of the sodium salt of rr-chloro- or rr-bromocamphoric acid. It crystallises from water in monosymmetric prisms, which contain one molecule of water of crystallisation, but from ethylic acetate it is deposited in anhydrous, monosymmetric, six-sided plates ; the anhydrous crystals change in crystalline form at about 130' and melt at 164-165", namely, at the same temperature as the anhydrous active acid. Active trans-rr-camphanic acid (Trans., 1896, 69, 929) has been further investigated, and has been found to exist in a number of different crystallographic modifications ; it separates from cold water in hydrated prisms, very similar to those of the inactive acid in all respects, and it is also deposited in hydrated monosymmetric prisms from its solution in ethylic acetate ; when crystallised from benzene, it affords either well-defined orthorhombic needles which contain one molecule of water of crystallisation, or a microci*ystalline powder of the anhydrous acid, according to the conditions of the experiment.From a mixture of chloroform and light petroleum, it is deposited in large, transparent, anhydrous orthorhombic prisuis which change in crystalline form at 100". The conclusions to be drawn from these and other facts bearing on the relation 1)&ween the active and inactive trans-a-camphanic acids are discussed in the following p~@er.liacictive cis-a-cceqihccnicucid, Cl,Hl,O,, is the principal product of the distillation of trans-7r-camphanic acid. It crystallises in large, trans- parent, hexagonal plates, which are indistinguishable from those of the corresponding active acid (Trans., 1896, 69, '343) except iil optical 135 behavioiir ;the crystals of the active acid are circularly polarising and all of one kind, whereas those of the inactive substance show either right-or left-handed circular polarisation. It is thus possible to separate this externally compensated cis-x-camphanic acid into it's (2-and I-isomeric components.Imxctive traiis-cc6~ap?~otricccl.box~/licctcid, Cl,H,,06, is obtained when inactive trans-r-camphanic acid is oxidised with nitric acid ;it crystal-lises from water in lustrous transparent, inonosymmetric prisms, which differ from those of the active acid (Trans., 1896, 69, 951) deposited under siinilar conditions in being anhydrous, and consequently also in crystalline form. It melts at 224-225', whereas the active acid melts at 196-197'. Ikccctive trans-cccnaphotl.iccLrboxy/lic nnhydl.ide forms transparent, monosymmetric crystals which are remarkably similar to those of the active anhydride ;it melts at 253-254' whether heated alone or with an approximately equal quantity of the active substance. "71. Racemism and pseudoracemism." By F.Stanley Kipping, Ph,D., D.Sc., and William Jackson Pope. The data afforded by a comparison of the physical and crystallo- graphic properties of the optically inactive substances described in the preceding paper with those of the corresponding active compounds (Trans., 1896?69, 913), and a number of other facts collected during the investigation of various active and inactive x-derivatives of cam-phor, have led the authors to the conclusion that the present classifica- tion of externally compensated Substances into (a) mere mixtures and (A) racemic compounds, requires modification. It has been found that optically inactive substances which are not mere mixtures of individual crystals of each of the enantiomorphous components are either very siinilar to, or extremely different from, their isomeric constituents in all those properties more immediately connected with crystalline structure ;no intermediate degree of simi-larity is, in fact, observable in any case where these properties have been thoroughly examined.Such externally compensated substances fall, therefore, into two groups. Those which closely resemble the corresponding active com-pounds are called pseuclo~cccenzic,the name racemic compound being reserved for those of the other group, of which racemic acid is the classical example. The subdivision of optically inactive compounds has, not only an experimental, but also a theoretical basis. It can be shown that, in accordance with the present theory of crystalline structure, optically active and racemic compounds cannot assume the same type of homo- geneous crystalline structiire, biit that an externally compensated sub- stance may form crystalline iiidividuals extremely similar to, but still not identical with, those of its active isomerides ;in the latter case, the crystals consist of mere intercalations of those of the active modifica- tions, and the non-identity is the result of the disturbance set up by intercalation.It is to these substances that the term psendoracemic is applied. Definitions of pseudoracemic and of racemic compounds bnsed on these considerations are given, and some of the properties of the two classes of substances are then discussed. It is pointed oiit that the melting point of an externally compensated substance does not afford concln- sive evidence as to its nature at ordinary temperatures, inasmuch as changes in crystalline form frequently occur with a change in tempera- ture, and a mere mixture rnay become a racemic compound, and vice versn before the melting point is reached ;numerous experiments are quoted in support of this view. It is also concluded that solubility determinations are valueless as a means of deciding between the three.classes of externally compensated substances. The properties of a number of inactive substances described by Aschan, Emil Fischer, Liebisch, Wallach, and others are briefly dis- cussed, and reference is made to a recent paper by Walden, which deals with the characteristics of optically active and racemic compounds.DISCUSSION. Dr. BONEenquired what was the practical criterion between a mixture of two optically active substances and a racemic compound proper, and whether there is any difference between the readiness with which the racemic and pseudoracemic forms can be resolved. Dr. KIPPINGsaid that, in the majority of cases, it is very difficult to distinguish bet ween mixtures and racemic compounds except by crys- tallographic examination, but Liebisch’s rule, that the density of a racemic compound is different from that of its optically active isomerido, if confirmed by further experimental data, might be made use of in many cases. Theoretically a racemic compound would probably be resolved into its components less readily than a pseudoracemic substance, but when using the methods at present known for the separation of externally compensated substances, it seems improbable that any general difference in this respect would be noticed.*72. “Note on some new gold salts of the Solanaceous alkaloids.” By H.A. D.Jowett, D.Sc. When hyoscine hydrobromide and auric chloride are mixed, either in concentrated, dilute, neutral or acid solution, a red precipitate is formed which can be crystallised from a hot aqueous solution aciclnlated with hydrochloric acid, On analysis, the salt is found to be an additive compound of auric chloride with hyoscine hydrobromide [B*HBr*AuCl,]. When this experiment is conducted in the presence of a large excess of hydrobromic acid, a chocolate coloured precipitate is formed which can be recrystallised from hot dilute hydrobroniic acid and forms chocolate coloured prisms, which, on analysis, prove to be the auribromide of the base [B*HBr*AuBrJ. Even when excess of hydrochloric acid is present the aurichloride is not formed.The analogous compounds of hyoscyamine and atropine were formed by similar reactions and resemble the corresponding salts of hyoscine in chemical and physical properties. Experiments were made to determine whether the bromaurichloride of formula B*HBr*AuCl, was an isomorphous mixture of aurichloride ancl auribromide, in view of the evidence adduced by Herty (J.Am. C. X., xviii:, 130) regarding the composition of the salt formed by mixing solutions of plittinic chloride and potassium bromide (K2PtC1,Br,).It was proved, however, that this view could not be adopted for the con- stitution of the gold salt, which must therefore be considered a true chemical compound. “73. “Production of camphenol from camphor.” By J. E. Marsh, M.A.,and J. A. Gardner, M.A. The authors have described (Trans., 1897, 71, 285) the produc-tion of an isomeride of camphor, camphenol. This substance was obtained by the .action of strong sulphuric acid on chlorocamphene, C,,H,,Cl. Camphenol is produced by the action of the same reagent on camphene dichloride, C10H16C12, which is the immediate product of the action of phosphorus pentachloride on camphor. The same cam- phenol is apparently produced from both the isomerides of the formula Cl0Hl6CI2,obtained from ordinary camphor, and a satisfactory yield is obtained in both cases.The action of strong sulphuric acid on other chloro-derivatives of terpenes has been examined. In particular, turpentine dihydrochloride behaves in a manner very similar to the camphor derivative, but the nature of the product of the reaction has not yet been determined. *74. “Preliminary note on the oxidation of fenchene.” By J. A. Gardner and G. B. Cockburn. Fenchene prepared from the fenchone of fennel oil by a modification of Wallach‘s method was oxidised on the water bath by moderately dilute nitric acid (1 part strong acid to 1 part water). The oxidation VAS complete in three days.After distilling with steam, the acid liquid 138 was neutralised with sodium carbonate and extracted with ether, to eliminate some insoluble oily matter. The alkaline liquid was now acidified and repeatedly extracted with ether. On evaporating the ether, a syrup was obtained which gradually crystallised. The crystals were purified from oily matter by washing with chloroform, and after recrystallisation from water melted at 207"; they proved to consist of cis-camphopyric acid. The oily substance, separated by chloro- form, was distilled under diminished pressure. A considerable amount of decomposition took place, and an oil: and a solid distilled over. The solid was crystallised from alcohol, and proved to be camphopyric anhydride (m.p. 187"). The yield of camphopyric acid was about 9-10 per cent. of the fenchene taken. 75. 6c Apiin and apigenin," By A, G. Perkin. In a preliminary notice upon this subject (PYOC.,1897,13, 53), some derivatives and decomposition products of apigenin were described ; these, together with an account of further work upon this colonring matter are included in the present paper. The formation of phloro- glucol and parahydroxyacetophenone,as the principal products of the gentle action of alkali upon apigenin, have been confirmed, and it is now shown that, at 200°, protocatechuic acid, parahydroxybenzoic acid, and phloroglucol are obtained in the same way. These results confirm those of Gerichten (Bey., 18'76, 9, 1124), except as regards the pro- duc tion of parahydroxyacetophenone, which is not mentioned by him.On methylation, apigenin forms a dimethyl ether, C,,H,O,(OCH,),, yellow needles, m. p. 171-172", which furnishes with alcoholic potash a potas-sium salt, decomposed by water, and with acetic anhydride a monacetyl derivative, C,,H70,(OCH,)2C,H30, colourless needles, m. p. 195-1 96". The diethyl ether, ClSH8O,,(OC,H,),, yellow needles, melts at 161-1 62O, and its monacetyl derivative, C1,H7Os(OC,H5),C,H,0, colourless needles, at 181-182°. As previously shown, apigenin contains 3 hydroxyl groups, consequently one is in the ortho-position to a carbonyl group. Decomposed with alcoholic potash, the dimethyl ether yields anisic aldehyde, anisic acid, and a phloroglucol derivative, et hylparahy droxy- benzoic acid being formed from the diethyl ether under similar conditions.These results, with the exception of the production of protocatechuic acid by means of alkali, point to a close relationship between apigenin nncl chrysin, CI5Hl0O4, the colouring matter of poplar buds, which yields on decomposition phloroglucol, benzoic acid, and acetophenone. It is probable that apigenin is a hydroxychrysin. This suggested relationship is borne out by the dyeing properties of 139 the two colouring matters, which show a close similarity. The forma tion of protocatechuic acid from apigenin appears to be the result of an oxidising action, for there is no evidence of a catechol nucleus in this substance. Further experiments upon its constitution are in progress.In the previous communicafion (Zoc. cit.), the author erroneously assigned the discovery of the glucosoidal nature of apiin and the pre- paration of pure apigenin to Gerichten, instead of to Lindenhorn (Inaug. diss. Wurxhwg, 1867). ‘76.(( Rhamnazin.” By A. G. Perkin and H.W.Martin. Rhamnazin was isolated from Persian berries by one of the authors and J. Geldard (Trans., 1895, 67, 496), and shown to be a quercetin-dimethylether. The present investigation was instituted to determine the position of the methoxyl groups, On methylation, it yielded quercetintetramethyletlier, and from this result and other experiments described in the paper, it evidently contains no methoxyl group in the phloroglucol nucleus in the ortho-position relatively to the carbonyl group. By fusion with alkali at 200°, rhamnazin yielded phloroglucol and protocatechuic acid, and digestion with boiling alcoholic potash gave vanillin, vanillic acid, and a non-crystalline phloroglucol derivative.Oxidised by air in alkaline solution, vanillic acid and a similar phloroglucol derivative were obtained. No free phloroglucol resulted from either of these decompositions. Taking into consideration that though the dyeing properties of rhamnazin are extremely feeble it must still be considered a colouring matter, these results indicate that it has the constitution of a rhamnetinmonomethylether. 77. ‘( Experimental verification of van’t Hoffs constant in very dilute solutions. By Meyer Wilderman, Ph.D.In van’t Hoff’s t,hermodynamic argument, the solutions are assumed to be very dilute, and the same assumption is made in the deductions from it of Planck, Riecke, Lorentz, Bolzmann, and others. The experi- mental verification in dilute solutions of van% Hoff’s law is therefore especially important. The freezing point method has been worked out with greater accuracy for the purpose of this investigation (Trans., 1895,67,1 ;Lewis, ‘‘On the Real and Apparent Freezing Point and the Freezing Point Methods,” PYOC.Royal Society, 1896; Zeitsch.fiiy pl~ysik. Chemie, 1896, 19,233). The author has determined van’t Hoff’s constant in dilute solutions with thermometers graduated to &th and -,-&&h of a degree re- spectively, simultaneously for a series of compounds, cane sugar, alcohol, urea, acetone, aniline, phenol, dextrose, resorcin, maltose, milk sugar, at 140 converging temperatures above and below the freezing points, using different parts of the scale of both thermometers.Small deviations only from the theoretical value of 1.87 are found, due to the different sources of experimental error, van’t Hoff’s constant being thus confirmed in dilute solutions. 78. The isomeric dibromethylenes.” By Thomas Gray, B.Sc. This paper contains a record of an attempt to prepare the stereo- isomeride of symmetrical dibromethylene. The following reactioxs are discussed : (1) the reduction of tribromethane by sodium ethoxide ; (2) the union of acetylene with bromine ;(3) the reduction of acetylene tetm- bromide ;and (4)the addition of hydrogen bromide to bromacetylene.By the first of these methods, Tawildarow (Ann., 1875, 176, 22) obtained, in addition to CH,:CBr,, a liquid boiling at 157” and having the formula C,H,Br,. The author confirms the observation of Michael (Aw2ev. Chenz. Joum., 1883, 5, 192), and finds that the only product of this reaction, under varying conditions of concentration, is CH,:CBr, and he attributes Tawildarow’s observation to the formation of bromacetyl bromide by oxidation during the process of distillation. The product of three other reactions is shown to be in every case the same symmetrical dibromethylene (CHBrzCHBr), boiling at 110”. The author considers that the formation of this substance by the fourth method, and the probable instability of the cis-modification, which should result from the second reaction, point to the formula H*Cj *Br asBr*C *H representing the structure of the symmetrical dibromethylene at present knomn.At the next meeting, on Thursday, June 17th, there will be a Ballot for the election of Fellows, and the following Papers mill be received. The authors of those marked with an asterisk have announced their intention of being present. ‘[The reduction of perthiocyanic acid.” By F. D. Chattaway, M.A., and H. P. Stevens, B.A.* ‘‘Molecular refraction of dissolved salts and acids.” Part 11. By 3’. H. Gladstone, D.Sc., F.R.S., and W. Hibbert. * ‘6 On a space formula for benzene.” By J. Norman Collie, Ph.D., F.R.S. Q ‘6 On the production of some nitro- and amido-oxypicolines.” By A. Lapworth, D.Sc., and J. Norman Collie, Ph.D., F.R.S. ‘(The so-called hydrates of iso-propyl alcohol.” By T. E. Thorpe, LL.D.,F.R.S. ~ RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNCAY.
ISSN:0369-8718
DOI:10.1039/PL8971300129
出版商:RSC
年代:1897
数据来源: RSC
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