ORGANIC CHEMISTRY.PART I.-ALIPHATIC DIVISION.A CAREFUL survey of the research work in the Aliphatic Divisionof Organic Chemistry done during the past year shows that prac-tically all the investigations have been carried out along more orless well-known lines, and that no strikingly original discovery hasbeen made. The work nevertheless represents a steady advance inthis section of Organic Chemistry.Hydrocarbons.Pring and Fairlie1 find that a t a temperature of 1200O and a tpressures from 10 to 60 cm. carbon and hydrogen unite to give,not only methane, but also ethylene, the rate of formation of thelatter being about 1/100th that of the former. The rate of forma-tion of ethylene increases with rise of temperature, and a t 1400Othe amount of this gas is comparable with that of the methane.The amount of acetylene formed a t 1650O was sufficient t o enableits presence to be experimentally demonstrated, but at 1200O theamount was insufficient for this purpose.I n a later communication 2 i t is shown that the rate of formationof methane from its elements proceeds with increased velocity a thigh pressures, the equilibrium stage being reached in two hours,when the temperature was 1200-1300° and the pressure 30 to 50atmospheres.The relative amount of methane produced increasedwith the pressure t o the extent demanded by the law of mass actionas applied to the equation G'+ 2H,=CH4. Methane is the onlysaturated hydrocarbon formed a t any temperature between l l O O oand 2100O or pressure up to 200 atmospheres.It is probable thatby using finely divided carbon and working a t high pressures thedirect unioc of carbon and hydrogen would be sufficiently rapidto enable this method to be used for the preparation of methaneon a large scale.T., 1911, 99, 1796; Ann. Report, 1910, 102.Ibid., 1912, 101, 91.774 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Hauser and Herzfeld3 find that ozonised oxygen reacts a t theordinary temperature with methane to produce formaldehyde,CH, + 20, = CH20 + H,O + 20, and that the reaction is practicallyquantitative even for low concentrations of the reacting substances.Since methane is the only hydrocarbon which is in this mannerdirectly oxidised to formaldehyde, the reaction may with advantagebe used for the detection of this gas.This action of ozone onmethane affords an explanation of GrBhant’s observation 4 thatmethane fires much more easily with oxygen obtained by electro-lysis than with ordinary oxygen.A study 5 of the action of acetylene and of substituted acetyleneson cuprous chloride shows that the initial product of the action isthe compound C,H,,ChCI, or C,HR,CuCl. Hence the equationCRICH + CuCl= CRICCLZ + HCI fails to show that the formationof an additive compound of the reacting substances is the firstphase of the reaction, and precedes substitution.Berthelot’s experiments on the pyrogenic condensation ofacetylene have been repeated 6 on a large scale and under carefullycontrolled conditions. The acetylene was diluted with an equalvolume of hydrogen in order to minimise its decomposition intomethane and hydrogen, and the mixed gases passed through twoelectrically-heated tubes, the first of these being maintained at640-650°, and the second at 800O.The resulting t a r was of alight brown colour, had an aromatic odour, and in one experimentamounted to 63 per cent. of the weight of the acetylene used; thegases leaving the apparatus contained a considerable amount ofmethane. The tube heated a t the lower temperature gave a tar richin light oil, whereas that obtained from the other tube containedmore of the hydrocarbons of high molecular weight. The followinghydrocarbons were obtained from the tar by fractional distillation :benzene, toluene, diphenyl, naphthalene, anthracene, indene,fluorene, pyrene, and chrysene, the first-named forming aboutonefifth of the whole tar.No styrene could be found, and thesubstance which Berthelot isolated and regarded as styrene wasin all probability indene, the properties of these two substancesbeing very similar. The low percentage of acetylene in ordinarycoal gas is regarded as due to its decomposition into methane andcarbon, and also t o its condensation to cyclic hydrocarbons; in fact,the formation of the latter during the manufacture of coal gas is ina large measure due to this condensation, although it is true thatBey., 1912, 45, 3515 ; A . , 1913, ii, 77.Conapt. revad.: 1907, 145, 625 ; A., 1907, ii, 990.W. Manchot, J. C. Witliers, and H. C. Oltrogge, Annalcn, 1912, 387, 257 ;A., i, 230.6 R.Meyer, Ber., 1912, 45, 1609; A., i, 525ORGANIC CHEM ISTRY. 75Pictet and Ramseyer 7 have isolated hexahydrofluorene from coalitself.The compound 5Na,S,03,5Cu2E$0,,5Cu,C,,C,H2,10H,0 is obtainedas a red precipitate by passing acetylene into a solution of sodiumthiosulphate and copper acetate.8 It burns like gunpowder whenheated, and dissolves in water, giving a red solution, the colour ofwhich is destroyed by acids and restored by alkali only if the latteris added immediately after the removal of the colour by the acid.Caoutchouc.-W. H. Perkin 9 has published an account of thework which he and several collaborators have carried out in thedirection of the preparation of synthetic rubber by methods whichmay ultimately admit of commercial application.A careful con-sideration of the question showed that for a process to be a com-mercial success it must be capable of producing the rubber a t2s. 2d. per kilo. [Is. per lb.], or even less. This limits the choice ofraw materials t o substances such as wood, starch or sugar, petrol-eum, and coal, and of these, starchy substances would appear to holdout the most hope of success. These considerations led to experi-ments on fuse1 oil, and as a result a method was devised by whichisoprene can be obtained readily and in quantity from isoamylalcohol. Commercial fuse1 oil on distillation gives a fraction (b. p.12&130°) which consists approximately of 87 per cent. of isoamylalcohol and 13 per cent.of active amyl alcohol. This fraction wasfirst converted into the chloride by the action of dry hydrogenchloride, and then chlorinated in a special apparatus designed forthe purpose, and with the object of limiting as far as possible thechlorination to the formation of dichlorides. The resulting product'on fractional distillation gave y&dichloro-B-rnethyIbutane,C'HMe,*CHCI*CH,Cl,fl&dichloro-fl-methylbutane, CCYMe,*CH,-CH,Cl, and a8-dichlorefl-methylbutane, CH,Cl*(,'BRMe*CH,*CH,Cl. In subsequent experi-ments these isomerides were not separated, and the portion of thechlorinated product which boiled a t 140-180° was passed oversoda-lime a t 470° and the resulting vapours condensed. The liquidthus obtained was fractionally distilled, and yielded isoprene in a40 per cent.yield of that theoretically possible. The formation ofisoprene from y&dichlorclB-methylbutane is no doubt due to amolecular rearrangement of the isopropylacetylene, CHMe,*CICH,which is first formed. I n order to polymerise the isoprene to rubberit was sealed up in tubes with about 3 per cent. of thin sodium7 Ber., 1911, 44, 2486 ; A . , 1911, i, 850 ; also B L I ~ ~ C S S ant1 Wlieeler, T., 1911,* K. Bliaduri, Zeitsch. nnorg. Chcm., 1912, 76, 419 ; A., i, 597.9 J. SOC. Chin. Ind., 1912, 31, 616; A., i, 636.99, 64976 ANNUAL HEPOK'I'S ON THE PROGRESS OF CHEMTS'l'KY.wire (Matthews' sodium process), and heated for several days a tabout 60°; the dark brown product was then treated with acetone,and the precipitated rubber washed with alcohol or treated withsteam to remove acetone and any unpolymerised hydrocarbon.Metallic sodium is a very effective agent for the polymerisation ofsuch hydrocarbons as isoprene, butadiene, etc., as its action ispractically quantitative, and is not seriously affected by thepresence of other hydrocarbons which do not polymerise to rubber.Perhaps the greatest difficulty which the above process offers toits being employed on a manufacturing scale is the limited supplyof fusel oil, and in order to overcome this difficulty Fernbach10worked out fermentation processes by which, not only this substance,but also acetone can be obtained much more cheaply.Moreover,the fusel oil obtained by Fernbach's method contains a large pro-portion of butyl alcohol, from which butadiene is readily obtainedby submitting i t to a process similar to that employed for thepreparation of isoprene from isoamyl alcohol.The resultingAmy-butadiene on treatment with sodium yields a rubber of betterquality than that obtained from isoprene.llI n the third method worked out, acetaldehyde was treated withvery dilute potassium carbonate, and the resulting aldol reducedby neutral reducing agents or electrolytically, when ay-butyleneglycol was obtained. This glycol on treatment with hydrogenchloride gave the corresponding dichlorobutane, from whichbutadiene was obtained by the soda-lime method.The product obtained by the polymerisation of vinyl bromide,and known as caouprene bromide,lZ exists in three modifications,a -+ /3 -+ y, which are capable of change in the direction indi-cated when submitted to the action of ultraviolet light or boiledwith anhydrous acetic acid.Harries' butadiene-caoutchoucbromide,l3 which also exists in three modifications, is either identi-cal or isomeric with caouprene bromide, the isomerism being dueto a difference in the distribution of the bromine in the molecule.The constitution of caouprene bromide is most probably expressedby the formula:$X€,-CHEr-CH2--CHBr -CH,-yHBrCHBr*CH2*CHBr*CH2 - - - - CH2-CHBr'in which the dotted lines represent an unknown number of*CH,*CHBr* groups.Both caouprene bromide and butadienecaoutchouc bromide yieldlo Eng. Pcct. 15,203, June 29, 1911 ; zbM., 16,925, July 24, 1911.11 Harries, A m a h , 1911, 383, 157 ; A ., 1911, i, 798 ; Ann. llcporrt, 1911, 108.l2 I. Ostromisslensky, J. Russ. Phys. Chcnt. Soc., 1912, 44, 204 ; A , , i, 280.Annalen, 1911, 383, 157; A , , 1911, i, 798ORGANIC CHEMISTRY. 77the same caoutchouc when treated with zinc dust, this reactioncompleting a new synthesis of butadiene-caoutchouc :CH,:C’HBr -+ caouprene bromide _“& butadiene-caoutchouc.A large number of processes have been worked out for thepreparation of unsaturated hydrocarbons like isoprene, butadiene,etc., which admit of polymerisation to caoutchouc-like substances,and in the majority of cases these have been patented. No usefulpurpose would be served by the publication in this report of allthese various processes, because unless they eventually admit ofcommercial application the great majority of them are of littleinterest.Caout.chouc when treated with ozone free from oxozone gives thetrua diozonide, C,,H,,O,, whereas crude ozone gives the dioxozonide,C,,H,,O,, which is more soluble than the true diozonide.14 Bothozonides on hydrolysis give lmdinaldehyde and lzvulic acid, inthe proportion of 4 to 3 in the case of the diozonide, and 2.8 t o 4for the dioxozonide. Synthetic rubber gives results similar to thoseobtained with natural caoutchouc.Spence 15 and his collaborators have continued their investigationon the vulcanisation of caoutchouc.They regard as “ free ” sulphurthat portion 6f this element which is extracted from vulcanisedcaoutchouc by acetone or hot sodium hydroxide solution, the undis-solved portion being the “fixed” sulphur.From the results oftheir experiments they conclude that it is possible to vulcanisecaoutchouc SG that no “free” sulphur is present in the product,the process under these conditions being essentially a chemical onewith the formation of a product which in composition agrees closelywith that required by the formula (TlOH,,S,; this view that vulcan-isation is a chemical process is in direct opposition to the adsorptiontheory. With regard to the “ free ” sulphur present in vulcanisedcaoutchouc part only is adsorbed, the remainder being in the non-adsorbed condition. With good specimens of caoutchouc there ispractically no vulcanisation a t 40°, and only very little at 60°, butabove this temperature it increases rapidly.On the other hand,partly decomposed caoutchouc undergoes considerable vulcanisationa t 40°.Bary and Weydertl, are of opinion that the reaction of vulcan-isation of caoutchouc is a reversible one, but the numericaldata obtained are not in agreement with the law of massaction, whatever hypothesis may be adopted as to the degreeI5 I). Speiicc, Zcitsck. Chcin. h d . Kolloide, 1911, 8, 304 ; 9, 83, 300 ; 1912, 10,C. Harrics, Ew., 1912, 45, 936; A., i, 407.299 ; 11, 28 ; A., 1911, i, 657, 801 ; 1912, i, 123, 638, 706.Coiqx. ~ e 7 ~ c l . , 1911, 153, 676 ; A., 1911, i, 100378 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of polymerisation of the hydrocarbon. In the process of vulcan-isation the sulphur first becomes attached to the terminaldouble linkings of a chain, and any further vulcanisation canonly occur after depolymerisation.Bary 17 has obtained anapproximate value for the molecular weight of caoutchouc ; thus,when sulphur is added to caoutchouc in quantity insufficient forvulcanisation of the whole of the caoutchouc, and the mixturesuitably heated, the resulting product consists of the sulphide(ClOHI6)& and caoutchouc ; the former is insoluble in cold benzene,whereaslthe latter dissolves in this solvent. By gradually increasingthe proportion of sulphur in success?ve experiments a point isreached a t which there is just sufficient sulphur to convert thewhole of the caoutchouc into the compound (c!l()H16)&; in thesecircumstances the whole of the product is insoluble in benzene.Analysis of the compound thus produced shows that it containsThis 2.5 per cent.of sulphur, from which n=value of n, is in fair agreement with Weber's formula, C,,H,,S,,and it would thus appear that the molecular weight of caoutchouca t the temperature of vulcanisation (140O) is approximately 2720.Beadle and Stevens 18 have shown that the nitrogenous substancepresent in Para rubber plays an important part in the process ofvulcanisation. Natural rubber from which this protein has beenremoved vulcanises less readily, and combines with less sulphurthan the same specimen in which the protein is present. Althoughthe protein-free rubber is much more distensible than the other,yet its tensile strength is much less.The absence of protein fromsynthetic rubber no doubt renders it inferior to the naturalproduct; even if a protein is added to the synthetic rubber it isvery unlikely that it will be possible to give it the reticulatedstructure so characteristic of the protein in the natural product.I n a lecture delivered before the Verein Deutscher Chemiker atFreiburg in Breisgau, Harries dealt with synthetic caoutchoucfrom the scientific point of view, and in a second lecture byHofmann the same subject was treated from the technical side.19A series of articles by I. L. Kondakoff on '' Synthetic Rubber, itsHomologues and Analogues," have appeared during the currentyear in the Revue Ge'ne'rale de Chimie.l7 Compt.rcnd., 1912, 154, 1159; A . , i, 481.1912, 4, 554; J. SOC. Chem. Id., 1912, 31, 1099.97.5 x 32 x 2 =18.4.2.5 x 136Zeitsch. Chem. Ind. KoZZoide, 1912, 11, 61 ; A . , i, 789 ; Jndiu-ruhber Joiwn.,Zcitsch. angezu. Cliem,, 1912, 25, 1457, 1462 ; A . , i, 706ORGANIC CHEMISTRY. 79Alcohols and Aldehydes.The action of dry potassium hydroxide on various alcohols hasbeen studied by Guerbet,20 who finds that when a primary alcoholcontaining six or more carbon atoms is heated a t 230° with potass-ium hydroxide it is oxidised to the corresponding acid, the yieldbeing almost quantitative; with a lower primary alcohol the yieldof acid is less, because a considerable amount of unsaturated hydro-carbon is formed. When a secondary alcohol is submitted to asimilar treatment very little is oxidised, the greater portion con-densing to higher alcohols, thus : isopropyl alcohol gives &methyl-pentan-5-01, CHMe2*CH,*CHMe*OH, and fi&dimethylheptan-y-ol,CH31e2*GH2*C"HMe*CH2*CHMe*OH. Tertiary alcohols are scarcelyattacked by pocassium hydroxide a t 230°, but above this tempera-ture they are slowly oxidised t o acids containing fewer carbonatoms.The above reaction is suggwted as a simple method fordistinguishing between primary, secondary, and tertiary alcohols.Senderens21 has published a full r6sum6 of the work done byhimself and others on the catalytic dehydration of alcohols byvarious elements, oxides, and salts ; the comparative efficiency ofseveral catalysts being given in a tabular form.The mechanismof t.he reaction is discussed, and the view favoured is that a com-pound of the catalyst and the alcohol is first formed, and that thissubsequently decomposes. I n view of the fact that the majority ofthe work has already been dealt with in previous reports,22 thisshort notice of the present publication will be sufficient.The formation of unsaturated hydrocarbons from alcohols bymeans of sulphuric acid has been shown t o be greatly facilitatedby the presence of such a catalyst as anhydrous aluminiumsulphate,23 and the results of an inquiry as to whether the sulphuricacid itself acts as a true catalyst or merely in virtue of its powerto absorb water, point to the former alternative being the correct0118.24 For every catalytic action there is a definite temperature,below which the effect of the catalyst does not come into play.Fortertiary aliphatic alcohols and sulphuric acid this temperature isbelow the boiling point of the lowest member of the series; forsecondary alcohols it is below the boiling point of the C5 member;and in the case of the primary alcohols it is near that of the C,member ; hence all tertiary alcohols, secondary alcohols above the2o Compt. rend., 1911, 153, 1487 ; 1912, 154, 222, 713; A., i, 67, 154, 331.21 J. 13. Senderens, Ann. Chim. Phys., 1912, [viii], 25, 449 ; if., i, 406.y2 Ann Xeport, 1907, 75 ; 1908, 77 ; 1909, 76 ; 1910, 99.23 J. B. Senderens, Compt. Tend., 1910, 151, 392; A., i, 649; Ann. lieport, 1910,oA J.B. Senderens, ibid., 1912, 154, 777 ; A , , i, 331.100 ; J. B. Senderens and J. Aboulenc, Compt. rexd., 1911, 152, 1671 ; A . , i, 60080 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.C5 member, and primary alcohols above the Cs member readilyyield the corresponding unsaturated hydrocarbon when boiled with3 to 4 per cent. of their volume of sulphuric acid. In the case ofthe lower alcohols, as, for instance, ethyl alcohol, by using a largeexcesB of sulphuric acid the alcohol is prevented from boiling awaybefore the temperature at which catalytic action takes place isreached.The dehydration of alcohols can also be effected by the use oftoluenep-sulphonic acid 25 ; thus tert.-butyl alcohol is readily con-verted into isobutylene by heating with 1.7 to 5 per cent.of itsweight of the sulphonic acid.Senderens26 has shown that ketones are readily prepared bypassing the vapour of an acid or a mixture of two acids overthorium oxide heated a t 3 8 0 4 0 0 ° , and the principle of thismethod has now been extended to the preparation of aldehydes.27For this purpose a mixture of the acid and excess of formic acidis passed over titanium oxide at 250--3OOO. The formic acid isdecomposed into carbon monoxide and water, and the carbon mon-oxide reduces the other acid to the corresponding aldehyde:R*CO&C+H*C'O,E=R*CHO+ CO,+%O.The yield of aldehyde is quite satisfactory, varying from 50 percent, in the case of acetic acid t o 95 per cent. in the case of octoicacid.Romijn's 28 method for the estimation of formaldehyde is basedon the interaction of this substance and potassium cyanide, wherebythe reaction CH,O + ECN = CN*CH,=OK is supposed to take place.Kohn 29 obtained potmsium glycollate and hexamethylemtetramineas products of the interaction of these two substances when anexcess of formaldehyde was used.The action of potassium cyanideon formaldehyde has been recently reinvestigated by Polstorff andNeyer,30 who have identified ammonia, glycollic acid, iminodiaceticacid, and nitrilotriacetic acid as products of the interaction whena 25 per cent. aqueous solution of potassium cyanide and one ofabout 18 per cent. of formaldehyde are mixed at Oo, and themixture kept a t the ordinary temperature for twenty-four hours.The following equations represent the changes which take place :25 H.Wuyts, Bull. Soc. chini. Belg., 1912, 26, 304 ; A., i, 598.J. B. Senderens, Compt. rend., 1908, 146, 1211 ; 1909, 148, 927 ; 149, 213, 9951910, 150, 111, 702, 1336 ; A., 1908, i, 494 ; 1909, i, 286, 627 ; 1910, i, 11, 179,318, 489.27 P. Sabatier and A. Mailhe, ibid., 1912, 154, 561 ; A . , i, 238.28 Zeitsch. an$. Chem., 1897, 36, 18 ; A . , 1897, ii, 166.29 Monatsh., 1899, 20, 903; A . , 1900, i, 205.30 Ber., 1912, 45, 1905 ; A., i, 605 ; see also H. Pranzen, J. y?'. G'Iwm. 1912, [ii],86, 133 ; A., i, 677.ORCIANIC CHEMISTRY, 81KCN + CH,O = CN*CH,*OK.CN*CH,*OH + 2H20 = CO,H*CH,*OH + NH,.CN*CH,*OH + NH, = CN*CH2*NH, + H,O.NH,*CH,*CN + HO.CH2.CN -+ NH(CHz*CN), -+NH(CH,*CO,H),.A good yield of glycollic acid can be obtained by distilling withsteam the mixture of potassium cyanide and formaldehyde five toten minutes after mixing.An attempt 31 to determine the composition of the resin producedby the action of dilute alkali on acetaldehyde a t low temperatureshas resulted in the separation of the resin into two isomerides,C24H3606 ; these have been converted into chloro- and bromo-deriv-atives, but the form in which the oxygen is present has not yetbeen determined.Substances like acraldehyde which readily polymerise haverecently become of special interest in view of the preparation ofbaekelite and synthetic caoutchouc.I n the elimination of theelements of water from glycerol the hydroxyl group may comefrom a primary or secondary alcoholic group, and the changeswhich takes place may be formulated thus:NH,*CH,.CN + 2HO*CHz*CN--+ N(GH,*C;N),--,N(CH,*002H)3.OH*CII[OH* CH,* C( OH): CH 23 ++ OH *CH2*CO* CH, - -+ + CH,O + CH,-CHO (r)J.*,CH(OH)*CH,*OH[OH *CH,*CH:CH*OH] ++ OH*CH,*CH,*CHO -3CH,:CH*CHO (IT)Secondary alcoholic groups are dehydrated more readily thanprimary ones, and so in accordance with the above schemes theproduction of acraldehpde should be facilitated by the dehydrationof the glycerol a t a low temperature.Potassium hydrogen sulphateand the sulphates of aluminium, copper, and iron are suitablefor the dehydration, but unfortunately the acraldehyde contains a,considerable amount of sulphur dioxide; on the other hand, thesulphates of the alkaline earths and of the heavy metals yield anacraldehyde free from this impurity.Granular dehydratedmagnesium sulphate gives the best results, and by heating theglycerol with this substance a t 330-340° and in a special appara-tus, a yield of 60 per cent. of acraldehyde is obtained,32 as much asone kilogram having been prepared in one day. I f the temperatureis appreciably (30O) higher than the ane quoted then the acraldey1 T. Ekecrantz, Arkiv. Kenz. Min. Geol., 1912, 4, No. 2 7 ; A , , i, 778.32 A. Wolil and B. Mylo, Be?.., 1912, 45, 2046 ; A . , i, 677.REP.-VOL. 1X. c82 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,hyde contains a considerable amount of acetaldehyde formed inaccordance with scheme I.The preparation of aliphatic dialdehydes is always a matter ofconsiderable difficulty on account of the ease with which theypolymerise ; this difficulty is greatly increased when the dialdehydeto be prepared is also a hydroxy-compound, for hydroxy-aldehydesare very sensitive to acids and alkalis. Wohl and MyloF3 by theirpreparation of tartardialdehyde, have successfully overcome thedifficultiee associated with the preparation of a substance of thistype :EtMgBr + C,H, -+ BrMgCiCMgBr -$ (EtO),CH*CiC*CH(OEt), 2CH(OEt)jH +colloidal I platinumc (E t 0) ,CH C H( OH) CH (0 H) CH (0 E t )s y?!!CHO*CH(OH)*CH( OH)*CHO (A*)J%? (lI=tO),CH*CH:CH*CH(OEt),The unimolecular form of tartardialdehyde was obtained inaqueous solution only; this had a sweet taste, and on slow evapora-tion deposited needles which were sparingly soluble, and no doubtrepresented a polymeric form of the aldehyde.The needles hada bitter taste, and dissolved slowly in warm water, giving a sweetsolution, in which the aldehyde was present in a unimolecular form,as shown by cryoscopic measurements. When oxidised withbromine water the dialdehyde gives mesotartaric acid, a resultwhich indicates that the ethylenic acetal (A) has a cis-configuration.(EtO,),CH*CH:C)H-CH( OE t),,with very dilute sulphuric acid, the same authors34 have obtainedmaleic dialdehyde. This substance has a bitter, burning taste,and a strong, pungent odour not unlike acrolein or formaldehyde,but perhaps its most remarkable property is its yellow colour,which is even deeper than that of diacetyl.This depth ofcolour is remarkable in a compound with such a low molecularweight, and is, no doubt, due to the accumulation of double linlr-ings; and regarded from this point of view the formuke of maleicdialdehyde and p-benzoquinone are seen to be very similar :By the hydrolysis of the diacetal,CH:CH o:c<;H:c~>c:o c: o<cH; ,,>c:o.Acids, Acid Chlorides, am? Esters.The evidence in support of the view that addition precedes sub-stitution in organic compounds, especially those containing acarbonyl group, is gradually becoming more conclusive. Lapworth,Bb83 Ber., 1912, 45, 322; A., i, 161. y4 lbid., 1746. 3B T., 1904, 85, 30ORGANIC CHEMISTRY. 83some years ago, brought forward evidence in support of it by hisinvestigation of ths action of bromine on acetone, and furtherevidence in the same direction is supplied by the work of Dawsoii,Miss Leslie, and Powis 36 on the reaction between acetone and iodine,the results obtained leading these observers to the conclusion thatthe reaction takes place in three stages:CH3*CO*CH3 -+ CH2:C(OH)*CH, .. . . . . . (1)CH,:C(OH)*CH, + I, -+ CH,T.*CI(OH)*CH, . . . (2)CH,I*CI(OH)*CH, -+ CH,I*CO*CH,+HI . . . , (3)changes (2) and (3) being of relatively high speed in comparisonwith the primary isomeric change (1).The mechanism of the reaction for the preparation of a-bromeacids by th4 Hell-Volhard method is probably of the same nature,and may be formulated thus:OH Br2 IC*CH2*COC1 -+ IZ*CH:C<cl -+R*CHBr*COUl + HBr.R*CHBr*CO.Gr + HCI.R*CHBr*C-OH Pr\ClEvidence in support of the above scheme is furnished byAschan,37 who shows that the product of the action of bromineon various acid chlorides is a mixture of the brominated acidbromide and brominated acid chloride, in which the former p r edominates. A very similar result has been obtained by Smithand Lewcock38 in their investigation of the action of bromineon isobutyryl cliloride; in this case the brominated productconsisted almost entirely of a-bromokobutyryl bromide. Theevidence brought forward by Meyer,39 although leading to thesame conclusions, is based on entirely different considera-tions.Meyer points out that, according to Lapworth, if theprocess is one of direct substitution, then the reaction must bea bimolecular one, and its velocity must depend on the con-centration of both the acid and the bromine.On the otherhand, if enolisation first occurs (slowly) and is then followed byaddition (rapid) of bromine, etc., then the reaction is unimolecular,and its velocity is independent of the concentration of the bromine.Experiments on the action of bromine on malonic acid show thatthe velocity of the reaction is quite independent of the concentration of the bromine. Meyer also points out that the formation ofthe brominated acid bromide in the experiments of Aschan mayequally well be explained by the theory of direct substitution; in36 T., 1909, 95, 1864; 1912, 101, 1503.su Ibid., 2358 ; A., i, 826.37 Ber., 1912, 45,1913; A., i, 599.39 Ibid., 2864 ; A., i, 941.a 84 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.this case the hydrogen bromide set free reacts with the brominatedacid chloride :CH,*COCI ?$ CH,Br*COCl+ HBr = C€€,Br*COBr + IICljust as potassium bromide reacts with acetyl chloride to give acetylbromide and potassium chloride.Similar criticism can be appliedto the results obtained by Smith and Lewcock.Two new isomerides40 of oleic acid have been prepared fromricinoleic acid as a starting point. When this acid is reduced byhydrogen in presence of platinous hydroxide i t gives h-hydroxy-stearic acid; this latter acid when heated with hydrobromic acidyields a bromostearic acid, which by treatment with alcoholicpotassium hydroxide gives a solid and a liquid product. From thesolid product one of the isomeridea was isolated and identified asAA-oleic acid (m.p. 34-36O). The liquid product contained theother isomeride, which from its reactions is in all probabilityAK-oleic acid.The rate of absorption of halogens by unsaturated acids isundoubtedly dependent in some measure on the relative positionof the double bond and the carboxyl group; ordinary oleic acid,for instance, readily absorbs bromine, whereas the absorption ofthis element by A@-oleic acid is very slow. Further evidence insupport of this has been obtained41 .by the determination of theiodine values for undecenoic, crotonic, AP-hypogxic, and As- oleicacids; thus with AP-oleic acid the following iodine values wereobtained: 18.0 after thirty minutes, 37.7 after three hours, 76.2after twelve hours, 84.2 after twenty-four hours, and 86.8 afterseventy hours, the theoretical value being 89.7.It is suggestedthat the determination of the iodine value may help in locatingthe position of the double bond in an unsaturated acid.Fenton and Jones42 obtained oxalacetic acid (m. p. 180-184°)by the oxidation of malic acid with hydrogen peroxide in thepresence of ferrous iron, the acid being isolated from the reactionmixture by the addition of sulphuric acid and extraction withether. Wohl and Oesterlin 43 shortly afterwards obtained by adifferent method an acid having the composition and propertiesof oxalacetic acid, but melting a t 1 5 2 O ; it was shown later thatthe new acid when dissolved in sulphuric acid and extracted withether is converted into the acid melting at 184O. From a compari-son of their physical and chemical properties it was concluded thatthe two acids are geometrical isomerides, and that the acid meltingS. Fokiii, J.Ems. Phys. Chm. SOC., 1912, 44, 653 ; A . , i, 534.41 G. Poiizio a d C. Gastaldi, Gnzzettn, 1912, 42, ii, 92; A., i, 74s.4'L T., 1900, 77, 77.4J Ber., 1901, 34, 1139 ; A . , 1901, i, 365ORGANIC CHEMISTRY. 85a t 184O is hydroxyfumaric acid, the other being hydroxymaleicacid. When tartaric acid is oxidised in the presence of ferrousiron an acid, C,H,0,,2H20, is obtained, which, from its readinessto form an anhydride, etc., is regarded as dihydroxymaleic acid.44Fenton and Wilks 45 now show that the “ oxalacetic acid ” meltinga t 1 8 4 O can be directly transformed into “ dihydroxymaleic acid,”and point out that from this result it would appear that if “ t h espacial relations of the original molecule persist in the newproduct,” then the “oxalacetic acid” melting at 184O and“ dihydroxymaleic acid ” must have the same geometrical con-figuration; in other words, this is evidence in favour of ascribingthe fumaroid configuration to ‘I dihydroxymaleic acid.” Thisevidence cannot, however, be regarded as conclusive, for the resultcan be explained in other ways.The sub joined scheme summarises the various transformationswhich have been accomplished with these acids and other alliedcompounds :Malic acid Tartaric acid Glyceric acidOxalacetic acid 2% Dihydroxymaleic acid -+ DihydroxyacrylicI J.I ir2o2~e I l l ? $llzO,Fe +I1202F’clrcatacid ( 1 ) ? 1 \4&a I ’ d : y / G& . ” 3 P - L l T 2 1 / \: xGlyoxalone-4 : 5-dicarb- s * @2 Pyrazinedicarb-oxylic acid oxylic acidl&Glyoxalone Glycoll- Diliyclroxytartaric Mesoxalic Pyraziiiealdehyde acid sernialdehyde\ dc IJ. $ J. %Formaldehyde Hexoses Mesoxalic y’z Tartronic Glyoxal Glycolurilacid Fe acidDuring the last two years J. F. Thorpe46 and his collaboratot-shave published six important papers dealing with the constitutionof glutaconic acid and its derivatives. Glutaconic acid is knownin one form only, although the formula generally assigned to it,CO,H*@H,*C‘H:CH-CO,H, requires the existence of cis- and trans-44 H.J. H. Fenton, T., 1905, 87, 801.45 T., 1912, 101, 1570.46 F. B. Thole and J. F. Thorye, ibid., 1911, 99, 2187, 2204 ; JS. Flmd and J. F.Thorpe, ibid., 1912, 101, 856, 871, 1557, 1739 ; Ann. Beport, 1905, 91 ; 1910, 8986 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.modifications, but all attempts to obtain these have failed. Further,it has been shown that the a-alkylglutaconic acids,CO,H*CHR*CH:CH*CO,H,and y-alkylglutaconic acids, CO,H*CH,*C'H:CR*CO,H, are the samesubstances ; also, that a-methyl-y-ethylglutaconic acid,G'O,H*CHMe.CH:~Et*CO,H,and y-methyl-a-ethylglutaconic acid, CO,H*CHEt*CH:CMe*CO,H,are identical. To explain these facts, it has been suggested thatthe constitution of glutaconic acid is best represented by theformula CO,H*CH*CH[HJ*CH*CO,H, the hydrogen atom withinthe bracket being regarded as a mobile atom in equilibriumbetween the two neighbouring carbon atoms.An acid containingsuch a mobile hydrogen atom is termed a'mobile acid, and it isassumed that for every mobile acid there is a static stable statecalled the normal state, in which the tautomeric hydrogen atomis attached to the central carbon atom of the three-carbon system.Such an acid is called a normal acid, and its structure is similarto that of isophthalic acid.B B\9/ CO,Hy C- - C *CO,K B Y\9/ C0,H.C- -C*CO,HC H CHGlntaconic acid. isoPhthalic acid.Although the manner in which the free valencies of the twoterminal carbon atoms of the three-carbon system are combinedis left an open question, they are regarded as being on the samesides of the two terminal tetrahedrons, corresponding with themeso- or non-resolvable form, thus :HI--H.-- -I? CO, HThe normal acids are the so-called trans-modifications of theacids of this series.Attempts to prepare an anhydride from a mobile acid by theaction of acetyl chloride lead, not to an ordinary anhydride, butto an hydroxy-anhydride (11), which, on subsequent hydrolysis,yields, in the case of glutaconic acid itself, the normal form ofthe acid (I).Now, if formula (11) correctly represents the constitution of theanhydride formed by the dehydration (by acetyl chloride) of thenormal form of the acid, it is obvious that the first product ofhydration of this anhydride must be the acid (111), called thORGANIC CHEMISTRY.87labile acid. I n the case of glutaconic acid itself, only the normalform (I) is known, and the non-isolation of the labde form (111)YH- CO, H EH-CO dehydrationCH :C( OH) CH*CO,H( p 2YH >o t-s H * CO,KCH,*CO,H(111.) Labile acid(nnknown for glataconic acid).YHis accounted for by the supposition that a t the moment of itsformation from the hydroxy-anhydride, the initial momentum ofthe entering hydrogen atom is sufficient to carry it a t once intothe three-carbon system. If, however, the initial momentum isdecreased by the introduction of an alkyl group on one of thecarbon atoms, it is possible to cause the hydrogen atom to remainwithin the carbonyl system by effecting the hydration of thehydroxy-anhydride by strong alkali or dilute alkali in the presenceof casein.If, however, the hydrolysis is brought about by wateralone or dilute alkali without casein, then the normal acid results,Thus, for a-methylglutaconic acid, we have:vMo*CO,H-? p,a,ks~i alone CH*CO,HNormal acid,gMe* C0,HCH,. CO,HEMe--CO ailUte?I3 m. p 145-146".CH: C(0H) >O StroDGalkali(?= Hydroxy-anhydride, -2m. p. 74.5".Labile acid, m. p. 118".The labile acids are the so-called cis-forms of the acids of thisseries. It is evident that a labile acid should be capable ofexisting in cis- and trans-modifications, but in the case of thesimpler members of the series the very unstable character of thelabile acids causes them to pass into the stable normal form byall reactions which should give the fumaroid modification. Thestability of a labile acid, however, is greatly increased by thepresence of a heavy group attached t o one of the terminal carbonatoms of the three-carbon system, more especially if a methyl groupis also present attached t o the central carbon atom of the system;in other words, the labile form of a-benzyl-P-methylglutaconic aci88 AKNUAL 1tEPORl'S ON THE PROGRESS OF CHEMISTRY.might be sufficiently stable to admit of its isolation in both thecis- and trans-modifications.Bland and Thorpe 47 have conse-quently prepared this substance, and find that the labile acidwhich they obtain has the truns-configuration, and all attempts toget the corresponding cis-form have been unsuccessful :CH,Ph*#*CO,H CH,Ph *$*CO,HYHMe YMe -CH-CO,H CO,H* CH,The fact therefore remains that up to the present no labile formof a glutaconic acid has been obtained in both cis- and truns-modifications.The reactions of substituted glutaconic acids of thetype CO2H*CR,CH:CI-T*C0,H, in which there is no mobilehydrogen atom, are normal in all respects, and the isomerism ofthese acids is of the ordinary cis- and trans-variety, thus:Noririal acid, In. p. 148". tram-Labile acid, m. 1). 134".CO,H*CHCO,H* CR,*C 13cis-form.CO,H-EHCH CR,*CO,Htrans- form.If the dehydration of the substituted glutaconic acid,a-methylglutaconic acid, is effected by the use of phosphorus penta-chloride 48 instead of acetyl chloride, then the anhydride producedis the ordinary anhydride, CHGCHR' CH- CO 'O>O ; these ordinaryanhydrides, when distilled, are converted into the hydroxy-anhydrides :Aconitic acid may be regarded as a @-substituted glutaconicacid, and it follows, from what has been said about the glutaconicacids, that aconitic acid should exist in the normal form (I) andthe labile form (11); moreover, since it is a @-substituted acid, thestability of the labile form should be sufficient to admit of itsisolation.49-$lH*COzH EH*CO,HYH-CO,H $?*CO,H-CH*CO,H CH,* CO,H(I.1 (11.)Normal aconitic acid.When aconitic acid is treated with ordinary acetyl chloride,Labile aconitic acid.47 T., 1912, 101, 1744.4* F. Feist and G. Pomme, AnnaZen, 1909, 370, 61 ; A , , 1910, i, 9.49 N. Bland and J.F. Thorpe, T., 1912, 101, 1490ORGANIC CHEMISTRY. 89which always contains phosphorus trichloride, it is converted intothe normal anhydro-acid50 (IV), melting a t 76O, whereas if pureacetyl chloride be used, then the product is the hydroxy-anhydro-acid (111), melting a t 135O. That formula I11 correctly representsthe constitution of this latter substance is proved by t'he fact thatit gives an intense coloration with ferric chloride, behaves as adihasic acid, and on heating undergoes the following changes:heated just abovo -S/H*Co2H heated -+ -$ $!H-CO >O at 170" cH.c(oH)>~ its melting point2 H C0,Hf."--co ----CH*CO(111.) M. p. '135". (IV.) M. p. 76".Itacoiiic anhydride. Citraconic anhydride.When the normal anhydro-acid (IV) i s treated with strong alkalior dilute alkali in the presence of casein, it gives the ordinaryform (I) of aconitic acid (m.p. 19l0), whereas the hydroxy-anhydro-acid (111), when similarly treated, gives the Iabile form(11) of aconitic acid, melting a t 1 7 3 O .The labile acid is a comparatively stable substance, which,although exhibiting no points of difference from normal aconiticacid in respect of its salts, yet differs markedly from this acid inits behaviour on dehydration, since on treatment with pure ofimpure (containing phosphorus trichloride) acetyl chloride it iscompletely converted into the hydroxy-anhydro-acid. When boiledwith dilute hydrochloric acid, the labile acid is slowly convertedinto the normal acid.The reactivity51 of the acid dichlorides of fumaric acid and itshaloid derivatives is very much greater than that of the correspond-ing compounds of maleic acid.Thus, whereas all fumaroiddichlorides react almost instantaneously with aniline t o formanilides, and with methyl alcohol to form esters, the interactionbetween malenoid dichlorides and bases or alcohols is very muchslower, and in some cases requires days before it approaches com-pletion. This low reactivity of the malenoid dichlorides cannotbe due t o the proximity of the two *COCl-groups, for if this wereso, then s-o-phthalyl chloride should also act slowly, whereas experi-ments show that the opposite is the case. These differences inreactivity are explained by assigning a cyclic ketonic structure,R.Anschiitz and W. Bertram, Ber., 1904, 37, 3967; A., 1904, i, 972 ; com-pare Easterfield and Sell, T., 1892, 61, 1009.51 E. Ott, Anmlen, 1912, 392, 245 ; A., i, 82890 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.>0, t o the malenoid dichlorides, the reaction between * t C O*C*CCI ,these subs€ances and aniline being formulated thus :Rl'~-co>O + NH,Ph - Rl*~*C(oH)*NHPh >o -+ R, C* CCI, R, C--- CCI,R,*g*CO*NHPh + HC1R,*C*COCIthe remaining *COCl-group reacting in the usual way.Much evidence can be brought forward in support of this viewas to the constitution of the malenoid dichlorides, for instance,the aluminium chloride compound of chlorofumaryl dichloride isa yellow mass, melting a t 50°, and from which the chlorofumaryldichloride is regenerated by treatment with water a t 00.If,however, the yellow mass is warmed, its colour deepens, andeventually becomes reddish-brown ; the substance now melts a t 1000,and is the aluminium chloride compound of chloromaleyl dichloride,because it yields this substance on treatment with water. Thisdeepening in colour is in agreement with the formula now assignedto the malenoid dichlorides, since the aluminium chloride com-pounds of cyclic ketones are intensely coloured. The aluminiumchloride compound of chloromaleyl dichloride, when heated a t180-230°, gives carbonyl chloride as one of its decompositionproducts, a result which strongly supports the cyclic formula,especially as no acid chloride has hitherto been known to givecarbonyl chloride on heating. Further, the two carbonyl groupsbeing in conjugated positions in the fumaroid dichlorides, shouldconfer on these substances a degree of unsaturation much greaterthan that of the malenoid dichlorides, which have only one carbonylgroup, and this conclusion is proved to be correct by experiment.chloromaleyl dichloride has been obtained in two forms, whichcan be easily converted into one another, and this observationsupports the formula now assigned t o this substance, sincey-lactonea are frequently dimorphous.Lastly, the molecularvolume of chlorofumaryl dichloride exceeds that of chloromaleyldichloride by 4.4 units, which is in close agreement with thedifference calculated on the assumption that the latter compoundhas a cyclic structure.By the action of barium peroxide on an ethereal solution ofacetic anhydride, Clover and Richmond 69 obtained acetic peroxide,and showed that this substance in aqueous solution graduallyhydrolyses to molecular proportions of acetic acid and peraceticacid, and further, that the per-acid itself decomposes into aceticacid and hydrogen peroxide.These observers were, however,62 Amer. Chem. J., 1903, 29, 179 ; A . , 1903, i, 396ORGANIC CHEMISTRY. 91unable to isolate the peracetic acid. It is now shown63 that thereaction, R*CO*OOH + H,O ++ R*CO,H + H,O,, is reversible, andthat the reaction in the direction right to left is brought intoeffect by the use of such catalysts as sulphuric acid, nitric acid,etc.I n actual practice, the per-acid is best obtained by theinteraction of the acid anhydride and hydrogen peroxide in thepresence of sulphuric acid,(R*CO),O + H202= R*C02H* + R*CY)*OOR,and subsequent distillation of the mixture under diminishedpressure. The substance may also be conveniently prepared bydecomposing the mixed anhydride of boric acid and the organicacid with hydrogen peroxide,R(OAc), + 3H,02= 3Ac0,H + B(OH),.Peracetic acid is a clear, colourless, pungent liquid, soluble inwater, alcohol, ether, or sulphuric acid. I t s aqueous solution iscomparatively stable, but acids, alkalis, and salts hasten itshydrolysis to hydrogen peroxide and acetic acid. It is extremelyexplosive, and when slowly heated to llOo it explodes violently.It attacks the skin, and acts as a powerful oxidising agent, convert-ing aniline and ptoluidine into the corresponding nitroso-compounds, and manganese salts into permanganates.Per-propionic, perbutyric, and performic acids have also been prepared ;the latter is not stable a t the ordinary temperature, and couldonly be obtained as a 48 per cent. solution.Hydrochloric or hydrobromic acid is capable of convertingferricyanic acid into ferrocyanic acid 54 with evolution of chlorineor bromine, which proves that the reaction:2H4Fe(CN), + C1, + Aqc+2H3Fe(CN), + 2HCl+ Aq,is reversible. I f the halogen is removed as quickly as it is formed,and this may be done by means of silver for the chlorine, andphenol or chloroform for the bromine, then the whole of the ferri-cyanic acid is converted into ferrocyanic acid. Theoretical con-siderations lead to the conclusion that the precipitate obtained bymixing solutions containing equivalent amounts of cupric andferrocyanogen ions should have the same composition as thatobtained under similar conditions from cuprous and ferricyanogenions, and this is confirmed by experiment.65 The precipitateobtained from cupric sulphate and potassium ferrocyanide has aconstant composition only if one of the two components is in largeexcess; if the ratio CuS04: K,Fe(CN), is greater than 2.5, thena J.D'Ans and W. Frey, Ber., 1912, 45, 1845 ; A . , i, 601.51 C . Gillet, Bt~1.l. SOC. china. Be@, 1912, 26, 236 ; A . , i, 614.55 E. Muller, G .Wegelin, and E. Kellerhoff, J. pr. Chern., 1912, [ii], 86, 82A., i, 61492 ANNUAL XEPOKTS ON THE PROGRESS OF CHEMISTRY.the precipitate has the composition Cu”,Fd(CN),, but if the ratiohas a lower value, then the precipitate contains potassium as oneof its constituents.The electrolytic reduction of alkyl derivatives of ethyl aceto-acetate has been regarded hitherto as taking place in accordancewith the scheme :CH3*UO*CHR*CO,Et -+ CK3*C€12*CHK*CH,.A careful comparison of the boiling points of the hydrocarbonsresulting from these reductions with the boiling points of hydro-carbons of known constitution has led Tafel56 to the conclusionthat the reaction is not as expressed above, but that the methylgroup resulting from the reduction of the carbethoxy-group occursas part of the main chain and not as a side-chain.Thus, takingethyl isobutylacetoacetate, CH,*CO*CH(CO,Et)-CH,*CHMe,, as anexample, it should give, according to the old scheme, the hydro-carbon CH,*CH,.CH(CR,)*C~,*CHMe,, the boiling point ofwhich is 110°/763 mm. The boiling point of the product isolatedwas 117~5-118°/760 mm., which agrees with that of the hydro-carbons which would be formed according to the scheme nowproposed by Tafel:*CH,*CHz*CHz*CH2*CH2*CH<~~~ f- CH3*CO*$lH*CH2*C 11 <:;:B. p. 116‘/761 mm. Y--...- *CO,Et 3 7%--3 CH,-CH~~CH,~CH,~CK.CB,.C*‘H,B. p. 117*6”/760 nim.Wislicenus57 is of opinion that of the four known forms ofethyl formylphenylacetate only two are chemically individual ;these are: the liquid a-form, which is the enolic modification,OH*CH:CPh*CO,Et, and the solid y-form, m.p. about looo, whichis the enol-aldu-form, CHO*GPh:C(OH)*OEt. The other twoforms: the &modification (m. p. about 70°) and Michael’s modifi-cation (m. p. about 50°), he regards as mixtures of the a- andy-modifications. The modification melting a t about 70° has beenregarded hitherto as the true aldo-form, CHO*CHPh*CO,Et, butWislicenus’s view as to its composition is supported by Meyer,58who finds that the compound is entirely enolic. Michael 59 is alsoof opinion that the solid modification melting at about 70° is amixture, but recognises the existence of three forms of ethylformylphenylacetate : the a-ester, boiling a t 125--126O/9 mm.,56 Ber., 1912, 45, 437 ; A ., i, 234.57 Annalcn, 1912, 389, 265 ; A . , i, 623.Bs Ber., 1912, 45, 2843 ; A., i, 940.59 AnnuZen, 1922, 391, 235, 2 i 5 ; A., i, 861ORGANIC CHEMISTRY. 93&ester, melting a t about 40°, and the y-ester, melting a t aboutlooo.Michael's 60 statement that ethyl 1-methylcyclobutan-3-one-1 : 2 : 4-tricarboxylate (I) is formed by the condensation of ethyl citracon-ate with ethyl sodiomalonate in alcoholic solution is now 61 shownto be incorrect, the substance actually formed being ethyl CYC~O-pentan-2-one-1 : 3 : 4-tricarboxylate (11) :CH,. QH CO,E t C O , E t * ~ H - ~ O CO, Et*CH<CO,Et*CMe*CH*CO,Et CO-CH*CO,Et(I. 1 (11.)I f the condensation is carried out in such a manner that noconsiderable elevation of temperature occurs, then the product isethyl but ane-aj366-t etr acarboxylat e,CO,E t*CH,*CH(CO,Et)-CH,*CH(CO,Et),.This compound is, no doubt, an intermediate substance in theformation of the above cpclopentanone, and its production by thecondensation of ethyl citraconate and ethyl sodiomalonate is in allprobability due to the act)ion of traces of sodium ethoxide on theethyl citraconate, whereby it is transformed into ethyl ethoxy-methylsuccinate.This compound by the loss of alcohol gives ethylitaconate, CH,:C'(CO,Et)*CH,*CO,Et, which on condensation withethyl sodiomalonate, in the normal way, gives ethyl butane-apbb-t e t r acarboxylat e.The condensation of ethyl citraconate with ethyl sodiomalonatein ethereal solution has always been assumed to take place inaccordance with Michael's positive-negative rule.According toMichael, the negative portion, *CH(CO,Et),, of ethyl sodiomalon-ate should attach itself to that carbon atom in ethyl citraconate towhich the methyl group is joined, since this carbon atom, owingto the presence oi the methyl group, is more positive than the otherwhich has the hydrogen attached to it. The product would thus beethyl p-methylpropane-aa/3y-tetracarboxylate :C'0,E: t. C ,\I P C? 13 .CC E t -+ CII( CO, I3 t )2 C: Me( ('O,Ett)*C'H,* O,? E t,Thi; is now shown to be incorrect, and the compound actuallyformed when the condensation takes place in solvents like etherand benzene, which do not react with sodium, is ethyl butane-aafly-tetracarboxylate, (CO,Et),CH*CH(CO,Et)-CTHMe*CO,Et.Ruleslike the one enunciated by Michael are of little value in deter-mining the course of a condensation like the one under discussion.It seems much more probable that steric influence is the pre-dominating factor in condensation of this type, there being gener-ally great resistance to the formation of a quaternary carbon atom,Bw., 1900, 33, 3731 ; A., 1901, i, 123 ; Michael mid Schulthess, J. pr. Chem.,1892, [ii], 45, 55 ; A., 1892, i, 591. E. H o ~ J ~ , T., 1912, 101, 89294 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.more especially if the groups involved have a large molecularmagnitude.Curb ohydrat es.A new anhydride, anhydromethylglucoside, C,H,,O,, has beenobtained by Fischer and Zach 62 by warming triacetylmethylgluco-side bromohydrin with barium hydroxide solution.This anhydridedistils undecomposed a t very low pressure, forms a crystallinehydrate, and is not converted into sugar by emulsin, but acidshydrolyse it easily to a crystalline compound, C'6H1005, which isregarded as an intramolecular anhydride of dextrose, andprobably represents a new type of sugar derivative. It differsfrom the hexoses in that it restores the colour to Schiff's reagent,but strongly resembles them in many other respects, as, for instance,in its reactions with phenylhydrazine and alkalis, and in itsbehaviour on reduction and oxidation. The fact that the anhydro-sorbitol obtained from it is isomeric with styracitol, a naturallyoccurring substance isolated by Asahina 63 from Styrax obassia, isevidence in support of the view that the anhydrides of dextroseand of glucosides occur in nature.Anhydrogluconic acid probablyhas an OH group attached to its y-carbon atom, since it veryreadily forms a lactone; further, since the anhydrodextrose fromwhich it is derived forms an osazone, it follows that the onlyformulae possible for anhydrogluconic acid are limited to the threefollowing :CH,*CH*CH( OH)*CH(OH) CH (OH) *CO,H,I--() _ICH, * C H( OH) CH (0 11) CH C H( OH) CO,H,I -0 -1CH,(OH)*CH*CH( OH)*CH* CH(0H) *CO,H.I-_ 0-1Lack of material unfortunately prevented any definite conclusionbeing arrived a t as to which of these three formulae is the correctone.d-Glucosamine is the first well-defined carbohydrate compoundisolated from animal tissue, and although numerous attempts havebeen made to convert it into the corresponding hexose, these havehitherto proved unsuccessful.It is true that Tiemann 64 isolatedphenylglucosazone from it, but the osazone was obtained in asmall yield, and its melting point was inconclusive; further, theformation of the osazone still leaves open the possibility that62 Ber., 1912, 45, 456, 2068 ; A., i, 239, 678.G3 Arch. Pharm., 1907, 245, 325 ; 1909, 247, 157 ; Ber., 1912, 45, 2363 ; A.,1908, ii, 59 ; 1909, i, 288 ; 1912, i, 832.Ber., 1886, 19, 5 0 ; A., 1886, 329ORGANIC CHEMISTRY. 95glucosamine may be derived from mannose, and not from glucose.Attempts to eliminate the amino-group from glucosamine bynitrous acid or the silver nitrite method of Fischer do not lead t oa simple hexose, but to a hydrated furan derivative known aschitose.Now chitose also results from the dehydration of a hexose,and it was thought that if the bydroxyl groups in glucosamine weresubstituted the resulting compound would have its amino-groupremoved by the action of nitrous acid in the normal way, and thata derivative of the parent hexose would result. In the course ofan investigation based on the above considerations, Irvine andHynd66 obtained a methylglucosamine, which a t first appeared asif it might be identical with an aminomethylglucoside obtained byFischer and Zach 66 from dibromotriacetylglucose. If these twocompounds had proved to ba identical, this would have meant thedirect synthesis of glucosamine from glucose.A close comparisonof the properties of these two compounds has shown, however, thatthey are not identical, but isomeric, and it is concluded that themethylglucosamine prepared by Irvine and Hynd is a-aminomethyl-glucoside, whereas in Fischer’s aminomethylglucoside the amino-group may occupy the j3-, &, or €-position. As the conversion ofa-aminomethylglucoside (methylglucosamine) into methylglucosidecannot be carried out directly, it was methylated by the silveroxide reaction, and thus converted into a-dimethylaminomethyl-glucoside, from which the dimethylamino-group was removed byheating with barium hydroxide. As the resulting methylglucosidecould not b8 crystallised, it was completely methylated, and thetetramethyl methylglucoside purified by fractional distillation.The hydrolysis of this tetramethyl methylglucoside was effected intwo stages: the first stage gave tetramethylglucose, the identity ofwhich was proved by its melting point and specific rotation; andthe second stage gave d-glucose, which was also fully identified byits specific rotation, and the specific rotation and melting point ofits osazone.The conversion of glucosamine into glucose by Irvine and Hynd 137has thus been effected through the following reactions:d-Glucosamine hydrochloride (from chitin obtained from lobstershells) -+ bromotriacetylglucosamine hydrobromide -+ triacetyl-aminomethylglucoside hydrobromide -+ aminomethylglucosidehydrochloride -+ methylaminomethylglucoside -+ dimethylamino-methylglucoside -+ [methylglucoside] -+ tetramethyl methylgluco-side -+ tetramethyl glucose-+ d-glucose.The evidence is in favour of the view that no Walden inversion6b T., 1911, 99, 250.67 T., 1912, 101, 1128.66 Ber., 1911, 44, 132; A ., 1911, i, 17796 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.takes place during the series of changes which leads from d-glucos-amine to d-glucose, and that the former must consequently beregarded as a-amino&-glucose.Constitution of a-Aminomethylglucoside and i t s HomoZogue8.-The adoption of the formula1- 0--,NR2OH*CH,*CH(OH)*CH*CH(OH)* f: H*CH*OMe(where R=Me or H) for a-aminomethylglucoside and its N-alkylhomolopes is, generally speaking, in accord with the properties ofthese substances.Several objections, however, can be raisedagainst this formula; for instance, the very great difficulty withwhich it is hydrolysed, whereas such substances as a- and &methyl-glucosides, Fischer’s isomeric aminomethylglucoside, etc., are com-paratively easily hydrolysed. This resistance to hydrolysis is inti-mately connected with both the presence and position of thenitrogen atom as shown by the remarkabIe fact that when treatedwith cold dilute nitrous acid i t yields a product which has avigorous action on Fehling’s solution. The glucosidic part of themolecule thus seems to be affected whenever the amino-group isattacked.This points to the existence of a betaine-like structure in themolecule, thus :,-O-OH*CH,*CH (OH)-~H.CH(OH)-~: H-+H.N--0/ I \H H MeEvidence in support of this formula is afforded by the fact thatboth ammonia and methylamine are produced when the substanceis heated with sodium hydroxide.Only monohydric phenols have hitherto been used in the pre-paration of phenolic g’ucosides, although it is true that polyhydricphenols have been combined with sugars, but the products were ofa complicated nature, and were not ordinary glucosides.Fischerand Strauss 68 have now succeeded in preparing phloroglucinol-d-glucoside by shaking an alkaline solution of phloroglucinol withan ethereal solution of acetobromoglucose, and subsequent removalof the acetyl groups. This synthetic glucoside is identical withthe phloroglucinol-glucoside obtained by Cremer and Seuffert 69 bythe action of barium hydroxide on phloridzin, and both are hydrelysed by emulsin.Phloroglucinol-glucoide is of physiologicalinterest, because it is capable of producing diabetes. Resorcinol-Ber., 1912, 45, 2467; A . , i, 884. 63 Ibid., 2565 ; A,, i, 885ORGANIC CHEMISTRY. 97d-glucoside and 2 : 4 : 6-tribromophenyl-d-glucoside have also beenprepared by a similar method.The presence of maltose amongst the produck3 of acid hydrolysisof starch has been denied 'by early workers, but in recent yearsWeber and Macpherson 70 and others have demonstrated the presenceof as much as 20 per cent. and more of maltose in commercialglucose prepared by the acid hydrolysis of starch. This is nowconfirmed by Fernbach and Schoen,71 who have isolated and com-pletely identified maltosazone from the interaction of phenyl-hydrazine and the products of hydrolysis of starch mucilage byacids under pressure.These observers regard the processes ofhydrolysis of starch by malt diastase and by acids as essentiallyidentical, tho only difference being that in the former case thehydrolysis stops a t the maltose stage, whereas in the latter it goesa stage further.When the sugars dihydroxyacetone, erythrulose, lzvulose, sorbose,and perseulose in aqueous solution are exposed in quartz tubes tosunlight or ultra-violet light, they are decomposed into carbonmonoxide, a little carbon dioxide, and the alcohol correspondingwith the original sugar, but containing one carbon atom less.When starch in solution is exposed to X-rays it is converted intosoluble starch and dextrin.72The dehydration73 of starch in a vacuum containing phosphoricoxide shows that a t 2 5 O as much as 28 per cent, of the starch isconverted into water-soluble matber; this rises to 57 per cent.a t50°, and to 90 per cent. a t 1 2 0 O . The conversion of starch intodextrins is regarded as essentially a process of dehydration ratherthan hydrolysis, a supposition which is supported by the fact thata much better yield of dextrins is obtained when the starch isheated alone than when i t is heated with water. Starch is regardedas consisting of molecular aggregates or complexes of C6HI0O5,which are held together by water, thus:{[(CGH,,O,*OH)H],[(C,H,,O,*OH)J,H,- ,}H***.I n the process of dehydration the loss of water causes a breakingdown of these complex aggregates into simpler ones, and it is thusthat, the various dextrins result.Starch paste is converted by Bacillus macerans into substancesJ.Amer. Chew, Soc., 1895, 17, 312 ; A., 1895, ii, 296.Bull. SOC. chim., 1912, [iv], 11, 303 ; A., i, 336.7'J D. Berthelot and H. Gaudechon, Compl. rend., 1912, 155, 401 ; A . , i, 750 ;H. A. Colwell and S. Russ., PTOC. Physical SOC., 1912, 24, 217 ; A , , i, 608;J. Bielecki and R. Wurmser, Compt. re?<., 1912, 154, 1429 ; A . , i, 538 ; L. Massol,ibid., 1645 ; A., i, 538 ; J. Stoklasa, J. Sebor and W. ZdobnickJi, Biochem. Zeikclh.,1912, 41, 333 ; A., i, 606 ; W. Lob, ibid., 1912, 43, 434 ; A., i, 750.'8 G.Malfitano and Mlle. A. Moschkoff, Compt. rend., 1912, 154,443 ; A., i, 240.REP.-VOL. 1X. 98 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.completely soluble in water, and from these two crystalline dextrins,a- and 8-, have been isolated.74 The a-isomeride crystallises incolourless, hexagonal plates or lancetrshaped needles, has [a], +12P, and is doubly refractive ; determination of its molecularweight by the cryoscopic method gave values corresponding with(C6H1005)4, The P-isomeride crystallises in rhombic crystals, andhas [a]= + 1 3 6 O ; owing to its insolubility its molecular weight couldnot be determined. The generic term amylose is proposed for thepolysaccharides having the formula (CsHloOj)n.On acetylationthe a-isomeride gives a hexa-acetate, and the &compound gives anona-acetate, a result which shows that hydrolysis of the dextrinshas taken place simultaneously with the acetylation. These acetylderivatives on hydrolysis give respectively diamylose,and triamylose, (C6H,o05)3,4H20, each of which crystallises inneedles and does not reduce Fehling’s solution. The originala-dextrin is therefore tetra-amylose, and the 6-dextrin, from itsanalogous behaviour to the a-compound, is regarded as hexa-amylose,Gerber75 has shown that hydrogen peroxide, even in very dilutesolutions, is a very powerful agent for the hydrolysis of starch, theproducts being maltose and dextrins. I f concentrakd solutionsof the peroxide are used, the maltose is oxidised.Scyllite from the kidneys, etc., of certain plagiostomous fishes,quercine from acorns, and cocosite from Cocos plumosa and Cocosnucifera, are now shown to be identical, and it is proposed that infuture they should all come under the heading “ scyllitol.” 76 Theisomeric substance inositol has been obtained in two new forms:isoinositol and $-inositol.Harden and Young77 have published a detailed account of amethod by means of which glycogen free from nitrogen, yeast-gum,and pracGcaIly free (0.02 per cent.) from ash can be obtained fromyeast.Details are also given for the isolation of the yeast-gumfrom the glycogen mother liquors.When dry cotton78 is submitted to the action of ozone (2 percent.) a small quantity of carbon dioxide is evolved, and a celluloseperoxide and an acid derivative are formed; the properties acquiredby the cotton as a result of this treatment being very similar tothose possessed by cotton and linen which have been bleached byF.Schardinger, Centr. Bakt. Par., 1911, ii, 29, 188; A., 1911, i, 181 ;H. Pringsheim and A. Langhans, Ber., 1912,45, 2533 ; A., i, 832.Compt. rend., 1912, 154, 1543; A,, i, 538.(C6H1005)2,2H20,(CBH1005)6.76 H. Miiller, T., 1912, 101, 2383.77 ., 12, 101, 3928.78 Miss M. Cunninghain and C. Dorke, ihid., 497ORGANIC CHEMISTRY. 99chloride of lime and washed without the use of an '' antichlor." 79When the ozonised cotton is boiled with water or digested withalkali the acid derivative is removed, and the residual neutralproduct closely resembles the typical oxycelluloses.I n the indw-trial method of bleaching by alternate treatment with ozoneand bleaching powder, both the peroxide and the acid derivativeplay a part, the peroxide being decomposed by the bleachingpowder, and the acid derivative increasing the activity of thebleaching powder.When benzene is added to a solution of cellulose in sulphuricacid the hydrocarbon and the carbohydrate combine to form acompound which appears to have the composition C,H,O,Ph, ;toluene, xylene, and $-cumene also form analogous compounds, forwhich the generic term desoxyn is proposed. The carbohydrateresidue appears to enter the benzene nucleus in the para-positionrelative to the methyl group. Dextrose, like cellulose, also combineswith benzene to produce a desoxyn, for which two formulz aresuggested : (1) c6H,0,Ph,, representing the anhydride of dextrose,in which three hydroxyl groups are replaced by phenyl groups;(2) C,H,O,Ph,, according t o which the formation of the desoxynwould be represented by the equation:When a desoxyn is oxidised by permanganate i t gives the aromaticacid corresponding with its aromatic constituent, thus : phenyldes-oxyn gives 45 per cent.of benzoic acid, and tolyldesoxyn gives20 per cent. of terephthalic acid.80Mixtures of alcohols and ethers possess the property of dissolvingcertain varieties of nitrocellulose, although the latter compoundsare insoluble in either component. Baker81 has determined theviscosity of such mixtures, and concludes from his results that theycontain an ether-alcohol complex, and to this complex he atkri-butes the solvent power of the mixtures for nitrocellulose.Although the results show that dissociation of the alcohol,(R*OH)n 2 nR*OH,does take place, yet the function of the ether cannot be merelythat of a dissociating solvent. For if this were so, and assumingthat the solvent action is due to the non-associated alcohol, then itshould he possible to replace the ether by other indifferent liquidswithout decreasing the solvent power of the mixtures, a deductionwhich experience proves to be incorrect.Further, if the solventA. M. Nastukoff, J. Rws. Phys. Chcnt. Soc., 1902, 34, 231, 505 ; A., 1902, i,362, 747 ; Zeitsch. Farb. Ind., 1907, 6, 70 ; A., 1907, i, 413 ; A.M. Nastukofl'and1. I. Kotukoff, J. IZuss. Phys. Chem. SOC., 1912, 44, 1152; A . , i, 762.CCHIoOj + 2CGHG - 3H2O = C18H16O2.79 Cross and Bevan, Zc'itxh. nngczu. Chein., 1906, 19, 2101.I:, 1912, 101, 1409.I3100 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,action is dependent entirely on the dissociation of the alcohol, thenthe higher alcohols should prove better solvents than the lowerones, since they are less associated, whereas the opposite is the case.Nitrogen Compounds.Amines.-The new method for the separation of tertiary fromsecondary and primary asmines which has been worked out byHibbert and Wises2 is based on the instability of the additive com-pounds of the Grignard reagent with tertiary amines, and is, briefly,as follows: To the mixture of amines, either alone or dissolved inether, is added an excess of an ethereal solution of magnesium ethylbromide (or methyl iodide), and the ether distilled off.Theproduct is then heated in an oil-bath to 200-280° (dependingon the nature of the amine), whereupon the pure tertiary aminedistils over. The primary or secondary amine may be recoveredfrom the residue by addition of sodium hydroxide and steamdistillation.The results of an investigation83 of the action of acetyl chlorideon various organic bases show that in the majority of instancesan additive compound of the base and the acid chloride is theinitial product; this is certainly always the case with tertiary bases,and the compound formed has the composition R,N,CH,*COCl.This last statement is contrary to the view generally accepted thattertiary bases have no affinity for acid chlorides, and the compoundsnow described are the first of their kind.Zmino-compounds.-From the results of his researches on ‘‘ theformation and reactions of imino-compounds,” Thorpe 84 has formu-lated the following generalisations : (1) the imino-compounds reactwith sodium ethoxide in their amino-form only; (2) the 8-imino-derivatives of the ay-dicarboxylic esters are then derivatives ofglutaconic ester, and conform, as such, to the third generalisation;(3) compounds containing the complex X,C:CR*CH,X, in which Xmay be any negative group and R any univalent radicle or group,react with sodium ethoxide so as to retain the mobile hydrogenatom, and therefore yield sodium derivatives of the typein which the mobile hydrogen atom is hepresented by (*).Thereplacement of the sodium in this compound by an alkyl groupyields the alkyl derivative, X,C:CR*CHRX, and the action ofsodium ethoxide on this substance causes the replacement of themobile hydrogen atom, but the metal then takes up the mostX,C:CR&N~X,T., 1912, 101, 344.w W. M. Dehn, J. Amer. C’hem. Soc., 1912, 34, 1399 ; A . , i, 833. * T., 1912, 101, 249ORGANIC CHEMISTRY. 101negative position in the system, yielding the sodium derivative,X,CNa*CR:CRX. In certain cases the compound X,C:CR*CNaRXis also formed, but to a small extent only. The following may betaken as an illustration : CO,Et*CH(CN)*C'(NH)*CH,*C"O,Et reactsas CO,Et*C(C'N):C'(NH,)*CH,*CO&t, which with sodium ethoxideand methyl iodide yields first CO,Et*C(@N)X(NH,)*CHMe*CO&t,and then, by further action, a mixture of the two dimethyl deriv-atives, CO,Et*CMe(CN) C(NH,) :CMe*CO,Et andCO,Et*C(CN) :G'(NH,) *CMe,*CO,Et.d mides.---Storch,s5 by the oxidation of thiocarbamide, obtaineda substance having the constitutionNH,*C(:NH)*S*S*C( :NH)*NH,,which is named formamidine disulphide by Fichter and Wenk,86who have recently obtained it by the electrolytic oxidation of t h bcarbamide.The formation of this substance from thiocarbamidehas been regarded as strong evidence in support of the unsym-metrical formula, NEI,*C(:NH)*SH, for the latter. It is now shownby Werner87 that the formation of the formamidine by oxidationof thiocarbamide by means of nitrous acid only takes place in thepresence of a strong acid ioniser, such as nitric acid, sulphuric acid,etc.; and that if the oxidation be effected in the presence of aceticacid or other feeble acid ioniser, then the main product of thereaction is thiocyanic acid.To explain these and other factsWerner suggests a slight modification of the unsymmetricalformula for thiocarbamide, and proposes the formula HN:(TcT H3,which represents the result of a combination between the acidgroup, SH, and the basic group, *NH,, of the unsymmetricalformula. This formula affords an explanation of the capability ofthiocarbamide to form salts with the stronger acids only. Alsoweak acids would have no disturbing effect on such a compound,and the action of nitrous acid in the presence of a weak acid wouldbe represented thus :HN:C<?"S + HONO = HSCN + N, + 3H,O.On the other hand, a strong acid, HX, would first form the saltbs -..which would then react with nitrous acid to give formamidinedisulphide and nitric oxide.The formation of nitrogen in the firstcase and of nitric oxide in the second are in complete agreementwith experiment.85 Mon,ntslt., 1850, 11, 452 ; A. 1891, 548.86 Bcr., 1912, 45,1373 ; A . , i, 423.87 T., 1912, 101, 1167, 1982, 2166, 2180102 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.If the formula now proposed be accepted as representing theconstitution of thiocarbamide under normal conditions, that is, ina neutral solution or even in the presence of a weak acid, then anexplanation is afforded for the fact that thiocarbamide can glverise to products derived either from the symmetrical or unsym-metrical structure, thus :nSymmetrical.Norm a1 strut: t w e . Unsymmetrical.Dixon and Taylor 88 are of opinion that ‘ I thiocarbamide,”together with its monohydric substitution derivatives containinghydrocarbon radicles not attached to sulphur, has the configurationrepresented by the typical formula H,N*CS*NH,; so long, a t least,as these compounds remain in the static condition. They object tothe formula NH,*C(:NH)*SH, because a substance having that con-stitution would be (1) probably very unstable, (2) a stronglymarked base The cyclic modification of this formula proposed byWerner is, in tlie opinion of the writer of this report, free fromthese objections.The formation of carbamide from ammonium cyanate can nolonger be regarded as entirely due to isomeric change; nor to aninteraction between ammonium ions and cyanate ions, since ammon-ium cyanate in 90 per cent.alcohol is converted into carbamideabout thirty times as fact as when dissolved in water; further, puredry solid ammonium cyanate is readily transformed into ureawhen heated. The view that the carbamide results from the inter-action between free ammonia and free cyanic acid has been putforward by Michael and Hibbert,89 and is now supported by Chatta-way,M who regards the interaction between these two substances asdue to the tendency of the carbonyl group to add on groups suchas g>XH or R-OH.Chattaway formulates the reaction thus:NH,*N:U:O H*N:C:O+NH, Z HN:C<OH H,N*CO*NH,.NH2The formation of alkyl-carbamides from isocyanic esters, ofcarbamic esters from carbamide and alcohols, etc., can be explainedin a similar way.Wheeler 91 and others introduce the idea of partial valency to* 3 T., 1912, 101, 2502.T., 1912, 101, 170.y1 J. Amcr. Chem. Soc., 1912, W, 1269 ; A . , i, 752.8y Aiwt. Ikport, 1909, 70ORGANIC CHEMISTRY. 103explain the interaction of ammonia and cyanic acid, which theyexpress thus :H*N*C:OA ntino-acids.-The glycerides of amino-acids when obtained willfio doubt prove of great physiological interest, but all attempts toprepare these compounds have so far proved unsuccessful 92; thusglycerol and glycine do not combine when heated alone or in thepresence of hydrogen chloride or sulphuric acid, nor does silverglycine react with the monohalohydrins of glycerol. Bromoiso-valeric acid, sulphuric acid, and glycerol, however, interact whenthe mixture is heated at 70--80° to give bisbromoisovalerylglycerol,OH-CH(G'R2*O*C0.C,H,Br),, and it was thought that the bromineatoms in this compound would be readily replaced by the amino-group, but all attempts to do this by means of aqueous, alcoholic,or liquid ammonia only resulted in the hydrolysis of the compoundand formation of a halogenated acid amide.When glycerol and anamino-acid are heated together, the glycerol appears to act as adehydrating agent, with the result that the anhydride93 of theamino-acid is formed; in fact, this is a convenient method forpreparing these substances; thus an 80 per cent.yield of diketo-piperazine is obtained when glycine and four to five times its weightof glycerol are heated together a t 170° for some hours, By thesame method sarcosine and alanine are transformed into theircyclic anhydrides, and leucine into leucinimide.A new and simple method for the separation 94 of betaine hydro-chloride from molasses residue has been worked out by Stoltzen-berg. It is based on the fact that whereas the solubility of thealkali chlorides and 'of glutamic acid hydrochloride is very muchless in concentrated hydrochloric acid than in pure water, that ofbetaine hydrochloride is slightly greater in the former than in thelatter solvent. The molasses residues are saturated witch hydrogenchloride, and the precipitated alkali chlorides and glutamic acidhydrochloride, etc., filtered ; the filtrate is concentrated, and alcoholadded to the residue, when the betaine hydrochloride, which issparingly soluble in alcohol, is precipitated.The method is applic-able t o the separation of betaine from other mixtures.The aminotyrosine obtained by redhction of the nitro-compoundresulting from the nitration of tyrosine is not 3-aminotyrosine,E. Abdarhalclen and RI. Giiggeiiheim, Zcitsch. physiol. Chem., 1910, 65, 53 ;A., 1910, i, 226 ; R. Alpern and C. Weizniann, T., 1911, 99, 84.9d L.C. Maillard, Compt. rend., 1911, 153, 1078; A., i, 13.9 j Ber., 1912, 45, 2248 ; A . , i, 680104 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.but a mixture of this compound and its isomeride, 2-aminotyro-sine.95Amino-acids readily react with various sugars (dextrose,galactose, maltose, lactose, arabinose, etc.), with evolution of carbondioxide and formation of cyclic condensation products, whichappear to be identical with the melanin pigments obtained in thehydrolysis of proteins. I f this identity is confirmed,it will providean explanation for the comparatively low yield of amino-acidsobtained in those cases where amino-acids and sugars are amongstthe products of hydrolysis.96A synthesis of racemic arginine from ornithuric acid (dibenzoyl-ornithine) as a starting point has been effected by Sorensen,Hoyrup, and Andersen.97 I f ornithuric acid is hydrolysed withwarm concentrated hydrochloric acid 6-monobenzoylornithine isobtained, but by using N/5-barium hydroxide the 6-benzoyl groupis removed, and the product is a-monobenzoylornithine,NH,*CH,*C€€,*CH,*CH(NH*COPh)*CO,H.This on treatment with cyanamide and subsequent elimination ofthe benzoyl group givesNH,*C (:NH)*NH* CH,= CH,*CH,*CR( NH,) *C'O,H,which is found to be identical in every respect with racemicarginine.The isomeric 6-amino-ctguanidino-n-valeric acid was alsoprepared, and found to have quite different properties.An important step in the determination of the constitution ofthe protamine clupeine98 has been worked out.When this sub-stance is nitrated a nitro-compound is obtained, which on hydro-lysis yields nitroarginine ; this nitroarginhe on treatment withnitrous acid by van Slyke's process evolves nitrogen in amountcorresponding with the decomposition of one amino-group. Sinceneither guanidine, nitroguanidine, nor clupeine itself givesnitrogen with this reagent, it follows that the amino-group in nitro-arginine which is decomposed by the nitrous acid is not free inclupeine, but forms part of the main chain. Further, clupeine andguanidine behave similarly when nitrated, and have the same acid-fixing power. It follows, therefore, that the arginine groups inclupeine are linked up thus:***CO*NH*TH--CO-N H-TH*CO*NH***y 3 H 6 y8Hf3NH*C(NH)*NH, NH*C(NH)*NH,95 C.Funk, T., 1912, 101, 1004.96 L. C. Maillard, Compt. rend., 1912, 154, 66 ; A., i, 169.97 Zeilsch. yhysiol. Chem., 1911, 76, 44 ; A., i, 13.98 A. Kossel and A. T. Cameron, ibid,, 1912, 76, 457 ; A., i, 326ORGANIC CHEMISTRY. 105Mercuric acetate (25 per cent. solution) in the presence of sodiumcarbonate is an efficient reagent for the precipitation of amino-acids.99 The precipitate appears to be a ba& salt of a carbamicacid formed from the aminc-acid by the action of the sodiumcarbonate. The amino-acid is readily regenerated by the action ofhydrogen sulphide on the mercury salt:NH,*CH,*CO,H 5'3 COzNa*NH*CH2*C02Ka 3~ H - " ~ ~ > H ~ . H ~ oC H,*C02N€T,*CH,*CO,H + CO,.The methods available for the estimation of the amino-acidsresulting from the hydrolysis of proteins give an approximate resultonly; in fact, in the majority of cases only about 60 per cent.ofthe protein is accounted for from the amount of amineacidsobtained. With the view of devising a more accurate method,Nov6k 1 has studied the action of methyl sulphate on several amino-acids, and finds that methylation occurs a t both the nitrogen atomand a t the carboxyl group, the action being similar to that ofmethyl iodide. With methyl sulphate, however, the action is almostquantitative, and much more easily carried out. An abnormalresult was obtained with Z-aspartic acid, which was converted almostquantitatively into fumaric acid.That proline is a primary product of protein hydrolysis has nowbeen definitely proved by its direct isolation as hydantoin from theproducts of fermentative hydrolysis of casein or gelatin.lapMiscellaneous.NNCarbon pernitride, N~C*N<I I or NiC*N:NiN, has been obtained 2by the action of cyanogen bromide on a well-cooled aqueous solutionof sodium azoimide'; it forms colourless, odourless needles meltinga t 35'5--36O, and soluble in water and the ordinary organicsolvents.It sublimes when heated in a vacuum just above itsmelting point, commences to decompose a t 70°, and explodes veryviolently a t 170-180°; since it is very sensitive to shock, it shouldbe prepared in small quantities only. I n aqueous solution it soonhydrolyses, giving azoimide and carbon dioxide as final producta :99 C.Neuberg and J. Kerb, Biochem. Zeitsch., 1912, 40, 498 ; A., i, 540.* Ber., 1912, 45, 834; A., i, 337.In E. Abderhalden and K. Kautzsch, Zeitsch. pkysiol. Chem., 1912, 78, 96 j A . ,I, 492. G. Darzens, Compt. rend., 1912, 164, 1232; A . , i, 542106 ANNUAL REPOKTS ON THE PROGRESS OF CHEMISTRY.M7hen pure i t is quite stable, but in the presence of traces ofbromine it is converted into a polymeride insoluble in ether.Pure diazomethane3 has been obtained by the addition 6f analcoholic solution of chlo-roforxn t o a hot alcoholic solution ofpotassium hydroxide and hydrazine, a slow stream of nitrogen beingpassed through the apparatus, whereby the diazomethane is removedand then absorbed by ether :H,N*NI-T, + CHCI, + 3KOlC -+ >C:N*NH, + 3KC1+ 38,O>C:N*NH, -3 H,C:NiN.Pure diazomethane boils at - 2 4 O to - 2 3 O , and is an extremelydangerous substance, exploding spontaneously or by contact withiodine, etc.When carbon monoxide is passed through a 1 per cent.ethereal solution of diazomethane and the gaseous mixture heateda t 400--500°, the methylene resulting from the decomposition ofthe diazomethane combines with the carbon monoxide to formketen.A solution of tetranitromethane in petroleum or other paraffinhydrocarbon gives intense colorations with compounds containingethylenic linkings, and can be used as a delicate reagent for thedetection of this class of substance^.^ The coloration is producedby unsaturated hydrocarbons, alcohols, ketones, ethers, esters, andaromatic substances, but not by aromatic nitro-compounds or bymany unsaturated carboxylic acids.The enolic form of a taut+meric compound also produces a coloration with the reagent,whereas the ketonic form does not.Ozonised oxygen produced by the silent electric dischargecontains a t least two allotropic modifications of oxygen, that is,ordinary ozone, 0,, and oxozone, 04, the latter forming about one-third of the “crude” ozone.5 When “crude” ozone is passedthrough sodium hydroxide and concentrated sulphuric acid, theoxozone is destroyed and the residual gas forms normal ozonides.The presence of oxozone in ozonised oxygen accounts for the forma-tion of ozonides containing more oxygen than that correspondingwith their degree of unsaturation, and also for the discordantresults obtained by different workers when investigating the actionof ozone on unsaturated compounds ; thus Ap-butylene when treatedwith ozone, freed €rom oxozone by treatment with sodium hydr-oxide and sulphuric acid, gives the normal butylene ozonide,and bisbutyIeiic ozonide, (C4H80J2; the former is O-YHMeO<O- CHMe’H.Staudinger and 0. liupfer, Bey., 1912, 45, 501 ; A . , i, 245.I. Ostromisslensky, J. pr. C?tm., 3911, [ii], 84, 489 ; A., i, 1.C Harries, Ber., 1912, 45, 936 ; A., i, 407 ; Annalm, 1912, 390, 235 ; A , ,i, 673ORGANIC CH EM ISTHY. 107an oil with a stupefying odour, and the latter an odourless liquid,which explodes a t 1 2 5 O . With ‘‘ crude ” Ozone Afi-butylene gives,not only the normal ozonide, but also butylene oxozonide, C4H80,,and bisbutylene oxozonide, (C,H@,)2.By further treatment with“ crude ” ozone the normal butylene ozonide remains unchanged,whereas the bimolecular form is converted into bisbutylene oxozon-ide. When treated with boiling water all four substances aredecomposed, and yield acetaldehyde, acetic acid, hydrogen peroxide,and oxygen.As an example of the discordant results which have often beenobtained in the past by different workers when studying the actionof ozone on one and the same compound, we may take the caseof the well-defined substance cholesterol. I n 1908 Dor6e andGardiierG obtained an ozonide from it, to which they gave theformula c 2 7 1 3 4 6 0 4 ; in the same year Diels stated that the ozonidecontained more oxygen, and that its formula was C2,H4,O,; lastly,Molinari and Fenaroli8 stated, also in 1908, that the ozonide whichthey had obtained had the composition C2,H4607, and that conse-quently there were two double linkings in the cholesterol molecule.Harries 8a has recently investigated the action of ozone free fromoxozone on cholesterol, and has shown that the ozonide has thecomposition C2.;H,,(OH)03, thus confirming Tschiigaeff’s 9 statementthat the cholesterol molecule contains only one double linking.Bamberger and Suzuki lo have obtained nitroglyoxime in theform of white, silky needles by the action of concentrated nitricacid on glyoxime dissolved in a mixture of ether and water.Sincei t appears necessary that the nitric acid should contain traces ofnitrous acid it is probable that a nitroso-compound is first formed,which is subsequently oxidised by the nitric acid, the reduction ofthe latter affording a fresh supply of nitrous acid:H*$XN*OII HS02 ON y:N*Ot€ RS03 O,N*$XN*OHH*C:N*OH -+ H*C:N-OH ---* I-T*C:N*OH’That the substance is really a nitro-compound and not thenitrite (I) is very highly probable, since i t does not give a typicalLiebermaim reaction, and can also be obtained by the action ofnitrous acid on methazonic acid (11):ON*O*$XN*OH O,N*VH,H*C: N *OH H-C: N~OH(1.1 (11.)Nitroglyoxime has certain properties characteristic of nitrolicacids, in that it dissolves in alkalis to a deep red solution, and givesBcr., 1908,41, 2596 ; A , , 1908, i, 728.T., 1908, 93, 1328.Ibid., 2785 ; A., 1908, i, 882. 8IC L O C . cit.lo Bcr., 1912, 45, 2740; A , , i, 839. 9 Annalen, 1911, 385, 352; A , , i, 30108 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRP.deeply coloured salts. The substance @2H&N3, which Ulpianiobtained by the action of nitric acid on glyoxime, and which heregarded as a furoxan derivative of the constitution :0is now proved to be a mixture of nitroglyoxime and glyoxime.The various methods available for the determination of theproportion of ketonic and enolic isomerides in a deemotropic com-pound were briefly described in last year's report.11 One of these,the bromine @-naphthol process, has been applied recently byMeyer 12 to a large number of such compounds, with the followingresults : Keto-enolic tautomerism does not occur in crystalline sub-stances, the crystals consisting of one form only.The modificationin which a desmotropic substance exists in the crystalline state isnot necessarily the one which will predominate in solution; thusdibenzoylacetylmethsne is ketonic in the solid state, but in solutionin alcohol or benzene over 90 per cent. of it is enolic; also methyloxalacetate is enolic in the solid state, whereas the keto-form largelypredominates in alcoholic solution. Acetaldehyde, acetone, pyruvicacid, and acetophenone, which contain one *COR group, are presentin alcoholic solution almost entirely in the keto-form, even in thepresence of sodium ethoxide. A comparison of substances contain-ing a methylene group attached to two *COR groups (R=H, Me,Ph, OH, OMe, OEt, NH,, CO,Me, or C0,Et) shows that insimilarly constituted compounds the influence favouring enolisationexerted by various radicles increases in the order OMe, OEt, OH,NHPh, Me, Ph, CO,Et, C0,Me.Ethyl malonate consists entirelyof the keto-form. Its sodium salt in methyl alcohol solution has theconstitution CO,Et*CJH:@(ONa)*OEt, and when it is acidified theresulting enolic modification of the ester very quickly changes t othe ketonic form.Tetramethylammonium amalgam 13 is obtained by the electrolysisof a solution of tetramethylammonium chloride in absolute alcoholkept a t -34O, a mercury cathode being used. The resulting semi-solid product a t the cathode is washed free from alcohol by carbontetrachloride, and the liquid mercury removed by suction, whenthe amalgam is left as a silver-white, crystalline, metallic mass,which if kept a t 0" under carbon tetrachloride undergoes very11 Ann.Report, 1911, 100.l3 H. I?. McCoy and W. C. Moore, J. Amer. Chcm. SOC., 1911, 33, 273; A.,1911, i, 270 ; H. N. McCoy and F. L. West, J. Physical Chc?n., 1912,16, 261 ; A , ,i, 539.Rer., 1912, 45, 2843, 2864 ; A . , i, 940, 941ORGANIC CHEMISTRY. 1013little change in the course of several hours. During its spontane-ous decornposition the amalgam emits negative electricity, and theresidual mercury, if insulated, acquires a positive charge.ClmZesteroZ.-From the acid,l4 C,&4404, obtained by the oxida-tion of cholesterol, Windaus 15 has obtained the following degrad*tion products :(:,Hl,*C,7H2,*CH : CH, distillatioll "'it11 C,H,, *Cl7.t€,,* C H CH, +--(CH$O),C, / \ (C27H4404)CO,H CH,*C02H/ \CO--CH2I+02(C26H420)C,Rl ,*C17T3,,*C0,H/ \CO,H C0,HJheatedLactone, C24H3603 o2 C,H,,*C17H2,*C0,Hor f- \/ coI c,4H3803+O'CO,H*CH,~C,,H,,(CO,H), 2:~- / \(CH,),CO and 'sH1l *CMH!24*C02H(C21H3008) CO,H C0,HCH,-CO,H, etc.I $distilledC,H,l~C,,H24~C0,H+02\/ coThe ketone C2,H4,0 is the next lower cyclic homologue ofcholesterol, and since it is obtained by the distillation of the freeacid, cuH4404, it follows that the two carboxyl groups in this acidare in a 1:6- or l:7-position t o each other; consequently, incholesterol itself the ring containing the *CH*OH-group mustcontain 6 or 7 carbon atoms.The conversion of the acid, C2,H4,06,into the ketonic acid, C,H,03, is analogous to the conversion ofhomocamphoronic acid into camphononic acid 16; hence, in the acidC2,H4,06 the two carboxyl groups which disappear are also in the1 : 6- or 1 : 7-position. Further, the formation of the tribasic acid,C24H3806, from the ketonic acid, C24H3803, shows that this sub-stance has a *GH,-group next to the carbonyl group (compare con-version of camphononic acid into camphoronic acid lea), and so themode of attachment of another carbon atom in the cholesterolmolecule is ascertained. The formation of acetic acid by oxidationl4 Diels and E. Abderhalden, Bm., 1904, 37, 3092 ; A . , 1904, i, 880,la Ber., 1912, 45, 1316, 2421 ; A., i, 449, 854.Iti Lapworth and Chapman, T., 1899, 75, 986, 1003.16(c Ibid110 ANNUAL REPORTS ON TEE PROGRESS OF CHEMISTRY.of the tetrabasic acid, GlH3008, shows that this acid contains amethyl group, and its formula, may be written:A similar conclusion as to the presence of a methyl group in theC1,Hz6 nucleus is arrived a t by Minovici and Vlahutza,l7 who haveobtained the acid C2,H,,0, by the action of hydrogen peroxide onchlolesterol.The following formula for cholesterol is now proposed byWindaus :CHMe,*CH2-CH,*CllH17C‘H CH/\The two resins, “jalapin,” from the root of Zpomoea urkz&cnsis,and “ scammonin,” from scammony root, have been hithertoregarded as identical substances, and as consisting of a homogene-ous substance of glucosidic character.Both resins have now 18 beensubmitted to a very thorough chemical examination, and shown tobe very complex substances, and to differ very considerably in theirComposition. They appear to consist to a large extent of the gluco-sides and methylpentosides of jalapinolic acid (hydroxyhexadecylicacid), CI,HN(OH)*CO2H.Hankow Chinese wood oil19 on exposure t o light in glass bottlesfitted with air-tight stoppers gradually deposits crystals, which a tthe end of a year amount to about 6 per cent. of the oil. Thesecrystals consist of the glyceride of 8-elaeostearic acid, and on hydro-lysis yield the free 8-elzeostearic acid, C18H3202 or C,,H,O,, meltinga t 7 2 O , of which several derivatives have been prepared.Both thefree acid and its derivatives readily absorb oxygen on exposure toair, but although the ethyl ester soon gains 12 per cent. in weight,yet it does not set like the Chinese wood oil. The study of thiscrystalline glyceride may help to throw light on the changes whichoccur when a drying oil is exposed to air.Fossek has shown that when the product of the interaction ofphosphorus trichloride and an aldehyde, R*CHO, is treated withwater, a31 acid of the type R*C?H(OH)*PO,H, is obtained. ThisBulZ. SOC. chim., 1912, [iv], 11, 747 ; A., i, 697.’8 F. B. Power and H. Rogerson, T., 1912, 101, 1, 398.l9 R. S. Morrell, ibid., 2082ORGANIC CHEMISTRY. 111work has been confirmed and extended by Page,zo who has suc-ceeded in preparing hydroxymethylphosphinic acid,OH*CH2-P0,H2,by using paraformaldehyde or trioxymethylene instead of theformaldehyde itself.Kipping 21 has revised the nomenclature of the organic deriv-atives of silicon, and suggested systematic names for the complexcondensation products resulting from the silicanediols.The same author22 has succeeded in preparing pure diphenyl-silicanediol, SiPh,(OH),, by the hydrolysis of dichlorodiphenyl-silicane. The isolation of the diol in a pure state presented excep-tional difficulties, as the impurities were apparently adsorbed bythe crystals. Pure diphenylsilicanediol usually decomposes andliquefies below 132O, but occasionally tho decomposition does notoccur below 160O.This apparently " double" melting point is notregarded as due to the existence of an isomeride, but is explainedas follows : the crystalline form of diphenylsilicanediol, which sepa-rates from solvents a t about 10-60°, decomposes and liquefiescomplehly a t about 128-132O, but near its melting point it is ina metastable state, and may, especially if certain impurities arepresent, change into another crystalline form, more stable a t thishigher temperature, which only decomposes a t 160° ; usually, how-ever, the pure compound decomposes and liquefies before thischange occurs.Perhaps the most cl .racteristic property ofdiphenylsilicanediol is the ease with which i t loses the element.3 ofwater, the presence of traces of alkalis or acids being sufficient toeffect this loss, four well crystallised compounds having beenisolated from the products of this change, namely:(1) anhydrobisdiphenylsilicanediol, HO*SiPh,*O*SiPh,*OH ;(2) dianhydrotrisdiphenylsilicanediol,(3) trianhydrotrisdiphenylsilicanediol,HO*SiPh2*O*SiPh2*O*SiPh2*OH ;(4) tetracanhydrotetrakisdiphenylsilicanediol,iPh,*O*SiPhO<iiPh 0.S iPh;>"The study of the formation of analogous anhydrides from mixeddiols like phenylbenzylsilicanediol, and also of mixed anhydridesfrom mixtures of, say, diphenylsilicanediol and dibenzylsilicanediol,will no doubt afford valuable information as to the structure ofthe complex inorganic silicates.r, T., 1912, 101, 423.21 Ibid., 2106. 'La Ibid., 2108, 2125112 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.I n a previous communication, Robison and Kipping 23 describedthe decomposition of dic hlorodibenzyl$ilicane, Eli (CH,- C6H,),C12,and stated that the products were the isomerides a-dibenzylsilicoland P-dibenzylsilicol; the same authors 24 now show that the a-com-pound is dibenzylsilicanediol, Si(CH,*C,H,),(OH),, and the/3-compound is an anhydro-derivative or oxide of dibenzylsilicane-diol, crystallised with one molecule of water, and having the com-position HO Si (CH,*C,H,),*O*Si ( CH2*C6H5),*OH,H,0, and nownamed anhydrobisdibenzylsilicanediol.H. R.I,E SUEUR.PART II.-HOMOCYCLIC DIVISION.Although a t the present. time the difficulty of tracing the genesisof an idea in Chemistry in the vast literature is an excuse for thefrequent claims to priority, which every journal contains, it seemsindeed remarkable that fifty years ago a monograph,l in which notonly was valency used in the modern manner, but also Kekule‘forestalled by more than four years in the famous benzene formula,could entirely escape notice.Loschmidt’s monograph, which hasbeen rescued from forgetfulness by Anschutz,2 will be deservedlyplaced among the ‘(cla~sics” of science. He recognises the“ polarity ” (localisation or direction) of valence, and states withrare lucidity the ideas which should be a t the basis of the ordinarystructural formuh; the analogy between benzene and marsh gasas the first members of series, and the relation between the homo-logues and derivatives of the former were perceived a t a time whenno complete hand- or text-book of organic chemistry had beenwritten, and the literature, especially of aromatic chemistry, waschaotic.That Kekul6 was aware of Loschmidt’s work is provedby his own words 3; but i t seems highly probable that he had onlyheard of the monograph from Kopp, who had come across it aseditor of Liebig’s Jahresb ericht.4 Although Loschmidt saw thepossibilities of isomerism depending on the attachment of thesubstituent to a side-chain or the nucleus, he did not go so far asKekul6 in the recognition of the isomerism of the nuclear di- andtri-derivatives of benzene.Structure of the Benzene Nucleus.-The fifty-two years which2B T., 1908, 93, 441. z k Ibid., 1912, 101, 2142, 2156.J. Loschmidt, Chemische Studien, 54 pp., Wien, 1861.R.Anschutz, Ber., 1912, 45, 539 ; A., i, 247.Bull. SOC. chim., 1865, [ii], 3, 100.1861, 335ORGANIC CHEMISTRY. 113have elapsed since Loschmidt recognised the molecule of benzene asformed of a remarkably stable ring of six carbon atoms, have addedvery. little to our knowledge as to the exact structure of thebenzene nucleus. Willstatter and Waser’s 5 recent discovery ofcyclooctatetraene has once more revived interest in the question :CH*CH/ / \YHCH =(? HCThis tetraene (like cyclobutadiene) is just such a closed systemof an even number of alternating double and eingle linkings as isbenzene. Yet in chemical properties it offers the most strikingcontrast, and behaves simply as a cyclic olefine; it reduces perman-ganate vigorously, and adds on bromine instantly; it takes up fourmolecules of hydrogen in the presence of platinum, and with nitricacid gives no substitution products, but becomes a tar. Moreover,on heating it is converted into stable, more saturated isomerides,probably by forming bridge linkings (see p.145).I n the light of this great difference in character, Willstiitterurges that there must be some fundamental difference in molecularstructure. Thiele’s theory of partial valence shows that the residualaffinity of any closed system of alternating double and single link-ings would be very much the same; and hence the chemical char-acter of two such rings would not vary greatly with the number ofatoms of which the ring is composed. Willstatter claims, therefore,that the discovery of cyclooctatetraene gives a final demonstrationthat KekulB’s formula is to be replaced by some other, and decidesin favour of Armstrong’s centric formula.6 It is suggested thatthe tetraene cannot change into a similar centric configuration onaccount of the distance of the carbon atoms from the centre offigure.The comparison of benzene, cyclooctatetraene, and naphthalene,more especially in their tendency to combine with hydrogen, leadsWillstatter to the conclusion that Harries’ formula for naphthalene(in which one ring onTy has a centric structure), based on itsbehaviour with ozone, is to be preferred.’Another interesting observation on the character of compoundswith a, para-bridge-linking has been interpreted as indicating thecentric structure of benzene.Although it is by no means unusualto find formulae in which a bridge-linking is used, the undoubtedBey., 1911, 44, 3423 ; A . , i, 17. T., 1887, 51, 264.7 Annalan, 1905, 343, 311 ; d., 1906, i, 225.HE P.-VOL. 1X. 114 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.synthesis of one in spite of many attempts has only just beenachieved by J. von Braun,* who has converted p-aminopropyl-benzene into pindole,the complete similarity between the p- and o-indoles is held to beexpressed only by a centric or diagonal structure of the nucleus.The conceptions as to the exact relations of the carbon atomsin the benzene ring are naturally dependent on the precise viewsof valency on which they are based. Accepting the constantquadrivalency of carbon, and fixity of the directions in which thevalency is exerted, the Kekul6 formula, represents benzene ashaving a much smaller ring tension, 2O35’, than a ring of sixsingly-linked carbon atoms, of which the ring tension is 5O16/, suchas the hexamethylene ring, and the ring in the centric formula.Thedifference in reactivity between the Kekul6 ring and the octa-tetraene ring may well be referred to this fact.9 With the newerand less rigid conception of valency, the relation of the membersof the ring may obviously be far more varied and elastic than isexpressed by the usual alternative formulation. Moreover, adynamic rather than a static structure has in addition been reliedon to account for many of the properties (mainly optical) of thearomatic series ; thus largely on the ground of the peculiar opticalproperties (fluorescence, etc.) of aromatic compounds, von Liebig 10911urges that a t the double linkings in benzene, a continuous rockingmotion is to be found (a suggestion which differs little from manyearlier ones), whereas in the tetraene, which is of yellow colour,there are two pairs of double linkings each analogous to the pairin a henzoquinone; the oscillations at the four double linkings donot fall into the rhythm characteristic of benzene, and hence thedifference in chemical character.In Thiele’s and Armstrong s benzene formulze, the originalvalency theory is extended, if not abandoned; in the former eachcarbon atom is quinquevalent, and in the latter each has a generalattachment to the five other carbon atoms.On the basis of Werner’stheory of a universal a f i i t y acting in all directions from atomiccentres, a new way of representing the peculiar properties of thebenzene ring is described in an interesting paper by Boeseken.12 I ne. Ber., 1912, 45, 1274; A., i, 497.9 J. Boeseken, Proc. I?. Akad. Wctensck. Amsterdam, 1912, 14, 1066; A., i,lo J. pr. Chem., 1912, [ii], 86, 175 ; A . , i, 686.430.R. Casares, Anal. Fis. Quim., 1912, 10, 14 ; A., i, 247. LOC. citORGANIC CHEMISTRY. 115order to account for the union of two like atoms to form amolecule, a certain difi’crence analogous to that between opticalisomerides, which is not a difference in energy, must exist.Thisdifference is represented by opposite rotatioils of the atoms, a deviseby which a “dynamic” condition can also be simply expressed.13When applied to the benzene ring, this idea is symbolised as in theannexed figure. It will be seen that the contrast between the ortho-and para- on the one hand, and the meta-moreover, the equality of tihe two orthGpositions. When a carbon atom is /‘groups, they occupy the angles of a tetra-hedron. I f , however, three atoms orposition on the other, is shown, and, 0 0 attached to the maximum four atoms or “0 Q”groups are attached to a carbon atom, 0 t-Josince, following Werner, a fixed valency “ 0 direction does not exist, the three atomslie in one plane grouped round thecarbon. Hence it is conceived that the six carbon and sixhydrogen atoms of benzene lie in one plane, when in a configura-tion of most stable equilibrium, and that the unsaturation orresidual affinity is evenly distributed over the whole molecule. Lessclearly defined, but somewhat similar, views are expressed by H.Kauffmann 14 in the statement of his auxochrome theory (seeThe best test of this formulation is its ability to bring intoharmony the various facts of substitution, and the other reactionsof benzene; thus a particular advantage of the centric formula,and t o a certain degree of Thiele’s modification of KekulB’s, is thatthey represent the great change of properties on adding a moleculeof hydrogen to such a derivative as terephthalic acid.I n the unsub-stitutecl benzene the even distribution of affinity will tend toprevent the local addition of chlorine or bromine, which mayprecede substitution; and, in the absence of a catalyst, i t has beenfound that even when the benzene is in excess the additive benzeneliexahaloid is alone produced.15 The addition of hydrogen tonaphthalene and other condensed rings may be an example of localaddition, but here there is a possibility of a less even distributionof residual affinity.Whether, however, substitution in benzene byhalogens in the absence of a catalyst is preceded by local additionmust a t present be left an open question; the primary additivewill, to obtain the simplest arrangement, c,p. 137).Rec. trnv cJ~iwt., 1910, 29, 86.BcT., 1906, 39, 1959 ; A., 1906, i, 811 ; ‘ I Die Valenilc*hre,” 1911.l5 T.van der Linden, Bw., 1912, 45, 231 ; A . , i, 174.1 116 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.products have not been isolated at least in this case.lG The existence of a very large number of additive compounds of the usualcatalysts with hydrocarbons, which have been recently studied,17suggests that the catalyst acts by modifying rather the benzenethan the halogen. The disturbance of the even distribution of theaffinity by the catalyst will render easy the local addition ofhalogen. The subsequent elimination of hydrogen bromide wouldobviously be accompanied by a considerable fall of chemicalpotential, but the catalyst may also accelerate this part of theprocess of substitution. In the case of nitration and sulphonationthe evidence is clear that the agents themselves provide thecatalyst, which is most probably the anhydride of the acid.In a monosubstituted benzene the residual affinity can nolonger bs evenly distributed, a fact which may be expressed inBoeseken’s diagram or by modifications of KekulB’s formula inthe manner suggested by Flurscheim 18 by the help of partial orsubsidiary valence.The presence of a group, X, attached to carbona t one end of the conjugated double linkings, 1,6 and 5,4, willaffect the power of addition a t pwitions 1 and 4 and a t the posi-tions 1 and 6, but not, or not to such an extent, a t the positions2 and 319:XR\I! ill \>’The mere presence of the group for this reason favours ortho-para-rather than metmmbstitution.Substitution will occur in the threepositions, but with very different velocities, which will vary withthe nature of X, and hence produce different proportions of thethree di-derivatives in the final products. The results of the nitra-tion of many monosubstituted benzenes give excellent illustrationsof this proposition.A second factor has to be taken into account, namely, the attrac-tion exerted by X on the substituting agent. When this is suffi-ciently great the group X will be chemically changed, as in the16 A. F. Hollenian and J. Roescken, Proc. h7. Aknd. WetensciL. A?izsterdam,1910, 18, 535; A. Werner, “Neuere Anschauuiigen,” 2nd. Ed. ; E. Fischer,Annaten, 1911, 381, 123 ; A., 1911, i, 418 ; W.Manchot, Annulen, 1912, 387,257 ; A , , i, 230.l7 Among others, B. N. Menschntkin, J. Xius. Phys. CJLem. Soc., 1911, 43,1275, 1785, 1303, 1329, 1805 ; A . , i, 98, 99, 100, 177, 193; P. Pfeiffer, Annulciz,1911, 383, 92 ; A . , i, 783.18 T., 1909, 95, 718 ; ibid., 1910, 97, 84.19 A. F. Holleman, “Die direkte Einfuhrung von Substituenten in denBenzolkern,” 1910 ; Holleman and Biieseken, Zoc. cit. ; J. Obermiller, “ Dieorientierenden Einfliisse und der Benzolkcrn, ” 1909ORGANIC CHEMISTRY. 117reduction of the nitro-group, oxidation of the thiol group, etc., orwill form only unstable additive products, which have occasionallybeen isolated, especially in the case of amines.20 The attractionbetween X and the agent may, however, under the given conditionsfall short of reaction or addition, and only result in a very rapidortho-paraaubstitution, for example, when X is hydroxyl in phenols ;or the attraction may be still slighter and meta-substitution accom-pany the ortho-para, as in toluene, the process now having a smallervelocity.Finally, the nature of X (for example, a nitro-group)may be such as t o inhibit substitution, whence it follows theposition, 2,3, which is least under its influence, will be attacked,and meta-substitution, which is always a relatively slow reaction,predominate. It is obvious that in the addition t o the 2,3 linking,a t least some ortho-derivative should be formed; and exact workhas demonstrated that, a t least so far, pure meta-substitution hasnot been observed.21 Although the group X may inhibit theaction of the ordinary substituting reagents, it may yet render thebenzene derivative more accessible to others ; then, however, anortho-para-reaction will follow.As examples will serve the replacement of chlorine by hydroxyl when orthepara to a nitro-group,and the ready reduction of benzoic acid and still more phthalic acid(to A3:6-dihydrophthalic acid) in the ortho-para-positions by hydro-gen, (These are also examples of the primary local addition.) Thereaction (or union) of the substituting agent with the group X,and the fact that the products can often be converted into nuclearderivatives (sometimes isomeric, as, for instance, nitroamino-benzenes and nitroanilines, benzoyl nitrate, and m-nitrobenzoicacid) has resulted in the popular opinion, which so often findsexpression in the literature, that these substances are necessaryintermediaries, and that the conversion, when it occurs, is intra-molecular.An intramolecular change may occur in this as inother reactions, but the evidence that such is the case must beforthcoming.22The foregoing gives a very brief summary of the views a t presentheld by those who are now engaged in studying the problem ofsubstitution in aromatic compounds. It cannot be said that therecent exposition of the mechanism of substitution in benzenecontains much that was not embodied in earlier conceptionse3; the2o H. Wieland, Be?.., 1907, 40, 4260; A., 1907, i, 1076; ibid., 1910, 43, 699 ;A., 1910, i, 242.21 A.F. Holleman and collaborators, Zoc. cit. ; and Bey., 1911, 4.4, 704; Rev.trav.-chinz., 1911, 30, 48 ; BzdZ. Xuc. chirn., 1911, [iv], 9, i.; Ber., 1911, 44, 2504,3556 ; A . , 1911, i, 364, 535, 713, 849 ; 1912, i, 20.T2 Brit. Assoc. Reports, 1910, 85 ; Xcience Progress, 1909, 4, 213.Armstrong, ibid., 1899118 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.newer views on valency have given freedom, and exact quantitativework has brought precision, but the fundamental ideas are littlemodified.Nitro-co ntpounds.The study of the absorption spectra24 of a very large iiuniber ofnitro-compounds, and of their metallic and alkyl derivatives, hasbrought to light some very striking facts with regard to the isomer-ism of this group. Up to the present there was no doubt that twodesmotropic forms existed, the true nitro-group, *NO,, and theiso- or aci-nitro-group, present always in the salts, to which variousconstitutions have been assigned.The Michael-Nef formula,RR'C:NO*OH, is more generally accepted, although the formulaRR'C*N*OH, originally put forward by Hantzsch, finds someadherentszs; but the reactions, which have been urged as evidencef o r the latter, are those exhibited by compounds in which othernegative groups (carbonyl, phenyl, etc.) are present, and hencemay be due rather to the general character of the compound thanto the particular arrangement of the nitro-group.The spectroscopic investigations of Hantzsch 26 have convincedhim that a third type of nitro-compound exists, the " conjugatedmi-nitro "-compound.I n the spectra the three types are distin-guished in that the true nitro-compound has a feeble selectiveabsorption, the uci-nitro-compound feeble general absorption, andthe " Conjugated " mi-nitro-compounds very strong selective absorp-tion. The simple aci-nitrocompounds are only found in the other-wise unsubstituted nitrclparaffins. The conjugated is the invariableform of the salts whenever a negative (unsaturated) group(NO,, CO*, CO,H, Ar, CN, etc.) is combined with the carbonatom which bears the nitro-group; and i t is found uncombinedas well as in salts, esters, etc. So fundamentally different are thespectra of the " conjugated " mi-nitro-compounds from the othertwo classes, and at the same time so little affected by the characterof the compounds in which they are present, that Hantzsch urgesthe existence of some peculiar and characteristic constitution.Asix-membered ring, which is constructed with the aid of a sub-?4 Absorption spectra are now so universally described that reference cannot bemade here to all the papers, but attention may be directed t o a research dealingexclusively with the subject of this palagraph. G . T. Morgan and collaborators,T., 1911, 99, 1945 ; ibid., 1912, 101, '1209.\/025 W. Steinkopf and B. Jiirgcns, J. pr. Chem., 1911, [ii], 84, 686 ; A . ,i, 152.26 A. Hantzsch aud K. Voigt, Ber., 1912, 45, 85 ; A., i, 151ORGAXIC CHEMISTRY. 119sidiary valence, is this chromophore, and is represented in typicalexamples, thus :I n no case has a simple aci-nitro-form been observed when the" conjugated " aci-nitro-ring is capable of existence ; the equilibriumis directly between the true nitro- and the conjugated aci-nitro-forms, and not through the aci-nitro, thus:This fact, and t,he far-reaching optical and chemical analogybetween the negatively substituted ketones and the conjugatedacd-nit,ro-compounds, has led Hantzsch to modify his former opinionas to the relation between the ketones and the salts of theenolides, which are classed as similar conjugated " compounds,-C 0.C K ~ : ~ > M , in that an int.ermediary true enolide is now regardedas superfluous. The equilibrium is dependent on the nature of themedium, the dilution, and the temperature, and hence Beer's lawis not applicable to these solutions.27 Ionisation is, as usual, notrecognisable optically ; both the ion and the non-ionised compoundshow the same absorption.The chromoisomeric salts of nitro-compounds have the typicalspectra of the conjugated aci-nitro-form.Hence the earlier opinionthat i t was the isomerism of aci-nitro- and conjugated aci-nitro-compounds is abandoned, and since polymorphism is excluded, theauthor falls back on valency-isomerism, thus :*C:O-MMoreover, grounds are advanced for the existence of an equili-brium between the two forms in solution. It is, however, highlysignificant, that a compound which shows this chromoisomerism doesnot show the equilibrium with the isomeric true nitro-compound ;and, conversely, where this type of isomerism is observed, chromo-isomerism does not exist.It is here, perhaps, that the weak spotin this otherwise wonderfully clear-cut and convincing theory lies.The nitro2henols offer a very good example of the manifoldrelations of the nitro-group; i t is only, however, in the para-seriesthat the behaviour can be interpreted.28 p-Nitrophenol and the37 J. Piccard, Annnleit, 1911, 381, 347 ; A . , 1911, ii, 561 ; A. Hantzsch,Anmbn, 1911, 384, 135 ; A . , 1911, ii, 951.See also W. P. Ureaper, T., 1911, 99, 2094120 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.stable series of ethers have typical conjugated aci-nitro-spectra, andhence have the structure (I) of these compounds. The salts andthe red labile esters exert, however, a far stronger absorption, andhence they are given a quinonoid constitution, and a t the sametime a new position for the subsidiary valence (11):A neat demonstration 29 that salt formation in aromatic nitro-compounds only causes the special type of absorption just referredto, when a quinonoid rearrangement is possible, has been given ina comparison of the spectra of the following substances in neutralor alkaline media : pnitrobenzoic acid, phenylacetanitrile andphenylacetic acid, with those of p-nitrophenylacetonitrile, ethylp-nitrophenylacetate, and finally pnitrophenylacetic acid.I n thefirst group the spectra of the two solutions are practically identical,but in the second group a characteristic additional band appearsin the alkaline solution. I n the case of pnitrophenylacetic acidthis change is only observed in the presence of considerable excessof alkali, as a salt of the type NaNO,:C,H,:C'B:*CO,Na would beextensively hydrolysed.A constitutively unchangeable nitro-compound,30 which yetexhibits intense colour, has been found in 4'-nitro-2 : 5-dimethoxy-benzophenone.The authors find in it an excellent illustration ofKauffmann's theory (see p. 137) of the division of the valence-unit, brought about in this case by the interaction of the nitro-and methoxy-groups, as the cause of colour.Another interesting ob~ervation,~~ which may be related to thatlast mentioned, is the final demonstration tha.t there are twodistinct o-dinitrobenzidines, yielding distinct acetyl derivatives anddistinct dinitrodiphenyls.It is suggested that this is anothercase of the isomerism, referred to in other places in this report,which depends on the limitation of the free rotation of singly-linked carbon atoms.Some researches which cannot be dealt with a t length show thatmuch is yet to be learnt about the reduction of nitrobenzene byvarious methods.32~ 33"3 .J. T. Hewitt, P. G . Pope, and Miss W. I. WiIlett, T., 1912, 101, 1770.3O H. Kauffmann and A. de Pay, Ber., 1912, 45, 776 ; A., i, 365.31 J. C. Cain, A. Coulthard, and Miss F. M. G. Micklethwait, T., 1912, 101,33 R. C. Snowdon, J. Physical Chrn., 1911, 15, 797; A . , i, 100.33 E. F. Farnau, ibid., 1912, 16, 249 ; A., i, 436 ; H. C. Allen, ibid., 131 ; A , ,2298.i, 249ORGANIC CHEMISTRY. 121Diphenylarnine.The chemistry of the well-known blue reaction of diphenylaminewith nitric acid and other oxidising agents34 has been up to thepresent mainly a matter of speculation ; the most attractive hypo-thesis was that the salts of the halochro,mic diphenylhydroxyl-amine 35 produced the colour.Although the first product of the oxidation of diphenylamine ist8etraphenylhydrazine,36 which in an acid medium yields diphenyl-henzidine,37 yet H. Wieland came to the conclusion 38 that the tetra-liydrazine was hydrolysed to diphenylamine and diphenylhydroxyl-amine, which then condensed, and finally oxidised to theo-quinonoid sulphate of a phenazine :a compound the constitution of which now seems extremely doubt-ful.Eehrmann 39 has now demonstrated that the diphenylbenzidineis undoubtedly formed under the usual conditions of the reaction,and, moreover, yields with oxidising agents an intensely blue saltof a haloquinoneimonium type :which was isolated as the platinichloride.reaction is to be found in the formation of this compound.The cause of the colourXeto-enol Is0 rn erism.During the year the results of some extremely interesting andimportant researches on this subject have been published; theincreasing power and delicacy of the agencies a t the command ofchemist,s is particularly well illustrated in the advances which haverecently been made in this difficult subject.The methods which can now be used, not only for the recogni-tion of a compound as an enolide or ketone, but for the quantita-tive estimation of a mixture, are various.Of the chemical methodsthe ferric chloride colour reaction with the enolide (Wislicenus)is only applicable when the transformation takes place veryslowly, for this reagent disturbs the equilibrium by its powerfulcatalytic acceleration of the enolisation. Claisen’s method of34 Merz and Weith, Ber., 1872, 5, 283.35 A. von Baeyer, ibid., 1905, 38, 583.36 F. D. Chsttaway and H. Ingle, T., 1895, 67, 1090.37 V. Kadiera, Ber., 1905, 38, 3575; A . , 1905, i, 934.39 F. Kehrmann and St. Micewicz, Ber., 1912, 46, 2641 ; A., i, 1020.Annnlcn, 1911, 381, 200 ; A . , 1911, i, 569122 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.extracting the enollde by a dilute solution of sodium carbonate isconfined to solids, and is useless for solutions or liquid mixtures.The reaction with tertiary amines4O may give correct results inisolated cases, but is certainly not generally applicable.Themethod of bromination 41 in its improved form 42 is not only exceed-ingly trustworthy, but can be used for liquid, solid, and solutionwith equal ease. A high speed of enolisation would, however, asin all chemical methods, invalidate the conclusions as to thecomposition of the equilibrium mixture, and for this reason i thas not. been found applicable in the case of the phenylindan-di~nes.~sOf the physical methods, the molecular refraction (Bruhl) hasbeen shown recently by Auwers44 to be susceptible of exact quanti-tative application : where comparisons are possible and close agree-ment has been found between this and the bromine method.Theabsorption spectrum appears, however, to be the most delicatemethod when the equilibrium in solutions is t o be examined, andhas recently been used with great success by Hantzsch (Zoc. c i t . ) .By mea.ns of the method of bromination, K. H. Meyer has madean exact study of a large number of substances, and of the equili-brium between the keto- and enol forms in the molten state or insolution. It is now possible to state approximately the relationsbetween the constitution and the relative proportions of the twoforms in an equilibrium mixture.Such equilibrium mixtures are only found in the liquid or dis-solved, but never, as has been suggested, in the crystalline state;the solid consists of one form only.I f the solid (ketone or enolide)is the metastable, i t will gradually change completely into thestable form; so far a transition point where coexistence would bepossible has not been observed. Stability of one form in the solidstate bears no relation to the composition of the equilibriummixture, either in the molten state o r in solution; thus the stableketone, acetyldibenzoylmethane, (C,H,*CO),C’H*CO~CH,, in alcoholis enolised to the extent of 90 per cent. The nature of the solventshas, of course, a great influence; for example, methyl benzoyl-acetate is enolised to the extent of 0.8 per cent. in water, 13.4 inmethyl alcohol, 15.3 in chloroform, 69 in hexane, and 16.7 whenmolten.The value of the ratio (KijR’) of the equilibrium con-stants (equilibrium constant = K = [enolide]! [ketone]) of any twocompounds, a t least when &milady constituted, is nearly the same40 A. Michael an4 H. D. Smith, Aiznnlcn, 1908, 363, 20 ; A., 1908, i. 943.41 Ann. Report, 1911, 101.4: K. H. Meyer, Ber., 1912, 45, 2843; A., i, 040.J3 A. Hantzsch, AnnnleiL., 1912, 392, 286 ; A., i, 869.44 K. Auwers, Ber., 1911, 44, 3530; A., ii, 3ORGANIC CHEMISTRY. 123whatever the medium; thus the value of R for methyl benzoyl-acetate is about 2.2 times as great as the value of h- for ethylacetoacetate. Moreover, the same relation holds often, but not souniformly, for the molten state.Ziidandiones and 0xindones.-The keto-enol isomerism of theindandiones and bisindandiones (11) has been fully investigated byHantzsch and his pupils,45 mainly with the aid of the absorptioiisnectra :(1.1 (11.)The absorption spectra of the indandiones of the type I, whichare Learly colourless and not capable of enolisation, are continuous,and not markedly or sharply affected by the nature of the solventsor subcstituents.On the other hand, the indandiones containingthe group *CO*CHR*CO* yield salts exhibiting selective absorptionwhich are oxindone derivatives, *C(OH) :CR*CO*. These indan-diones, like ethyl acetoacetate, have in solution very variablespectra; in the active solvents (alcohol, etc.) enolisation is shownby the selective absorption, whilst in indifferent solvents the colourfades and the general absorption, typical of ketones, is observed.As will be seen, these relations are the converse of those found tohold with the ketonic esters, where enolisation is most prominentin indifferent media. A comparison of the spectra of the saltswith other enolic derivatives has led Hantzsch 46 to suggest that theformer have a peculiar structure, with the metal attached by asubsidiary valence to the carbonyl group as well as to the oxygen(111) :Po\ c:,GO ..... ...... 15\CR I C,iH4\- //CR 4b--# (J C-OAC(111.) (1V.)This type is called the '' conjugated " enolide. The new observa-tions on indandiones, etc., afford strong confirmatory evidence forthis suggestion. The acyl-oxindones, which are also enolic deriv-atives of the indandiones (IV), show spectra in which the selectiveabsorption is both less and simpIer than in the salts.In thebisindandiones and the hydroxytrisindandiones :the enolides and the enolic ethers have spectra resembling, and45 Annalen, 1912, 392, 286, 302, 319, 322, 328; A., i, 869.46 A ~ H . Report, 1910, p. 80124 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.often identical with, the salts, a fact which is interpreted asevidence for a “ conjugated ” structure in these compounds as wellas in the salts. The formula (111) shows that in the conjugatedstructure a six-membered ring exists; to this is attributed thepeculiar absorptive power as a consequence of a “strong isorropesicstate of vibration ” (“ lebhafte isorrhopische Schwingungs-zustand ”).The two types of salts, both enolides, which certainindandiones yield, are distinguished by the form of this “ conju-gated” ring. The indandiones, in which R in the group*CO*CHR*CO*is an alkyl radicle, produce red salts having high selective absorp-tion, whilst those in which R is an acyl radicle or contains acarbonyl group, yield yellow salts, the selective absorption of whichis feebler. This difference is attributed to the absence of the six-membered ring in the yellow salts, which have instead as a chromo-phoric group a fivemembered ring, thus:a,m,(c~>c*co x,‘O*Malso possessing a subsidiary valence.The peculiar existence of isomeric ketonic modifications of1 : 3-diketones has been studied by Michael 47 and his collaboratorsin the case of dibenzoylacetylmethane and dibenzoylpropionyl-methane.In both cases the more stable ketonic form (8) is con-verted into a second (y) by treatment with acetyl chloride. Thesetwo compounds are both unimolecular, and have widely differentmelting points. Since this isomerism cannot be accounted for bythe usual formulze, i t is suggested that it is due to a limitation ofthe free rotation of the singly-linked carbon atoms. Generally freerotation occurs until the configuration, in which the system hasthe ‘‘ maximum entropy ’’ is attained. When there is little differ-ence in the entropy between two or more of the possible configura-tions, then these forms may exist, and, moreover, be interconvert-ible by feeble chemical agencies if the difference in entropy is suffi-ciently small.The great difficulties of the investigation of the isomerism of the1 : 3-diketones are emphasised by the recent researches on ethylformylphenylacetate.48 Until recently, this compound was sup-posed to exist in four different forms, two of which were possiblystereoisomerides. Michael’s reinvestigation (Zoc.cit.) has led himto the conclusion that there are only three forms, one liquid and47 Annalen, 1912, 390, 30; A., i, 631.48 W. Wislicenns, ibid., 389, 265 ; A., i, 624 ; A. Michael, ibid., 391, 235, 275 ;A., i, 861; K. H. Meyer, Ber,, 1912, 45, 2843; A., i, 940ORGANIC CHEMJSTRY. 125two solid, all of which are, however, enolides. Wislicenus (Zoc. cit.),on the other hand, has reduced the number to two, the liquid ester(a), the hydroxymethylene (I), and the crystalline y-form (m.p.l l O o ) , which is considered to be the enol-aldo-form (11), owing toits reaction with decolorised magenta :OH*CH:CPh*CO,Et OCH*CPh:C(OH)*OEt OCH*CHPh*CO,Et(1. ) (11.) (111 )The other forms are merely mixtures of these, whilst the truealdo-form (111) has not been isolated, but may be present inalcoholic solution. The method of bromination, however, seems tooffer a ready way of solving the problem. The liquid a-form, andthe liquid obtained by melting any of the so-called solid forms,are, as usual, an equilibrium mixture, containing about 76 per cent.of enolide, probably both (I) and (11); the y-form (m. p. llOo) is apure enolide, as is also the P-form (m.p. 50.). One of these, most,probably the y-ester, is the hydroxymethylene (I). All solutionscontain the true aldo-form in equilibrium with enolides; in 50 percent. methyl alcohol as much as 91 per cent. of the ester is thealdehyde.MetaZZic Derivatives.-Although there seems clear evidence thatmost metallic derivatives of 1 : 3-diketones and such-like compoundsare salts of the enolides, the mercury compounds seem uniformlyto be derivatives of the ketones; in fact, in the case of some bis- andtris-indandiones, these salts are the only representatives of theketonic form.49 The various formulz given in the literature showthat some uncertainty still exists as to the constitution of themetallic derivatives of compounds of the malonic ester type.Although this type reacts in the same manner as the 1 : 3-diketones,no enolide can be discovered either in the liquids or in solutionsby the methods described in the foregoing. That the relation:-CH*CO*OR C:C(OH).OKdoes hold, and that the metallic derivatives are salts of the enolide,can be readily demonstrated by the bromination method, for onadding a solution in alcoholic sodium methoxide to an acidifiedbromine solution, as much as 90 per cent.of the compound appearsas enolide. The interval of one minute is, however, sufficient forthe entire disappearance of the enolide.50Bromination of Desmotrop-c Compounds.-Since Lapworth 51 ori-ginally demonstrated that the bromination of compounds containingthe carbonyl group (ketones, acids, etc.) must be a reaction betweenbromine and an enolic form, as the speed of the reaction is indepen-dent of the concentration of the bromine, and hence most probablyfixed by some slow change of the ketonic into the enolic form, little50 K.H. Meyer, Zoc. c i ~ . 49 Hantzsch, loc. cit. 51 T., 1904, 85, 30126 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.has been added to our knowledge of the phenomena until Meyer's(Zoc. c i t . ) recent application of the process as a method of estimat-ing the quantity of enolide in an e9uilibrium mixture, and therecent study of the speed of production of the chemical 'active formby means of its reaction with iodine.52 This reaction of brominewith compounds containing this group is greatly accelerated bymany catalysts (acids, bases, ferric chloride, etc.), but it offers aremarkable contrast to the action of chlorine and bromine on mostother compounds, in that it is not accelerated by light.53 This factbrings out clearly the difference between the direct substitution andthe indirect substitution, which may be formulated thus :Whether the Hell-Volhard reaction of bromine with acidchlorides, in which both hydrogen chloride as well as hydrogenbromide is eliminated, has a similar mechanism is doubtful, forhydrogen bromide and an acid chloride yield an acid bromide andhydrogen chloride.54Of the many papers which deal directly or indirectly with thesubject of this section, reference may be made to the study of thereaction of benzylamine on acetylacetone,55 of the desmotropic alkylderivatives of benzoylacetone,56 and of the so-called '' dibenzoyl-methane," 57 and to the preparation of C- and O-alkyl derivativesin general of diketones or anilides.58Quinones and Quinoneammonium Compounds.Q&n o n e-n m m o nium Corn po unds .-0 n e of the most interestingdiscoveries of the year is that of the quinone-ammonium com-pounds 59 obtained by the extreme methylation of picra.mic and ;so-picramic acids by methyl sulphate.Three methyl groups becomeattached to t,he acid, and there is no doubt that they are combinedwith the nitrogen, for the derivatives from isopicramic acid isisomeric with dinitrociimethyl-p-anisidine,~O and secondly, demetliyla-B2 11. M. Dawson and F.Powis, T., 1912, 101, 1503.53 K. H. Neyer, Bcr., 1912, 45, 2867; A , , i, 941.54 0. Aschsn, An?znZc~i, 1912, 337, 10; A . , i, 198 ; E. lfohr, J. y". C'hem.,1912, [ii], 85, 334 ; A., i, 362.L. Riigheimer and G . Ritter, Ber., 1912, 45, 1332 ; A . , i, 474.56 W. Dieckmann, ibid., 2685 ; A,, i, 868.57 B. D. Abell, T., 1912, 101, 989, 998.58 K. Auwers, Ber., 1912, 45, 976, 994 ; A., i, 484, 486.59 R. Meldola and W. F. Hollely, P., 1910, 26, 233 ; T., 1912, 101, 912.Bo F. Reverdin and A. de Luc, J. pr. Chem., 1911, [ii], 84, 555 ; A . , 1911, i,965ORGANIC CHEMISTRY. 127tion can only be effected by vigorous treatment, which would not bethe case if one methyl group were attached to a nitro-group. Thesequaternary bases both have an ochreous colour, but the p-derivativecombines with water, forming bright red crystals.The salts,however, are colourless, and very readily hydrolysed. The com-pounds are not phenolic, and have not been acylated. The remark-able colour is confined t o the nitro-compounds, for the correspondingtrimethyl derivatives of paminophenol and of 2 : 6-dibromc~paminophenol are colourless. The exact constitution of the basesis not an easy matter to determine. The colourless salts seemobviously derivatives of dinitrohydroxyphenyltrimethylammoniumhydroxide (I), but the colour of the anhydrous bases suggests somedeeper constitutional change than a simple elimination of water(IIj. The quinonoid (111) structure, alone, necessitates the use ofthe very unusual linking of quinquevalent nitrogen entirely toO H 0 ..(IK)carbon.A quinonoid formula (IV), in which an mi-nitro-group islinked to the quaternary nitrogen, would not be open to thisobjection, and also would account for the fact that only the nitro-derivatives are coloured. The constitution of the red (‘ hydrate ’’of the p-compound is yet more of a puzzle. If the ochreousanhydrous bases are “inner” salts, i t would seem necessary thatthe neutral hydrate should also have that structure; then thodisposal. of the hydrate water (hydroxyl group) is most simplyarranged for by a quinole formula (V). The fact that this com-pound has an intense colour, whilst all known quinoles, none ofwhich are, however, nitrated, are colourless, is not a special diffi-culty, since the cause of the colour of the “hydrate,” as well asof the anhydrous base, may lie in the formation of the “inner”salt.The attachment of two hydroxyl groups to the same carbonatom is not without analogy, when the carbon atom bears thesame relation as is found here, to negative groups (for example,mesoxalic acid). The adherents of the subsidiary valence hypo128 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.thesis, which has not been called into use by the authors, shouldfind no difficulty in constructing a formula which would accountfor the exact tint. The properties of these quinoneammoniumcompounds are strongly reminiscent of the quinonediazides, ofwhich the anthraquinone derivatives are now known.61 The latterare invariably coloured, but form colourless salts, which are veryextensively hydrolysed.Assuming the absence of colour in thesalts to be due to their benzenoid diazonium structure,HO*C6H,*N2*X, i t is difficult to understand the extensive hydro-lysis. A remarkable example62 of an analogous phenomenon hasrecently been observed in 4'-hydroxy-4-diazodiphenyl,the highly unstable diazophenol is deeply coloured, and yields paleyellow, hydrolysable salts, which, however, form ruby-red hydrates(with 2H20). It is probable that similar constitutional changesare the origin of these properties. Still more striking is thesimilarity between the nitroquinoneammonium compounds and thedinitrophenylpyridinium compounds.63 An oxygen compound andthe sulphur compound, to which the formula= (VI) and (VII) areNO2 NO, NO2I O*O" \/*C5% C,H,N--- ' No", C5H5N-- I i--/\+ H\:s (or 0) f\-0NO,\/ jW.) (VIJ.) (VIII.)given, are both coloured, but form colourless, hydrolysable salts.The sulphur compound, moreover, forms a hydrate, which is farmore deeply coloured. From the resemblance to the quinone-ammonium compounds, it might be suggested, since the pyridinering is not opened, that the free base is a quinonoid " inner " salt(VIII), the colourless salts benzenoid, and the coloured hydrateof the quinole type. Since in this case the nitrogen and oxygen(or sulphur) are not respectively para or ortho to one another,and yet all the same properties are observed, the quinonoid " innersalt" structure for the free base seems the more probable.Theconstitution of the coloured " hydrates " which may be quinoles(or, it may be suggested, possibly compounds of quinhydrone type,which would harmonise with the intensified colour) is moreR. Scholl, F. Ebcrle, and W. Tritsch, Moualsh., 1911, 32, 1043 ; A . , i, 143.fi.2 E. Bamberger, Annulen, 1912, 390, 131 ; A., i, 691.63 F. Reitzenstein and J. Rothschild, J. pr. Cliem., 1906, [ii], 73, 257; A . ,1906, i, 454 ; T. Zincke and G. Weisspfenning, J. pr. CIzcm., 1910, [ii], 82, 1 ;i b i d . , 1912, [ii], 85, 211 ; A., 1910, i, 585; 1912, i, 302ORGANIC CHEMISTRY. 129uncertain; it is significant that neither have hydroxyl groups beenrecognised, nor the molecular weights determined.o-23enaopuinones.-A large number of derivatives or homologuesof o-benzoquinone have now been prepared, but the colourlessform?& in which the parent substance was originally obtained, hasonly been once again observed (3 : 4-toluquinone).Kehrmann 66urges that there is as yet not even sufficient evidence to concludethat the two forms are isomeric, much less desmotropic, andsuggests that the colourless compound is possibly the first phasein the oxidation of catechol, thus:or even a compound of the quinone with ether.Besides the study of many reactions of the quinones, a verylarge amount of preparative work is being done in the anthracene,phenanthrene, and other series of quinones or quinonoid compounds,of which this indication must suffice.Some Phthalyl Derivatives.Phthalyl Chloride.-The evidence on which the asymmetricconstitution of phthalyl chloride rests has been again examinedin detail,66 with the result that the symmetric formula is favoured.The proximity of the eCOCl-groups in phthalyl chloride is con-sidered as s d c i e n t cause for such reactions as that with ammonia,in which o-cyanobenzoic acid is formed, instead of a diamide.Thereactions with ethyl sodiomalonate and sodioacetate supply thechief grounds for this opinion, since, for example, the constitutionsof the two malonic compounds are best expressed by the formulae:Preliminary work with a few dichlorides seem to show thatabsorption spectra will be of use in distinguishing between thetwo types of constitution of this and similar dichlorides. Thisview has found definite proof in Ott's *7 elaborate investigation ofcertain acid chlorides of dibasic acids, which mainly deals with theconstitution of maleic and fumaric dichlorides.As criteria todistinguish between the lactonic and the symmetric formulze, theIX R. Willstatter and others, Ber., 1911, 44, 2171, 2182 ; A . , 1911, i, 728, 729 ;C. L. Jackson and G. L. Kclley, Amer. Chem. J., 1912, 47, 197 ; A., i, 275.Ber., 1911, 44t, 2632; A . , 1911, i, 883.cB Scheiber, Annalen, 1912, 389, 121 ; A . , i, 559 ; Ber., 1912, 45, 2252 ; A , ,6/ Annulen, 1912, 392, 245 ; A , , i, 828.REP.-VOL. IX. Ki, 701130 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.rates of reaction with aniline and methyl alcohol are taken, aswell as the molecular volume, which is known to drop by aboutfour units in the formation of a lactone ring.Both these testsindicate that ordinary phthalyl chloride is symmetrically con-stituted. Further, the author has been able to convert phthalylchloride by heating with aluminium chloride into an isomeride, acrystalline solid, melting a t 88-89O. By distillation, prolongedheating a t looo, or in the presence of hydrogen chloride, it isreconverted into the ordinary chloride. It reacts with aniline andmethyl alcohol far more slowly than the ordinary chloride, andis taken to be the asymmetric chloride:The interaction of phthalic anhydride and hydroxylamine yieldstwo isomeric oximes,a one colourless and the other yellow, whichare mutually convertible the one into the other.Both can berecrystallised, and yield red alkaline solutions, from which therespective oximes can again be isolated, and also distinst ethylethers and acetates in which the colour persists. The colour isdue mostly, if not entirely, to fluorescence. The evidence seemsin favour of stereoisomeric formulz :,--CO--, ,---co---,0-C-C,H, O-C-C,H,HO-k! andM*OHAs a contraet to these observations, the two differentlyvarieties of phthalylhydrazides, which are normal andcolourednot dso-compounds, -have been shown to be polymorphs, and notisomerides.69The chromoisomerism exhibited by a number of imides andhmides of dibaisic acids has been investigated by means of theabsorption spectra of solutions. The identity of the spectra ofdifferently coloured solid forms is taken to indicate the absenceof chemical isomerism. Thus, on this criterion, the yellow andwhite forms of pmethoxyphenylphthalimide itre not chemicalisomerides, whilst p-methoxy- and p-ethoxy-phenylmaleinimides,and the corresponding phenylfumardiamides, each of which existin two forms, are.7068 W.R. Orndorff and D. S. Pratt, Amer. Chem. J., 1912, 47, 89. CompareLassar-Cohn, Annalen, 1880, 205, 295 ; A . , 1881, 585, and R. Meyer and S. M.Kissin, Ber., 1909, 42, 2825 ; A., 1909, i, 652.69 F. D. Chattaway and D. F. S. Wiinsch, T., 1911, 99, 2253.7O A. Piutti and E. de’Conno, dlem. B. Accad. Lincei, 1911, [v], 8, 793 ; A., i,360 ; compare Piutti and Calcagni, Rend. Accad. Sci. Fis. Mat. Napoli, 1910, [iii],16, 255 ; A., 1911, i, 124ORGANIC CHEMISTRY.131Benzeins a n d PhthaZeins.Phenolphthalein.-Although there has been much discussion asto the constitution of the salts of phenol- and other phthaleins,71which cannot be considered as final, the formula of the phthaleinsthemselves has not been called in question, but von Baeyer’sformula generally accepted. When tested by the very strikingway of ascertaining the presence of “ active ” hydrogen (hydrogenlinked to oxygen, nitrogen, sulphur), which has been devised byB. Odd072 on the basis of Sudborough and Hibbert’s73 originaluse of Grignard’s reagent for estimating hydroxy- and amino-groups, phenolphthalein does not appear t o contain an activehydrogen at0m.7~ Moreover, it should be noted that throughouttho phthalein series the carbonyl group of the lactone ring isindifferent to Grignard’s reagent, with which phenolphthalein doesnot react.On the other hand, one active hydrogen is found inthe monopotassium salt, the iminophenolphthalein, and in thediacetyl, but none in the triacetyl derivative. I n fluorescein,however, two active hydrogen atoms are indicated. Since the usualformula for phenolphthalein, as well as that for fluorescein, showstwo hydroxyl groups, it is argued that the former requires modifi-cation. The formula (I) is suggested, which represents the com-pound as having an ether-like constitution, but it is hinted thata still more revolutionary formula (11) may represent free phenol-phthalein. The monopotassium salt (111) would still be repre-/-\\-/(I. 1 (11.) (111.)santed by the quinonoid formula most generally accepted. Thecause of the different structures of phenolphthalein and fluoresceinis sought in the fact that in the latter the benzene nuclei carryingthe hydroxyl groups become fixed by the formation of theanhydride, whereas in the former free rotation is possible, andt h e most stable arrangement is found in the formula (I) suggested.Recent work on the use of phenolphthalein and its derivativesas indicators76 brings out the fact that the presence of negative71 Ann.IZeprt, 1909, 66.73 T., 1904, 85, 933 ; ibid., 1909, 95, 477 ; Th. Zerewitinoff, Ber., 1907, 40,93 ; 1912, i,74 Ber., 1911, M, 2018; A., 1911, ii, 826.2023 ; 1908, 41, 2233 ; 1912, 415, 2384 ; A., 1907, ii, 509 ; 1908, i,841.74 B.Odd0 and E. Vassallo, Gazzelta, 1912, 42, ii, 204 ; A., i, 792.75 E. Rupp, Arch. Phnn., 1911, %9, 56; A., 1911, i, 301; J. W. McBain,K 2T., 1912, 101, 814132 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.groups in the phthalein nucleus, but not in the phenol nuclei,sharpens the colour change, that is, increases the rapidity of theformation of the coloured quinonoid form, and hence increasesthe value of the phenolphthalein as an indicator. The preparationof colourless monobasic and tribasic salts 76 from phenolphthalein,which contain water or alcohol, may perhaps be taken as evidencethat only the formation of the dibasic salts causes the developmentof the colour, thus : .-.Phi%ateins and Benzeins.-The complicated isomerism in thephthaleins and benzeins has been accounted for by F.Kehrmannand others 77 by constitutional formula: showing quadrivalentoxygen; the salts with acids are held t o be, on the one hand,oxonium salts (I), or, on the other hand, from the similarity withthe salts of triphenylmethyl, generally carbonium salte,78 (11),thus, in typical formulze:? 0A new light has, however, been thrown on the problem by vonLiebig's 79 final demonstration that some, if not all, of theisomerides are, in fact, easily resolvable polymerides, the correctmolecular weight of which is only found in certain solvents(acetone) ; the polymerides are, however, sufficiently stable to yieldsalts and other derivatives.In the formulze of these compoundsoxygen is not represented as quadrivalent, but the author isobliged to fall back upon limitations to the free rotation of thephenyl groups, about the central methane carbon atom, to whichthey are singly linked, in order t o account for the existence ofthe certain isomeric unimalecular fluoresceins. The polymeridesare considered to be of a quinhydrone type, and analogous to the76 P. A. Kober, and J. T. Marshall, J. Amer. Chem. SOC., 1911, 33, 59 ; 1912,34, 1424 ; A., 1911, i, 300 ; 1912, i, 865 ; R. Meyer and k'. Pouner, Bet.., 1911,44, 1954 ; A., 1911, i, 654.77 A., 1900, i, 61 ; Annalen, 1910, 372, 287 ; A,, 1910, i, 406 ; Ber., 1912, 45,3346, 3504 ; A., i, 1012.Vt( M. Gomberg and collaborators, Annalen, 1909, 370, 142 ; A., 1910, i, 55 ;J.Amer. Chem. Soe., 1911, 33, 1211 ; A , , 1911, i, 737.79 H. von Liebig, J. pr. Chem., 1912, [ii], 85, 97, 241 ; 86, 472 ; A , , i, 376ORGANIC CHEMISTRY. 133compounds of benzeins with alcohol and other hydroxy-compounds.Thus, y-resorcinolbenzein, 4C,,H,,O,,H20, which only loses watera t 240°, is given a quinhydrone formula:0 OH 0 0 OH 0-4s will be seen from the formulze, these quinhydrones are represented by definite structural formulae, with full atomic linkings;in fact, in discarding subsidiary linkings, the author is reverting toC. L. Jackson'.s original formula for quinhydrone 80 :0 OH/\/The salts with acids are not regarded as oxonium nor as carboniumderivatives, although the acid radicle is attached to carbon (rV),but it9 compounds of the quinhydrone type.It is admitted thatthe solubility in water of these salts is a difficulty, but it issuggested that in solution they are represented by (111). Basinghis conception on von Baeyer's81 recent discoveries on the methodof opening up the dimethylpyrone ring, the author considers thatthe formation both of the salts and of the quinhydrone additivecompounds is brought about by the hydrolysis of the anhydridering; the varying, sclcalled, " basicity " of this class, which isadmittedly not commensurate, a5 is usual, with the character ofthe substituents, is merely a question of the readiness with whichthis hydrolysis occurs :(111.)Diaao-corn pounds.The data of the absorption spectra of a large number of diazo-compounds of various types which have been accumulated byseveral observers make it now possible to associate the constitutionsgo Ber., 1895, 28, 1614 ; A., 1895, A., i, 513.Annalcn, 1911, 384, 208; A., 1911, i, 901134 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of the different classes with certain characteristics of the spectra,and to state the modifications in the typical spectra produced bythe presence of certain groups or radicles.Moreover, by this meansthe current conceptions as to the constitution of many diamcompounds can be checked, or in some cases corrected.82The diazo-compounds are by their absorption spectra divided intotwo groups, the diazonium salts and the azo-compounds. Thediazonium derivatives possess a characteristic deep band in theultra-violet, the exact position and intensity of which is modifiedby, but the character of which remains unchanged by, substituents.The coloured and colourless salts are quite similar in this respect,and hence have the same constitution, a view which is now heldby G. T.Morgan,m on the ground of chemical behaviour. Thispowerful selective absorption is attributed by Hantzsch to theinteraction between two “ unsaturated centres,” 84 which producesa peculiar vibratory molecular state. H e represents it by ancillarylinking or subsidiary valence. I n this case the tervalent nitrogenof the diazo-group is linked to the benzene nucleus by such avalence, thus: Ar-N-X. This structure is, however, not the same“d I 1NIas, or even similar to, Cain’s 85 quinonoid diazo-formula, N2., ‘ .,=\I __ /\--Ifor the nucleus is supposed to retain its benzenoid type, and nonitrogen-bridge linking to be formed.It is pointed out that theso-called diazo-phenols show a very different and characteristicabsorption, which is taken to indicate that they have a quinonoidstructure, not a benzenoid with a bridge linking, a formula which&/-\.‘k*,\-/has again recently found adherents. At the same time this differ-ence in the absorption between the two types is an argument for thebenzenoid structure of the diazonium salts.The spectra of the azo-compounds is quite different from that ofthe diazonium salts, and is, moreover, extremely variable. Theazo-group does not appear to be an “independent ’’ chromophore,but resembles the carbonyl, only to a higher degree, in its depend-ence on the groups to which it is linked.The azo-paraffins have anultraviolet absorption band, and the azo-benzenes have, in addi-tion, a “colour” band in the visible spectrum. Prom the great82 A. Hantzsch and I. Lifschitz, Ber., 1912, 45, 3011 ; A . , ii, 1116.83 T., 1910, 97, 1961, 2537 ; compare ibid., 1907, 91, 1311.8% See also A. K. Macbeth, A. W. Stewart, and R. Wright, T., 1912, 101, 599.85 T., 1907, 91, 1069ORGANIC CHEMISTRY. 135similarity of the diazomethane derivatives to azo-compounda, theN cyclic formula for the group >C<- - is preferred to the formulaN>C:NiN, suggested by Angeli and Thiele.86The isomeric azocyanides, Ar*N,.CN, and azosulphonates,rnAr*N,*SO,M*, behave as stereoisomerides, showing a nearly identi-cal absorption.The two series of diazotates show, however,considerable difference, the normal or (( syn "-salts showing no ultra-violet band. Further, i t is to be noted that faintly alkaline solu-tions of diazonium salts in which it has been asserted that thediazohydrate (normal) is present, are now shown by the absorp-tion to contain the diazonium hydroxide. This fact suggests thatthe conversion of the diazonium into the diazo-constitution whichwas offered as an explanation of many diazo-reactions (transforma-tion into phenol, chlorobenzene, etc.), does not a t least find con-firmation in this searching analytic method.The free iso(anti-)diazohydrate can be obtained in solution, showing absorptionidentical with that of its salts, but quite different from that of thenitrosoamines, the absorption of which resembles rather that ofthe normal diazotates. The opinion is expressed, however, thatthe normal and isodiazotates are stereoisomerides, and that thedifference in the spectra is to be attributed to the peculiar chromephoric character of the azo-group. It will be seen, however, thatit is just where a decisive proof was most needed that some uncer-tainty still remains.The evidence for the existence of the primary nitrosoamines asthe +-acids of the isodiazotates, Ar*N:N-OM f Ar-NH-NO., hasagain been examined, more particularly in the case of pnitrodiazo-benzene, and a remarkable effect of solvents discovered. I n ether(or alcohol) the absorption is that of an isodiazotate, but in chloro-form that of a nitrosoamine; moreover, the compound cannot beextracted from the latter solution by alkali, but only after additionof ether.88 Although the absence of any equilibrium mixture insolution is very singular, if not unique, the reciprocal conversionof one isomeride to the other seems to take place with the rapiditywhich would be expected of such a change.Some Reactions of Diazo-compounds.-The actions of sodiumarsenite and a mixture of potassium cyanide and sodium hydrogensulphide afford unusually clear chemical distinctions between thegG Atti 2.Accnd. Lincei, 1911, [v], 20, i, 625; A., 1911, i, 620 ; Ber., 1911,441, 2522, 3336; A, 1911, i, 845; 1912, i, 16.87 J.J. Dobbie and C. K. Tinkler, T., 1905, 87, 273. Private cominunicationsfrom C. H. Desch.E. Bamberger and 0. Baudisch, Bcr., 1912, 45, 2054 ; A., i, 733; A.Hantzsch, ibid., 3036 ; A., i, 1039136 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.various classes of diazo-compounds. With diazonium salts, thenormal diazotates, and the labile diazosulphonates, the diazo-groupis replaced by hydrogen:Ar*N:N*ONa + Na,AsO, + H20 = ArH + N2 + Na3As04 + NaOHAr*N:N*ONa + NaSH + KCN + H,O = ArH + N, + KGNS + 2NaOH,whilst the isodiazotates, the stable diazosulphonates, and azo- andaeoxy-compounds do not react. A constitutional difference for thetwo sulphonates, Ar*N2*O*S02K and Ar-N,-SO,K, is revived toaccount for this distinct reactivity ; and am-formulze are suggestedfor nitrosoacet- and nitrosobenz-anilides, Ar*N2*O*Ac, since theyreact whilst the nitroso-derivatives of amines do n0t.89Two of the simplest derivatives of azo-benzene, o-hydroxy- 90 ando-amino-azobenzene 91 have been prepared by convenient methods ;the former is obtained by coupling diazonium salts with p-acetyl-aminophenol, and the latter, of which derivatives have also beenobtained?, by condensing benzoyl-pphenylenediamine with nitroso-benzene.Aniline-black and Allied Compounds,Since aniline-black was last dealt with in the Annual Reports(1909), the two chemists who are authorities on this subject, Greenand Will~tlitter,~3 have maintained a long controversy as to theexact nature and relations of aniline-black, or perhaps more accu-rately, of tho primary products of the oxidation in which aniline-black is ultimately formed.Since Willstatter’s discovery 94 thatone-eighth of the nitrogen appears as ammonia on treatment of anyof the products with acids, it has been generally agreed that anoctzmuclear indamine-like complex is the parent substance, theleuco-fomrm of which (‘( leucoemeraldine ”), C48H42Ns, is representedby the annexed formula:The four coloured compounds derived from this contain respec-tively one, two, three, and four quinonoid nuclei. Inasmuch as allB9 A. Gutmann, Ber., 1912, 45, 821 ; A., i, 398.im J. T. Hewitt and W. H. Ratcliffe, T., 1912, 101, 1765 ; N. N. Voroschtsoff,91 F.H. Witt, Ber., 1912, 45, 2380 ; A., i, 921.;93 R. Willstatter and C. Cramer, BET., 1910, 43, 2976 ; A., 1911, i, 90 ; Ber.,1911, M, 2162; A . , 1911, i, 736; A. G. Green and A. E. Woodhead, T., 1910,97, 3388 ; 1912, 101, 1171 ; Ber., 1912, 45, 1955 ; A. G. Greenand S. Wolf€, Bcr.,1911, M, 2570 ; A . , 1911, i, 900.J. Rzus. Php. Chem. SOC., 1911, 43, 787; A., 1911, i, 818.G . M. Norman, T., 1912, 101, 1913.O4 Bar., 1909, 42, 2147, 4118 ; A , , 1909, i, 585, 976ORGANIC CHEMISTRY. 137these compounds are unstable and amorphous, and cannot be puri-fied by recrystallisation, the difficulties experienced in demonstrat-ing, much more in defining, these stages, has been very great. Will-statter relied on the quantitative reduction with the evolution ofnitrogen of the quinonoid nucleus by phenylhydrazine as a meansof measurement; but Green has shown that although accuratewithin certain limits of temperature, 80-90°, phenylhydrazineitself decomposes rapidly a t the temperatures which were used ;hence the conclusions were falsified.On the other hand, the oxida-tion of titanium chloride appears to be a more trustworthy guide;i t reduces each of the quinOnoids to the leucecompound, and notmerely to the monoquinonoid stage as was first believed.The colour-bases are all completely soluble in 80 per cent. aceticacid; their salts, with the rise in the number of quinonoid nuclei,are respectively grass-green, green, blue, and purple. The namesproto-emeraldine, emeraldine, nigraniline, and pernigraniline aresuggested for the four stages in oxidation.These compounds areunstable, and pernigraniline especially readily becomes degradedto a lower quinonoid stage. In attempts to purify, treatment withpowerful reagents, strong acids, cause, besides degradation, theformation of insoluble compounds. This instability, as well as thecolour, indicates that none of these compounds is aniline-black ;they are rather to be regarded as intermediaries in its formation.It may be suggested that aniline-black is a quinhydrone-like complexof one or more of them.Tripheny 2me thane Dyes ana? Tri p h e r y Erne t 7~ y 2.The discussions on the constitution of this group of compoundsis so closely connected with the problem of the relation betweencolour and constitution that the recent evolution of ideas on thissubject will have to be mentioned.H. Kaufhann has recently developed in a monograph 95 views asto the interatomic linkings in aromatic (and other) compounds,which are suggested by their varying behaviour in a Tesla electricfield.96 H e regards the benzene nucleus as a structure in which theinteratomic relations are most delicately balanced, and hence highlysensitive to the influences of substituents.I n this way groups actas auxochromes in varying degrees by causing changes in thechromophoric aromatic nucleus, with consequent changes in theabsorption of light (Kauffmann’s ‘‘ Auxochrome theory ”). Thesechanges are not, however, the simple conversion from the benzenoidto the quinonoid structure, but they are a t once more varied andg5 “ Die Valenzlehre,” 1911 ; Bcr., 1912, 45, 766, 781 ; A ., i, 351, 397.96 3w., 1900, 33, 1725 ; 1901, 34, 682 ; A , , 1900, i, 480’; 1901, i, 318138 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.more complex; thus in order to show the influence of a substituenton the nuclear structure, he represents dimethylaniline by theformula :in which the substituent is connected with four of the carbon atomsof the nucleus. The collection of the sub-valencies on certain atomsis looked upon aa determining the well-known direction given to asecond substituting group.It is in particular in this extreme division of the valence unit(“ Valenzzersplitterung ”), brought about by auxochromic groups(which is a t least in part merely an extension of the use ofsubsidiary valencies), that the author sees the cause of colour.Attention has been called to the fact that auxochromes are not, asmight be expected on this theory, always similarly effective; theaction holds for the aromatic series, but in the aliphatic thesegroups rather decrease selective absorption.97 The particular appli-cation to the triphenylmethane dyes well illustrates Kauff mann’sviews ; thus pararosaniline (I) and aurin (11) are represented thus :C H -NH,,f / 4- /C,H,--NH,C-C H -NH,X C6H,--NH2(111.)\ 6 *The single valenceunit of the anion.is divided in this ca.se intofour parts, which are not necessarily equal, but determined by thestrength of the auxochromic group; in the breaking up of the fourvalence-units of the central carbon atom lies the cause of thecolour.The three benzene rings are exactly alike and each modifiedto an equal extent, whereas in Fittig’s formula one only is quino-noid, and on von Baeyer’s theory98 each is successively quinonoidin the vibratory movement of the molecule, to which the colouris ascribed. One of the difficulties of the usual quinonoid formulais the fact that the salts of pararosaniline are not hydrolysed, whilstin general the salts of such $-bases containing the carbirninechromophore, *C:NH,HCl, are highly unstable. Again this theoryeasily represents the fact that on weakening the auxochromicgroups (by acetylation) the colour fades, and the molecule may besupposed to pass over finally into Rosenstiehl’s formula (III).W97 A.Hantzsch, Ber., 1912, 45, 3036 ; A , , ii, 1116.Q8 Annalen, 1907, 354, 164 ; A., 1907, i, 757.99 Compt. rend., 1895, 120, 192, 264, 331, 740 ; Bull. SOC. chim., 1895, [iii], 13,427, 431 ; A., 1895, i, 377, 476, 667ORGANIC CHEMISTRY. 139The intense halochromy of hexamethoxytriphenylcarbinol and evenof hexamethoxytriphenylmethane, would be anticipated from thegreat auxochromic subdivision of the carbon valence.1As a result of his study of the coloured compounds of metallicsalts, mainly tin tetrachloride, with the carbonyl group, Pfeiffer 2has arrived a t somewhat similar views as to the development ofcolour. I n these compounds the metallic salt or acid (called the(‘ addendum ”) unites co-ordinatively ” a t the carbonyl oxygen,X,Sn*- ....O:CRR,, thereby neutralising free affinity and renderingthe carbonyl carbon more unsaturated. The appearance of un-saturation is the cause, the degree determining the intensity ofd o u r . Hence it must depend both on the addendum and on thenature of the groups R and R’. A very large body of facts hasbeen gathered together, which affords a remarkable confirmation ofthis proposition. According to Kauff mann’s theory, the addendumwould be united both to the carbon and oxygen (and to otherpoints in the groups R and R’, or to any auxochromic groups),and the consequent breaking up of the carbon valence, which, itmust be remembered, also occurs in the increase of (I unsaturation ”of Pfeiffer, gives rise t o colour.The hypothesis of Pfeiffer has theadvantage in that these additive compounds are, in fact, more,not less, reactive, and hence more unsaturated than the originalcarbonyl derivatives ; thus the catalytic hydrolysis of an ester byan acid is accounted for by the attachment of water to the carbonylcarbon, thus :,.- 0: CRR’?EtR-C:O..---.H’I >H20Moreover, when such a (‘ ternary ” compound can be produced, andthe unsaturation of the carbon atom thereby diminished, it isfound that the colour fades. This theory can be used as Kauf€-mann’s to account for the colour of the triphenylrnethane dyes,without the assumption of the change of a benzenoid to a quinonoidnucleus, and of triphenylmethyl and the corresponding carbinolsalts.Trip~eityZmet7tyZ.-Schlenk’s 3 discovery of the unimoleculardeeply-coloured tridiphenylmethyl, (Ph*C6H4),C, supported by J.Piccard’s4 demonstration that the yellow colour of a solution ofH.Kauffinann atid F. Kieser, Ber., 1912, 45, 2333 ; A., i, 853.P. Pfeiffer, AnnaZcn, 1910, 376, 285 ; 1911, 383, 92 ; A., 1910, i, 852 ; 1911,AnnnZen, 1910, 372, 1 ; A , , 1910, i, 236.Ibid., 1911, 381, 347 ; A, 1911, ii, 561.i, 788140 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.triphenylmethyl in absolute ether increased on dilution, has con-firmed the suggestion 5 that the coloured (solutions) and colourlessforms of the latter are simply the coloured triphenylmethyl andthe colourless hexaphenylethane, which exist in the equilibrium :P h P hPh/ \PhP h b C L P h -- 2 PI@.The colour is therefore not to be ascribed to the presence of aquinonoid nucleus in a coloured bimolecular form, the ionisationof which in solution (sulphur dioxide) into quinonoid andbenzenoid triphenylmethyl is regarded by Gomberg 6 as thecause of the conductivity.On Pfeiffer's hypothesis the colouris merely caused by the unsaturation of the methyl carbon atom.I n an equally simple manner the appearance of colour in thetriarylmethyl salts (for example, triphenyl- or trianisole-methylchloride) in acid solution, or when combined with metallic salts oracids, is attributed t o the decrease in the saturation of the centralcarbon atom, and not t o the constitutional change which is shownin Gomberg's carbonium formula, Ph,C:C6H4<C,.i1 A remarkabledifference7 has been found ta exist between the absorption spectra,of t.he coloured non-conducting solutions of triphenylmethyl and ofthe conducting triphenylcarbinol or triphenylmethyl derivatives(salts) ; apparently the ion, Ph,C*, has a characteristic spectrum.Whether these facts can be harmonised with the above viewsremains to be seen. The authors regard this contrast, not as indi-cating a constitutional change, but as being in favour of vonBaeyer's 8 suggestion of a special ionisable carbonium valence,represented thus : Ph,C-X, in the triphenylmethane salts.The discovery of two isomeric tridiphenylcarbinols,( C6H5m C6H4) 3 ' OHand coloured unimolecular tridiphenylmethyls, respectively preparedfrom them, does not simplify the problem; once more the onlysuggestion offered is that one isomeride has an ionisable carboniumvalence, whilst the other has not?The simple amine bases of the triphenylmethane series,J.Schmidlin, Ber., 1908, 41, 2471 ; A., 1908, i, 623.6 M. Goniberg and collaborators, ibicl., 1907, 40, 1847 ; A., 1907, i, 504 ; ibid.,1909, 42, 406; A., 1909, i, 144; J. Amar. C'hem. soc., 1911,b 33, 531, 1211 ; A . ,1911, i, 361, 737.7 I<. H. Meycr and H. Wieland, ibid., 1911, 44, 2557 ; A., 1911, ii, 952.Ber., 1905, 38, 572; A., 1905, i, 281.J, Schmidlin, ibid., 1912, 45, 3171 ; A., 1913, i, 3ORGANIC CHEMISTRY. 141NE,*CAr,, which have for the first time been prepared,lo resemblethe carbinols so closely that they have probably been often over-looked.Ar,C*NH, + 2HC1 ZT Ar,CCl + NH,CI,but on making alkaline the triarylmethylamine is again obtained.With alcohols a carbinol ether is produced in a quantitative reac-tion, which can be used to estimate the amino-group:R3G'*NH2 + EtOH = R,C*OEt + NH,.The auramines, Ar,C:NH, which are very strong bases, offer aremarkable contrast in their stability to the triarylmethylamines.11With acids they yield dyes and an ammonium salt:Fluorescence.As an illustration of the general theory of fluorescence of organiccompounds (the luminophorefluorogen theory l2), the influence ofamino-groups as auxochromes (fluorogens) in fluorescence has beenfully studied in the case of the methyl amino- and 2 :5- and2 : 6-diamino-terephthalates.13 The displacement of the fluorescentband towards the red is most marked in the diamines, more especi-ally when the amino-groups are in the para-position with respectto one another.On acetylation or benzoylation the weakening ofthe auxochrome causes a reverse movement of the band; that is,in terms of the theory, the connexion by means of subsidiaryvalence of the nucleus (the lwninophore) with the amino-group(the auxochrome or fluorgene) is diminished. The investigationof the effect of numerous solvents on the fluorescence of thesecompounds makes clear the fact that the fluorescent colour exhibitedby a given substance depends on the dissociating power of thesolvent. The fluorescence is both intensified and of longer wave-length in alcohols and acetic acid, whilst the position of the bandis either unchanged or even shifted towards the blue by chloroform,benzene, and hexane.These effacts are, however, only marked whenstrong auxochromes are present. Carbon disulphide stands apartin nearly extinguishing all fluorescence. Among fluorescent com-pounds, methyl dimethylamiuoterephthalate is also an exceptionin that it only shows fluorescence (blue) in inactive non-dissociatingsolvents-a property which has been used to show that tin tetra-ethide belongs to this class of solvent. The author merely statesthat all these new observations are in accord with his general theoryof fluorescence.la V. Villiger and E. Kopetschni, Ber., 1912, 45, 2910 ; A . , i, 1030.i1 L.Semper, Annulen, 1911, 381, 234; A . , 1911, i, 577.l2 H. Kauffmann, Ber., 1907, 40, 838; A., 1907, ii,{ 215. See also Ann.l3 H. Kauffmann and L. Weissol, Annulen, 1912, 393, 1 ; A., i, 863.Beport, 1907, 10142 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The fact that ( ? 2 : 5-)dicyanodihydroxy-p-benzoquinone, whichhas recently been prepared by the action of alcoholic potassiumcyar.ide on chloroanil,l4 is strongly fluorescent, is difficult to explainon Kauffmann’s theory, as quinones are not luminescent, and hencenot luminophores. It is suggested that in spite of the markedcolour, the compound has a peroxide, and not the typical quinonoidstructure.An attempt16 has been made this year to formulate a generalmolecular theory of fluorescence (and phosphorescence).It isassumed that a molecule, more especially a complex molecule, mayexist in several states, in which the subsidiary valence is “satis-fied” t.0 different degrees. In the final stable state, the “residualaffinity” reaches a minimum when the maximum satisfaction ofthe subsidiary valence with the consequent loss of free energy hasbeen attained. From analogy this process is spoken of as thecondensation of the lines of force which radiate from each atom asa centre. By the absorption of light, energy is provided for the‘‘ opening up ” of the system. By the selective absorption of lightof wave-length, $, the stages 1 and 2 are brought into photo-dynamic equiiibrium. I n solution in a suitable solvent it is possibleto produce the phase (3) with absorption of light, A,. Now it isconceived that the process 1 +2 brought about by the absorptionof A*, must disturb the whole system, and as one of the possiblevibrations of the system has a frequency corresponding with A,, solight of wave-length A, will be emitted-and hence fluorescence.Very striking evidence is found in the fact that o-aminobenz-aldehyde and other similar compounds absorb in alcoholic hydro-chloric acid solution (that is, in the “opening up ” 2 -+ 3), lightof the same wave-length as they emX as fluorescence in alcoholicsolution. Moreover, it is suggested that the development of colourin concentrated sulphuric acid solutions of triphenylcarbinol maybe accounted for in the same way,since the fluorescent light of thealcoholic solution is identical with the light absorbed in sulphuricacid solution, without resource to the hypothesis of a quinonoidstructure.This suggestion as to the structure of these salts, it willbe noted, is identical with that reached by Kauffmann and Pfeifferon other grounds.This thwry has been effectively criticised from the point of viewof the Mass Law.16 It is urged that in any such system as postu-lated in the foregoing, there must be equilibrium between thevarious states, 1 -- 2 --- 3, whether when constantly illuminatedor not. Hence a “ balance of light ” would be attained in addition14 M. M. Richter, Ber., 1911, &, 3469 ; A . , i, 34.15 E. C. C. Baly and R. Krulla, T., 1912, 101, 1469.16 A. K. Macbeth, P., 1912, 28, 271ORGANIC CHEMlSTRY.143to the original absorption effect. The same argument may beapplied to the absorption of each subsequent “state” which isinduced in the system; but emission finds no place. The fluorescencewhich only occurs a t low temperatures, and the fact that the wavelength of the exciting light may vary over a wide range withouteffecting that. of the fluorescence, can also not be brought intoaccord with the theory.Hydroaromatic Compozmds, Terpenes, and ,4 llied Compounds.Physical Comqtants and Constitution.-The systematic study ofphysical constants has long been used as a supplementary guidein assigning constitutional formula: to members of the terpeneseries. Recently, work on the absorption spectra and on therefractivity emphasises the great assistance which may be expectedfrom these properties.A vivid controversy17 between the sup-porters of the respective methods has served to show that theabsorption spectra are more delicately sensitive to slight constitu-tional differences, for example, the degree of conjugation of a pairof double linkings,l8 but that the refractivity indicates with preci-sion the different types of double linking. The purity of theterpene can be accurately gauged by means of the absorptionspectra, very slight differences (0*lo) in the boiling point beingreflected in the spectra. As an example of the results of thestudy of the absorption spectra of three isomeric p-menthadienes,limonene (A’ :S) has less absorptive power than terpinolene (A1:4(*))and terpinene.As the absorptive power of the two latter isnearly identical, it is proposed to revert to the former symbol(A1:*) for terpinene, notwithstanding the fact that the chemicalevidence is decidedly in favour of the Harries’ formula (A1:3). Asthe result of much laborious statistical work, data of refraction anddispersion have now been collected,lD which render possible a sharpdifferentiation between endocyclic and semicyclic double linkings inhydroaromatic and similar compounds. Endocyclic unsaturatedcompounds are optically normal, whereas a semicyclic double linkingcauses an exaltation, both of the specific refraction and specificdispersion. I n a number of pairs of isomeric hydrocarbons, whichhave keen compared, alkylidenecy clohexanes with alkyl-A1-cyclo-l7 K.Auwers, Ber., 1911, 44, 3525 ; 1912, 46, 963; A., ii, 4; ii, 505; A,Hantzsch, Ber., 1012, 46, 663, 569, 1742 ; A , , ii, 313, 709.l8 C. R. Crymble, A. W. Stewart, R. Wright, W. G. Glendinning, and MissF. W. Rea, T., 1911, 99, 451, 1262.l9 K. Auwers and F. Eisenlohr, Ann. a p o r t , 1910, 67 ; 1911, 51 ; K. Auwersaud W. Moosbrugger, Annalen, 1912, 387, 187 ; A . , ji, 213; K. Auwers andP. Ellinger, ibid., 200; A., i, 187 ; K. Auwers, Ber., 1912, 45, 2764, 2781 ; A . ,i, 2013, 1016144 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.hexenes, the specific exaltation of the semicyclic compounds amountsto 0-28-0*47 of 8,, and to 6-10 per cent. of P,-S,. A1-cyclo-Hexenylacetic acid and its derivatives are optically normal, whilstthe isomeric cyclohexylideneacetic acid and its derivatives show aneven greater exaltation than the hydrocarbons-a behaviour whichis attributed to the conjugated double linking present with the semi-cyclic linking.It is suggested that the constitution assigned tomany hydrocarbons is in this respect erroneous; for example, manyof Sabatier and Mailhe's alkylidenecy clohexane derivatives are,in fact, endocyclic hexenes ; and Zelinsky and Gutt's 3-methyl-l-ethylidenecyclohexane must be 3-methyl-1-ethylcyclohexene.20Among the numerous observations which have been recorded,the depression in refractivity which is not accompanied by a, similardepression of the dispersing power, of unsaturated five-memberedrings, containing the group *CH:CH*CH:CH-, is shown to holdfor homocyclic as well as heterocyclic compounds.21 Previously theoptical abnormality of cyclopentadiene was thought to be due toits ready polymerisation, but the monomeric form, which is nowfound to be not difficult of preparation,2z gives similarly low opticalconst ants.In a similar manner Ostling 23 has made measurements and accu-mulated data of the refractive and dispersive powers of compoundspossessing a cyclopropane or a cyclobutane ring ; twenty-five of theformer and sixteen of the latter class were available.The incre-ment in the molecular refraction ( M a ) due to the closing of thecyclopropane ring is +0*67, and to the closing of the cyclobutanering + 0.45. The molecular dispersion is unaffected.The conjuga-tion of the cyclopropane ring with a double linking raises thevalue of the increment somewhat, but the effect of this conjugationis not perceptible when an alkyl or alkyloxy-group is attached to acentral carbon atom of the system. Data are now available formaking a preliminary comparison as to the relative sensitiveness ofmolecular refraction and magnetic rotation to constitutive influ-ences :Change in Change iiimolecular in ag u e t icrefract iou. rotation.- 2.2 - 0.6 Formation of 5- or 6-monibered ring ......,, ), cyclopropane ring ............ - 1 . 5 - 0.5,, ,, a double linking ........... - 0-5 $. 0.7cyclo 0 c tat e traen e .-T he preparation of cy clooct atet r aene, whichis one of the most remarkable discoveries of the year, by Will-'Lo Ber., 1902, 35, 2142 ; A ., 1902, i, 585.21 K. Auwers, ibid., 1912, 45, 3077 ; A . , i, 956.22 H. Stobbe and I?. Renss, Annulen, 1912, 391, 151 ; A . , i, 842.23 T., 1912, 101, 457OKGAXIC CHEMISTRY. 145stLtter 24 and Waser from N-methylgranatenine, C,H,,*NH*CH,obtained from the alkaloid t)-pelletierine, was achieved by use ofthe ve.ry elegant method of eliminating two atoms of hydrogenfirst used in preparing cycloheptadiene from suberone.2sFrom the quaternary methylammonium base from N-methyl-granatenine, cyclooctatriene (I) was obtained by distillation in ahigh vacuum:The scheme shows the series of changes in which the tetraene isfinally isolated.I n a similar manner 20 cyclohexanol was converted into benzene.The A1:3-cycZohexadiene,” which was passed en route, can be pre-pared in this way in a purer state than by treatment of cyclohexenedibromide with quinoline :C,H,,*OH -+ C,H,,, -+ C6H10B~*2 --+ C,H9*NSi~2 --+ C’,,H, --+C6H813r2 -+- C6H8(NMe,), -+ CtiH6.The octatetraene a t higher temperatures undergoes a rearrange-ment to an isomeride, which is unsaturat.ed, but no longer has fourdouble linkings, nor can be reduced to cyclooctane, but only to theconipounds C&t1, o r C,H,,.The most probable explanation of thischange is that a, more stable configuration has been produced withthe formation of a di- or tri-cyclic compound :FH*YH*C]WEHCH:CH.CH.CFi’ orSH * yH*CH: KCH*CH*CH:CRThis fact has led t o the suggestion that caoutchouc (dehydro-caouprene) has a similar cyclic structure 28 :Reducing Agents.-There has been much discussion during theperiod under review as t o the efficacy and trustworthiness of the24 Bey., 1911, 44, 3423 ; A ., i, 17.‘35 Ibid., 1901, 34, 129 ; A , , 1901, i, 223.26 Ibid., 1912, 441, 1464 ; A . , i, 544.a A. W. Crossley, jT., 1904, 85, 1103; C. D. Harries, Ber., 1912, 45, 809,2586 ; A., i, 343, 842 ; N. D. Zclinsky and A. Gorsky, Ber., 1911, 44, 2312; A.,1911, i, 847.2s I. von O~tromisslensky, J. Rim. Phys. Chrm. SOC., 1912, 44, 204 ; A., i, 280.REP.-VOL. 1X. 146 ANNUAL REPORB ON THE PROGRESS OF CHEMISTRY.reducing agents which are in use for the addition of hydrogen t ocyclic carbon compounds. Wallach 29 has pronounced in favour ofPaal’s reagent, that is, colloidal palladium (or platinum) and hydro-gen?O as being less prone to cause constitutional change than anyother.Willstatter,31 on the other hand, presses the advantageof platjnum-black and hydrogen preferably in the presence ofacetic acid-a reagent to which attention has been drawn byFokin.2 I t is claimed that this method is far superior to that ofSabatier and Senderens,% in that the hydrogenation is quantitative,and can be carried out a t the ordinary temperature. There seems,however, to be as yet some difficulty in its application,3* but this isascribed to the presence of sulphur compounds (for example, thio-phen), which inhibit the reduction of such compounds as benzene,naphthalene, benzoic acid, etc., but only retard the reduction ofcyclic olefines, such as limonene.It is noteworthy that caoutchoucdissolved in benzene is not attacked by this reagent, but the solventis reduced t o hexaiie if the caoutchouc be not vulcanised.s5Numerous applications36 of this method to the most diverse typesof compounds are €ound in the literature of the year; and a criticalinvestigation to determine the best procedure has been made bySkit a .37The synthesis of nitriles of this series by the interaction ofmagnesium alkyl bromides and cyanogen is also noteworthy; itoffers a means of preparing saturated cyclic nitriles, acids, and soforth.38During the period under review, continuous progress has beenmade with the syntheses of o-, m-, and pmenthenols, and thecorresponding menthadiene~.~g An interesting method 40 of preparingbenzo(p1ieno-)cycloheptadienes is found in the condensation of2 : 2’-dimethyldiphenyl-ww’-dicarboxylonitrile under the influence of29 Annulen, 1911, 381, 51 ; A., 1911, i, 469.3o C.Paal, A . , 1905, ii, 397, 533 ; 1907. ii, 559 : 1908, i, 599 ; 1909, i, 926 ;3l Ber., 1911, 44, 3423 ; ibid., 1912, 45, 1164, 1471; A., 1912, i, 17, 544,32 J. Russ. Phys. Chem. SOC., 1908, 40, 276, 700 ; A . , 1908, i, 311 ; ii, 637.s3 Compare G . B. Neave, T., 1912, 101, 513.a H. Wieland, Ber., 1912, 45, 484, 2615; A., i, 247, 956.55 F. M’. Hinrichscn and R. Iiempf, ibid., 2106; A . , i, 687.36 L. C. Kelber and A. Schwarz, ibid., 1946 ; A., i, 617 ; A. Kiitz and E. Schrreffer,87 Ber., 1912, 45, 3312, 3.579, 3589 ; A ., 1913, i, 53, 54, 63.38 V. Grignard and E. Bellet, Comnpt. rend., 1912, 155, 44; A . , i, 623.39 W. H. Perkin, jun., and others, T., 1911, 99, 118, 518, 526, 727 ; G. G.Henderson and R. Boyd, Z’., 1911, 99, 2159.40 J. Kenner and Miss E. G. Turner, ibid., 2101 ; P., 1912, 28, 277.1912, i, 703 ; A. Skita and H. Ritter, Ber., 1910, 43, 3393 ; .A., 1911, i, 71.545.ibid., 1952 ; A., i, 603ORGANIC CHEMISTRY. 147sodium ethoxide, when 1-imino-2-cyano-3 : 5-dibenzo-Aa : 6-cyclohepta-diem was obtained :/\ i i ,,-%,I C:NH.What promises to be a very useful general method of convertingketones and aldehydes into hydrocarbons has been found41 in theaction of alcoholic sodium ethoxide on the semicarbazones orhydrazones :The temperature must be fairly high, 16O-2OO0, but the amountof sodium ethoxide which apparently acts catalytically is of littleimportance. Fenchone and camphor are nearly quantitativelyconverted into fenchane and camphane respectively.The problem of the conversion of unsaturated hydrocarbons tocyclic isomerides, the technical importance of which is of peculiarinterest a t the present time, was fully discussed in last year'sreport (pp.107-108). The exact work on the polymerisation,42more especially of as-dimethylallene, (CH,),C:C:CH,, to cyclo-butanes, has led to interesting results. Two types of dimerides arepossible :>C:N*NH*CO*NH, + >C:K*NH, -+ >CIl,+N2.andy ' y : Cc*c:cy*f.':cc:c.c 'with three isomerides of each type.The three cyclobutanes of thefirst type have now been obtained by correct choice of conditions,and their constitutions settled by oxidation with ozone, but thereis no sign of the dimerides of the second type.The first example of the direct synthesis of a meta-linking in asix-membered ring is the formation of the norpinone 43 (bicycle-1 : 1 : 3-heptanone) :CHCH,*yB*CH,CH,*CH*CH, I c;*I *(11.) (111.)CH2(1.141 L. Wolff, Annalen, 1912, 394, 86 ; A., i, 988.*2 S. V. Lebedeff, J. Buss. Phys. Chem. Soc., 1910, 42, 949; 1911, 43, 820,1735; A . 1911, i, 26, 774; 1912, i, 173 ; compare H. Stobbe and F. Reuss,Anna.len, 1912, 391, 151 ; A., i, 842.43 0. Stark, Ber., 1912, 45, 2269 ; A., i, 868.L 148 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The distillation of the calcium salt of homohexahydroisophthalicacid results in the formation of a bicyclo-1 : 2 : 2-heptan-&one (II),44whilst similar treatment of the barium hexahydroterephthalate issaid to yield the isomeric bicycloheptan-7-one (IIJJ.46 Stark uses asimilar method, namely, the distillation of calcium hexahydroisoaphthalate.The reaction with bromine excludes the presence of adouble linking, and hence of six- or seven-membered rings witha double linking as possible constitutions.Ozonides and Ozozomides.-The abnormally large addition ofoxygen which has frequently been observed in the combination ofozone with double linkings has now found an explanation in thediscovery that ordinary strongly ozonised oxygen, “ 14 per cent,ozone,” contains another polyatomic molecule, oxozone, probably04, besides ozone.40 On washing crude ozone with sodium hydr-oxide and sulphuric acid, when the oxozone is destroyed, theabnormalities disappear and pure ozonides are obtained.Anozonide, RO,, is not converted into an oxozonide, RO,, by “ mixed ”ozone, hence pure oxozonides can only be prepared when theirrate of formation is much speedier than that of the ozonides. Sofar this condition has only been found in the case of caoutchouc.The decomposition products of the oxozonide, CI0Hl6O8, are thesame as those of the ozonide, but there is a greater proportion oflmn.dic acid than aldehyde.Terpenes a d Allied Compounds.-Of the very large number ofpapers, having as their subject the terpenes or ethereal oils, byfar the greater proportion describe the extraction of these sub-stances from various natural sources which have in recent yearsbecome more accessible.The methods of procedure appear to bebecoming standardised ; but the intricate chemistry of this vastgroup is not sufficiently explored to allow of the recognition ofmany of the compounds which have been isolated.Campherre.-Since this puzzling member of the terpene series waslast mentioned in the reports (1910), several investigators havebeen engaged with the attempt to solve the problem of its constitu-tion. There seems now no doubt as t o its individuality, and,moreover, that the materials obtained from all natural sources I areidentical.47 Wagner’s formula (I) has steadily risen in favour,replacing Semmler’s (XIV), mainly owing to the simplicity of theoxidation of camphene by ozone 48 ; dimethylnorcampholide and44 G . Komppa arid T.Him, Uer., 1903, 36, 3610 ; A . , 1904, i, 60.45 N. D. Zelinsky, ibid., 1901, 34, 3800.46 C. D. Harries, Zeilsch. Elektrochem., 1912, 18, 130 ; A , , ii, 343; Ber., 1912,45, 936 ; A . , i, 407 ; Annaien, 1912, 390, 235 ; A . , i, 673.47 0. Aschan, Annalen, 1911, 383, 1, 3 9 ; A., 1911, i, 794, 796.48 F. W. Semmler, Bcr., 1909, 42, 246, 962 ; A , , 1909, i, 170, 312 ; C. D. Harriesan3 J, Palmhn, Ber., 1910, 43, 1432 ; A., 1910, i, 497ORGANIC CHEMISTRY. 149camphenilone, the products, are certainly represented by theformulz (11) and (111), since the latter has been converted intothe acid (IV), the constitution of which has been demonstrated bydirect synthesis.49 Among other difficulties in the way of acceptingWagner's formula is the fact that some 70 per cent.of the productof oxidation of camphene is camphenic (" camphenecamphoric ")acid.60 The constitution of this acid was given by Aschan, whoproposes the formula (V) on the grounds that it only formed amonobromo-derivative, which could be converted through anunsaturated acid (VIII) to a hydroxy-acid (VII), which does notform a lactoDe. Moreover, the unsaturated acid yields the lactoneof a, tribasic acid (IX), the constitution of which was based on theresults of alkali-fusion. W. N. Haworth and A. T. King 51 have,however, synthesised in a simple manner a lactone of this constitu-tion, which differs unmistakably from Aschan's compound.Hencemuch of the evidence for the constitution ascribed to camphenicacid fails. Haworth and King suggest that since a second isomerideof the acid is known,52 Aschan's acid may have the constitution(XI), when camphenic acid would have the formula (XII).The formation from bornylene (XIII) of camphenilanaldehyde,which can be prepared simply by several different methods fromcamphene, as well as other considerations, has led G. G. Hendersonand I. M. Heilbron 53 to urge that the carbon-skeleton of campheneand bornylene is more closely related than is shown by Wagner'sand Aschan's (VI) formulae, and to suggest the revival of Semmler'sformula (XIV), as that which permits the formation of thealdehyde, with the least rearrangement from both hydrocarbons.CH,*yH-C Me,CH, CH-C: C H,(1.)CH,*QH*CHMe,CH,*CH* C0,H(IV.1CH,*?H-?Me,UH,*CH-CH1 Q"2 II QH2I FH2 fiHw.1CH,*~H-~Me, CH,*C]H-CMe,C'H,*CH-CO 1 F H 2 I CH,*CH---CO I QH2 v(11.1 (111.)CH,-~H*CMe,-CO,H CH,°FH*CM~,*CO,HCH,*CH*CO,H I QRzUH,*C(OH) *CO,H I ?"2(V. 1 (VII.)CH,*QH*CMe,* C0,H CH,* Q( CO,H)*CMe,*CO,RCB,*C*C02H I ? CH,*CO I FiH(VIII.) (IX. 149 L. Bouveault and G. L. Blanc, Compt. rend., 1908,147,1314 ; A., 1909, i, 108.50 0. Aschan, Annalen, 1910, 375, 336; A., 1910, i, 709.51 T., 1912, 101, 1975.53 W. H. Perkin, jun., and J. F. Thorp, ibid,, 1901, 79, 764.53 T., 1911, 99, 1887, 1901150 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.CH,-F]O CH,--F]( C0,H) *CH,*CO,HCMe,* C (C0,H) CH,* CO,H I ? CMe,*CO I ?(X.) (XI.)C H2--Q H*CH,*CO,H CH,*?Me-CH CH,*$!Me-x,CMe,* CH* C0,HI QRle,,CH:CH,CH,*CH-(XII.) (XIII.) (XIV.)CH,*QMe-\ CH2*QMe-\CH,*bH -I FMe2 I I CH,*CH-CH I FH2I CMe, / ‘CH*CHO I FMe2,COC‘H,*CH--(XV.1 (XVI.)This view necessitates an alteration of the formula of bothcamphenilanaldehyde and camphenilone [Henderson’s and Heil-bron’s formula3 are respectively (XV) and (XVI)]. That of thelast-named seems, however, fairly certain, and has found confirma-tiori on further recent study.%A very striking light is thrown on the constitution of campheneby its spectro-chemical properties.65 It shows a molecular opticalexaltation or increment (M,) of +2*12, which, as was stated in theforegoing, could not be caused by an endocyclic, but only a semi-cyclic ethylene linking. Moreover, the exaltation which has beenshown to be caused by a tricyclic linking, whether in cyclopropanederivatives,m or in terpenes (cyclene, etc.), does not exceed +0.9;hence camphene cannot be a saturated compound possessing such astructure.Finally, the normal refractivity of isocamphane 67(dihydrocamphene) demonstrates that the increment cannot beattributed to the carbon-skeleton of camphane. Aschan’s formulaseems, therefore, to be excluded in favour of Wagner’s, or possiblySemmler’s, both of which have a semicyclic ethylene linking.Canzphor.-Among the numerous researches dealing with deriv-atives of camphor, some of which have rather a secondary objec-tive, the investigation of the behaviour of the various groups,weighted by the camphor complex,m or a study of morphotropicrelations,59 attention may be directed to the reinvestigation, which54 S.V. Hintikka and G. Komppa, Annalen, 1912, 387, 293 ; A., i, 2i8.55 K, Auwers, ibid., 240 ; A., ii, 214.56 G. J. Ostling, T., 1912, 101, 457.57 P. Lipp, Annulen, 1911, 382, 285 ; A,, 1911, i, 731.68 M. 0. Forster and collaborators, T., 1911, 99, 478, 1982 ; 1912,101, 1327 ; A.Haller, Compt. rend., 1912, 154, 742 ; A, i, 359 ; J. Bredt, Ber., 1912, 45, 1419 ;A., i, 411 ; J. pr. Chern., 1911, [ii], 84, 786 ; A., i, 112.59 W. H. Glover and T. M. Lowry, T., 1912, 101, 1902ORGANIC CHEMISTRY. 151is accompanied by a re-naming, by Noyes and his pupils,80 of thedegradation products of camphor.It seems that in the formationof the cis- and trans-hydroxydihydrocampholytic acids from amino-dihydrocampholytic acid,if the stereoisomerism of the hydroxy-acids is accepted, change ofthe type of the Walden inversion occurs. It is worthy of mentionthat the period under review has seen the close of a famous contro-versy concerning the synthesis of camphoric acid61; i t is nowadmitted that Komppa’s synthesis 62 is well founded.Another isomeride of camphor, epicamphor, or j3-camphor,which has recently been preparedF3 but by somewhat inconvenientprocesses, has now been obtained easily from methyl bornylenecarb-oxylate.64 With hydroxylamine this compound yields the hydrox-amic acid, C,,,H,,-C(OH):NOH, which on heating decomposes intoepicamphor and ammonia.Both the stereoisomerides of isonitroso-epicamphor, together with other nearly-related compounds, havebeen prepared through phenyliminocamphor from camphorquinone,of which all the oximes are now known.65is&amphor.-A very interesting discovery has been made byWallach66 with regard to the constitution of this isomeride ofcamphor. Under conditions, the use of colloidal palladium, whichadmit of no profound change, it has been found that the reductionof isocamphor gives dihydropinolone, which is l-acetyl-3isopropyl-cyclopentane. Hence isocamphor, which is not identical with pinolone, is a l-acetyl-3-isopropylcyclopentene,>CH,YH,--CAcCH,*CHPrPfor which the name isopinolone is suggested.* J .Amer. Chem. SOC., 1912, 34, 62, 174, 1067; A . , i, 159, 786.61 G. L. Blanc and J. F. Thorpe, T., 1910, 99, 2010 ; Q. Komppa, ibid., 29.82 Ann. Pikport, 1904, 112.63 F. R. Lankshear and W. H. Perkin, jun., P., 1911, 27, 166 ; J. Bredt and W.64 J. Bredt and W. H. Perkin, jun., P., 1912, 28, 56.65 M. 0. Forster and H. Spinner, T.? 1912, 101, 1340.66 Annalcn, 1912, 392, 49 ; A,, i, 879 ; compare Annalen, 1911, 3M, 198 ; A,,Hilbing, Chem. Zeit., 1911, 35, 765 ; A . , 1911, i, 657.1911, i, 891152 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Natural Products.Tannin.-With the synthesis 67 of compounds which closelyresemble tannin a great advance has been made in the attemptto determine the chemical nature of this substance.Although itwas originally supposed that tannin was a compound of sugar andgallic acid,68 the view that the essential constituents of the materialwas a digallic acid has found general acceptance, and alone appearsin the textb~oks.~g The low acidity, small electrical conductivity,and high molecular however, render this hypothesis unten-able, and, moreover, have led Nierenstein71 to abandon his viewthat tannin was a mixture of digallic and leucodigallic acids. Hisnew formula represents tannin or tannins as polygalloylleucodigallicanhydrides 72 :the optical activity being due to the leucodigallic acid, and not tothe presence of a glucose residue. Fischer and Freudenberg havesatisfied themselves (Zoc.c i t . ) that purified tannin contains a smallproportion (7-8 per cent.) of dextrose, which cannot be presentas an impurity, and to which they ascribe the optical activity. Theisolation of a crystalline glucogallic acid as a companion of tanninin certain galls as collateral evidence may be recorded.73 Theysuggest that tannin is therefore a penta$igalloylglucose,7* whichshould yield 10.6 per cent. of dextrose,[c6s2( OH),*CO*O*C6H,( OH)2CO]5C6H706.This compound is to be regarded rather as an ester than as aglucoside. Starting from tr&ethylcarbonatogalloyl chloride anddextrose, a pentagalloy$$ucose, [~6H2(OH)3*CO],,C,H706, wasprepared, which had the greatest resemblances to tannin, in taste,optical activity, slight acidity, colour reactions, and the power offorming precipitates with gelatin and alkaloids.Moreover, methyl-tannin, which is prepared from diazomethane and tannin, is identi-cal with the material obtained from pentamethyldigalloyl chloride0’ E. Fischer and K. Freudenberg, Ber., 1912, 45, 915, 2709 ; A . , i, 471, 887.@ A. Strecker, Annulen, 1852, 81, 245 ; ibid., 1854, 90, 328.1 3 ~ H. Schiff, Ber., 1871, 4, 232, 967 ; ibid., 1879, 12, 33.70 P. Walden, ibid., 1897, 30, 3151 ; 1898, 31, 5167.jrl Ann. &port, 1909, 107 ; Ber., 1908, 41, 77 ; 1909, 42, 1122 ; 1910, 43, 628 ;A., 1908, i, 90; 1909, i, 897; 1910, i, 265; compare R. J. Manning arid M.Nierenstein, Ber., 1912, 45, 1546 ; A., i, 666.72 AnnaZen, 1912, 388, 223 ; A., i, 468.73 K. Feist, Ber., 1912, 45, 1493 ; A , , i, 566.7r Compare H.C. Biddle and W. P. Kelley, J. Amer, Chem. Soc., 1912, 34,918 ; A., i, 713ORGANIC CHEMISTRY. 153and dextrose (Fischer and Freudenberg). Hence methyltannin,?6which is a mixture probably of two stereoisomerides, is a penta-[pentamethyl]digalloylglucose. It is noteworthy that by this methodcompounds of very large molecular weight can be synthesised ;thus there is no difficulty in preparing the compound from tri-benzoylgalloyl chloride and glucose with a molecular weight ofnearly 3000.76Damascenine.-The synthesis 77 of damascenine, the “ alkaloid ” ofATigeZZa dumascena, has proved that Keller’s 78 “ betaine ” formulais incorrect. Damascenine is methyl 2-methylamino-3-methoxy-benzoate, which Reller isolated, but believed to be the methylderivative of the alkaloid.Scopole tin.-Another natural product, the constitution of whichappears t o be finally settled, is scopoletin; this compound is2 : 4-dihydroxy-5-methoxyphenylpropionic acid, and can be con-verted with ease either into 2 : 4-dihydroxyanisole or 2 : 4-dihydroxy-5-methoxycinnamic acid.79The most cursory perusal of the foregoing review in this sectionwill show that much that is both important and interesting in theyear’s work is not even mentioned.I n making a selection of thesubjects to be reviewed, the extent to which they have been dealtwith in the reports irnmediately preceding, has been taken intoaccount; thus the organic compounds of arsenic and sulphur werefully considered last year, whereas little reference was made to theterpenes and hydroaromatic group.Moreover, it is obvious that alarge proportion of the work in organic chemistry must be givensimply to exploration; vast numbers of compounds which arepossible on our present theories still remain to be prepared. Theexplorers mainly follow well-beaten tracts, and the new groundwhich is mapped out by a familiar procedure only occasionallyshows features which differ more than in details from that alreadybroken. That such work is absolutely necessary, and when con-sidered as a whole forms a fine monument of achievement, is shownby several well known classic examples, but it does not lend itselfto review a t very frequent intervals.KENNEDY J. P.OBTON.75 J. Herzig, Ber., 1908, 41, 2890 ; A . , 1908, i, 183 ; Monatsh., 1909, 30, 543 ;1912, 33, 843 ; A . , 1909, i, 713 ; 1912, i, 792.76 See also H. Crompton, P., 1912, 28, 193.77 A. J. Ewins, T., 1912, 101, 544.0. Keller, Arch. Pharm., 1904, 242, 299 ; 1908, 2416, 1 ; A., 1904, i, 768;C. W. hlnore, T., 1910, 97, 2224 ; 1912, 101, 1043,1908, i, 283154 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.PART III.-HETEROCYCLIC DIVISION AND STEREOCHEMISTRY.The notable features of the year’s work appear to have been theadvances which have been made in the study of alkaloids, and alsothe growing tendency to apply the conceptions of physical chemistryto the study of stereochemical problems. I n the latter classmention may be made of the investigations of the Walden inversionmechanism, and also Michael’s application of the entropy principleto stereoisomerides.These and kindred researches suggest that wemay shortly see a considerable augmentation of interest in stereo-chemistry, and many of the problems which were left unsolved bythe older methods may yield t o the newer methods of attack.The AIkaloids.Summaries of alkaloid chemistry are exceptionally difficult to.produce in any circumstances, owing to the intricate nature of thesubject; and in the current year the task has been rendered evenless easy thsn usual, for the progress during the last twelve monthshas been very marked, and consequently an enormous amount ofmaterial has accumulated which is very hard to weld into a con-nected whole without expending too much space.A selection oftypical advances has, therefore, been made, preference being givento those points which lend themselves best to concise treatment. A tthe same time, it is hoped that a fair conspectus of the field as awhole has been furnished.I n view of the controversies which have arisen from time to timewith regard to the natural syntheses of alkaloids which go on inplants, it is not without interest to find that Paternb and Maselli,lin the course of their studies in photochemistry, have discoveredthat when acetophenone is dissolved in a concentrated alcoholicsolution of ammonia and then exposed to sunlight for severalmonths, a 20 per cent. yield is obtained of a substance whichappears to resemble the natural alkaloids in many respects.Thisproduct has the composition C,,H,,N,, gives rise t o various salts,and forms a nitroso-derivative. Up to the present, its constitutionhas not been determined.The simplest alkaloid synthesised during the year appears tobe damascenine,2 which h’as the structure :NHMe OMeCo2Me(--> .Gazzelta, 1912,42, i, 65 ; Atti R. A d . Llincei, 1912, [v], 21, i, 235; A., i, 295.Ewins, T., 1912, 101, 544ORGANIC CHEMISTRY. 155Strictly speaking, this compound does not fall into the presentdivision of the subject, but it has been included on account of itssimple structure and for the sake of completeness.I n the tropine gr0~p,3 a substance hitherto termed $-hyoscyamine,and regarded as an isomeride of hyoscynmine, has recently beenproved to be really nor-hyoscyamine, differing from hyoscyaminein having no methyl group attached to the bridge nitrogen atomin the ring:CH,* 7 H-7 €3, C H , - ~ H - - - ~ H , VaH,CH2-CH-CH, CH,*OH CH,*CH---CH, CH,*OHThia relationship has been established by the following treatment.It was shown that the alkaloid contained no N-methyl group,whilst it formed a nitrosecompound, thus proving that it was asecondary amine.The action of methyl iodide on it produced amethyl derivative, which was found to be identical withZ-hyoscyamine. Hydrolysis with barium hydroxide yielded tropicacid and nor-tropanol. Just as hyoscyamine is racemised and formsatropine, so nor-hyoscyamine can be converted into the opticallyinactive nor-atropine.I n physiological properties there is a con-siderable difference between hyoscyamine and nor-hyoscyamine, thenew alkaloid being eight times less active than the former inmydriatic action.I n the group of the cinchona alkaloids, various workers havestudied the intramolecular changes which these substances can bemade to undergo. Bottclier and Horovitz4 find that when quinineis heated a t looo with sulphuric acid, two bases result, which theyterm A and B; and these compounds are also formed when quinineis treated with hydrogen iodide. It appears that the base B isidentical with Lippmann and Fleissner’s isoquinine.5 A somewhatsimilar treatment seems to convert quinine and cinchonine intotheir poisonous isomerides, quinotoxine and cinchotoxine ; for whena salt of quinine is heated at 95-98O in aqueous solution, withor without excess of acid, it undergoes rearrangement with theproduction of quinotoxine.6 Cinchonine gives the analogouscinchotoxine.The velocity of the rearrangement appears to dependto a great extent on the strength of the acid employed; weakacids seem to favour the process, whilst strong acids, such as hydro-Carr and Rejnolds, T., 1912, 101, 946.Monatsh., 1911, 32, 793 ; 1912, 33, 567 ; A., 1911, i, 1011 ; 1912, i, 717.Ibid., 1891, 12, 327; A., 1892, 81.Biddle, Ber., 1912, 45, 526 ; A., i, 296 ; Rabe, ibid., 1447, 2927 ; A., i, 488,I TH FH*O*CO*7H 1 YMe ~ H - O * C O * ~ HNor-hyoscyaniine. Hyoscyaminc.1014156 ANXUAL REPORTS ON THE PROGRESS OF CHEMISTRY.chloric, inhibit it. Even at a temperature of 36O the changetakes place, although more slowly; and the same may be said forthe exposure of salt solutions to direct sunlight a t the ordinarytemperature.Similar results were obtained with other membersof the cihchona group.Mention may be made of some preliminary synthetic experi-ments7 in the cinchonine group, but the results could be satisfac-torily dealt with only by entering into greater detail than spacepermits.The group containing narcotine and its allies has been the centreof a considerable amount of investigation during the year. It willbe remembered that Liebermann 8 endeavoured t o producenarcotine by condensing together hydrocotarnine and opianic acid ;but that, instead of the expected product, he obtained a substance,isonarcotine.The constitution of this substance has now beenexp1ained.Q When hydrocotarnine (I) is treated with form-aldehyde, the hydrogen atom left unsubstituted in the benzenering ( 5 ) is attacked lo; and this suggested that in the condensationwhich leads to isonarcotine the same hydrogen atom might be theone which becomes replaced by the opianyl radicle. To prove this,hydrocotarnine was brominated, thus exchanging the labilehydrogen atom for a bromine atom and producing bromohydro-cotarnine (11). An attempt was made to condense the latter com-pound with opianic acid, but no reaction took place. This provesMe0 C'H, Me0 CH,(I. ) Hydrocotarnine. (11.) Bromohydrocotarnine.Me0 CH,' I / b oI \ )MeGMe(111.) GoNarcotine.CH,6H.OOMe(IV. ) Narcotine.7 Rabe, Ber., 1912, 45, 2163 ; A., i, 718.Ber., 1896, 29, 184, 2040 ; A., 1896, i, 264.9 Freund and Fleischer, ibid., 1912, 45, 1171 ; A ., i, 490,10 Freund and Daube, ibid., 1183 ; A,, i, 491ORGANlC CHEMISTRY. 157that some factor is missing in the bromohydrocotarnine which ispresent in hydrocotarnine itself; and the missing factor can onlybe the labile hydrogen atom which is present in hydrocotarnine.The constitution of isonarcotine may therefore be written as shownon p. 156 (111), and the formula for narcotine is given in (IV) forcomparison.I n connexion with the isonarcotine condensation, another pointmight be mentioned. Liebermann employed 73 per cent. sulphuricacid as his condensing agent; but later work by Kersten11 showedthat concentrated hydrochloric acid might also be used with goodeffect.The use of this reagent in the coiidensation of phenolicethers appeared to Jones, Perkin, and Robinson12 t o leave somedoubt as to the identity of products obtained in this way; andthey have therefore investigated the behaviour of various etherswhen submitted to condensation by this method. The results showthat the reaction takes the ordinary course, so that a possibleobjection to the isonarcotine structure was thus removed.The behaviour of narcotine when submitted to the action ofheat in various solvents13 has shown that decomposition ensues inalcoholic, aqueous, or acetic acid solution, whereas mineral acidshave but little influence,The condensation of cotarnine with nitromeconine produced asubstance, nitrognoscopine.14 This work has now been continued,’6and it is found that when the nitro-compound is reduced to anamino-derivative, the latter yields a hydrazine, which, on oxidation,is converted into an isomeride of gnoscopine.It is suggested thatT-narcotine should be termed a-gnoscopine, whilst the new stereo-isomeride should be called B-gnoscopine; and there is reason tobelieve that the a-modification corresponds with racemic acid, andthe fl-form with i-tartaric acid. Similar reactions16 have beenapplied to the preparation of anhydrohydrastininemeconine withvery good results. Gnoscopine17 appears to be produced whennarcotine is heated in various solvents for long periods.I f a Grignard reagent prepared from ethylene bromide andmagnesium is allowed to act on hydrastinine,lB two isomeric dihydro-hydrastinines are produced, which owe their isomerism to spatialdifferences.This reaction is similar to that discovered19 in thel1 Ber., 1898, 31, 2099 ; A., 1898, i, 702.l2 T., 1912, 101, 257,l 3 Rabe, Bcr., 1912, 45, 2927 ; A . , i, 1014.14 Hope and Robinson, P., 1910, 26, 228.l5 ]bid., 1912, 28, 16.17 Rabe, Ber., 1912, 45, 2927 ; A., i, 1014.1s Preuud arid Shibata, ibid., 855 ; A . , i, 488.1Q Freund and Kupfer, AnnnZen, 1911, 384, 1 ; A . , 1911, i, 911.l 6 X d . , 17I58 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.case o€ cotarnine. The case is somewhat complicated by thepresence of a methyl group attached to a nitrogen atom in thering ; and there is a possibility of cis-trans-isomerism entering intothe question. I f we assume such isomerism, two isomeric meso-forms of the substance would be possible.A general method whereby hydrastinine bases may be obtainedfrom berberine derivatives has been devised,zO the outline of whichis as follows.The dihydroberberine derivative (I), in which Rrepresents an alkyl, alkaryl, or aryl radicle in the a-position, isconverted into the tetrahydro-compound (II), then into thequaternary compound (111), and finally into the ammonium base(IV) and the $-base. Further elimination of water may then takeplace, or oxidation will convert the base into derivatives ofhydrastinine (V) :C,H&O,N + H2 = @2$32$304N(1.) (11.)C20€&,R0,N + Me1 = C2,H2,R04NMeIC,H2,R04NMeOH = H,O + C2,H,,RO4NMe(IV.) ( V .)( 1 11.)Turning now to thO berberine group, a comparison of theformuh of berberine (I) and hydrastine (11) will show that a(I. ) Berberine. (11.) Hyclrastine.O-CH, /\ACH I I/\/\/\/hZeO!,/,), I )CH2Me0 CO CH,(111.) Oxyberbcrine.close relationship exists between the two. Hydrastine is evidentlythe lactune corresponding with the unsaturated acid which wouldbe obt.ained if 8, methyl group could be attached to the nitrogenatom of oxyberberine (111). With a view to producing thischange,21 oxyberberine was submitted to the action of methyl iodideFreund, D.R.-P. 241136; A., i, 383.Bland, Perkin, and Robinson, Z'., 1912, 101, 262ORGANIC CHEMISTRY.159in the presence of water, but the ultimate product appears to bean isomeride of oxyberberine, which probably has the structurerepresented by :0-CH, /\;,CH I I/\/\(/\,/I '''eo(/\/NH CH:CI-I,i~w0xyberberiue.The function of the methyl iodide is apparently merely t ofurnish hydriodic acid, the presence of which is necessary to thereaction, for the conversion of oxyberberine into isooxyberberinecan equally well be produced by heating oxyberberine with hydrclchloric acid.Other work in the berberine series includes the preparation ofnumerous derivatives of berberine and tetrahydroberberine.22A considerable amount of attention has recently been paid tothe harmine group of alkaloids.Perkin and Robinson 23 considerthat the following formula, since it affords an explanation of thereactions of harmine, must be very close to the actual constitutionof the substance :Me0 COOMe/\I I CH CHHariniue. apoHarmine.If this view be-correct, then apoharmine should have the secondformula above, which is 2-methylindole in which one of the methinegroups of the benzene ring is replaced by a nitrogen atom. Suchcompounds containing a fused pyridine-pyrrole nucleus areunknown; and as each ring might be expected to modify the other'sproperties to some extent, the further experiments in the synthesesof such substances will be awaited with interest.Now when the methoxy-group is eliminated from harmine,24 abase, harman, is obtained, which, on the Perkin-Robinson view,would have either of the structures (I) and (11), according asharmine cont.ains a quinoline or an isoquinoline nucleus.To throwFreund, D.R.-P. 242217 ; A , , i, 487.ZJ T., 1912, 101, 1775.24 0. Fischer, CEem. Centr., 1901, i, 957 ; A., 1901, i, 405160 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.some lightit is foundto it. Theon this, the latter substance has been synthesised,25 andnot to be identical with harman, although very similarnew substance (11) has therefore been termed isoharman.CH/‘\I I (3rd\ \/\\/\/A/\/\\ I I 1 C*CH,\/\/\/ < I C-CH,N KH N NH(1.1 (11.1From these results, i t may be concluded that harmine itself containsan isoquinoline nucleus i19 shown above, and not one containing aquinoline group.It has been shown26 that, by heating harmic acid to 250--380°in a vacuum there is obtained from it apoharminecarboxylic acid,which in turn a t 330° decomposes with loss of carbon dioxide,yielding apoharmine.Frdm these results i t is deduced that harmicacid is apoharmine2 : 3-dicarboxylic acid. A new base 27 has beenprepared from upoharmine by applying Hofmann’s reaction. Thedecomposition does not take the usual course, but results in theformation of a substance containing four atoms of nitrogen, whichappears to be trimethyldiupoharmine. It has also been shownthat apoharmine csn be reduced to a tetrahydro-derivative inaddition to the dihydro-compound already known.28Some harmaline derivatives have been synthesised by 0.Fischerand Boesler.20P-Saphthasdphonium-quinone and the Sulphides of P-XaphthoE.When the a-sulphide of 8-naphthol, HO*C,oH6*S*C,oH,*OH, istreated with alkaline oxidising agents, i t loses two atoms ofhydrogen, and is converted into a stable scarlkt substance, firsttermed dehydro-/3-naphthol sulphide. Reduction of this leads tothe production of a naphthol sulphide, which appears to bedifferent from the original one. This series of compounds waevery thoroughly examined by Henriques,30 who was unable t o putforward any structural formulz to explain the existence of thetwo isomerides, and therefore assumed that they were stereoisomeric,the sulphur atom being supposed in some way to hinder freePerkin and Robinson, P., 1912, 28, 154.xi Hasciifratz, Conzpt.rend., 1912, 154, 704 ; A . , i, 383.27 Ibzd., 1520 ; A . , i, 577.?8 ]bid., 1912, 155, 284; A., i, 797.29 Bcr., 1912, 45, 1930; A . , i, 645.31) Ibid., 1894, 27, 2999 ; A . , 1895, i, 103ORGANIC CHEMISTRY. 161rotation of the two naphthol groups, so that the spatial formulaeof the isomerides might be written as follows :IIO*$,H6 H0*710H6B C,,H6*OH B HO* CloH,(1.) (11.1Thus, in the one case, the hydroxyl groups were on the sameside of the molecule, whilst in the second isomeride they were onopposite sides. With regard to the structure of the intermediatescarlet substance, Henriques concluded that it was a peroxide ofthe formula:C , 0 H 6 ~ ~ ? > c 1 0 H 6(111.)This structure would agree with the known reactions of thesubstance up to a certain point, and is especially suitable inconnexion with the hypothesis that the two sulphides are stereo-isomeric, since in the reduction of the peroxide it is to be expectedthat a naphthol derivative of formula, (I) (where the two hydroxylgroups are adjacent in space) would be formed in preference toone having the second formula.The investigation of this series of substances has been undertabenby Smiles and his collaborators; and their investigation has ledto wholly unexpected results.In the first place, the so-calledperoxide reacts with phenylhydrazine, forming a dihydrazone, asHenriques had shown; and this in itself tends to throw some doubton the applicability of the peroxide formula; for one would expecta true peroxide to be readily reduced by phenylhydrazine, givingthe sulphide instead of the hydrazone.Secondly, the scarlet sub-stance, when treated with alcoholic alkali hydroxide, produces anaphthathioxin. Now this result is parallel to those obtained31 inthe case of certain benzene derivatives :0 0 OH/\OH\/\ /\/\/\Me) ' I IMc -+ Me1 \ / \ / b e I \/\ /\/? ?OH OHHilditch and Smiles, T., 1911, 99, 973.REP.-VOL. IX. 162 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.so that it seems probable that the scarlet substance has thestructure (IV), and is really 8-naphthasulphonium-quinone. Anexamination of the new formula proposed for this substance showsthat it cQntains a quinonoid nucleus of a totally new type, and itsreactions are therefore of more than usual interest.When treated with hydrogen chlorideF2 the quinone is convertedinto chloronaphthathioxin ; whilst acetic anhydride in the presenceof camphorsulphonic acid gives acetoxynaphthathioxin. Takingthe case of the halogen acids, the reaction is formulated as follows:CI(V->? Q'OH blC10H6<~>~10H, * C10H6<E>C,,H6(VI. 1 (VII.)In the first place, the halogen acid attacks the quinonoid nucleus,but in 60 doing it produces a substance unstabk in the presence ofacids. This unstable substance tends to pass into a cyclic com-pound by intramolecular change; and an examination of thisintermediate compound (VI) will show that it is a $-base, whichhydrogen chloride would convert into the thioxonium salt (VII).In the presence of an alcoholic solution of sodium ethoxide, thescarlet quinone is reduced to Pnaphthol sulphide (m.p. 212O),namely, that from which the quinone was prepared. Now,Henriques, employing acid reducing agents, showed that an isomericsulphide was formed (m. p. 153O); and the possibility of a $-basebeing formed a,s an intermediate product in this reaction furnishesa clue to the cause of the different results obtained in the twocases.Turning now to the properties of the two sulphides themselves,it must be admitted that their isomerism must be of a peculiarcharacter. If the hypothesis of stereoisomerism be accepted, apostulate is made which has no parallel in stereochemistry; sothat it is clear that all other possibilities should be exhaustedbefore falling back on this.An investigation of the actions ofvarious reagents, such as sulphuric acid, potassium hydroxide, andferric chloride, on the two isomerides has been made,= and it was32 Christopher auci Smiles, T., 1912, 101, 710.3y Crymble, Ross, and Smiles, ibid., 1146ORGANIC CHEMISTRY. 163found that there are very marked differences between the twoforms. Thus, cold sulphuric acid with the stable sulphide producesnaphthathioxin oxide ; whilst the unstable isomeride yields naphtha-thiophen. A more striking difference even than this is observedwhen bromine is allowed to act on the two sulphides.34 The stablecompound yields bromo-derivatives of &naphthol, the sulphurbeing eliminated in exchange for the halogen ; the unstablesulphide, on the other hand, retains the sulphur atom and takesup three atoms of bromine in exchange for hydrogen.The tri-bromo-de,rivative formed in this last reaction readily gives uphydrogen bromide on treatment with pyridine, yielding a stablecrimson substance, which appears to be dibromonaphthasulphonium-quinone.The absorption spectra 35 of the two sulphides appear to resembleeach other to some extent in general character. Each contains twobands, which have their heads a t 3000 and 3500 units respectively.Residuul A finity and Spatid Conjugation.It is a well-known fact that when two unsaturated groups in amolecule are conjugated structurally, their mutual influence to someextent. destroys the specific character of each; for instance, thedouble bonds in the structure -C’H:CH*CTH:CH* do not behave likeordinary isolated double bonds.Now it is known that in a normalcarbon chain the positions 1:5 and 1 : 6 have certain propertieswhich lead t o the assumption that they are closely situated withregard to each other in space; and the same has been noticed withregard to the 1 :4-positions in a six-membered cyclic substance.We are thus driven to inquire whether any mutual influence canbe traced between two unsaturated groups which, although struc-turally unconnected, are placed in close proximity to one anotherin space.An examination 36 of optically active esters and salts of saturatedaliphatic acids which had two carboxyl radicles at the ends of anormal chain of carbon atoms has been made; and it was foundthat anomalous rotatory powers were shown when the carboxylgroups were in the 1 : 5- and 1 : 6-positions with regard to each other.This is an example of what is termed “spatial conjugation.’’A very complete investigation of spaceconjugation of the secondtype, in which the unsaturated groups lie in the 1 :4-position with34 Nolan and Smiles, T., 1912, 101, 1420 ; Ross and Smiles, 1912, 28, 275.35 Crymble, Ross, and Smiles, ibid., 1146.9(i Hilditch, ibid., 1909, 95, 1578.M 164 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.regard t o one another in a saturated ring, has led to interestingresults.37 The substances examined were the following :Rk 0 S 0 S S/\ /\ /'\ /\ /\ /\9 H , 9 H 2 7H2 Q", CH, CH, p z p 2 Q", QH, 7 4 FH2\/S r \/ 7CH, CH, CH, CH2 6H2 bH2 CH, CH, CH, CH, CH, CH,0\/ \/ \/ r R\/0R KPiperazines.1 : 4-Dioxan. 1 : 4-Dithian. Morpholines. 1 : 4-Thiazans. 1 : 4-Thioxan.and it will be observed that this series covers all possible permuta-tions and combinations of the three atoms : nitrogen, sulphur, andoxygen.Measurements of the reactivity of the various non-carbon atomswere made both qualitatively and quantitatively. I n the latter casethe method employed consisted in the addition of an alkyl bromideto the complex, by which means an ( ( onium " salt was formed ; andthe amount of bromine thus converted into the ionisable conditionwas estimated by titration a t fixed intervals. I n each series thecorresponding methylene compound was used as a standard ; thus,piperidine derivatives were compared with the correspondingmorpholine and thiazan compounds.It was assumed that devia-tions from the normal standard were due to the mutual influenceof the two non-carbon atoms in the 1 : 4-position with regard toeach other.cyclic compounds of the type :The chief results obtaine,d may be summarised as foCH,*CH,>y,X<C H , - c H 2in which X and Y are atoms capable of raising their vaexample, nitrogen risihg from triad to pentad), and maylows: Inency (forthereforebe supposed to have some residual affinity unsatisfied, the twoatoms X and Y do actually influence each other's reactivities.Further, if X and Y be atoms of the same element, their reactivepower is increased; whereas if X and Y are atoms of differentelements (as in the morpholines) their reactivity is diminished bythe spatial conjugation.The physical constants of the varioussubstances mentioned above have been examined, but in thisdirection the results have not been striking.These results are of considerable importance, as they establishbeyond question that two non-adj acent centres (structurally speak-ing) can influence each other's chemical reactive power to a marked37 Clarke, T., 1912, 101, 1788ORGANIC CHEMISTRY. 165degree; and i t may be anticipated that the observation that similaratoms stimulate one another whilst different elements diminish eachother’s reactivity will prove of value in further research along thesame lines, and may even provide a better knowledge of thebehaviour of such atoms when structurally conjugated.The same branch of the subject has been attacked from adifferent point of view.38 It has been shown that if the absorptionspectra of various stereoisomerides are examined, the two structur-ally identical compounds do not always exhibit identical spectra.I n those cases in which the two isomerides differ markedly fromeach other in spectra, i t was found that the change from oneisomeride to the other entailed the shifting in space with regardto one another of two centres of residual affinity; and that whenthe compounds did not fulfil this condition the difference in theirspectra was very slight, or even in some cases non-existent.Itwould therefore seem of interest if the cyclic compounds formulatedabove were investigated spectroscopically, as it appears probablethat the results might be important.The Chlorophyll Question.This subject hardly le’nds itself to annual summarisation, and infuture it would be preferable to devote a section to it at suchtimes as would enable the reporter to give a connected account ofseveral years’ work, so that the reader need not be confused withdetails carried on from year to year. I n the present section noattempt could be made to cover the whole field of work; all thatwas possible was to take up one or two points which appear likelyto have a bearing on future investigations.It may be recalled that if chlorophyll (phytyl chlorophyllide) istreated with acids, i t is decomposed into phaeophytin (phytyl phzo-phorbide); and that this substance when subjected to alkalisproduces a mixture of phytochlorine-e and phytorhodiri-y. The factthat the two latter substances are always produced in practicallyconstant quantities (1 mol.of the former to 2.5 mols. of the latter)whilst their molecular weights (after allowing for loss of phytol andmethyl alcohol) approximate t o that of chlorophyll, has suggestedthat chlorophyll may be a mixture of two substances, one of whichon degradation yields phytochlorine-e, whilst the other is a phyto-rhodin-g derivative. This view has now been shown to be correct 39by the separation of chlorophyll itself into two compounds, one ofwhich, chlorophyll-a, is bluish-green, and yields only phytochlorine-aas a degradation product, whilst the other, chlorophyll-b, is3c9 Macbeth, Stewait, niitl Wiight, T., 1012, 101, 509.39 Willstitter and lsler, Animlen, 1912, 390, 260 ; A., i, 710166 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.yellowish-green in colour, and produces only phytorhodin-g when i tis decomposed.The intermediate decomposition product of chloro-phyll, phaeophytin, has also been shown to be a mixture of twosubstances.The same process was applied a t a slightly earlier date 40 to somechlorophyll derivatives. Chlorophyll, as is known, is phytyl chloro-phyllide; and since the chief problem at issue is the constitution ofthe non-phytyl portion of the molecule, i t seemed simpler to replacethe phytyl group by ordinary alkyl radicles. I n this way methyl-chlorophyllide and its homologues are produced.These substanceshave now been shown to be mixtures of the a and b chlorophyllides,which give rise to the corresponding phaophorbides a and b .It will be remembered that in alcoholic solution chlorophyllidesand alkylchlorophyllides undergo certain changes which producesubstances different from the original one employed.41 The term“allomerism” is now applied t o such processes, and it is sug-gested that they are probably due to a rupture of the lactamgroup in the chlorophyll derivative and the subsequent formationof a new lactam form. It has been shown that allomeric changecan be catalytically accelerated by the presence of glass; it isprevented by the addition of a trace of acid, and is unaffected byeither platinumThe results offollowed on theor silver.various methods of decomposing chlorophyll can beformula below :$H-$0C0,Me*[C,lH,,N,Mg]*C~,*C20H,,Chloroph yll-a.B -( A ) If chlorophyll is submitted to the action of the enzymechlorophyllase, the a-group alone is attacked.The resulting sub-stances depend on the solvent used: in methyl or ethyl alcohol themethyl or ethyl group replaces the phytyl nucleus, whilst in aqueousacetone solution the phytyl radicle is replaced by a hydrogen atom,yielding the free chlorophyllide. ( B ) If chlorophyll is acted on byacids there occurs, as a result of gentle treatment, a displacementof magnesium by hydrogen ; and the corresponding phzeophytin isliberated.More vigorous treatment results in hydrolysis at thea-group, with the formation of free phaeophorbides. No allomerismoccurs under this treatment, showing that the original lactamgroup is unaffected. (C) The first point of attack of alkalis is they-lactam group, a new lactam group being subsequently produced.The next action is hydrolysis a t the a-group. Finally, with more40 Willstiitter and Stoll, An?taZcn, 1012, 387, 317 ; A., i, 285.dl Willstatter and Utzinger, ibid., 1911, 382, 129 ; A, 1911, i, 659167difficulty, the &group undergoes hydrolysis. At higher temperatures alkalis cause the elimination of carbon dioxide, resulting in adegradation t o phyllins and porphorins.The following diagram-matic scheme will make the results clear:ORGANIC CHEMISTRY.(4Chlorophyll-a.PC0,Me - acids -+ ~N4c3~H320]C0,C,,H,,aPhaophytin-a.Methyl chlorophyllide-a.(4 ~ Chloroph yljide-a..CO,H@)Methyl phaophorbide-a.UPhajophorbidc-a.isoChlorophyllin-e. Phy tochlorin-e.Several investigations of the absorption spectra of chlorophyllderivatives have been made during the past year,42 and the case israther an exceptional one, since it has been found that in thisseries chemical methods are more delicate than spectroscopic ones.This is probably due to the great complexity of the chlorophyllnucleus, and also to the fact that the absorption spectra were notextended far into the ultra-violet in this particular case.A considerable amount of work has been carried out on theporphorin group,43 but it does not lend itself to detailed treatmentin this place.42 Willstatter, Stoll, and Utzinger, Annulen, 1911, 385, 156 ; A., i, 40 ; Dhdrkand Rogowski, Compt.rend., 1912, 155, 653 ; A , , i, 387 ; Marchlewski, Biochein.Zeitsch., 1912, 413, 234 ; A., i, 791.43 Marchlewski and Robel, Ber., 1912, 45, 816; A, i, 376 ; Biochem. Zeitsclt.,1912, 39, 6 ; A., i, 290 ; Marchlewski and Znrkowski, Biochem. Zeitsch., 1912, 39,59 ; A . , i, 290 ; Marchlewski, An?mlen, 1912, 388, 63 ; A . , i., 238 ; Malarski andMarchlewski, Biochcm. Zcitsch., 1912, 42, 210 ; A., i, 641168 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Phyllopyrrole and Haemopyrrole.When hzmine is reduced with hydrogen iodide and phosphoniumiodide it yields among other products the substance haemopyrrole,which can also be produced as a decomposition product of chlorc+phyll.With a view to comparing the pyrrole derivatives whichform part of the nuclei of chlorophyll and hzemine, both compoundswere subjected to degradation proce~ses,~4 and it was found that thefinal hzmopyrrole produced was not a single substance, but was amixture of three pyrrole derivatives, which were named respec-tively, phyllopyrrole, hzemopyrrole,*5 and isohzemopyrrole.45 Theconclusive proof of the. constitution of these compounds by syn-thesis was not a t that time forthcoming; but in the present yeartheir structures have been placed beyond doubt. It has been shownthat when sodium methoxide or ethoxide is allowed to act onpyrrole derivatives a t high temperatures in alcoholic solution, theresult is a displacement of the hydrogen atoms of the methinegroups by methyl or ethyl radicles.By applying this process tocertain trisubstituted pyrrole compounds, the synthesis of phyllo-pyrrole has been acc~mplished.~~ The scheme below shows that theresults leave no doubt a~ to the constitution of phyllopyrrole;EMe*EHCMe CbhN H\/EMe-EEtCMe CHN H\/sMe*;CI)EtC.H CMeN H\/fiMe*EEtCMe CMe\/NHThe constitution of hEmopyrrole (Willstatter and Asahina’s iso-hzmopyrrole) has been definitely settled by a process of exclusion.47H2lemopyrrole is a trisubstituted pyrrol6, which can be convertedinto methylethylmaleimide; this proves that the ethyl group is inthe &position in the pyrrole ring.Further, when hzmopyrrole isethylated, it yields a substance which is not identical with 2 : 4di-methyl-3 : 5-diethylpyrrole ; therefore this compound obtained from44 N‘i1lst;itter and Asahina, Annalen, 1911, 385, 185 ; A., i, 41 ; H. Fischerand Bartholomaus, BcT., 1911, 44, 3313 ; A . , i, 50.45 Fischer and Bartholomaus, (Bey., 1912, 46, 1979 ; A., i, 646) propose to invertthese names, since Willstiitter’s iso-compound forms the major part of the mixture.Fischerand RartholomSus, Bcr., 1912, 45, 466 ; A . , i, 297 ; compare Colacicchi,Alti R. Accad. Lincei, 1912, [v], 21, i, 489 ; A., i, 646.Ibid., 1979 ; A., i., 646ORGANIC CHEMISTRY. 169haemopyrrole must have the two ethyl groups on the same sideof the molecule.Hence the hydrogen atom replaced in this ethyla-tion process must lie in the a-position next the ethyl radicle, whichfurnishes the following constitution for haemopyrrole :EMe*gEtCMe CLI *\/N HThis evidence is supported by the fact that a synthesis of 2 : 3-di-methyl-5-ethylpyrrole showed that this substance was different fromhaemop yrrole.A third pyrrole derivative, 2 : 4-diinethyl-3-ethylpyrrole, has beenisolated from the hzemopyrrole mixture, and to this the namecryptopyrrole has been given. Its constitution has been establishedby a comparison with the synthetic substance. The proportions inwhich these compounds occur in the volatile bases obtained fromhemine appear to be the following: phyllopyrrole, 5 per cent.;hEmopyrrole and cryptopyrrole, about 20 per cent.Piloty and Stock48 suggest that in view of the complexity ofthe haemopyrrole-phyllopyrrole mixture it would be preferable tocall all the constituents by the general name hzemopyrrole, dis-tinguishing them from each other by the suffixes -a, -6, etc., in theorder of their melting points.Thus, Willstatter and Asahina’s,isohaemopyrrole would be termed haemopyrrole-b. According toPiloty and Stock, Willstatter and Asahina’s liaeinopyrrole is amixture of two substances to which they have given the nameshaemopyrrole-b and hraemopyrrole-c according to the suggestednomenclature. There are thus four hEmopyrroles (a, b , c , and d ) ;the first of these is 3-methyl-4-ethylpyrrole ; the second is Willstatterand Asahina’s isohaemopyrrole; the third is identical with acompound, 3 : 5-dimethyl-4-ethylpyrrole9 which has been synthesisedby Knorr and Hess49; whilst the fourth is phyllopyrrole.A considerable number of other papers in this branch of thesubject have appeared.50Annulen, 1912, 392, 215 ; A ., i, 923.49 Ber., 1911, 44, 2758; A . , 1911, i, 1019.Leyko and Mnrchlewski, Bull. Acad. Sci. Cracoiu, 1911, A, 345 ; A., i, 56 :Willstatter and Asahina, Ber., 1911, M, 3707 ; A., i, 127 ; Grabowski andMarchlewski ; Bcr., 1912, 45, 453 ; A., i, 297 ; Kriorr and Hess, Ber., 1912, 45,2626 ; A., i, 900 ; Marchlewski, Zcitsch. physiol. Chem., 1912, 79, 351 ; A., i,646 ; Marchlewski and Grabowski, Zcitach.physiol. Chent., 1912, 81, 86 ; A . , i,1015170 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The Colouring Matter of the Blood.Closely connected with the chlorophyll question is the problemof the colouring matter of the blood; and as this seems to be withina few steps of its complete solution, a short summary of its laterstages may be given here.The colouring matter of the blood is composed of two portions,one of which is albuminous and is called globin, whilst the otheris non-albuminous in character, and is termed hzmatin. It iswith the latter part that we have to concern ourselves. I n thebody, it is supposed that hzmatin forms the source from whichanother substance, bilirubin, is produced; and the latter is oneof the constituents of bile.Now when hxmatin is reduced with hydriodic acid andphosphonium iodide, a series of four principal products is produced,namely, (1) a mixture of haemopyrroles, (2) xanthopyrrolecarboxylicacid, (3) phonopyrrolecarboxylic acid, and (4) haematopyrrolidinicacid.51 (See the scheme on p. 172.) Investigation of the haematinstructure on this line has been hindered by the fact that hzemato-pyrrolidinic acid is an amorphous substance which cannot becrystallised, and hence it has been impossible to make certain ofits constitution.Now, a t this point we are aided by the connexionbetween bilirubin and hzmatin. I n view of their close relationin the body,52 it seems reasonable to assume that there may be acertain relationship in structure between them53; and this idea isstrengthened by an examination of their behaviour under theaction of various reagents.When haematin is treated with acid,it yields a substance, haematoporphorin, which has the same com-position as bilirubin, namely, C16H180,Nz. When these two lattersubstances are fused with potassium hydroxide, they yield closelyanalogous products,54 of which the bilirubin derivatives are simplerthan those obtained from hamatoporphorin ; the former substancegives rise to four pyrrole compounds, whilst the latter producesonly two.Now, when bilirubin is reduced with hydriodic acid andphosphonium iodide, it yields a substance, bilic a>cid, which differsin composition from the amorphous hzematopyrrolidinic acid byonly one oxygen atom: hamatopyrrolidinic acid has the com-position C1,HZ6o2N2, whilst bilic acid is represented by C,,H2603N2.51 Piloty and Dormann, Annalen, 1912, 388, 313 ; A., i, 519.52 Kuster, Zeitsch,physiol.Chem., 1909, 59, 63 ; A., 1909, i, 319.53 It must be noted, however, that this is only an assumption, as in many casesone compound is transformed into another in the body by a series of dccompositiollsand syntheses which leave very little of thc original structure in existence.b4 Piloty and Thannhauser, Annnlcn, 1912, 390, 191 ; A . , i, 736ORGANIC CHEMISTRY. 171The chief point of practical interest, however, is that bilk acid is asubstance of a crystalline character in contradistinction from theamorphous analogue. An investigation of the properties of bilicacid is therefore much more certain of results than an examinationof the other compound.Let us now compare the effects of various reagents on these twosubstances.Both dissolve in warm water, giving a foamy liquid;neither crystallises out on cooling; but both may be salted outwith sodium chloride. Both have the faculty of holding pyrrolederivatives in loose combination (adsorption) ; and both giveamorphous metallic salts or picrates. When they are fused withpotassium hydroxide, both give similar decomposition products,although in the case of bilk acid no hxmopyrrole is obtained., Onoxidation with chromic and sulphuric acids, both produce hamaticacid and methylethylmaleinimide.The main difference between the two compounds, then, is thatIizematopyrrolidinic acid has one oxygen atom less than bilic acid;whilst bilk acid on fusion produces no hzemopyrrole fission productslike those obtained from hEmatopyrrolidinic acid.Piloty and Thannhauser 55 suggest that the following formula (I)is the most probable one to express the behaviour of bilic acid;whilst (11) would satisfy the necessities in the case of haernato-pyrrolidinic acid :IH,*CO,HCH NHQH,*CO,HCH NH/\/\ /\/\ CH,*S-QH C;H EaCH2*OHCH,*C CH CH-C*CH,*CH, CH,*C CH CH-C*CH,*CH,CH,=E-YH QH fi*CH,\/\/NH CH,\/\/NH CH,56(I.) Elic acid.(11.) Haematopyrrolidinic acid.The production of haematic acid (111) and methylethylmaleinimide(IV) from both (I) and (11) can be realised by an inspection ofthe formuh; and it will be observed that the presence of the thirdoxygen atom in bilic acid in the centxe of an alcoholic radiclewould sufficiently explain the lack of hzemopyrroles in the fissionCH,*CO,H\/NHNHA70 yoCH,*C==C*CH,*CH, - -(111.) Hzmatic acid.(IV.) Methylcthylmaleinimide.59 A ~ ~ n c c Z c ~ ~ , 1912, 390, 191 ; A . , i, 736.56 It seems possible that this group and the cthyl radicle should be interchanged172 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.products of the former substance under the somewhat trying con-ditions of an alkali fusion.Let us now turn back once more to hzmatin. On treatmentwith acids, this substance undergoes a change in the course ofwhich it loses its iron content and is converted into haema5o-porphorin; and on reducing this last substance we get a mixtureof haemopyrroles, some haematopyrrolidinic acid, phonopyrrole-carboxylic acid, and xanthopyrrolecarboxylic acid.When treatedby similar methods, bilirubin produces, among other substances,isoplionopyrrolecarboxylic acid, which is isomeric with phono-pyrrolecarboxylic acid.Xaiithopyrrolecarboxylic acid 57 has been shown to have(probably) the structure I ; and since isophonopyrrolecarboxylicacid and xanthopyrrolecarboxylic acid on treatment with nitrousacid both yield the same semi-oxime,58 it appears that isophono-pyrrolecarboxylic acid may be the homologue (11). Phonopyrrole-carboxylic acid probably has the structure represented by I11 :8 H C*CII,*CH, C H C-CH,CH 3* C---g C€T2*CH2*C0, H CH3*fi-$CH2*CH2*C02H\/NH\/NTI(I.) Xanthopyrrolecarboxylic (11.) isoPhonopyrrolecarboxylicacid. acid.C H,* fi--R CH, * CH2*C0,HCH;C CH' \/NH(111.) Plionopyrrolecarboxylic acid.The following scheme shows some of the chief relationshipsbetween the principal compounds in this group :Hzemine4H.1in organism acidBilirubin +- Hamatine -+ Hzmatoporphorin I reduction I recluction I reductionI + 4, .c. \y J. 4,isoPhono- Bilic acid Hsmatopyrrol- Phono- Xantho- Hzmo-pyrrol ecarb- idinecarb- pyrrolccarb- pyrrolecarb- pyrroleoxylic acid oxylic acid oxylic acid oxylic acid mixtureHaematic acid andinethylethylmal einimide.57 Piloty and Dormann, Annalcn, 1912, 388, 313 ; A., i, 519.Piloty and T!iannhanser, ibid., 1912, 390, 191 ; A., i, 736ORGANIC CHEMISTRY.173Complex Salts.I n recent years a considerable amount of attention has beendirected to the question of complex salts, and a short section onthis subject may not be misplaced in the present report, tcsapparently such compounds should be regarded as coming withinthe group of heterocyclic substances. It is well known that thecopper salt of glycine possesses a brilliant blue tint, even moremarked than the ordinary copper salts’ colour, and seeming moreakin to the blue solution obtained by dissolving a copper salt inexcess of ammonia. Now, copper acetate has been found capableof adding on two molecules of ammonia to form a deep bluecompound, the colour of which resembles that of the glycine coppersalt, and the assumption is currently made that these two moleculesof ammonia are directly attached to the copper atom by “ auxiliaryvalencies” so that the formula of the compound may be writtenas in (I) i f we designate the auxiliary valencies by dotted lines.On a similar assumption, the formula for the copper salt of glycinewould be written as in (11).NH,*CH, CO* 0 NHs CH,*CO*O/“’ \‘‘8>cuNI13 /‘ CHs-CO*O \ NH,*CH,*CO-0(1) (11)During the current year, a coiisiderable amount of work69 hasbeen done in this section of the field.An important class ofcompounds which has been fully studied in this connexion includesthose which give the biuret reaction. The peculiar tint obtainedwhen substances respond to this reaction is now ascribed to theformation of a complex copper or nickel salt; and the structuralconditions necessary to the production of such a salt have beenvery fully dealt with by Kober and Sugiura.60 It was found thatthe colour produced in the biuret reaction depends on the con-stitution of the complex salt formed ; substances containing oriecopper and two nitrogen atoms give a deep blue tint; those con-taining one copper and three nitrogen atoms show a semi-biuretcolour of varying shade; substances which contain one copper andfour nitrogen atoms give a red tinge.Thus, the dipeptides and59 Weinland and Biittner, Zeilsch. nnorg. Chem., 1912, 75, 233; A., i, 530 ;Costiichescu, Ann. Sci. Univ. Jassy, 1912, 7, 87; A . , i, 493; Costiichescu midSpacu, ibid., 132 ; A,, i, 494 ; Ley and Ficken, Ber., 1912, 45, 377 ; A., i, 243 ;Ley and Winkler, ibid., 372 ; A., i, 243.Bo J.Bwl. Chem., 1912, 13, 1 ; Amr. Cham. J., 1912, 48, 383 ; A , , i, 952, 9531'74 ANNUAL REPORTS ON THE PROGRESS OF. CHEMISTRY.their carboxyl derivatives give a tint like glycine; tripeptides andtheir carboxyl derivatives (excluding their amides), and the amidesof dipeptides give a semi-biuret tinge; whilst tetrapeptides and theamides of tripeptides give a purple-red colour in the biuret reaction.The further spectroscopic investigations in this direction will beof great interest when they are completed.Miscellaneous.In the following paragraphs a few points will: be consideredwhich, although of interest, do not lend themselves to the moreextended treatment which has been dealt out to the other subjectsin this section of the report.A new method of obtaining thiophen6l has been devised whichappears to give very good results.Acetylene is passed through aniron tube charged with pyrites, and so arranged that the usedpyrites can be removed. The tube is heated to 300° while tilegas is passed. On condensing the products, it is found that theyield contains 40 per cent. of thiophen; and on purification thesubstance can be obtained with a purity of 95 t o 96 per cent.Compared with the usual methods, this new one seems to beeminently satisfactory especially from the point of view of cheapness.A somewhat peculiar reaction between acetic anhydride anda-picoline has been described,62 which may be expressed by thefollowing equation :C,H,N + 2(C'H3*CO),0 = Cl2HIlO2N + CH3*C02H + 2H20.The nitrogen derivative thus obtained has no basic properties,reacts with hydroxylamine, phenylhydrazine, and semicarbazide,and condenses with two molecules of aromatic aldehydes, theproducts giving intensely coloured compounds with sulphuric acid.From the reaction with hydroxylamine, it is clear that the twooxygen atoms are true carbonyl oxygens, and are not acyl oxygens.When the substance is boiled with sulphuric or hydrochloric acid,it yields a base isomeric with indole, which, when reduced, takesup two atoms of hydrogen.The following names and formulz aresuggested for these compounds :CH CH\/ \\CH CH2Picolide. Pyrrocoline.a-Butaciienylpyrrole.61 W. Steinkopf, Yerh. Ges. deut. Natn~rforsch. Aerztc, 1912, ii, [I], 220 ; A . , i,292.62 Scholtz, Ber., 1912, 45, 734 ; A., i, 385ORGANIC CHEMISTRY. 175In the pyrazoline group, some investigations 63 have been begunwith the view of obtaining derivatives of cyclopropane by thedecomposition o,f pyrazoline compounds.Azodicarboxylimide derivatives 64 of the formula (11), in which(1.1 (11.1R is H, Ph, NH, or N:CHPh, have been prepared by the actionof an ethereal solution of iodine on the silver salts of the corre-sponding hydrazo-compounds of the formula (I). They are foundt o be decomposed by water in accordance with the equation:2fJ'co>N*R + 2H,O = N, + 2C0, + NH,*R -t $E:EE>NH. x-coA continuation of the investigation of the endoazo-compoundsdeserves notice, as the compounds described belong to the class ofspiranes in which interest is being taken a t the present time.Some glyoxaline derivatives 66 allied to the alkaloid pilocarpinehave been prepared, and their physiological effects have beentested.Mention must also be made of the very extensive investigationsof the pyrimidines 67 and hydantoins 68 which have been publishedduring the year.Molecular Asymmetry.Pope2 hasrestated his views more explicitly this yeas, and gives the followingdefinition, which seems to make his point of view clearer thanbefore." Every molecular configuration is enantiomorphous, andpresumably capable of exhibiting optical activity, which contams nocentre of symmetry ; and, conversely, every molecular configurationis potentially optically inactive which contains a centre of sym-This subject was dealt with in last year's report.'Kijner, J.Russ. Phys. Chem. SOC., 1912, 44, 165; A., i, 245.StollB, Ber., 1912, 46, 273; A., i, 225.65 DUVSI, Compt. rend., 1912, 154, 780; A., i, 398.66 Pyman, T., 1912, 101, 530.67 Johnson and Shepard, Amer. Chesn. J., 1912, 48, 279 ; A., i, 910 ; Johnsonand Hill, ibid., 296 ; A . , i, 912 ; Johnson and Moraii, ibid., 307 ; A., i, 913.68 Johnson and Hoffman, Amer., Chem, J., 1912, 47, 20; A . , i, 136;Johnson and Guest, ibid., 103, 242 ; A., i, 316, 807 ; Johnson and Nicolet, ibid.,459 ; A.. i, 585 ; Johnson and Ambler, ibid., 197 ; A., i, 799 ; Johnson, J. Biol.Chem., 1912, 11, 97 ; A., i, 390 ; Johnson and Brautlecht, ibid., 175 ; A., i.805 ;Johnsou and O'Brien, ibid., 205 ; A., i, 806 ; Johnson, Pfau and Hodge, J, Amer.Chem. Sos., 1912, 34, 1041 ; A . , i, 807 ; Johnson and Nicolet, ibid., 1048 ; A., i,808 ; Johnson and Bengis, ibid., 1054, 1061 ; A.: i, 808, 809 ; Johnson andChernoff, ibid., 1208 ; A., i, 810.Pope and Read, T., 1912, 101, 2325. A m . lieport, 1911, 71176 AKNUAL REPORTS ON THE PROGRESS OF CHEMISTRYmetry.” The confusion appears to have arisen owing to the useof the expression ‘( asymmetric atom ” in a sense different from thatin which this is usually employed. Pope’s view is that in anenantiomorphous molecular configuration every atom present isasymmetric, in the sense that it is devoid of geometrical associationwith a centre of asymmetry.In this connexion, attention may be drawn to the case of sub-stances having the general formula :Such substances exist in cis- and trans-forms, and the trans-isomeride(internally compensated) possesses no element of symmetry otherthan a centre of symmetry, whilst the cis-forms (optically active)have no cegtre of symmetry, but possess a two-fold axis of sym-metry. The case of the cis-1 : 4-diketo-2 : 5-dimethylpiperazines 3furnishes the only example of this type which has been successfullyexamined up to the present.The same kind of asymmetry exists inthe u- and p-2 : 5-dimethylpiperazines 4 which have recently beenexamined. Unfortunately, positive results were not obtained in thiscase; but the results of further experiments now in progress mayincrease our knowledge of this interesting class of isomerides.A New Method of Resolving Inactive Mixtu-res into theA ntipdes.A few years ago6 i t was found that d-oxymethylenecamphorcould be used as a reagent for determining whether a primary orsecondary arnine is externally or internally compensated.Oxy-methylenecamphor in the enolic form has the structure representedby (I), and when it is allowed to condense with secondary aminesit yields condensation products of the formula (11) :(1.1 . (11.)If the amine is internally compensated it yields only one productwith d-oxymethylenecamphor ; but two condensation products areformed by an externally compensated amine, and these can beseparated by fractional crystallisation.I n this way it is possibleto ascertain whether the m i n e is potentially optically active ornot; but the drawback t o the method has hitherto been that theamine’s two antipodic forms could not thus be obtained, as no3 Fischer, Ber., 1905, 39, 453; A., 1906, i, 145 ; Fischer and Raske,Silzungsber. R. Akad. Wiss. Berlin, 1906, 371 ; A . , 1906, i, 457 ; Ber., 1906, 39,3981 ; A., 1907, i, 18.Pope and Read, Eoc. cit. Ibid., T., 1909, 95, 171ORGANIC CHEMISTRY. 17’7method had been devised for splitting up the condensation productso as to liberate the amine portion. This defect has now beenremedied,G for it has been shown that by acting on the condensationwith bromine in carbon tetrachloride solution the hydrobromideof the base is obtainable.A syinrrie t ric Synthesis.A considerable advance in the study of this subject has beenmade by the discovery7 that an asymmetric synthesis can bebrought about by the use of an optically active catalyst, Whenbenzaldehyde and potassium cyanide are allowed to interact insolution, they yield racemic niandelonitrile ; but if benzaldehyde iscondensed with hydrocyanic acid in the presence of an opticallyactive alkaloid, the resulting mandelonitrile is found to be opticallyactive. The rotatory power of the product depends on the alkaloidemployed ; quinone produces a mandelonitrile which yields onhydrolysis Z-mandelic acid, whereas quinidine f avours the formationof d-mandelic acid.There appears to be no doubt that the alkaloidemployed enters into combination with the cyanohydrins ; and italso seems to be proved that the action of the alkaloids is a catalyticone, for the molar amounts of them necessary to produce thereactions are less than those of the products.Ra c e mism .Very little work has been done in this division of the subjectduring the year.Jerusalem 8 has examined the crystallography ofvarious active substances and the corresponding racemic forms, andfinds that a close morphotropic relationship exists between them.Such a relationship follows from Barlow and Pope’s theory, whichthus receives further support.The question of the existence of liquid racemates has been dealtwith in the case of fused methyl racemate.9 This work, which isbased on the application of measurements of the velocity of crystal-lisation, the temperaturecoefficient of the molecular surf ace energy,and the molecular heat of vaporisation, tends to prove that thefused substance is a mere mixture of the two antipodes, and not atrue racemic compound.The mechanism of the process of racemisation by heating hasbeen examined,lo and in the case of malic acid it has been shownli Pope and Read, T., 1912, 101, 2325.7 Bredig and Fiske, Biochem.Zeitsch., 1912, 46, 7 ; A., i, 983. * T., 1912, 101, 1268.lo James and Jones, T., 1912, 101, 1158.Gr6h, Ber., 1912, 45, 1441 ; A., i, 411.REP.-VOL. IX. 178 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.that fumaric acid is produced as an intermediate stage in thereaction. I n the case of the racemisation of tartaric acid, consider-able quantities of pyruvic acid were formed, and it is concludedthat the following reversible reactions play a part in themechanism :CO,H*$!H* OH - CO,H*E*OHCH(OH)*CO,H - CH*CO,HCO,H* 70CH,* C0,HThe Walden Inversion.With the present year this problem appears to have entered anew stage.The full summary which was given in last year’sreport 11 renders it unnecessary to enter into much detail here; buta single example may be given to make the matter clear. Ifd-alanine is treated with nitrosyl bromide the main reaction productis Z-a-bromopropionic acid, whereas if the d-alanine is esterified, theester treated with nitrosyl bromide, and then hydrolysed, there isobtained cE-a-bromopropioric acid ; thus in each case the startingpoint is the same dextro-acid, but in one instance the final productis dextrorotatory, whilst in the other it is the optical antipode; andtherefore a t some point or other in the series of reactions there musthave been a rearrangement of the groups around the asymmetriccarbon atom.Hitherto, those investigators who have touched on the problemhave confined their attention to this actual shifting of the groupsin space, and have brought forward the views which were summar-ised last year.Now, however, it is beginning to be realised thatthere is another side to the question, namely, the actual mechanismof the reaction, apart from any spatial considerations. It will bewell to take up these two points in the above order.Biilmann 12 has examined the explanations put forward byFischer13 and by Werner>* and he considers that although a t firstsight they appear to amount to the same thing, yet on closer exam-ination they are fundamentally different.I n the first place, takingas his example the action of ammonia on a-bromopropionic acid,Fischer assumes that the ammonia molecule which reacts with thebromo-acid is dissociated into hydrogen and the amino-group; butBiilmann, basing his conclusions on the similarity of the actionsof primary, secondary, and tertiary amines on bromo-compounds,regards this assumption as too great to be easily conceded, since,l1 Ann. Report, 1911, 60.l3 Ibid., 1911, 381, 123 ; A . , 1911, i, 418.l4 Ber., 1911, 44, 881 ; A , , 1911, i, 424.l2 Annnlen, 1912, 388, 330; A., i, 420ORGANIC CHEMISTRY. 179according to him, i t would entail the acceptance of the idea thattertiary amines also decomposed during such reactions.16 Therefore,on his view, i t is impossible to admit Fischer’s contention that theamino-group simply takes the place left vacant by the ionisedbromine atom.Secondly, to explain the optical inversion whichtakes place in the Walden change, Fischer assumes that in suchcases the following phenomena occur: the bromine atom firstbecomes ionised, and is removed from the complex; then one of theremaining three groups attached to the asymmetric carbon atammoves into the place of the bromine atom; and, finally, the amino-radicle takes up t b position left free by the shift of this group.As Biilmarin points out, this forms a possible explanation of howthe inversion occurs, but it merely carries us a step back, and leavesus still to discover why the groups should interchange their posi-tions.I n most cases it seems probable that, during the shifting ofthe groups from one position to another, racemisation would takeplace to an extent much greater than is observed in practice. Thesedifficulties might be overcome If it were assumed that the ammoniamolecule takes up a definite position sterically with regard to theother atoms concerned in the reaction; but in his paper Fischerexpressly stated that he only assumed the attachment of the amino-group to the carbon atom by residual affinity “on the grounds ofsimplicity,” and that such an attachment formed no part of theessentials of his hypothesis.16Now, according to Biilmann, Werner’s hypothesis differs fromFischer’s a t this critical point.Let us take a concrete ex-ample for the sake of clearness, namely, the action ofhydrochloric acid on a substance of the formula (I), producingAB > e H B(1.1 (11.1a substance with the formula (11). Such a change could be,assumed t o occur in either of two ways, according as the hydro-gen chloride molecule attaches itself to one side or other of theplane through ABD. If it attaches itself on the same side as thehydroxyl group, then, after water has been eliminated, the chlorineatom will occupy the same position it9 that of the original hydroxyl;if, on the other hand, the hydrogen chloride molecule attachesitself to the molecule on the side opposite to the hydroxyl, then 6hel5 Mr.P. J. Brannigan has pointed out to me that a similar dissociation of theammonia molecule is implicitly assumed in such reactions as amide formation andtlie production of aldehyde-ammonia ; which seems to destroy the force of this partof Biilmsnn’s argument.-A. W. S.l8 Fischer (Annnlen, 1912, 386, i, 187) has stated that hi3 paper was written’‘ critically ’’ rather than as a constructive explanation.N 180 ANNUAL REPORTS ON THE PROURESS OF CHEMISTRY.elimination of water will produce the mirror-image of the otherchloro-derivative, and we shall have an example of Walden’s inver-sion.Now Werner assumes this attachment of the hydrogenchloride molecule as part of his explanation; and if this be granted,it is clear that the deciding factor in the question will be theattractive forces exerted on the hydrogen chloride molecule by thevarious atoms which make up the compound ABCD-OR. Theassumption of the existence of such forces is one which we caneasily make, and from that the whole explanation of the Waldeninversion follows naturally. I f the attractive forces in questiontend to bring the hydrogen chloride molecule and hydroxyl groupto the same side of the plane ABD, then no inversion takes place;but if the tendency of these forces is to attract the hydrochloricacid to the opposite side of the optically active molecule the Waldenchange occurs.Biilmann further suggests that racemisation might be consideredas another case of intramolecular change analogous to the Waldeninversion, in view of the influence which hydroxyl ions are knownto exert on the former process.This suggestion, however, shouldbe judged in connexion with the results of James and Jones in theracemisation of tartaric acid.“He assumes thatin such reactions as the Walden inversion an additive compoundis prirr?arily produced, which is formed by the new group attachingitself to the halogen atom instead of to the asymmetric carbonatom. When the inversion takes place in the compound CabcC1,the halogen atom is supposed to be removed from the carbon,leaving three groups behind.These then vibrate in such a wayas to distribute themselves evenly about the carbon atom; but inthe course of their movement they overshoot the equilibrium point,and thus pass into a position which is the mirror-image of the onepreviously occupied. The hydroxyl group then attaches itself tothe carbon atom, and thus the inversion is accomplished. Gadamarassumes that the differing behaviour of the metallic hydroxides canbest be explained by supposing that the normal hydrolysis is due tothe action of the anion of the hydroxide, whilst abnormal resultsare due to the action of the cation. I f this hypothesis were correct,it seems probable that the temperature of the reaction mixturewould have a considerable influence on the amount of “overshootring” of the equilibrium position, and investigations in this direc-tion would be of interest.Turning now to the second problem, namely, the actualFinally Gadamar’s views may be mentioned.18See p.177. l8 Chern. Zeit., 1912, 36, 1327 ; A., i, 934ORGANIC CHEMISTRY. 181mechanism of the reactions involved in the Walden inversion, wemay begin by a summary of Biilmann's views. It is quite clearthat in the case of the reactions of the bromo-substituted acids thereare two possibilities : for if a given reagent reacts direct with thebromine atom, then we should expect a case of simple substitution;whereas if this is not the case, then we may have to deal with anintramolecular rearrangement in the course of the reaction. Let usexamine from this point of view the case of the reactions of thehalogen-substituted acids.Walden found that when 2-chlorosuccinicacid is treated with potassium hydroxide, d-malic acid is formed;whereas when silver oxide is substituted for the alkali, Z-malic acidis the principal product of the reaction. Now a t first sight thisappears strange, but a closer examination of the actual experimentalconditions helps to clear up the difficulty. I n most cases it appearsthat the reaction is not one between the halogen-substituted acidand silver oxide, but rather a mere decomposition of the silver salt;for instance, in the conversion of Z-a-bromopropionic acid intoZ-lactic acid by this method, Fischer,lg working a t the ordinarytemperature, shook together an aqueous solution of the acid andsilver carbonate.The result of this, of course, would be the forma-tion of the silver salt of Z-a-bromopropionic acid, and since thissubstance itself in aqueous solution rapidly eliminates silverbromide, Biilmann doubts whether the excess of silver carbonatehas any effect a t all beyond neutralising the lactic acid which isformed as a final product; thus in this case we are not dealing witha simple interaction between silver oxide and the bromine ion ofthe acid (since the solution must be saturated with carbonic acidduring the course of the reaction), and hence the case is not at allparallel to the interaction between the bromo-acid and potassiumhydroxide.On the basis of Senter's20 investigations of the hydrolysis ofhalogen-substituted acids, Biilmann considers that, in the first place,the bromo-substituted acids ionise, and that in consequence of thenegative charge on the acid ion the bromine atom becomes lessfirmly attached, and therefore more ready to react with the silverions in the solution.The results of this series of changes may beexpressed thus :7% Q"BvHBr+Ag+ = 7"' +AgBr.(20,- c0,-I9 BET., 1907, 40, 503 ; A., 1907, i, 192.20 T., 1907, 91, 460 ; 1909, 95, 1827 ; 1910, 97, 346 ; 1911, 99, 96 ; Zeilsch.physikal. Chem., 1910, 70, 511 ; A., 1910, ii, 276182 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.This “Zwitterion ” then unites with a negative hydroxyl ion ofwater, forming an ion of lactic acid:7 4 7%GO,- c0,-FH’ +OH- = $!H*OH.Since we are dealing with ionic reactions throughout this processi t is fair t o assume that no change of relative position takes placein the groups around the asymmetric carbon, and hence no Waldeninversion is observed.Similar arguments apply in the case of theaction of nitrous acid on amino-acids, for i t is known from analogyt o the diazo-compounds that the nitrous acid first attaches itselfto the nitrogen atom of the amino-group; so that in this case alsowe should expect to find simple substitution taking place withoutintramolecular rearrangement.Another view of the interaction between bromo-substituted acidsand alkali has been put forward by HoImberg.21 From a study ofthe change in rotatory power, rate of elimination of bromine, andneutralisation with sodium carbonate in the case of I-bromosuccinicacid, he deduces that the following process occurs.The Z-bromo-succinic ion breaks down rapidly into a bromine ion and an ion ofpropiolactonecarboxylic acid which is dextrorotatory. In neutralsolution this lactone is only slowly hydrolysed; but as more andmore malic acid is formed the hydrogen ion of this catalyticallyaccelerates the process of hydrolysis; whilst at the same time itretards the rate of lactone formation. On these assumptions theprocess of the Walden inversion would be represented thus :KOH I-bromosuccinic acid -+ d-malic acid lactone -+ d-malic acid.Senter 22 points out that Holmberg’s experimental data are con-fined to one dilution, and from his own results obtained a t anearlier period he throws further light on the question.A solutionof sodium bromoacetate was titrated a t fixed intervals with sodiumhydroxide and silver nitrate. In one case the acetate solution was,../lo, in another it was 2N in strength. The results show thatin the dilute solution iihe rates of formation of the bromine ionand the hydroxy-acid approximate closely to each other, and thereaction is one of the first order; but in the concentrated solutionthe velocity of bromine ion formation greatly exceeds that of acidformation, and the reaction in its first stages deviates more andmore from the first order. Senter concludes that these results canbest be interpreted by assuming that the mechanism of the reactioncan be expressed by the following equations:?l BLT., 1912, 45, 1713, 2997; A , , i, 603, 943.a fix, 2318 A ., i, 828ORGANIC CHEMISTRY. 183I.11. {There is also a possibility of a third reaction leading to theformation of acetoxyacetic acid. In dilute solution, Sentersupposes that the reaction is practically that which is representedby equation I, whilst in solutions of higher concentration the secondreaction comes more and more into prominence. Senter considersthat there is no evidence against the lactone formation assumed byHolmberg, t u t a t the same time points out that he himself, inapplying this very idea in his previous work, had assumed that suchinterzediate products would be very rapidly hydrolysed, and thatthere seems to be no reason for accepting the hypothesis that theywould bo very slowly decomposed under the given experimentalconditions.CH,Br*CO,Na + -0 = CH,(OH)*C02H + NaBr.CH2Br*C0,Na + CH,Br*CO,Na=CH,(O*CO*CTI,Br)*CO,Ne+ H20 =C!H,(O CO*@H,Br)*CO,Na + NaBr.CE&(OH)*CO,E + CH,Br*CO,Na.The Factors Znfluencing Optical Rotatory Power.This field still attracts numerous investigators, and the data,accumulated during the year testify to their unwearying industry.The subject, however, is complicated by so many obscure factorsthat it seems probable that a very long time will elapse before weare in a position to draw more than the most sketchy generalisationson the question of optical rotatory power regarded from the numeri-cal point of view.Those interested in the development of thequestion will find a very complete summary of its more importantbranches in the Presidential Address.*The work of the year has centred round the three main factorsin the problem, namely, the effects of temperature, solvent andconstitution, and the facts ascertained are very numerous.We mustcontent ourselves with the briefest survey of the more interestingpoints. Taking the effect of temperature first, Pickard andKenyon 24 have made a very exhaustive examination of the rotatorypower in a series of optically active carbinols having the generalformula R*CH( OH) *CH( @Ha),, where R represents methyl, ethyl,etc., up to n-decyl. The investigation hm been carried out ov0r awide range of temperature, extending a t times up to 200°, and allexcept where experimental difficulties intervened, the rotationa t the boiling point of the substances has been obtained, extrapolationbeing resorted t o in a few instances.I n the foregoing series it wasfound that the specific rotatory powers a t 20° increase as the seriesis ascended until a maximum is reached with isopropyl-lzrbutyl-23 Frankland, T., 1912,iOl, 658. Ibid., 620184 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.carbinol, after which the values decrease regularly to isopropyl-n-decylcarbinol. If we compare the values a t the boiling point,however, we find that the members of the series from n-butyl ton-decyl have a constant value of [MI, + 2 9 O (approximately); thusthe values rise regularly until R is of greater mass than theisopropyl group in R*CH(OH)*CH(CH,),, and then become practi-cally stationary.I n the course of an examination of various esters of di-trichloro-acetyltartaric acid the occurrence of a minimum 25 in the rotation-temperature curves has been observed.The influence of the solvent on the rotation of ethyl tartrate hasbeen examined,26 and certain relationships between the constitutionof the solvent and its action on the rot.atory power have beendeduced; but to enter into these in detail would occupy too muchspace. The dependence of molecular rotatory power on the concen-tration of solutions of salts of d-camphor-j3-sulphonic acid has beenstudied,27 and it was found that the changes observed cannot be theresult of the alteration of degree of electrolytic dissociation, butdepend principally on the character of the metallic atom or electro-positive grouping involved.Similar effects are produced bymembers of the same group in the periodic classification. Theatomic weight does not appear to be an important factor.In the Presidential Address,28 Frankland drew attention to apossible cause of anomalies in rotatory power in homologous series.Since on the van't Hoff theory of the asymmetric carbon atom theends of a straight carbon chain tend to approach one another whenthe chain contains five or six carbon atoms, it seems probable thatsuch a state of things might affect optical rotatory power in someway, such as producing a maximum rotation when this criticallength of chain was reached in a homologous series.Franklandquotes data which support his view, and the somewhat analogousresults of Hilditch 29 reinforce his argument. Pickard andKenyon,30 however, state that the rotatory powers in the seriesexamined by them do not agree with this conception; but as theproblem is certain to be complicated to some extent by any branch-ing in the chain, it seems best to regard the point as sub @diceuntil more data are obtained which are free from complication.I n some of his previous work Hilditch31 had established theimportance of unsaturated groups as influences on optical rotatory25 Patterson and Davidson, T., 1912, 101, 374.26 Patterson and Stevenson, d i d . , 241.28 T. ,1912, 101, 658 ; compare ibid., 1899, 75, 368.29 Ibid., 1909, 95, 1581.30 Ibid., 1912, 101, 1428.31 Ibid., 1909, 95, 331, 1570, 1678; 1910, 97, 1091; 1911, 99, 224.27 Graham, zhid., 746ORGANIC CHEMISTRY.185power, and from this he has been led to inquire whether unsatura-tion may not be a factor in producing the irregularities in rotatorypower which are sometimes observed among the lower members ofseries the higher members of which do not deviate to any markedextent from a constant rotatory power. The results obtained byHilditch and Christopher appear t o confirm this view. They haveexamined a series of menthyl esters of the a-bromo-aliphatic acids(in which the bromine atom is regarded as a centre of residualaffinity), and they find that menthyl bromoacetate and menthyla-bromopropionate possess rotatory powers markedly above thenormal; the anomaly rapidly declines in the next members to aminimum, slightly sub-normal value; thereafter it rises to anapproximately constant value when menthyl a-bromomyristate anda-bromopalmitate are reached.These investigations show that thereare still other factors to be taken into account before one can arrivea t any broad generalisation on the question of rotatory power andits connexion with chemical constitution ; and it appears improb-able that much progress will be made until an enormous mass ofdata has been accumulated. When this point is eventually reached,it seems evident that only a very clear thinker will be able topenetrate the maze of material a t his command.The Entropy Principle in, Organic C'hernistry.Michael33 has endeavoured to throw light on some of the moreobscure points of stereochemistry by an application to them of theprinciple of entropy. His views may be very briefly summarisedas follows: The factors which play a part in chemical reactionsare : (1) the bound chemical energy of atoms already united, and(2) the free chemical energy which remains over after the unionhas taken place.Free chemical energy may be converted intobound chemical energy either by the direct union of atoms or bywhat is nowadays termed space-conjugation, that is, the influenceon one another of atoms not directly united together in a chain.Now the conversion of free chemical energy into bound chemicalenergy is accompanied by a loss of energy in the form of heat, etc.,so it is clear that when a compound has settled into its most stablechemical and spatial state the entropy will be at a maximum.Letus apply this to the question of stereoisomerides. It will be remem-bered that in cltses like the tartaric acids van't Hoff in his theoryof the asymmetric carbon atom postulated that the two centralcarbon atoms were free to rotate about their common axis, and, inorder to avoid the deduction that in this way an innumerable3J T., 1912, 101, 192 ; Hilditch and Christopher, ibid., 202.33 Annulin, 1912, 390, 30 ; A., i, 631186 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.series of isomeric tartaric acids might be capable of existence accord-ing to the relative positions in which the two groups-CH(OH)=CO,H stood, he was forced to make the further assump-tion that the various forces of attraction between the differentatoms in the molecule tended to come into equilibrium in one parti-,cular favoured position.Now if we assume that the free chemicalenergy remaining in the groups *OH, *CO,H, and H can equateitself through space, then some energy will be liberated in theform of heat, etc., a t the time when the atoms pass into theposition most favourable to this change. After this there may beslight oscillatory movement in the molecule, but free rotation of thecarbon atoms will be impossible until heat is supplied t o the systemin quantities sufficient to reconvert the bound chemical energythus lost into free chemical energy.It is evident that this viewis perfectly general, and can be applied also to the case of geometri-cal isomerides of the ethylene type as well as to saturated com-pounds. Take the case of succinic acid and the corresponding un-saturated substances as an example. I n succinic acid itself, accord-ing to Michael’s view, the chemical resistance to rotation is small,and hence the cis-form passes into the stable trans-form with amarked increase in entropy. Now if two hydrogen atoms areremoved from the cis-configuration of succinic acid (one from eachmethylene group) there is an increase in the bound chemicalenergy between the two central carbon atoms and also between theremaining hydrogen atoms and carboxyl groups. I n this way thechemical hindrance to rotation is increased, which accounts for thegreater stability of maleic acid as compared with the cis-form ofsuccinic acid, and gives an explanation of the actual occurrence ofmaleic acid. Further, since the cpnversion of maleic acid intofumaric acid is accompanied by an increase of entropy, the freechemical energy of maleic acid will tend to bring about this con-version.With the aid of external energy supplied as heat, thistransmutation becomes possible.The catalytic action of hydrochloric acid on the maleic-fumarictransmutation is figured by Michael as follows: In the first place,a ‘‘ polymolecule ” of maleic acid and hyd.rochloric acid is formed.This contains more free energy than maleic acid alone, and conse-quently it is converted into the corresponding fumaroid “ poly-molecule.” Then, since hydrochloric acid has a greater affinity formaleic than for fumaric acid, the fumaroid ‘‘ polymolecule ” reactswith maleic acid, giving fumaric acid and a fresh maleic-hydro-chloric acid “ polymolecule,” so that the process continues until allthe maleic acid has been converted into fumaric acidORGANIC CHEMISTRY.187The Properties and Reactions of cis-trans-Stereoisomerides.A portion of the Presidential Address of this year 34 was devotedto a consideration of the problems involved in the additionreactions of ethylenic stereoisomerides. It is a well-known factthat in many cmes where we should expect to find two bromineatoms attaching themselves to a double or triple bond on the sameside of the molecule, we actually get in practice a trans-addition,that is, one bromine atom is attached to one side of t3he molecule,whilst the second atom becomes fixed t o tho opposite side; thus,for example, the action of bromine on maleic acid produces iso-dibromosuccinic acid, which has now conclusively been shown tobe the racemic form 35; whereas, if cis-addition took place we shouldexpect to find the internally compensated isomeride produced.Frankland has discussed the various cases which have arisen, andcriticises Pfeiffer’s hypothesis 36 to account for the phenomena. (Inthis connexion i t may be pointed out that van’t Hoff 37 had alreadybrought grave objections against Pfeiffer’s ideas.) Frankland’sown explanation of the matter is so simple that one can onlywonder why i t was not put forward a t an earlier period.If we aredealing with the relations of atoms in space, it seems inconsistentnot to carry the deductions out thoroughly, and Frankland there-fore takes into consideration the steric relations of the brominemolecule as well as those of the ethylenic or acetylenic compoundunder discussion. I f we assume that in the bromine molecule thetwo atoms are separated by a distance which is sufficient to bringthem to opposite sides of, say, a maleic acid molecule, then trans-addition is obviously the most probable process, since steric con-siderations would be against their coming into a position suitablef o r addition in t.he cis-position. This suggestion appears to clearup much of what was previously obscure.Our knowledge of the physical properties of geometricalisomerides is very scanty; for although it seems probable thatvaluable results might be obtained by a systematic survey of thefield, very few workers have gone far enough into it to provideus with material sufficient for generalisation.I n one direction thisdefect has been remedied by a very complete series of determirmtions of the viscosities of various pairs of stereoisomerides of thistype.38 For the sake of convenience we may term “adjacent” allthe isomerides of the cis-, syn-, and a-types, whilst the trans-, anti,and B-isomerides are classed as “ opposed.” Thole has shown thaty4 T., 1912, 101, 673.y6 Zeitsch. phgsikal.Chem., 1904, 48, 40 ; A., 1904, ii, 525.37 “Die Lagerung der Atome in Raume,” 3 Aufl., 1908, p. 103.38 Thole, T., 1912, 101, 552.35 hfcKenzie, G i d . , 1196188 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.acids and esters differ from one another as regards viscosity rela-tions; for the adjacent acids are less viscous than the opposedisomerides, whilst with the corresponding esters these relations arereversed. The oximes examined, with one exception (benzilmon-oxime), gave results parallel to those obtained with the acids, whilstthe phenylhydrazones appeared to give anomalous readings, and inaddition thei; configurations have not bsen determined with anycertainty.These results led Thole to the conclusion thn.t, of two compoundsthe constituent radicles of which possess small residual affinity, theopposed isomeride has the lower viscosity.This may be ascribedt o the tendency to potential ring-formation which usually existsin the adjacent isomerides, since such a condition notably enhancesviscosity values. I n compounds which possess greater residualaffinity, this factor is masked by the intramolecular neutralisationof the residual affinities, which results in inhibition of molecularassociation, and hence leads to a depression of viscosity. It wouldbe interesting to know, in view of these results, whether the spatialconjugation of unsaturated groups which have no tendency to ring-formation would affect viscosity to any great extent,The Transmutation of cis-trans-Stereoisomerides.One or two points of interest have arisen in this section of thesubject.I n his examination of the conversion of maleic intofumaric acid, Skraup 39 discovered that if hydrogen sulphide andsulphur dioxide were allowed .to interact in a solution of maleicacid, fumaric acid was produced; but that no such change in themaleic acid took place if it were added to the solution after thereaction between the other two substances had run its course; norwas maleic acid affected by the presence of hydrogen sulphide orsulphur dioxide singly. On these phenomena he based his “reson-ance ” hypothesis of transmutation, in which he assumed that everyreaction produces waves in the ether which are capable of settingin motion other reactions which are (‘ in tune ” with the first. Thisproblem has been taken up by Tanatar 40 in a somewhat similar setof reactions. Since in the Skraup reactions sulphur separates fromthe solution, Tanatar examined the action of sulphur on maleicacid. No effect was detected in the case of milk of sulphur or withthe sulphur produced when ferric chloride and hydrogen sulphideare allowed to interact in the presence of maleic acid. The actionof mineral acids on sodium thiosulphate was then tested, and it was3s Monatsh., 1891, 12, 146 ; A . , 1891, 1338..u) J. Auss. Phys. Cheni. Soe., 1911,43,1742 ; A., i, 160 ; Tanatar and Voljansky,ibid., 1912, 441, 1320; A., i, 941ORGAN I C CHEMISTRY. 189found that the presence of maleic acid prevents the normal separa-tion of sulphur, whilst a t the same time the maleic acid is convertedinto its stereoisomeride. It was further observed that the presenceof a mineral acid is unnecessary to produce the transmutation, formaleic acid in presence of s’odium thiosulphate alone is convertedinto fumaric acid. Tanatar concludes from this that in the latterreaction some product is formed which causes the transmutation,and this view makes it unnecessary to assume any “resonance ”phenomena.The action of ultraviolet light on various stereoisomerides hasbeen studied,41 and it is found that the results obtained are notby any means uniform. The influence of constitution appears tobe strongly marked, as can be seen from a comparison of the resultsobtained with the o-, m-, and p-forms of phenylnitrocinnamic acid.Ths o-compound melting a t 196O yields traces of the isomeridemelting a t 1 4 7 O ; the m-derivative melting a t 181O is partly andslowly changed into the isomeride melting at 195O, but the reversechange also takes place; whilst the p-compound, melting a t 143O, iscompletely transformed into its isomeride, which melts a t 2 1 4 O .A new exception to accepted views seems to have been discoveredin the case of a second form of oleic acid42 by keeping a specimenof ordinary oleic acid for some time at a temperature of 8-10‘].Including this new variety (which may, however, differ merely incrystalline form from the others), it appears that we now know offour isomerides in the oleic series, whilst the current stereochemicalviews-only allow for two. It is possible that this might be betterexplained under Michael’s assumptions (compare p. 185).The third isomeride of the erucic acid group, namely, isoerucichas been examined, and it was shown that it can be preparedby simply boiling brassidic acid in alcoholic solution with animalcharcoal. Its absorption spectrum was found to be different fromthose of the other two isomerides, so there appears t o be no doubtthat it is actually chemically individual. Attention might bedirected to these cases which form exceptions to the accepted views.The method devised by Patterson and McMillan44 has beenapplied to the question of the influence of solvent action on thevelocity of transmutation in the case of oximes.45 I n its essentials,this method consists in dissolving the oxime in ethyl tartrate andnoting the change in the rotatory power of the solution, which is41 Bakunin, Rend. Accnd. Sci. Fis. Mat. Napoli, 1911 [iii], 17, 372 ; A . , i,356 ; Stoermer and Heymann, Ber., 1912, 45, 3099 ; A , , i, 974.J2 Kirschner, Zeitsch. physikal. Chem., 1912, 79, 759 ; A., i, 533.Macbeth and Stewart, P., 1912, 28, 68.T., 1907, 91, 504.4J Patterson and Montgonlerie, ibid., 1912, 101, 36, 2100190 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.brought about by the change of the oxime from one isomeric forminto the other. If a neutral liquid be added to the solution of theoxime in ethyl tartrate, the effect of this third substance on therate of oxime transmutation can be deduced from the polarimetricreadings. I n this way the influence of a large number of sub-stances has been tested; for example, it is found that the followingcompounds affect the reaction’s velocity in the order given, thevelocity-constant being highest in the case of benzene : benzene,nitrobenzene, p-xylene, m-xylene, toluene, o-xylene, and mesitylene.I n the case of the aliphatic alcohols the velocity constant decreasesas the series is ascended, methyl alcohol showing most influence.The chief advantage of the method appears to be that the effect canbe traced even when comparatively small proportions of the inertsolvent are present in the reaction mixture.Esterifica tion and Hydrolysis Reactions.As is the case in other fields, the problem of residual affinity hasin recent years forced itself into the region of steric hindrance;and it is generally recognised by workers in this subject that a newfactor has to be taken into account in their investigations. It isnow assumed that in such a process as esterification, for instance,we have to take into account not only the spatial relations of thegroups involved in the reaction, but also their residual a5nity andits distribution within the molecule. I f these two factors remainedconstant, there would be little difficulty in apportioning its dueinfluence to each; but unfortunately they appear t o vary with theconditions of experiment, and thus anomalous results are oftenobtained ; for example, if we esterify acetic and trichloroacetic acidsby the direct method (heating with alcohol) the latter acid esterifiesmore rapidly than the parent substance; but when the two areesterified catalytically (by being allowed to react with alcohol inthe presence of hydrochloric acid) then the reaction velocities arereversed, and the parent substance forms an ester more rapidlythan does the chloro-derivative. Thomas and Sudborough 46 haveexplained this apparent anomaly very simply, by assuming thatboth cases are catalytic processes, but in the direct esterificationautocatalysis takes place, the acid acting as its own catalyst. Ifthis be the case, then the stronger acid, trichloroacetic, should be abetter catalyst than the weaker acetic acid, whereas in the presenceof the much more active catalyst, hydrochloric acid, this advantageis lost and the purely spatial factors come into play.With the view of testing this explanation, these authors haveexamined many acids which had already been studied by the cata-40 T., 1912, 101, 317ORGANIC CHEMISTRY. 191lytic method ; and their remlts certainly point to their explanationbeing correct. If the strengths of two acids (for example, a satur-ated one and its unsaturated analogue, which vary markedly fromeach other in the catalytic result) differ but little from each other,very little difference is observed in their esterification velocitieswhen determined autocatalytically. I n this case, the spatial factorappears to be the deciding one. When, however, this factor is over-borne by the great difference between the strengths of the two acids,the stronger acid is much more rapidly esterified than the other,although this is not the case when both acids react under theinfluence of it catalyst; much stronger than either, for in the latterinstance the spatial factor is again the deciding one.I n the esterification of the ketonic acids, Sudborough 47 has foundthat a carbonyl group in the a-position t o the carboxyl group has amarked retarding influence on the esterification velocity. I n orderto bring these results into line with the fact that the carbonylgroup of ethyl pyruvate was found by Stewart and Baly48 to beabnormally reactive, Sudborough puts forward an hypothesis withregard to the structure of the carboxyl radicle. H e assumes thatin the carboxyl group the hydrogen atom is not attached perman-ently to either oxygen atom, but oscillates from one to the other,so that the change shown below is continually taking place:Such a rearrangement would produce a highly reactive hydrogenatom, and would account for the fact that tho hydrogen atoms ofcarboxyl groups are more reactive than those of alcoholic orphenolic hydroxyl groups. On the other hand, when we come toconsider the rearrangement of valencies between the carbonylgroups postulated by Stewart and Baly:i t is clear that this could only take place a t the expense of thechange assumed by Sudborough, so that although the ketoniccarbonyl group would have an enhanced reactivity, the carboxylicgroup would decrease in reactive power. Sudborough’s suggestionsseem to fit the case very well, and it might be pointed out thatthey could, with very little modification, be brought into line withthe work of Miss Smedley,49 so that they are not devoid of supportin a totally different field.The esterification velocities of various polybasic aromatic acids 6047 T., 1912, 101, 12.27. 48 Ibid., 1906, 89, 489.Wegscheider slid Faltis, Monatsh., 1912, 33, 185 ; Wegscheider ard Black,ibitl., 207 ; A., i, 463 ; Wegscheidcr and Miiller, ibid., 1912, 34, 899 ; A . , i, 771.49 Ibid., 1909, 95, 231152 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.have been studied, and the rates of hydrolysis of various esters ofsubstituted fatty acids51 have also been examined. The results inthe latter case show that esters of halogen substituted acids aremuch more slowly hydrolysed than those of the parent acid.On re-reading the few pages of this report and comparing themwith the volume of the papers published during the year, theauthor feels only too conscious that much of importance has beenomitted, and that many subjects have been very cursorily treated.Not a few researches have been passed over on the ground thatjustice could be done t o them only by entering into details whichwould have necessitated sacrifice of space which could ill be spared;whilst others have been left out because it seemed probable thatfurther investigations would bring out clearer conclusions whichcould safely be left to the hands of later reporters when the subjecthas come into better perspective. A t the same time, it is hopedthat the main lines of progress during the year have been indicated,if not fully described, and that a fair survey of the field has beengiven. If this has been even partly accomplished, the author hasbeen more successful in the task set him than he anticipated whenhe was engaged in collecting the material on which this report isbased.A. W. STEWART.b1 Jhushel, Amer. J. Sci., 1912, [iv], 34, 69 ; A., i, 599