August i 2, 1922] 



NA TURE 



Obituary. 



Prof. W. Wislicenus. 



BY the death, on May 8, of Wilhelm Wislicenus. 

 professor of chemistry at the University of 

 Tubingen, organic chemistry lost one of its most 

 fruitful research workers, who contributed in no small 

 measure towards placing the science on the basis 

 which it now occupies. He was born at Zurich on 

 January 23, 1S61, and was the eldest son of Johannes 

 Wislicenus, that great organic chemist whose name 

 stands on the roll of fame co-equal with those of 

 Hofmann and Frankland. At the time of Wilhelm's 

 birth his father, who had. in the previous year, moved 

 from Halle to Zurich, where he had married Katherine 

 Sattler, the granddaughter of Wilhelm Sattler, joint 

 discoverer of " Schweinfurt green," held the chair of 

 chemistry and mineralogy under the council of the 

 Canton at the School of Industries. Wilhelm may be 

 said, therefore, to have inherited his chemical genius 

 both on his father's and mother's sides. 



W. Wislicenus received his early scientific training 

 at the University of Wurzburg, to which his father had 

 moved, in succession to Adolf Strecker, in 1872, and 

 it was from here that he published his first paper, 

 " On a New Reaction between Potassium Cyanide and 

 Phthalide," a reaction which he was able to prove to 

 lie df general application, and which he applied to 

 a number of other lactones with fruitful results. 

 In 1S85 his father succeeded Kolbe at Leipzig, 

 but Wilhelm continued to work at Wurzburg, 

 and thereafter, until 1903, he published a series of 

 important communications from these laboratories. 

 In this year he removed to Tubingen, where he con- 

 tinued to work until shortly before his death. 



The earlier work of Wilhelm Wislicenus is intimately 

 associated with the behaviour of metallic sodium 

 towards organic esters, a problem towards which the 

 attention of many chemists of his time was directed, 

 and in connexion with which bis father had already 

 published his epoch-making paper, dealing with ethyl 

 acetoacetate and its application as a synthetic agent, 

 in the " Annalen " of 1877. Indeed, we are told by 

 VV. H. Perkin in his Johannes Wislicenus memorial 

 lecture that the laboratory at Wurzburg was, during 

 the early 'eighties of the last century, busily engaged 

 in carrying out syntheses by the aid of ethyl aceto- 

 acetate and ethyl malonate. It is not surprising, 

 therefore, that the young Wislicenus should have 

 followed the general trend, and that one of his earliest 

 papers, published from Wurzburg in 1886, should have 

 dealt with the interaction of metallic sodium on a 

 mixture of ethyl acetate and ethyl oxalate, as an out- 

 come of which he was able to discover ethyl oxalyl- 

 acetic ester. Wislicenus at once realised the import- 

 ance of this discovery, and he was able later, both bv 

 himself and in association with his co-workers, to 

 apply the new reaction to the preparation of a large 

 number of a-ketonic esters, and, indeed, our know- 

 ledge of these important substances is mainly due to 

 him. 



About this time, also, the general question of the 

 movement of a hydrogen atom from carbon to oxygen, 

 as illustrated by the behaviour of ethyl acetoacetate. 



NO. 2754, VOL. I IO] 



and the co-ordination of this phenomenon with others, 

 notably that exhibited by hydrocyanic acid, was 

 receiving considerable attention, and, in 1885, C. Laar 

 published his famous hypothesis in which he coined 

 the word " tautomerism." Laar imagined oscillatory 

 conditions within the molecule which caused the 

 hydrogen atom to take up one or other position alter- 

 nately. He therefore presupposed the simultaneous 

 existence of both modifications, or, in other words, he 

 considered that the phenomenon was intra-molecular 

 and not inter-molecular. Even at the present time 

 this problem is by no means solved, and it cannot yet 

 be said that Laar was not right in regarding the basis 

 of change as intra-molecular. Still, there is no doubt 

 that, in one of its aspects, the Laar hypothesis did not 

 provide for the existence of the tautomeric individuals, 

 and it was, initially, due to W. Wislicenus that, 111 this 

 restricted sense, the hypothesis was shown to be wrong. 

 The discover}' of the existence of two forms of ethyl 

 formylphenylacetate was made by W. Wislicenus in 

 1887, during his experiments on the action of sodium 

 on mixtures of organic esters. Earlier in the year 

 Piutti had shown that when a mixture of ethyl acetate 

 and ethyl formate was used in this reaction the ex- 

 pected ethyl formylacetate was not produced, or if 

 produced, at once underwent inter-molecular con- 

 densation yielding the aromatic compound trimesic 

 ester. In order to avoid this, Wislicenus replaced the 

 ethyl acetate by ethyl phenyl acetate and obtained the 

 open chain formyl esters. He showed that the two 

 esters he isolated were distinct substances, one a liquid 

 giving pronounced enol reactions, the other a solid 

 which possessed the characteristic properties of the keto 

 modification. Since that time many examples of the 

 same kind have been recorded, several of which have 

 been discovered by Wislicenus and his pupils. The 

 whole question is summarised in a lecture given by 

 him at Leipzig in 1897, embodied later (1898) in one 

 of the Ahrens' Sammlungen, in which he clearly 

 enunciates his view that tautomeric phenomena are 

 reversible isomeric changes. Prior to this, in a paper 

 published in the Berichte for 1895, the following 

 passage occurred : " Uber die Natur der Isomerie ist 

 eine Entscheidung wohl erst nach ausfuhrlicheren 

 Untersuchungen zu treffen, wenn es mir audi am 

 wahrscheinlichsten zu sein scheint, dass hier die bei 

 den Aldehyden, Ketonen, und /i-Ketonsaurenestern 

 vermisste tautomeren Formen vorliegen " ; a view 

 which was to receive full verification in the later work 

 of Kurt Meyer and Knorr. 



Wislicenus continued to work on the general question 

 of tautomeric change for many years after this, and in 

 1912 he published a further paper in the Annalen 

 dealing with the chemistry of ethyl formylphenyl- 

 acetate. By that time four isomeric modifications 

 had entered the field, but, in the paper quoted, he 

 strongly expresses his view that only two of these, 

 namely, the liquid a-form (enol) and the solid y-form 

 (M.P. ioo°, enol-aldo), are chemical individuals. The 

 /i-form (M.P. 70 ) and Michael's modification (M.P. 50 ) 

 he regards as mixtures of the a- and y-forms. In 1916, 

 in a paper also published in the Annalen, he de- 

 scribes the two forms of the methyl ester of phenyl- 



