602 



NA TURE 



[April 26, 1906 



amount of information which is imparted : and the 

 stream of literature incessantly poured upon the 

 unfortunate chemist is now so voluminous that 

 few can attempt to read even the most interesting 

 work in detail ; the pages have to be merely skimmed 

 through, and the task of forming and storing an 

 adequate visualisation of the whole is possible only to 

 the highly trained memory. 



The general arrangement of the book, although 

 highly systematic, sometimes leads to difficulties in 

 finding any desired subject. Thus, the dihydro- 

 phthalic acids are dealt with on p. S27, the tetra- 

 hydrophthalic acids on p. 771, and the hexahydro- 

 phthalic acids on p. 702 ; yet all these substances were 

 prepared by v. Baeyer at the same time and described 

 in the same paper. The difficulty of finding one's 

 way about the book would, however, be far greater 

 were it not for the excellent index and detailed table 

 of contents. 



In the sections devoted to the terpenes and the 

 camphor group, we cannot but miss the spirit of 

 selection and criticism which lends such fascination 

 to the account of the same branch of organic chemistry 

 given by Prof. Harries in Meyer and Jacobson's 

 " Handbuch der organischen Chemie." But, after 

 all, Aschan's book is so replete with valuable detail 

 that any serious attempt on his part to exercise the 

 critical faculty might have impaired the usefulness 

 of the whole work. At the same time, the value o 

 the book as a comprehensive digest would certainly 

 be the greater if more stress had always been laid on 

 investigations which really mark an epoch. Thus, the 

 brief mention made on pp. 501 and 563 of Perkin 

 and Thorpe's recent synthesis of a-campholytic and 

 isolauronolic acids appears quite inadequate in view 

 of the way in which this synthesis cleared the field 

 and settled definitely the question of the constitutions 

 of these two important acids. 



A similar objection may be raised in connection 

 with the otherwise excellent discussion of the con- 

 stitution of pinene on pp. 170 to 186, from which it 

 is by no means easy for the casual reader to discern 

 the really essential points in the complicated argu- 

 ment. The whole discussion relating to this problem 

 centred for a long time upon the constitution of 

 isocamphoronic acid, and for this Tiemann and 

 Semmler offered the formula 



HO.OC.CMe 5 .CH(CH 2 .CO.OH),, 



whilst v. Baeyer suggested 



CMe.,.CH„.CO.OH 

 I 

 HO OC.CH.CHo.CO.OH 



The discussion was settled once and for all by Perkin, 

 who prepared both these acids and proved thereby 

 that the Tiemann and Semmler constitution correctly 

 represents isocamphoronic acid. No mention seems, 

 however, to be made in the work of these two 

 syntheses, although tiny arc vital to the argument. 



In such a comprehensive work as the one under 

 consideration it is surprising that so few slips and 

 omissions occur. On p. 22, lines 13 to 32, and p. 23, 

 NO. IQ04, VOL. 7$] 



lines 10 to 37, the action of sodioacetacetic ester 

 upon trimethylene bromide is stated, in accordance 

 with the original paper of 1883, as leading to the 

 formation of acetyltetramethylenecarboxylic ester, 



^CH.,, COMe 



CH„ 



/ 



2 \ 



ill 



/ \ 



CO.OEt 



but no mention is made of Perkin 's subsequent demon- 

 stration that this reaction, both in the case of acet- 

 acetic and of benzylacetic ester, really leads to the 

 production of oxygenated ring compounds, thus : — 



CH 2 — CH 2 — C.CO.OEt CH„-CH„-C. CO.OEt 



and I 

 CH 2 O CMe CH., O CFh 



although when sodiomalonic ester is employed a 

 tetramethylene derivative actually results. The reac- 

 tion is correctly stated in the special part of the work 

 at p. 418. 



Further, on p. 38, v. Baeyer's old condensation of 

 three molecules of malonic ester into one of phloro- 

 glucintricarboxylic ester is still figured in all that 

 simple symmetry which constitutes one of the gloiies 

 of our elementary text-books. No mention is made 

 of Moore's proof (Trans. Chem. Soc, 1904, 165) that 

 the product is really the phloroglucindicarboxylic ester 

 of Bally, although v. Baeyer himself refers to the 

 correction in his recently published collected works. 



A curious slip occurs on p. 585 — probablv as the 

 result of confusion with the work of Zelinsky — where 

 Perkin and Haworth are represented as having pie- 

 pared hexamethylene by the action of sodium on 

 bromocyclohexane in boiling alcoholic solution, but 

 where an equation is given representing the action 

 of sodium on hexamethylene bromide. The synthesis 

 was actually effected by the action of sodium on 

 hexamethylene bromide in metaxylene solution ; the 

 action of sodium in boiling alcoholic solution would 

 obviously have led to the production of normal hexane. 



A valuable section is devoted to the discussion of 

 the stereochemical relationships which may exist be- 

 tween isomeric alievclic compounds, and the elucida- 

 tion of the isomerism is materially facilitated by the 

 use of carefully designed figures ; the somewhat intri- 

 cate stereochemistry of the^e substances can hardly 

 be brought home to the reader more clearly than is 

 here done. On p. 354 an erroneous constitution is 

 assigned to isolauronic acid, and the deduction drawn 

 therefrom that this acid can exist in four optically 

 active modifications ;• isolauronic acid actually contains 

 no asymmetric carbon atom, and, as is clear from the 

 correct constitution assigned to it on p. 698, is 

 incapable of exhibiting optical activity. 



The section dealing with irone, ionone, and allied 

 substances possessing the odour of violets forms a 

 particularly lucid exposition of the finest piece of work 

 done by Tiemann. Amongst the copious references 

 given is to be noted one of the first fruits of the 

 system of abstracting chemical patents introduced 

 into the Chemisches Ccntralblatl during the last few 

 years. Now that so much of the pioneer work in 

 organic chemistry appears for the first time in patent 

 specifications, references to the patent literature are 



