35-2 



aiisreiclieiider Gescliwiudigkeii iiiiivvaudelbare Isomere init einer ziir 

 Lösung iiiiziireiclieiiden Meiige eines Lösungsmittels ziisammen, so 

 muss, wenn der Satz von van 't Hoi't' zn Hecht besteht, die RicliUing 

 des sich abspielenden Isonierisalionsvorganges ausscldiesslicli von 

 der Konstanten G abiiangen, also ganzlicli unabhangig sein von 

 der Natiir des L(")snngsmittels". 



Experience, says Dimrotii, is iiowever in conflict with this, for 

 it often occnrs that it is possible to con\ert isomers into each other 

 by treatment with different solvents. 



He refers in particular to the investigation of E. Bambkrgkr ') on 

 the isomers of lutrofonimklehi/ilrazons, the «-form of which is 

 converted by water or alcohol into the /?-form, the ^J-modification 

 being reversely transformed into the «-modification by benzene, 

 chloroform, or ligroine. 



In this connection he states explicitly: "Es kanii kein Zweifel 

 sein, dass diese mit Erfolg geiibte Laboratoriumspraxis mit dem 

 VAN 't HoFP'schen Satze in Widersprnch steht." 



This statement may seem somewhat strange, as in a test by 

 means of the aininodenvatives of triazol carbonic ester, which show 

 the following conversion, 



CeH, 



I H 



N N 



H,N— U N C„H,NH— C N 



II II II II 

 KOOC— C N ROOC— C N 



1 Phenyl-5-aminotriazol- 5 Anilinotriazol- 



carbonic ester (neutral) carbonic ester (acid) 



DiMROTH himself found a very tine confirmation, so that doubt of 



the true interpretation of the said laboratory expei'ience was sooner 



to be expected. 



DiMROTH determined the concentration of the two isomers Ca and 

 Cb in different solvents, in whi(;h the isomers had assumed equili- 

 brium at ± 60° under influence of the catalytic action of a trace 

 of acid. 



Further the solubility of each of the isomers, so La and Zg. 

 was determined at the same temperature in the same solvent, and 

 then the quantity G calculated by means of equation (1). 



The in\estigation of the isomers of the ethyl resp. inethyJ ester 

 yielded the following interesting result: 



1) Ber. 34. 2001 (1901). 



