Chemistry. — "n.n-SiiIfohutiirlc acid and its optical/t/ active com- 

 ponents". By Prut'. H. J. BACKKRand J. H. dk Hokh. (Coiiimuni- 

 cated l)y Prof. F. AJ. Jaegek). 



(Communicated at the meeting of .Tanu.ni'v '27. 1923). 



After it had been shown that «-siilphopropioiiie acid can be 

 separated into its oplicaliv active compoiieiils '), we tried to efilect 

 this resolution also for norm, «-sniphobutjric acid. At the same time 

 the occasion was taken to study this acid, which has been known 

 already since 1875, but iiitherto had not been obtained in a pure 

 crystallised state. 



Tiie acid is formed by direct suiphonalion of n. «-butyric acid or 

 of butyric iinhydride '). 



Just as in the case of the propionic acid, the sulplionic acid group 

 is attached to the «-carbon atom, as proved by its relation to «- 

 bromobutyric acid, of which the structure is fixed. 



Hkmilian caused the ester of this acid to react with ammonium- 

 sulphite and we have applied this reaction to the free «-bromo- 

 butyric acid; in both cases the same sidphobniyric acid was formed 

 as by direct sulphonatioti. 



We also obtained the sulphobutyric acid in a good yield (70 7o) 

 from ethylinalonic acid, which by sulphonation loses one molecule 

 of carbon dioxyde. Besides, this formation may serve as an argument 

 for the structure, the active hydrogen atom of the ethylmalonic 

 acid having the greatest chance of being substituted by the suiphonic 

 acid group. 



As a method of preparation we used the sidphonatioii of the 

 carefully fractionated n. butyric acid with sulphur trioxyde. In the 

 cold butyryl&ulphuric acid is formed, which on heating passes into 

 sulphobutyric acid : 



C,H, . CH, . CO, . SO,H -*. C,H, . CH (SO.H) . CO,H. 



The acid was separated in the form of its barium salt, which 

 was purified by crystallisation, and from which sulphuric acid 

 liberated again the organic acid. 



') Franchimost and Backer, These Proceedings 17. 653 (1914); Recueil d. trav. 

 chim. 39, 751 (1920). 



■') Hemilian, Ann. d. Chemie 176. 2 (1875). Franchimont, Recueil d. trav. 

 chim. 7, 27 (1888). van Peski, Recueil 40, 736 (1921). 



