Chemistry. — “On the preparation of a-sulphopropionic acid.” By 
H. J. Backer and J. V. Dussky. (Communicated by Prof. 
F. M. JAEGER.) 
(Communicated in the meeting of September 27, 1919). 
The only practical method for the preparation of the «-sulphopro- 
pionie acid has hitherto been the one found by FRANCHIMONT ') i. e, 
the action of sulphuric acid with propionic acid anhydride. 
Besides Francnimont’s general method, an analogical method has 
been used by Mersens*) for the preparation of the sulphonacetic 
acid, the first term of the sulphoearbonic acids, namely the action 
of sulphurie acid anhydride with acetic acid. 
These two methods show much similarity. In both cases the 
mixed anhydride, the acetylsulphuric acid, is formed as an interme- 
diary product, as FRANCHIMONT *) had already supposed and Stinuicn ‘) 
afterwards established, and as Van Peskr *) proved for the reaction 
of Mrtsens. | 
With a view to comparing it with the method of FRANCHIMONT 
we have applied Mersens’ method also to propionie acid, by treating 
it with sulphurtrioxide. 
In both cases the reaction turned out, just as in the ease of the 
acetic acid, to be indirect, while the mixed anhydride, the pro- 
pionylsulphuric acid, must be taken to be the intermediary product. 
GEGE: COH SO, — CH, CHROOSSOSR — 
= CH3.CH(SO;H).CO,H. 
(CH. CH. CO),O + H,SO,= ) 
= CH. CH,.CO,H-+CH,. CH,. CO,SO;H— CH. CH(SO;H). CO,H.$ 
When the substances are mixed carefully whilst cooling, a colour- 
less, very viscous liquid is formed, which yields the sulphopropionic 
acid only at a higher temperature, with development of heat and 
brown coloration. 
We were able to follow the process of this reaction by titration, 
Il. 
1) Recueil trav. chim. 7, 27 (1888). 
2) Ann. der Chemie 52, 276 (1844). 
3) Versl. dezer Akad. 16, 373 (1881). 
*) Ber. d. dtsch. chem. Ges. 38, 1241 (1905). 
5) Versl. dezer Akad. 22, 996 (1914). 
