654 



and with «-bromopropionic acid (inethjibromoacetic acid) Rambkrg ^) 

 Iiad obtained decided results, luit on the other liand, Pope and Read ^) 

 did not succeed in resolving the chlorosulphoacetic acid. The 

 question now arose whether perhaps the sulphogroup created the 

 difficuItA^ i. e, causes the rapid raceniisation. Tiiis became less 

 probable after Pope and Read ^) had succeeded in splitting the 

 chloroiodomethanesulphonic acid and had found that the optically 

 active acids thus obtained were not so readily transformed into the 

 racemic mixture. Hence, the investigation of sulphopropionic acid 

 was at once again taken in hand. 



Both chlorosulphoacetic acid and methylsulphoacetic acid («-sulpho- 

 propionic acid) arc dibasic and thus can form acid salts. Moreover, 

 the two groups that cause the acid reaction, have a different com- 

 position, the one being a carboxyl- and the other a sulphoxyl-group. 

 and of different strength, so that as the sulphoxyl is stronger acid, 

 salts will presumably contain the carboxyl-group in the free and the 

 sulphoxyl-group in the combined state. 



Whereas, previously, chiefly the neutral and mixed metallic salts 

 and the neutral strychnine salt had been experimented with, the 

 acid strychnine salt was now employed and the desired result was 

 obtained at once. 



«-Sulphopropionic acid itself was hitherto only known as a viscous 

 syrup, whilst sulphoacetic acid had been obtained in crystals; 

 therefore we have trie'd also to obtain «-sulphopropionic acid in a 

 crystallized condition. 



A dilute solution of the acid prepared by decomposition of the 

 barium salt with the theoretical quantity of sulphuric acid was 

 concentrated by partial freezing and draining by suction. The strong 

 solution was placed in vacuo first over sulphuric acid atid then 

 over P2O5. The viscous residue was kept for a day in an ice safe 

 at about 0^, when gradually large crystals were formed. The acid 

 thus obtained contains one mol. of water and is exceedingly hygro- 

 scopic. \\\ order to determine its melting point a little apparatus 

 was constructed, consisting of two tubes communicating with a 

 transverse tube, one of which contained P2O5 and the other the 

 «-sulphopropionic acid. After the apparatus had been evacuated and 

 sealed, it was allowed to stand for a few days. The m. p. of the 

 «-sulphopropionic acid was then found to be 100°. 5, therefore, higher 

 than that of sulphoacetic acid, which is stated to be 84° — 86°. 



1) Ber. d. D ch. G. 33. p. 3354 (1900). 



2) J. ch. Soc. 93. p. 795 (1908). 



3) J. ch. Soc. 105. p. 811 (1914). 



