* 



1917.] The Stereochemistry of Alanine Derivatives. 193 



converted into their barium salts, and these were recrystallised 

 until their rotatory powers were constant and equal knd oppo- 

 site It will be seen from the above that the strychnine salt of 

 the dextro-acid was obtained pure in the process* of the resolu- 

 tion, so that the corresponding barium salt was easily obtained 

 pure and its constants determined. It was analysed 'and found 

 to contain half a molecule of water of crystallisation, and its 

 molecular rotation was found to be [M] = + 1116 for the mer- 

 cury green line. 



The impure strychnine salt of the laevo-acid, containing a 

 small quantity of the strychnine salt of the dextro-acid, was 

 converted into the barium salt and this was very carefully 

 fractionated. After three crystallisations it had a molecular 

 rotation of [M] = - 1090 for the mercury green line, which 

 approximates to the value obtained for the barium salt of the 

 dextro-acid. 



The barium salts crystallise from hot water in very long 

 beautiful needles, and the two salts behave similarly in all res- 

 pects to the usual chemical reagents. It is thus seen that sul- 

 phonyl - /?-naphthylalanine has been resolved into its optically 

 active components, and it is interesting to compare the molecular 

 rotations of the salts sulphonyl-p-tolylalanine with those of the 

 compound above described. 



d and 1 — sulphonyl-p-tolylalanine [M] 64lft ,= ±819. 



d and 1 — sulphonyl-tf-naphthylalanine [M] >wl = ±110*3. 

 These figures indicate clearly that increasing the mass of 

 the group R has a very considerable effect in increasing the 

 rotatory power. 



The experiments on the resolution of externally compen- 

 sated sulphonyl phenylalanine have so far been unsuccessful, 

 and it is interesting to observe that this compound which is no 

 doubt very closely related to benzoyl alanine both in chemical 

 constitution and crystalline form is not resolved in the same 

 way as the latter compound. 





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