81 



on lieaHiig at 180° henzmiidmoIe-2-propylsul/>h<mic acid (I), whilst 

 from the siil|)hobut3Tate of 3,4-diaminotohiene was formeil in the 

 same way methijlbenzimi(lazole-2-propylsuJphonic acid (II). 



C.H,<55jj>C . CH < ^ (I) CH. . C.H.<gjj^C . CH < ^^^^ (11) 



These imidazoles were obtained as white crystalline snbstances. 

 They are almost insolnble in the common solvents, liave a very 

 high melting point, and, notwithstanding the presence ofa snlphonic 

 acid gronp, they do not combine with aromatic amines and they 

 are not hygroscopic. All these properties indicate, that the snlphonic 

 acid gronp forms an internal salt with the basic function of the 

 imidazole (III) and they completely recall the properties of taurine, 

 for which an analogous structure is assumed (IV). 



^."^<Sh><^CH.C,H. (Ill) CH, — CH, (IV) 



." I II 



: HO.S SO,H..NH, 



With strong bases, such as baryta, these imidazolesulphonic acids 

 give well crystallised salts. From the barium salt and copper sulphate 

 a green solution is formed, which, however, decomposes immediately 

 when heated and also when kept for a long time at the ordinary 

 temperature, so that the copper salt could not be separated in a 

 crystallised pure state. It deserves attention, that, in spite of many 

 efforts, also no copper salt of taurine has been obtained. 



The resolution of racemic «-sulphobutyric acid was attempted 

 with the aid of strychnine, by reason of previous experience with 

 sulphopropionic acid, and the attempt was successful. 



The acid strychnine salt of the d-acid is less soluble than the salt 

 of the 1-acid, just as in the case of sulphopropionic acid. 



After three or four crystallisations the acid strychnine salt of the 

 d-sulphobutyric acid is entirely free from the other component. It 

 crystallises with two molecu-les of water in small glistening needles. 



On concentration, the tirst mother liquor slowly gives a crop of 

 the acid strychnine salt of 1-sidphobutyric acid, which by repeated 

 crystallisation from alcohol is obtained in a pure state. 



Decomposition of the strychnine salts by baryta gives the barium 

 salts of the active acids. 



These barium salts crystallise from water in long needles which 

 contain 2| molecules of water, in contradistinction to the racemic 

 barium salt, which separates in small glistening leaflets with two 

 molecules of water of crystallisation. 



6 



Proceedings Royal Acad. Amsterdam. Vol. XXVI. 



