258 



dimethyl-piperazine 2 ) itself, but without result. Afterwards they made 

 it probable, x ) that here not the j-6-, but the 2-<5-a's-derivative was 

 present, which, of course, cannot be split up, because it has a single 

 plane of symmetry perpendicular to the plane of the ring, and 

 passing through both JV7/-groups: 



The molecule evidently possesses the symmetry of the group 

 of the second order S. 



In the case of the isomeric 3-j-diketo-2-6-dimethylpiperazines, 



T 



CH 3 CO 



CO 



A. 



(CIS -form). 



H..---NH f 

 CH 3 



B. 



(trans -form). 



however, just the opposite is true: here the as-form (A) has a 

 plane of symmetry S perpendicular to the plane of the ring and 

 can, therefore, not be separated into optical antipodes, while the 

 ^nws-form (B) possesses only a single binary axis A 2 in the plane 

 of the ring, and may be fissed into its enantiomorphous components. 

 The compound just mentioned 2 ), has, hitherto, not yet been studied 



*) W. J. Pope and J- Read, Journ. Chem. Soc. London, 105, 219, (1914). 

 2) J. V. Dubsky, Ber. d.d. chem. Ges. 49, 1058, (1916). 



