Studies with Deuterium Steroids 



33 



exchange reaction had an approximately equal distribution 

 of the isotope in the nucleus and in the side chain. We 

 re-investigated this distribution by somewhat different ana- 

 lytical procedures and confirmed the general conclusion of 

 Bloch and Rittenberg. However, the isotope was more 

 precisely localized than might have been anticipated and, in 

 fact, was nearly exclusively situated upon three carbon atoms, 

 C-6, C-26 and C-27. The evidence for this conclusion is 



CH^COO 



CHOLESTEROL ACETATE 



2.48 D 



1.34 D 



(1.14 D losl) 



COOCH-. 



CHjCOO'*--,-^''^:^-^ CH3COO 

 DEHYDROISOANDROSTERONE 

 ACETATE 



I.I7D 



(I 31 D lost) 



1.19 D 



(1.29 D lost) 



1.20 D 



(1.28 D lost) 



Fig. 6. Distribution of the isotope in cholesterol obtained by the 

 platinum catalysed exchange reaction. 



presented schematically in Fig. 6. The acetate dibromide of 

 cholesterol from the exchange reaction was oxidized with 

 chromic acid and from the reaction a sample of 3/3-hydroxy- 

 chol-5-enic acid was isolated. This compound contained 1 • 20 

 atoms of deuterium per molecule as compared with 2 • 48 

 atoms of deuterium per molecule in the cholesterol. The iso- 

 tope lost, 1 • 28 atoms of deuterium per molecule, must have 

 been attached to the i^opropyl group removed by oxidation, 

 or to C-24, the carbon atom which is now the carboxyl group. 

 While the possibility exists that the isotope was attached to 



ISOTOPES 



