32 



T. F. Gallagher 



by the exchange reaction is Hkewise an extremely useful 

 procedure as illustrated by the preparation of radioactive 

 cortisone acetate illustrated in Figs. 4 and 5. 



The amount of isotope incorporated by the exchange 



CH-7 



c = o 



CH3 



c = o 



AcO- 



0. 



2 DAY 150" 

 Pr 



70% CH3C00H*-H^0 



2 HOURS REFLUX WITH KOH 



HO- 



1.02X10'" DiSINT./min/m.m 



Fig. 4. Preparation of radioactive 3.-hydrox\pregnane-ll:20- 

 dione by the platinum catalysed exchange reaction. 



HO' 



X CH- 



KOH 



HO' 



3 STEPS 



3 90X10^ DiSINT/min./mm 



C0RTIS0^JE ACETATE Egjeo^'^-'OO 

 m p 245-246° 



U]d= +I86°(ACET0NE) , oo y ,^9 h.cmt / / 



[/]^+2ie-(CHCL3) 2 82X10 D,SINT/mm/m, 



Fig. 5. Preparation of radioactive cortisone acetate. 



reaction, while useful for the biological studies, was not as 

 high as we had anticipated from the results of Bloch and 

 Rittenberg (1943) with cholesterol. These authors had found 

 that cholesterol stably labelled with deuterium by the 



