THE CHEMISTRY ON CHOLESTERINE 93 



The work of the last few years may conveniently be con- 

 sidered under the following heads : 



(1) The ketone cholestenone. 1 



(2) Oxidation products. 



(3) Reduced cholesterine. 



Cholestenone 



The conversion of cholesterine to the corresponding ketone 

 proved difficult, as with most oxidising agents the action 

 proceeds too far. Diels and Abderhalden, however, in 1904, 

 succeeded in preparing cholestenone by using copper oxide 

 at a temperature of 28o°-300°. The finely powdered oxide is 

 added gradually to the melted cholesterine, and the black, 

 tough mass resulting dissolved in cold methyl alcohol. The 

 solution on standing deposits beautiful needles of the ketone, 

 which melt at 8i°-82°. The yield, as might be expected, is 

 somewhat low, being only 25-30 per cent, of the theoretical, 

 and the high temperature necessary for the reaction renders 

 it uncertain whether any other changes take place within the 

 molecule beside the simple oxidation. Windaus (1906) showed 

 that the ketone could be prepared under conditions which 

 rendered any such molecular alterations far less likely. The 

 cholesterine is converted to the dibromide, and the double 

 link, being thus " protected," the oxidation can be carried out, 

 either with chromic acid at 70 , or with 4 per cent, acid per- 

 manganate in the cold. The dibromcholestenone formed as 

 an intermediate product on treatment with zinc dust and acetic 

 acid leaves the ketone. Yield 60 per cent of the theory. Thus : 



(a) C a H 14 .CHOH + Br., = C M H 44 Br 2 . CHOH 



(b) C a H„Br 2 . CHOH + O = C.^H 44 Br,. CO + H 2 

 \c) C^H^Br, . CO + H 2 = CJi H . CO + 2HBr. 



The resulting body was shown to be identical with that of 

 Diels and Abderhalden, a very interesting result since it goes 

 to prove that cholesterine is not altered structurally by 

 oxidation with copper oxide at a temperature of 300 . 



1 It might be mentioned that the ending " -ol" indicates an alcohol ; " -one " a 

 ketone. The syllable " -ene " indicates an unsaturated, " -ane " a saturated body, 

 Cholesterol is thus more correct than cholesterine, but the latter name has long 

 usage to justify it. 



