94 SCIENCE PROGRESS 



The discovery of this ketone supplies us with a fresh 

 starting-point from which to carry out an experimental attack 

 on cholesterine. Instead of the comparatively inactive second- 

 ary group CHOH we now have the highly reactive carbonyl, 

 and further the properties of unsaturated ketones have already 

 been carefully investigated, 1 so that it should be possible at 

 once to draw accurate conclusions from the experimental data 

 It was, until recently, regarded as doubtful whether the con- 

 version of cholesterine to cholestenone was as simple as 

 represented above, or whether some intramolecular change 

 might not after all have taken place. But that the "carbon 

 skeleton" of these bodies is the same, is rendered very probable 

 by the recent work of Diels and Linn 2 (1908). By the action of 

 sodium in boiling ethyl alcohol, they were able to reduce 

 cholestenone to an (isomeric) # cholesterine of melting-point 

 160 . This substance they regard as a cis-trans modification 

 of cholesterine, since it gives the same dibromide and esters 

 as cholesterine itself. They also obtained /S cholesterine by 

 heating cholesterine to 300 C. with a trace of iron salt (loc. cit.). 

 In this reaction cholestenone was also produced — a very curious 

 result. Their conversion of cholestenone to cholesterine is 

 shown in the following scheme : 



(oxidised) 

 Cholesterine -> Cholestenone 



•^ (saponified) (reduced) ^ 



(benzoylated) 

 Cholesterine Benzoate <- & Cholesterine 



The relative position of the CO group and the double link 

 in cholestenone has given rise to some discussion. Diels and 

 Abderhalden (1906) considered the double link to be in the 

 a fi position to the carbonyl. They found that cholestenone- 

 oxime formed an additive compound with hydroxylamine, a 

 known property of a/3 unsaturated ketones, and that further, 3 



1 Especially by Harries and his students. — Annalen, 330, 185, and many 

 previous papers. 

 1 Ber. 41, 260. 

 3 Ber. 39, 884. 



