102 SCIENCE PROGRESS 



acid, acting on cholesterine, gives a small proportion of acid 

 bodies. The chief of these has the formula C^H^CX, and had 

 previously been prepared by Diels and Abderhalden by the 

 action of alkaline hypobromite. It is dibasic, giving on titration 

 with soda an acid, with potash a neutral salt, while by direct 

 esterification the monomethyl ester is obtained. Its formation 

 from cholesterine is simple : 



/CH 2 /COOH 



C25H4/ I becoming C25H4/ 



\CHOH \COOH 



Chromic acid also attacks cholestanonol and cholestandione, 

 giving in each case a well-defined body, cholestanone dicar- 

 boxylic acid, C 2T H420 5 . This melts at 21 8°, and, being difficultly 

 soluble in benzene, is easily crystallised. It forms a highly 

 characteristic methyl ester melting at 113 , and the presence 

 of the CO group is shown by the formation of an oxime and 

 a semicarbazone. The formula given to it assumed that the 

 CO . CH 2 group of cholestanonol is opened and replaced by 

 the two acidic groups COOH. In order to verify this Windaus 

 made use of the observation of Baeyer and Villiger x that 

 ammonium persulphate acts on cyclic ketones, changing them 

 to oxyacids or their lactones. For example, suberone gives 

 oxyaenanthylic acid thus : 



Suberone. Oxyaenanthylic acid. Pimelic acid. 



/CH,.CH..CH 2 /CHo.CH,.CH,.OH /CH 2 . CH,. COOH 



CH/ I "-> CH/ -> CH./ 



\CH 2 .CH 2 .CO \CH 3 .CH.,.CO .OH \CH 2 . CH 2 . COOH 



Cholestandione (I.) behaves analogously. With persulphate it 

 gives a monobasic acid C 2 7H 4l 04 (II.), and this, oxidised with 

 chromic acid, yields cholestanone dicarboxylic acid (III.). 



Using cholestanonol as a starting-point, some interesting 

 acids were obtained by Windaus and Stein. The numerous 

 difficult transformations, which were carried out with great 



1 Ber. 32, 3625, etc. 



