NATURAL WAXES 



345 



sliowed that it is a reduction product of allocholesterol wliich, in turn, may 

 1)0 derived from cholesterol. The structure of coprosterol was further 

 elucidated by the demonstration of the relationship of its hydrocarbon 

 coprostane, or psoudocholestane, to cholanic acid.^'-^ This latter compound 

 is known to be related to the bile acids. 



Cholesterol 



Allocholesterol 



Coprosterol 



Coprosterol crystallizes from ethanol in fine needles but, in contrast to 

 cholesterol and dihydrocholesterol, they contain no water of crystalliza- 

 tion. Like other sterols, it is insoluble in water and alkali but readily dis- 

 solves in alcohol, ether, chlorofomi, and other organic solvents, including 

 fats. It can be separated from cholesterol chromatographically.^" 

 Coprosterol melts at 102-104 °C., and it has a specific rotation of +24° (in 

 13.7% concentration in chloroform). 



Because it is saturated, coprosterol adds no halogens and has an iodine 

 value of zero. In spite of this, ozone reacts with it just as is the case with 

 dihydrocholesterol. Because of the fact that the position of the hydroxy 1 

 group on C3 is the same as in cholesterol, it is precipitated most completely 

 by digitonin. The color given in the Salkowski reaction is j^ellow, but this 

 changes gradually to a reddish color. The Liebermann-Burchard test is 

 similar to that given by cholesterol, but the intensity is only one-third that 

 of the latter sterol. It forms esters, of which the best known are copro- 

 sterol acetate (C27H47O • OCCH3) , which forms needles with a melting point 

 of 88-89 °C., and coprosterol propionate (C27H470-OCCH2CH3). When 

 crystallized from methanol, the latter ester forms long needles which melt 

 at 99-100 °C. 



"7 A. von Chri.'^tiani, Z. physiol. Chem., 280, 127-128 (1944). 



