344 IV. WAXES, HIGHER ALCOHOLS, ETC. 



epidihydrocholesterol, by reduction of cholestanone. Windaus"" found 

 that it occurs in association with coprosterol in the reduction of allochole- 

 sterol. 



Dihydrocholesterol forms anhydrous hexagonal platelets, which melt 

 sharply at 142 °C. As in cholesterol, the crystals contain one molecule of 

 water of crystallization when they are prepared from a saturated solution 

 in 95% ethanol. The sterol is optically active, having a specific rotation of 

 +28.8° at 22 °C. in ether. 



It is readily distinguished from cholesterol because of the absence of a 

 double bond. Thus, it does not form the characteristic insoluble dibromide, 

 nor will it absorb iodine; however, it will react with one molecule of ozone. 

 The color reactions which are given by cholesterol and which depend upon 

 the unsaturated linkage are not shown by dihydrocholesterol. However, 

 those reactions of cholesterol which are attributable to the alcohol group 

 are, of course, also produced by dihydrocholesterol. The latter forms 

 esters with the fatty acids. Since dihydrocholesterol has the hydroxyl 

 group in the normal position, it reacts with digitonin to form a difficultly 

 soluble digitonide whose acetyl derivative melts at 110.5 to 111°C. Epi- 

 dihydrocholesterol does not form a precipitate with digitonin. 



d'. Coprosterol: As early as 1862, Flint -'-' recognized that the sterol 

 which he had separated from human feces differed from cholesterol. He 

 called it stercorine, but it was later renamed koprosterin by Bondzynski,^^^ 

 who rediscovered it in 1896. In accordance with the current terminology 

 for alcohols, it is now commonly referred to as coprosterol. The name 

 originates from a Greek word, kopro, which means dung; the second part, 

 from which cholesterol is also derived, stereos, means solid. Although 

 coprosterol occurs as the chief sterol component in the feces of practically 

 all animals, Krueger--^ has proved that the so-called guanosterol obtained 

 from Peruvian guano is identical with cholesterol rather than with copro- 

 sterol. This is taken to indicate that marine birds do not excrete copro- 

 sterol. Ambergris, which is a product of the sperm whale, has been shown 

 to contain largely coprosterol and epicoprosterol, with small amounts of 

 cholesterol.^"^ 



Bondzynski and Humnicki^'" established the empirical formula of copro- 

 sterol as C27H48O. Thus, it has the same composition as dihydrochole- 

 sterol, but its properties differ markedly from those of the lattei-. Windaus^'-^ 



220 A. Windaus, Ann., 453, 101-112 (1927). 



221 A. Flint, Am. J. Med. Sci., U, 305-365 (1802). 



222 S. Bondzvriski, Ber., 29, 476-478 (1896). 



223 J. Krueger, J. Am. C'hem. Soc, 66, 1795-1797 (1944). 



22^ H. Janistyne, Felle u. Seifen, 4S, 501-504 (1941); C'hem. Ahstr., 38, 2163 (1944); 

 Chem. Zentr., 112, II, 3003-3004 (1941). 



22s S. Bondzynski and V. Humnicki, Z. physiol. Chem., 22, 396-410 (1896). 

 226 A. Windaus and K. Neukirchen, Ber., 52, 1915-1919 (1919). 



