300 



TV. WAXES, IIIOHEH ALCOHOLS, ETC. 



vioiis acptylation and treatment with maleic anhydride to form an ad- 

 dition product, dihydroergosterol can be prepared by removal of the pro- 

 tecting groups. Dihydroergosterol crystalhzes in plates which melt at 

 174 °C. and have a specific rotation of —20.1° (2% solution in chloroform 

 at 14 °C.). The two double bonds react with halogens. 



CH, 



I ' 



CHCHjCHoC-CH — CH, 



II 

 H CH, 



Dihj-droergosterol 



c'. Fucosterol: Heilbron et al.^^^~^^^ isolated a doubly unsaturated 

 sterol from algae. It has been found to be characteristic for all members of 

 Fucus (rock weeds) and all other phaeophycetes (brown algae and sea 

 weeds), bacillariophycetes (diatoms), and chrysophycetes (brown-orange 

 algae). ^^® The chlorophycetes (green, fresh-water algae) and rhodophycetes 

 (red sea weed) , which are more closely related to higher plants, usually con- 

 tain sitosterol, while the more primitive myxophycetes (blue-green algae) 

 have no sterols whatsoever. There appears to be a parallelism in the dis- 

 tribution of the carotenoid pigments and of the sterols, but the significance 

 of this interrelationship is not clear. Thus, xanthophyll is found in the 

 phanerogams, fucoxanthin in the cryptogams, and myxoxanthophyll in 

 the myxophycetes. 



CH3 CH3 



i I 



CHCHjCHjC-CH-CHj 



CH 



I 



CH, 



Fucosterol 



3" P. W. Carter, I. M. Heilbron, and B. Lythgoe, Proc. Roy. Soc. London, B218, 82- 

 109 (1939). 



31^ D. H. Coffey, I. M. Heilbron, F. S. Spring, and H. R. Wright, J. Chem. Soc, 1935, 

 1205-1207. 



''5 I. M. Heilbron, R. F. Phipers, and H. R. Wright, J. Chem. Soc, 1934, 1572-1576. 



3'6 1. M. Heilbron, J. Chem. Soc, 1942, 79-89. 



