NATURAL WAXES 



351 



dihydrobrassicastcrol),-^" as weW as some of tlic isomers of tlie stella- 

 stanols.*^** 



CH, CH, 



-CH-CHj-CHz-C-CH-CHj 



CH, 



I 



CH, 



/^-Sitosterol 



CH CHoCHo 



CH, 



I ^ 



CH? C H, 

 II 

 -C— CH- 

 I 

 H 



CH, 



7-Sitosterol 



According to the terminology suggested by Ruigh/^^ j8-sitostanol may be 

 properly called 24-dextro-ethylcholestanol, while 7-sitostanol is the 24- 

 levo-ethylcholestanol. The formula in which the ethyl group attached to 

 C24 is pictured below the side chain is arbitrarily considered as the dextro 

 isomer, while the case where the ethyl group is placed above the side chain 

 would connote the levo isomer. According to the terminology employed 

 by Fieser and Fieser,^^^ the isomer in which the stanol form gives a dextro 

 rotation is spoken of as the 24a-type ; the group attached to the C24 in this 

 case is represented by a dotted line. The epimer giving rise to the levo 

 saturated alcohol is considered as the 24b form, and the group attached to 

 C24 is represented by a solid line. The actual rotation on C24 is determined 

 from the rotation of the aliphatic ketone produced by severing the side 

 chain between d? and C2o.^^^ 



Two additional sitosterols, 5 and e, have been isolated by Ichiba-^^ and 

 by Simpson and Williams, ^^^ respectively. The solubility of 7-sitosterol is 

 quite low as compared with that of the a-form, while that of the /S-isomer is 



2M E. Fernholz and W. L. Ruigh, /. Am. Chem. Soc, 62, 3346-3348 (1940). 

 "61 A. Ichiba, Set. Papers Inst. Phys. Chem. Research Tokyo, 28, Nos. 605-606, 112-127 

 (1935). 



«2 J. C. E. Simpson and N. E. William.s, ./. Chem. Soc, 1.937, 733-738. 



