11. ClIKMISTRY 



483 



CH3 



/\ O 



CII, 



('II3 CH3 ("H, 



(CIL),CII(CII,)5CH(CHo)3C;ilCH3 



HO 



CH3 



CH3 

 H,C I CH, 



/3-Tocopherol 



CH3 CH3 CH3 



HO 



(CH2)3CH(CH.)3CH(CH2)3CHCH3 



-y-Tocopherol 



CH3 



.^/O 



CH3 



CH3 CH3 CHs 



HO 



(CH2)3CH(CH.)3CH{CH2)3CHCH3 



5-TocoDheiol 



II. Chemistry 



HENRY A. MATTH^L 



\'itamin E was first recognized by at least three groups of investigators'"^ 

 as a fat-solul)le substance necessary for reproduction in the rat. In place of 

 the original ''X factor,"' the designation of "E" was suggested by Sure,^ 

 since this was the next letter in sequence following the identification of the 

 antiricketic vitamin as a separate entity. After the isolation of vitamin E 

 in purity,'^ the name tocopherol was proposed (from the Greek, tokoa (off- 

 spring), pherein (to bear), and ol, to signify an alcohol). Because of the 

 multiple nature of vitamin E, the new name is used in the plural in the 

 generic sense, and it is supplied with Greek letter prefixes, a, (3, etc., for 



» H. M. Evans and K. S. Bishop, ./. Metabolic Research 3, 233 (1923); J. Am. Med. 



-l.s.soc. 81, 889 (1923). 

 2 H. Sure, J. Biol. Chem. 58, 693 (1924); 62, 371 (1924); 63, 211 (1925). 

 ■' H. A. Mattill, J. S. Carman, and M. M. Claj-ton, J. Biol. Chem. 61, 729 (1924). 

 ' n. M. Evans, O. H. Kmer.son, and O. A. Emerson, ./. Biol. Chem. 113, 319 (1936). 



