806 IX. THE VITAMIN E GROUP 



tone group, one deduces that the alcohol must be tertiary. This is sup- 

 ported by the fact that it is esterified only with difficulty. When these 

 facts were assessed in the light of knowledge of the empirical formula of the 

 a-tocopherol, as well as of the structure of the Cis ketone (IX) and Ci6 acid 

 (X), the structure of the whole molecule could be established. The Cie 



9"^ H, 



HOCs loC sCHj 



I i| I CH, CH, CHj 



HjCCr sa 20— CHzCHzCHzCHCHzCHzCHzCHCHzCHzCHaCHCHs 



^•c^ ^6^ 'CH3 



/ CH, \ 



I I n 



H,C— C=0 H,CC— C|^ 



\ 



m 2L 



IE 



0=Cio sCHj 



CH« CH« CH, 



I r I I I ,3- 



lCCHjCH2CH2CHCHjCHjCH2CHCH2CH2CHj,CHCH3 



CH, 



W 



CH« CH* ' CH* 



I 



K 



Q CH, CH, CHj 



V I I I I3' 



H0-CCH,CH,CHCH,CH,CH,CHCH,CH,CH2CHCH, 



Fig. 1. Decomposition products of a-tocopherol on treatment with chromic acid. 

 Superscript nimibers indicate the source of the atoms in the tocopherol molecules. 



acid was used to determine the number of methyl groups in the side chain, 

 which proved to be 3; from this information the position of these methyl 

 groups was assumed by analogy to other similar structures in naturally 

 occurring members of the terpene family which follow the isoprene rule. 

 Finally, Femholz was able to show that the structure which he postulated 

 for a-tocopherol would permit the production of all of these decomposition 



