OCCURRENCE AND STRUCTURE OF RELATED COMPOUNDS 



709 



X 5 



200 240 280 320 360 400 440 



WAVE LENGTH IN MJLL 



Fig. 4. The absorption spectra in ethanol of the following compounds: 

 (--) 5-dehydrohoniovitamin A ethyl ether obtained from carbinol; ( — ) 

 homovitamin A ethjd ether obtained by dehydrobromination of partially 

 hydrogenated glycol/^ 



(4) Vitamin A Epoxide 



According to Karrer and Jucker,"* vitamin A forms an epoxide by a 

 method analogous to that of the carotenoids. It is beheved that vitamin A 

 epoxide co-exists with vitamin A in fish liver oils and animal fats, in which 

 it originates by the autoxidation of the latter."* Karrer"^ suggested the 

 formula shown here for vitamin A epoxide. This author also assumed that 

 it was in equilibrium with its electromer. 



HjC CHj 



c chj c h 3 



/\ hhIhhhIh 



H2C 



I 



HzC 



C-c:g-c:c-c:c-c:c- CH.OH ^:: 



\ / \ 



C CH: 



Hz 



Vitamin A 

 epoxide 



H,C CHj 



C C H , C H 1 



/\+HH I HHH I H 

 HjC C • g:c- c: c • c: C- g: c- oh, oh 



I II 



HjG g-o~ 



\ / \ 



C CH3 



H2 



Electromer of 

 \'itamin A epoxide 



Vitamin A epoxide can be sjmthesized by treating vitamin A with phthalic 

 acid peracid.'*'* A similar procedure has also been used for the prepara- 



'™ P. Karrer and E. Jucker, Helv. Chim. Acta, 28, 717-722 (1945). 

 "5 P. Karrer, Hdv. Chim. Acta, 28, 474-475 (1945). 



