HYDROCARBON CAROTENOIDS OF THE C4n SERIES 537 



beard) and Ranunculus acris (buttercup or crowsfoot). Karrer and .lucker^^ 

 state that the epoxide possesses vitamin A activity. 



HjC CHj h.c ch, 



Q CHj CH, CHj CH, Q 



/\ hhIhhhIhhhhIhhhIhhh/\ 

 HjC c-c:c-c:C-c:C'C:g-c:c-C:C-C:C-c:C'C:c-C CHz 



1 l)o II 



H?C C^ C CHj 



\ / \ / \ / 



C CHj HjC C 



H? n 



a-Carotene mono-epoxide 



(6) Flavochrome, C40H56O. When the mono-epoxide is treated with a 

 dilute acid, i.e., chloroform-containing hydrochloric acid, thin yellow plate- 

 lets melting at 189°C. and having a strong luster precipitate from a ben- 

 zene-methanol mixture. These have been shown to be flavochrome, in 

 which the epoxide structure has been transformed to a furanoid ring 

 arrangement. The new pigment gives the same reaction with hydrochloric 

 acid as does the mono-epoxide. Flavochrome is not a provitamin A. 

 However, it does occur naturally in the Ranunculus acris and Trago-pogon 

 pratensis, just as the mono-epoxide does. a-Carotene mono-epoxide and 

 flavochrome both exhibit an epiphasic reaction. 



HjC CHj 



\ / 



C HjC CH, 



/ \ \ / 



HjC C=CH CHj CHj CHs CHj q 



I 1 I IhhhIhhhhIhhhIhhh/\ 

 HC C ch— C; C • c: C- C: C • C: C- C; C- C: C- C: C- C: C- C CHe 



\/\V I I 



C ' 



C CHz 



H2 CHj / % / 



HjC C 



H 



Flavochrome 



(c) Oxy-a-carotene, C40H58O2. When ct-carotene is oxidized with chromic 

 acid, oxy-a-carotene is formed in addition to a-semi-carotenone and a-caro- 

 tone, C40H56O5. ^"^'^^ '*■* Oxy-a-carotene crystallizes from a methanol-petro- 

 leum ether mixture in needles which melt at 183°C. This compound is 

 slightly soluble in petroleum ether. It is of especial interest since it is 

 optically active. It is not effective as a source of vitamin A.^** The 

 following foraiula has been postulated for this compound i^**^ 



HjC CHj HjC CHj 



Q CHj CHj CHj CHj r 



/\ hhIhhhIhhhhIhhhIhhh/\ 



HjC C<C:C-C:C'C:C'C:C'C:C-C;C«C:C-C:C'C:C-C CHi 



I I \ OH 11 



' ' / OH ' ' 



HjC C/"" C CHj 



\ / \ / % y 



C CHs HjC C 



Ha Hj 



Oxy-a-carotene 



>8'P. Karrer, H. v. Euler, and U. Solmssen, Helv. Chim. Acta, 17, 1169-1172 (1934). 

 18* P. Karrer, U. Solmssen, and O. Walker, Helv. Chim. Acta, 17, 417-419 (1934). 



