526 VI. CAROTENOIDS AND RELATED COMPOUNDS 



/3-carotene oxide was first assumed to be an epoxide, the more recent work 

 of Karrer and Jucker^'^-has demonstrated that it has a furanoid structure. 



HjC CH3 



\ / 

 c 



/ \ H 



HjC C^=C CHj CH3 CH3 CH 



HjC CHj 



\ / 



I I I IhhhIhhhhIhhh1hh/\ 

 HzC C CH — c: C'C: C* c: C* c:c- C: C- C: C« c: C' c: C* C CH? 



\ /l\ / 



C I 

 H2 CH3 



C CHj 



/ \ / 



H3C c 

 Ha 



/3-Carotene oxide (inutatochrome) 



(6) ^-Carotene Mono-epoxide, C40H56O. Karrer and his co-work- 

 gj.gio5,i62-i64 i^ave recently made extensive studies of carotene oxide 

 and related oxidation products. When /3-carotene was oxidized with 

 monoperphthalic acid, Karrer and Jiicker^^- obtained both the furanoid 

 compound and the epoxide. The epoxide readily crj^stallizes from a ben- 

 zene-methanol or from a methanol-ether mixture, in orange platelets with 

 beautiful glistening surfaces. The mono-epoxide melts at 1G0°C. When 

 an ethereal solution is shaken with concentrated aqueous hydrochloric 

 acid, it assumes a weak blue color which quickly disappears. 



HjC C Hj HjC CH3 



Q CH3 CH3 CH3 CH3 Q 



/\ hhIhhhIhhhhIhhhIhh /\ 

 hzc c • c : c' c; c- c: c* c: c • c:c« c: c- c: c- c: c' c: c- c cha 



I 1)0 II I 



HsC C C C Hz 



\ / \ / \ / 



C CH3 H3C c 



Hz Hs 



/3-Carotene mono-epoxide 



(c) ^-Carotene Di-cpoxidc, C40H56O2. When oxidation occurs on both 

 /3-ionone rings of j8-carotene, the di-epoxide results. Thus an oxygen bridge 

 is formed, not onlj^ between carbons 5 and G but also between carbons 5' and 

 G'. The di-epoxide can be crystallized from a benzene-methanol mixtuie 

 in yellow platelets, melting at 184°C. /S-Carotene epoxide shows true epi- 

 phasic behavior. For a description of epiphasic and hypophasic behavior, 

 see page 619. When the ethereal solution of the di-epoxide is shaken 

 with concentrated aqueous hydrochloric acid, the solution assumes a deep 

 blue color which is permanent over a period of several days. 



i''^ p. Karrer and E. Jucker, Helv. Chim. Ada, 2S, 427-436 (1945). 

 1" P. Karrer and E. Jucker, Hdv. Chim. Ada, 2S, 471-473 (1945). 

 i«* P. Karrer, Helv. Chim. Ada, 28, 474-475 (1945). 



