146 CAROTENOID HYDROCARBONS OF KNOWN CONSTITUTION X 



furanoid oxides. (Cf . p. 61 concerning the constitution of these compounds). The 

 oxides of ^-carotene are very similar to the corresponding derivatives of crypto- 

 xanthin (p. 178) and zeaxanthin (p. 189), from which they differ only by the 

 absence of the hydroxyl groups. 



^-Carotene mono-epoxide C40H55O : 



CH, CH, CH, CH, 



C CH3 C/H3 CH3 CHo C 



/\ I I I I /\ 



CHa C-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-C CHg 



)0 ' ' 



C CH2 

 CH, C /\/ 



\^ / ^ /3-Carotene mono-epoxide HjC CHj 



CH2 CH3 



This compound crystallises from a mixture of benzene and methanol, or 

 ether and methanol, in lustrous orange leaflets, m.p. 160° (uncorr., in vacuum). 

 On shaking an ethereal solution of the pigment with concentrated aqueous 

 hydrochloric acid, the acid layer slowly develops a pale blue colouration which 

 is not very stable. 



Solvent: Absorption maxima: 



Carbon disulphide 511 479 m// 



Benzene 492 460 m^ 



Petroleum ether 478 447 m/^ 



Chloroform 492 459 m/f 



^-Carotene di-epoxide C40H55O2: 



CHo CHo CHo CHo 



C CHo CHo CHo CHo 



CH2 C-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-C CH^ 

 )0 0( 



CH2 C CH2 



\^ /\ /S-Carotene di-epoxide /\/ 



CH2 CH3 H3C CHjj 



j5-Carotene di-epoxide crystallises from a mixture of benzene and methanol 

 in yellow-orange leaflets, m.p. 184° (uncorr., evacuated capillary). On shaking 

 an ethereal solution of the pigment with concentrated aqueous hydrochloric 

 acid, the acid layer is coloured dark blue. The colouration is stable for several 

 days. /5-Carotene di-epoxide exhibits entirely epiphasic properties. 



Solvent: Absorption maxima: 



Carbon disulphide 502 472 m/i 



Benzene 485 456 m/< 



Petroleum ether 470.5 443 mpi 



Chloroform 484 456 m/x 



References p. 16^-iyo. 



