138 CAROTENOID HYDROCARBONS OF KNOWN CONSTITUTION X 



CHq CHo 



\V 



-CH CH3 CH3 CH3 CH3 C 



II I I I /\ 



CH-C=CHCH=CH- C=CHCH=CHCH=C- CH=CHCH=C- CH=CH- C CHj 



HoC* C CHo 



\/ 



CHj 

 For the properties and reactions of mutatochrome see p. 147. 



'^-Carotene oxide' = Mutatochrome 



Dihydroxy-^-carotene C4oH5g02* : 



CHo CHo CHo CHo 



C OH CH3 CH3 CH3 CH, C 



/\/ I I I r /\ 



CHa C-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-C CHjj 

 CH, C-OH H,C-C CH, 



CH2I Dihydroxy-j5-carotene ? CHj 



CH3 



Dihydroxy-j3-carotene is formed during the careful oxidation of j3-carotene 

 with aqueous o.i N-chromic acid (1.5 atoms O). It crystalhses from a mixture 

 of petrol and methanol in orange-red needles, m.p. 184° (Kuhn and Brock- 

 MANN^^^). Dihydroxy-j3-carotene is easily adsorbed on aluminium oxide from 

 benzene solution, but it is not adsorbed on calcium carbonate. (The lack of 

 adsorption on calcium carbonate is unexpected for a compound assumed to 

 contain two hydroxyl groups). Dihydroxy-^-carotene is easily soluble in 

 benzene, chloroform and carbon disulphide, sparingly soluble in petrol, and 

 insoluble in alcohols. On partition between petroleum ether and 90% methanol, 

 it is found almost entirely in the upper layer. (The insolubility in alcohols and 

 the epiphasic character of the compound are irreconcilable with the proposed 

 formula). 



Solvent: Absorption maxima: 



Carbon disulphide 508 475 446 m/^ 



Chloroform 487 456 429 m^i 



Petrol 478 448 420 m^ 



Hexane 476 446 419 m/i 



Benzene 489 457 428 m/i 



Dihydroxy-j3-carotene shows vitamin A activity. 



Concerning the molecular formula of dihydroxy-^-carotene see R. Kuhn and H. 

 Brockmann, Ber. 6y (1934) 1408 and Ann. 516 (1935) 99. 



References p. 165-ijo. 



