144 CAROTENOID HYDROCARBONS OF KNOWN CONSTITUTION X 

 ^-Apo-2-carotenal C30H40O: 



\V 



C CH3 CH3 ^113 CH3 



/\ I I I I 



CHa C- CH=CH- C=CHCH=CH- C=CHCH = CHCH=C- CH=CHCH=C- CHO 



CH2 C*CH3 



\^ / yS-Apo-2-carotenal 



CH2 



This aldehyde is formed by the potassium permanganate oxidation of 

 /9-carotene^^^. j8-Apo-2-carotenal crystaUises from methanol in violet plates, 

 m.p. 139°. On addition of concentrated hydrochloric acid to an ethereal 

 solution of the pigment an intense stable blue colouration is produced. The 

 aldehyde shows strong vitamin A activity. 



Solvent: Absorption maxima: 



Carbon disulphide 525 490 m^u 



Petroleum ether 484 454 m/z 



Ethanol (498 . . . 447)m/i 



/3-Apo-2-carotenal oxime crystallises in glistening violet rhombs or prisms, 

 m.p. 180°. 



Solvent: Absorption maxima: 



Carbon disulphide 507 473 m/i 



Petroleum ether 471 441 m/z 



Ethanol 475 445 m^ 



)3-Apo-2-carotenal semicarbazone melts at 212° (sinters above 205°). 



^-Apo-2-carotenol C30H42O: 

 CH3 CH3 



C CH3 CH3 CH3 CH3 



CH2 C- CH=CH- C=CHCH=CH- C=CHCH=CHCH=C- CH=CHCH=C- CHjOH 



I II 



CHj C" CH3 



\ / /3-Apo-2-carotenol 



CH3 



This compound was obtained by voN Euler, Karrer and Solmssen by 

 the reduction of /5-apo-2-carotenal with isopropyl alcohol and aluminium iso- 

 propoxide^^". It crystallises from a mixture of benzene and petroleum ether in 

 yellow plates, m.p. 145°. 



Solvent: Absorption maxima: 



Carbon disulphide 486 456 m/x 



Petroleum ether 453 423 m/i 



Ethanol 456 426 m// 



(cf. Fig. 29, p. 360) 



References p. 165-iyo. 



