3 ^-CAROTENE 141 



j8-carotenone with chromic acid^^^. ;S-Carotenone crystaUises from a mixture of 

 benzene and hght petroleum in scarlet, hexagonal flakes with a blue lustre, 

 m.p. 174-175° (corr., evacuated capillary^-^) . The pigment can be adsorbed on 

 aluminium oxide or calcium carbonate from petroleum ether solution. On 

 partition between petroleum ether and 90 °o methanol it is found mainly in the 

 lower layer. ^-Carotenone is easily soluble in chloroform, carbon disulphide and 

 benzene, sparingly soluble in cold methanol and ethanol, and very sparingly 

 soluble in petroleum ether. 



Solvent: Absorption maxima: 



Carbon disulphide 538 499 466 m,u 



Chloroform 527 489 454 mn 



Petroleum ether 502 468 440 m// 



Benzene 522 486 453 m/z 



Hexane 500 466 436 m^ 



(cf. Fig. 29, p. 360) 



Quantitative extinction measurements in hexane have been recorded by 

 HAUSSERand Smakula^24_ ^-Carotenone iorm.sa.dioxime, m.p. 198° (corr., evacuated 

 capillary) . 



Bis-anhydro-^-carotenone C40H52O2 : 



CH, CH, CH, CH, 



C CH, CH, CH3 CH3 C 



/\ \ \ \ \ /\ 



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



I i . II I 



CHj — C • CO • CH3 Bis-anhydro-/3-carotenone H3C • OC • C CH2 



This derivative was obtained by Kuhn and Brockmann^^s ^y treating 

 ^-carotenone with methanolic potassium hydroxide. It crystallises from a 

 mixture of benzene and methanol in steel-blue prisms or plates, m.p. 209°. It is 

 almost entirely epiphasic in the partition test. Bis-anhydro-^-carotenone is 

 soluble in chloroform, benzene and carbon disulphide, but almost insoluble in 

 petrol, methanol and petroleum ether. 



Solvent: Absorption maxima: 



Carbon disulphide (567) (525) (477) m/z 



Chloroform (545) (506) (481) m^ 



Benzene (545) (505) (478) m/z 



Petrol 530 494 462 m/x 



Dihydro-bis-anhydro-^-carotenone C4(,H5402 : 

 CH, CH, CH3 CH3 



C CH3 CH3 CH3 CH3 C 



/\ I I I I /\ 

 OH. C=CH-CH=C-CH=CHCH=C-CH=CHCH=CH-C=CHCH=CH-C=CH-CH=C CH^ 



II . II 



CHa — CH-C0-CH3 Dihydro-bis-anhydro-^-carotenone H3C-0C-CH — CHg 



(Keto form) 



References p. i6§-iyo. 



