246 CAROTENOIDS CONTAINING CARBONYL GROUPS XII 



and ethanol in leaflets, m.p. I2i-I22°(?). The dibenzoate is more soluble in 

 alcohols than the fatty acid esters. 



Capsanthinone C40H58O5: 

 CH3 CH3 OH3 CHj 



C CHo CH3 CH3 CH3 C 



/\ I I I I /\ 



CH2 OC-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-CO CHj 



HOCH OC-CHa HsC-CHj CHOH 



\ / Capsanthinone \ / 



CH2 CH2 



Capsanthinone is prepared by the oxidation of capsanthin diacetate with 

 chromic acid^^. Capsanthinone diacetate crystallises from a mixture of benzene 

 and petrol in glistening needles, m.p. 123-124° (corr.). The acetate is hypophasic. 

 It is readily soluble in ethanol, ether, benzene and carbon disulphide, somewhat 

 less soluble in acetone and practically insoluble in petrol. On treating an ethereal 

 solution of the pigment with concentrated aqueous hydrochloric acid, the latter 

 is coloured deep blue. 



Solvent Absorption maxima 



Carbon disulphide 541 503 468 m^ 



Benzene 524 487 454 m/t 



Hexane 503 472 440 m^ 



Anhydrocapsanih inane C43H5504 : 



CHo CH« CHo CHq 



G GH3 Gri3 GH3 GH3 C 



/\ I I I I /\ 



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



I II 1 



HOCH — C-CO-CHs HgC-CHj CHOH 



Anhvdrocapsanthinone \ y' 



CH2 



KuHN and Brockmann^'' obtained anhydro-j3-semicarotenone by splitting 

 off water from j3-semicarotenone (cf. p. 140). Anhydrocapsanthinone is obtained 

 by an analogous reaction from capsanthinone diacetate^®. The compound 

 crystallises from methanol in small red needles which have no sharp melting 

 point. On partition between methanol and petroleum ether, the pigment is 

 found in the lower layer. In contrast to capsanthinone, the reaction with hydro- 

 chloric acid is negative. The spectral properties are in agreement with the 

 proposed structure, the chromophoric system of which differs only by an addi- 

 tional conjugated double bond from that of capsanthinone. This results in the 

 displacement of the maxima towards longer wavelengths by 16 m/,( compared 

 with capsanthinone. 

 References p. 233-235. 



