288 CAROTENOID CARBOXYLIC ACIDS XIII 



Apo-i-azafrinal oxime C25H3703N^'^: 

 Melting point: 185°. 



Solvent Absorption maxima 



Carbon disulphide 445 416 m/x 



Petroleum ether 415 m/j, 



Ethanol 423 m/j, 



Azafrin methyl ester (methylazafrin) C2s^-i:)Oi^^'- 

 CHo CH« 



\V 



C OH CH, CH, CH, 



/\/ I I I 



CH2 C- CH=CH- C=CHCH=CH- C=CHCH=CHCH=C- CH=CH- COOCH3 

 CHg C'CH» 



^ Azafrin methyl ester 



CHj OH 



This ester is prepared by the esterification of azafrin with dimethylsulphate 

 and potassium hydroxide. 



The ester crystalhses from methanol, or from a mixture of methanol and 

 ether or acetic acid, in yellow-red leaflets or needles, m.p. 191°. It is very 

 readily soluble in chloroform, and easily soluble in all organic solvents with the 

 exception of petroleum ether and ligroin. Optical rotation in chloroform 

 We^s-s = -32°. 



Solvent Absorption maxima 



Petrol 447 442.5 m/z 



Chloroform 458 428 m/i 



Carbon disulphide 476 445.5 419 m// 



(cf. Fig. 23, p. 357) 



With hydrogen chloride, hydrogen bromide, hydrogen iodide, perchloric 

 acid, sulphuric acid or trichloracetic acid in acetic acid solution, azafrin methyl 

 ester gives coloured addition products from which it cannot be regenerated^''^. 

 With methyl magnesium iodide, 2 mols of methane are evolved^'^^. In biological 

 tests methylazafrin exhibits no vitamin A activity^''^. 



j:8-Di7nethylnndecapentaene-ii-al-i-carboxylic acid methyl ester ("azafrinal I" 

 methyl ester) C^^H-^gO^ (I) : 



0CH-CH=CH-C=CHCH=CHCH=C-CH=CH-C00CH3 



CH3 CH3 



I 



This ester is formed besides other products by the chromic acid oxidation 

 of methylazafrin"^. 

 References p. 290-294. 



