270 CAROTENOID CARBOXYLIC ACIDS XIII 



Norbixin mono-ethyl ester, ethylnorbixin C26H3JO4 : 



Ethylnorbixin was prepared by van Hasselt by the saponification of labile 

 bixin with ethanolic potassium hydroxide and treatment of the reaction 

 product with diethyl sulphate. The diethyl norbixin which separated was then 

 filtered and washed with dilute acid^^. The ester crystallises from ethyl acetate 

 in red needles with a green lustre, m.p. 176°. It forms a potassium salt which 

 crystallises in needles and is insoluble in water. 



Methylethylnorbixin C27H34O4 : 



a) M.p. 149°. This form is obtained by the methylation of ethylnorbixin*'. 

 It crystallises in red rhombic crystals. 



b) M.p. 138° (ethylbixin) . This form is obtained by treating labile bixin in 

 ethanol solution with one mol of potassium hydroxide and diethyl sulphate in 

 the presence of ethyl acetate^. It separates from ethanol in red rhombic crystals. 

 It is readily soluble in chloroform, ethyl acetate and acetone. 



Diethylnorbixin CggHjjO^ : 



The preparation of this ester is similar to that of ethylnorbixin. Diethyl- 

 norbixin separates from acetone in blue crystals m.p. 121° ^*. 



Methyl-n-octylnorbixin (n-octyl bixin ester) C^^^f^O^: 



This ester was obtained by Karrer and Oswald^^ by the action of w-octyl 

 iodide on potassium bixinate. Dark violet crystals from ethanol, m.p. 132°. 



Methyl-n-butylnorbixin (n-butyl bixin ester) C29H3g04: 



This ester is prepared in the same way as the previously described derivative. 

 Dark crystals, m.p. 160°. 



Methyl-n-octadecyl norbixin (n-octadecyl bixin ester) C43H85O4 : 

 Dark crystals, m.p. 118°*®. 



i:i:2o:20-Tetramethyldihydrobixinol C2gH4202 (I) : 



H3C CH3 CH3 CH3 CH3 CH3 



HO- C- CH2CH=C- CH=CHCH=C- CH=CHCH=CH- C=CHCH=CH- C= CHCHjC- OH 



H3C (I) CH3 



This compound was obtained by Karrer and Rubel^" by reacting di- 

 hydrobixin methyl ester with methyl magnesium iodide. It crystallises from 

 ethyl acetate in golden-yellow needles, m.p. 166-167° (uncorr.). It is entirely 

 hypophasic in the partition test. 

 References p. 2go-2g4. 



