I BIXIN 267 



solidifies in the cold. B.p. i98°/o.i2 mm. It is readily soluble in chloroform 

 and benzene, but only dissolves in acetic acid, ethanol and petroleum ether on 

 warming. 



4:8:1 3:iy-Tetramethyleicosane (Bixane) C24H50: 



CH3 ^i^S V-'-tl3 v^ils 



II II 



H3CCH2CHJCHCH2CH2CH2CHCH2CH2CH2CH2CHCH2CH2CH2CHCH2CH2CH3 



Bixane 



Bixane can be prepared by heating i : 20-dihydroxybixane with 66 % 

 aqueous hydrobromic acid for 15 hours in a sealed tube at 230° and then 

 warming the dibromide formed with activated zinc and 60 % acetic acid at 100° 

 for 14 hours. It is a mobile colourless liquid, which boils at i62°/o.5i mm 

 (corr.) D^° 0.8054; np° 1.4502. Bixane is readily soluble in chloroform, carbon 

 disulphide and petroleum ether, and more sparingly soluble in ethanol and 

 acetic acid. 



Labile bixin, monomethyl oster of labile norbixin C25H30O4: 



Labile (natural) bixin crystallises from acetic acid in deep violet, dichroic 

 prisms. From ethyl acetate the pigment is obtained in rhombs. On rapid 

 heating it melts at 198°, on slow heating at 191.5°. 100 Ml of chloroform dissolve 

 only 0.5 g of labile bixin at 18°. The pigment is even less soluble in ethanol, 

 ether and cold acetic acid but readily soluble in boiling acetic acid, pyridine 

 and nitrobenzene, i Litre of boiling ethyl acetate dissolves 4 g of labile bixin. 



Solvent Absorption maxima 



Carbon disulphide 523.5 489 457 m/z 



Chloroform 503 469.5 439 m// 



Bixin remains unchanged for long periods on keeping in air, but undergoes 

 some decomposition on heating to 110°. By heating above the melting point, 

 VAN Hasselt^^ obtained w-xylene (cf. p. 49). The isomerisation of labile bixin 

 into the stable form has been described on p. 259^^. Pummerer, Rebmann and 

 Reindel^* found that only about six of the double bonds in bixin are saturated 

 by reaction with perbenzoic acid. 



With regard to a new method of oxidation of labile bixin with manganese 

 acetate, see a communication by Viebock^^. 



By the reduction of labile bixin with sodium amalgam, Karrer and co- 

 workers^^ obtained a light yellow oil which on oxidation with alkaline pot- 

 assium permanganate gave succinic acid. 



With regard to the action of chlorine and bromine^', iodine in benzene^^ 

 iodine chloride^*, hydrogen chloride^^ and thiocyanogen^* see the original com- 

 munications. 

 References p. 2go-2g4. 



