I LYCOPENE 121 



Optical activity: Lycopene is optically inactive. 



Colour reactions: Lycopene dissolves in concentrated sulphuric acid with 

 an indigo blue colour. With fuming nitric acid, it yields a purple colouration 

 which rapidly disappears^^. On adding a solution of antimony trichloride in 

 chloroform to a solution of lycopene in chloroform, an intense unstable blue 

 colour is produced^^. 



Partition test: Lycopene is completely epiphasic. 



Chromatographic behaviour: Lycopene is adsorbed six times more strongly 

 than carotene on alumina from petroleum ether solution. Similar behaviour is 

 shown on adsorption on calcium oxide or calcium hydroxide. Petroleum ether 

 containing a little methanol is used for elution^*. Like other carotenoid hydro- 

 carbons, lycopene is only weakly adsorbed on calcium or zinc carbonate and 

 can thus be separated from phytoxanthins^^. 



Detection and estimation: After saponification of the whole extract, lycopene, 

 together with the carotenes, is present in the epiphasic fraction. It is best 

 identified by chromatographic separation on calcium hydroxide, followed by 

 a determination of the absorption maxima. 



CoNNELL^^ recommends a solution of potassium dichromate and cobalt 

 sulphate as standard for colorimetric determinations. According to Kuhn and 

 Brockmann^^, an alcoholic solution of azobenzene can also be employed. 



Physiological properties: As would be expected from its structure, lycopene 

 possesses no vitamin A potency. 



Derivatives 



Perhydrolycopene C^^Hg^ 



Perhydrolycopene is formed by the catalytic hydrogenation of lycopene^. 

 It has also been synthesized by treating dihydrophytol with phosphorus penta- 

 bromide and heating the dihydrophytyl bromide {i6-bromo-2:6:io:i4:-tetra- 

 methylhexadecane) with potassium at 130-140°^^. 



Perhydrolycopene is a colourless oil. B.p. 238-24070.3 mm.; 212-214°/0.02 mm". 

 dl^ 0.822 from lycopene, 0.824 from phytol*o, n^^ 1.4560 from lycopene; 1.4567 

 from phytol. 



Dehydrolycopene C^qH^2 



Lycopene is dehydrogenated by the action of bromsuccinimide (2 mols) 

 and converted into dehydrolycopene (Karrer and Rutschmann*^) : 

 References p. 165-ijo. 



