548 VI. CAROTENOIDS AND RELATED COMPOUNDS 



dark-colored and melt at 168°C. A red crystalline dioxime can be prepared 

 which sinters at 210°C. 



CH3 CH3 CH3 CH3 



0^ hhIhhhIhhhhIhhhI ,p 

 HC'C:c-c:C'C:C'C:C'C:C'C;C'C:c«c:C'CH 



Apo-3,12-lycopendial 



Qi) Lycopersene, C40H66. Karrer and Kramer^^'' synthesized lycopersene 

 by reactions analogous to that used in preparing squalene.^" This hydro- 

 genated compound is a colorless viscous oil which distills at 0.02 mm. at 

 225-228°C. On treatment with hydrochloric acid, it forms a crystalline 

 octahydrochloride, C40H74CI8 (m.p., 126°C.) 



3. Structure and Occurrence of Carotenols and Oxycarotenols of 



the C40 Series 



Several of the most important natural carotenoids are those which con- 

 tain oxygen, either in the form of one or more hydroxyls (carotenols) or, in 

 some cases, as a carbonyl group. The carotenols are also known as the 

 xanthophylls ; they are widely distributed in the plants. Because they con- 

 tain one or more alcoholic groups, they are frequently found as esters of the 

 fatty acids in the so-called colored fats (see Chapter IV, Section 4). 



(1) Lycoxanthm and Lycophyll 



Zechmeister and Cholnoky^*^ discovered that several hydroxy-deriva- 

 tives of lycopene occur naturally. They were able to isolate both a 

 monohydroxylycopene, lycoxanthin (C40H56O), and a dihydroxy-derivative, 

 lycophyll (C40H56O2), from the bitter nightshade {Solarium dulcamara). 

 Lycoxanthin has likewise been prepared from Solanum melongena var. 

 esculentum (egg-plant) and from Tamus coynmunis (black bryony).^^* It 

 was found by Lederer^^^ in the sphere fungus causing "red spot" on plum 

 leaves {Poly stigma ruhrum) . 



Lycoxanthin crystallizes from a benzene-petroleum ether mixture in red- 

 brown round crystals which are somewhat jagged. On crystallization 

 from carbon disulfide, the pigment forms violet, needle-shaped crystals. 

 Carbon disulfide and benzene are excellent solvents for the phytoxanthin, 

 while it dissolves less readily in petroleum ether and very poorly in alcohol. 

 When an ethereal solution of lycoxanthin is shaken with concentrated 

 hydrochloric acid, no blue coloration can be noted. 



2« P. Karrer and H. Ivramer, Helv. Chun. Acta, 27, 1301-1302 (1944). 

 2" P. Karrer and A. Helfenstein, Helv. Chim. Acta, I4, 78-85 (1931). 

 2« L. Zechmeister and L. v. Cholnoky, Ber., 69, 422-429 (1936). 

 2« E. Lederer, Bull. soc. chim. bioL, 20, 611-634 (1938). 



