m'DROCARBON CAROTENOIDS OF THE C40 SERIES 547 



Tlio apo-2-aldehyde originates tlirougii a cliromic acid oxidation of a 

 lycopene solution in an acetic acid-benzene mixture. ^^^ When crystallized 

 from a benzene-ethanol mixture, it separates in deep pomegranate-red 

 platelets which melt at 147°C'. It dissolves readily in chloroform, carbon 

 disulfide, and benzene, but with difficulty in ethanol. It behaves epi- 

 phasically. It is rcaxHly oxidizabhs on treatment with chromic acid, it 

 yields bixin dialdehyde and 2-methyl-2-hepten-()-one.^-^ Apo-2-lycopenal 

 is converted by hydroxylamine to apo-2-lycopenal oxime, which forms glis- 

 tening blue-violet prisms melting at lOS^C.^^" 



CH, CHj CH3 CHj CHj CHj 



0^ hhIhhhIhhhhIhhhIhhhIhhhI 

 hc'c:c-c:c-c:c'c:c'c:c-c;c'c:c-c:c'c:c-c:c-c-c«c:c'ch, 



H H 



Apo-2-l.vcopenal 



(e) Apo-S-Iycopenal, C30H40O. Karrer and Jaffe^^^ prepared an aldehyde 

 with two less carbons than apo-2-lycopenal by the use of potassium per- 

 manganate. The apo-3-aldehyde separates in brownish black crystals 

 (m.p., 138°C.) from petroleum ether. 



CHj CHj CHj CHj CHj CH3 



0^ IhhhIhhhhIhhhIhhhIhhhI 

 HC-c:c-c:c-c:c-c:c-c:c-c:c-c:c-c:c-c:c«c«c-c:c-cH3 



H H 



Apo-3-I.vcopenal 



(/) Apo-2,l2-lycopendial (Bixindialdehyde), C24H28O2. When lycopene 

 or lycopenal is oxidized with chromic acid, the dialdehyde originates through 

 oxidation on both ends of the lycopene molecule. ^-^ The pure product can 

 be prepared by crystallization from pyridine; it forms glistening blue- 

 violet prisms which melt at 220°C. It is decomposed at 180°C. without 

 melting when heated in the air. It is readily soluble in pyridine and chloro- 

 form, and is somewhat soluble in hot benzene. It dissolves with difficulty 

 in hexane, alcohol, carbon disulfide, ether, acetone, and dioxane. It ex- 

 hibits hypophasic properties. Bixindialdehyde dioxime is an excellent 

 derivative for the characterization of the dialdehyde; it gives needle-like 

 crystals (pyridine) which decompose Avithout melting at 2oO°C. 



CHj CHj CHj CHi 



0^ hhIhhhIhhhhIhhhIhh/0 

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



Apo-2,12-Ij-copendial 



(g) Apo-S,l^-lycopendial, C22H26O2. This second dialdehyde derivative 

 of lycopene has been characterized by Karrer and Jafl"^.^^^ j^. originates on 

 chromic acid oxidation of lycopene. Crystals prepared from methanol are 



2« P. Karrer and W. Jaffe, Heh. Chim. Ada, 22, 69-71 (1939). 



