ii8 CAROTENOID HYDROCARBONS OF KNOWN CONSTITUTION X 



2 zsopropylidene groupings (CH3)2C = . Ozonisation also furnished succinic acid, 

 but no higher fatty acids were obtained. The succinic acid is derived from the 



^^°^P^"^ =CH.CH,CH,CH = - 



By means of oxidative degradation of lycopene with permanganate and 

 chromic acid, Karrer, Helfenstein, Wehrli and Wettstein^^ proved the 

 presence of 6 side-chain methyl groups. Finally, Karrer, Helfenstein and 

 WidmerI' synthesized perhydrolycopene from dihydrophytol and showed that 

 it was identical in all respects with the product obtained by the catalytic 

 hydrogenation of lycopene. As the result of these investigations the formula 

 for lycopene shown above was put forward by Karrer, Helfenstein, Pieper 

 and Wettstein^^. 



This formula has been confirmed by later investigations by Kuhn and co- 

 workers. KuHN and Winterstein^^ isolated toluene and m-xylene from the 

 products of the thermal decomposition of the pigment and Kuhn and Grund- 

 mann^'' obtained lycopenal, a complex degradation product, together with 

 methyl heptenone from the oxidation of the pigment with chromic acid. 

 Further oxidation of lycopenal with chromic acid gave bixin dialdehyde and 

 methyl heptenone. The structure of lycopenal was established by the conversion 

 of bixin dialdehyde into norboxin, the constitution of which had been elucidated 

 earlier by Karrer and co-workers. 



CH, CH, CH, - CH, 



C CHo Clio CHo CH3 C 



y I I I I V 



CH CH-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-CH CH 



CH2 C*CH3 H3C"C CHg 



\ / Lycopene \^ / 



CH2 CH2 



CHo CHo 



CHo CHo 



Cxin CHo OHo OHo \j^ 



/ I I I I V 



CH OHC-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-CH CH 



CHj C=0 HjC-C CH2 



\/^| . Lycopenal \^y 



HgC CH3 CHj 



Methylheptenone 



CHo CHo 



\V 



CH3 CH3 CH, CH3 C, 



I II I V 



OHC- CH=CH- C=CHCH=CH- C=CHCH=CHCH=C- CH=CHCH=C- CH=CH- CHO CH 



0=C CHj 

 Bixin dialdehyde l\/ 



H3C CHg 

 References p. 165-iyo. Methylheptenone 



