HYDROCARBON" CAROTENOIDS OF THE C40 SERIES 531 



(m) ^-Caroienone Aldehyde, C27H36O3. When /3-carotene or /S-carotenone 

 is oxidized with chromic acid, a rupture of the polyene chain results gi\'ing an 

 aldehyde of considerably shorter chain length. '''•^^ This is obtained from a 

 benzenc-hexane mixtiu'e in yellow-red needles, having a bluish cast, which 

 melt at 14r)-147°C. It is quite soluble in chloroform, carbon disulfide, 

 benzene, and hot methanol, and poorly soluble in cold hexane and petro- 

 leum ether. After prolonged treatment with an excess of hydroxylamine, 

 the dioxime is foiTned, which melts at 183-184°C. When only one mole- 

 cule of hydroxylamine and one molecule of /3-carotenone are used, the re- 

 sulting product is a mixture of the aldoxime and ketoxime. 



HjC CH 



\ / 

 c 



CHj CH3 CH: 



/\^° hIhhhIhhhhIhhh 

 HzC c— c :C'C:c-c;c-c:C'C:c-c;c-c:c- c=o 



I ^ 



HjC = 



\ / \ 



C CH3 



^-Carotenoiie aldehj^de 



(n) 0-Apo-2-carotenal, C30H40O. When /3-carotene is oxidized with 

 potassium permanganate at room temperature, the second /3-ionone ring is 

 completely destroyed and the hydrocarbon chain is ruptured between car- 

 bons 7' and 8'. Karrer and Solmssen^^* obtained as much as 60 mg. of the 

 aldehyde from 700 mg. of j8-carotene by isolating it on a chromatographic 

 column. The name for this compound was suggested by Karrer et al.^^^ to 

 indicate where the mpture in the carbon chain had occurred. The apo-2- 

 carotenal can be crystallized in violet plates from methanol. They melt 

 at 139°C. The aldehyde forms a characteristic oxime (shin}^ violet plate- 

 lets or prisms melting at 180°C.) and a semicarbazone (sinters at 205°C.). 

 A\Tien the ethereal solution is treated with concentrated hydrochloric acid, 

 a strong peraianent blue coloration results. i8-Apo-2-carotenal has strong 

 pro\atamin A activity. 



HjC CHi 



C CHj CH CH: CHj 



/\ hhIhhhIhhhhIhhhIh 

 HzC C-c:c-c:C'C:c-c:c-c:C-c:c-C:C-C:C-C=0 



1 II 



HaC C 



\ / \ 

 C CHj 



Hz 



/3-Apo-2-caroteMal 



(o) ^-Apo-2-carutenul , C'3oH420. An alcohol corresponding to /3-apo-2- 

 carotenal is likewise well kno\Mi. Euler and co-workers ^^^ obtained the 



i« P. Karrer and U. Solmssen, Hdr. Chim. Ada, 20, 682-690 (1937). 



!« P. Karrer, U. Solmssen, and \V. Gugclinann, Heir. Chim. .\c(a, 20, 1020-1024 (1937). 



1" H. V. Euler, P. Karrer, and U. Solmssen, Helv. Chim. Acta, 21, 211-222 (1938). 



