SYNTHESIS 



6i 



PuMMERER and co-workers^ for the determination of the number of double 

 bonds in polyene molecules (cf. p. 44). By the action of perbenzoic acid on 

 /S-carotene, Karrer and Walker^" prepared /^-carotene oxide which has been 

 shown by Karrer and Jucker^^ to be identical with mutatochrome. Numerous 

 investigations^^ by the two last-named authors have also shown that by using 

 small quantities of monoperphthalic acid it is possible to oxidise individual 

 double bonds in a carotenoid molecule. Well-defined crystalline compounds 

 are obtained, which from their method of formation and their properties are 

 regarded as i : 2-epoxides. Their properties show that only the double bonds in 



CH« CHo 



\V 



c 



CHj C-CH=CH- 



IV 



CH. C/ 







CHq CHo 



\/ 



c 



/\ 



CH=CH-C CHjs 



II I 



C CH, 



/\/ 



HoC CHg 



CH« CHo 



\V 



C 



/\ 

 CH, C-CH=CH- 



I \)o 



CH, cr 



•CH=CH-C 



CH, CH^ 



H3C 



CHj CHj 



C 



\ 

 CH^ 



CHj 



CH, 



II 



the /5-ionone rings have been oxidised, and mono-epoxides or di-epoxides are 

 obtained, depending on the number of /5-ionone rings in the carotenoid mole- 

 cule. No example of the oxidation of the isolated double bond in an a-ionone 

 ring has so far been encountered. Thus, a mono-epoxide I and a di-epoxide II 

 have been obtained from /5-carotene, whereas a-carotene only yields a mono- 

 epoxide. 



CH, CH, 



CH, CH, 



C CH3 



/\ I 



CH. .C-CH=CH-C=CH- 



I II 



X-CH C-CH, 



CH, 



perphthalic CH- C-CH=CH-C=CH- 



acid 



X-CH C/" 



CHjj 

 Carotenoid, X = H or OH 



CHj CH3 



Epoxide 



CHjI 

 CH3 



Furanoid oxide 



References p. 64-63. 



