Maleic anhydride in the study of naturally occurring isomers of vitamin A

tone) in the dog suggest that the butyl chain undergoes very little co-oxidation, since 75-6 % ofthe dose was excreted as the (a)l)-oxidation product, 5- ethyl-5-(3-hydroxy-1-methylbutyl)barbituric acid, and only 4.5 % as the co-oxidation product, 5-ethyl- * Note added 29 May 1956.According to Oroshnik's latest work [Oroshnik, W. (1956) J. Amer.ch/em.Soc., 78, in the press], neovitamin Ab is 11-cw vitamin A and the isomer with AM.X 311 m,u. in n-hexane (11-ci8 vitamin A of Wald et al. 1955) is 11:13-di-cw vitamin A.