Oxidation and isomerization of retinoic acid by iodine and light: A novel preparation of all‐<i>trans</i>‐ and 13‐<i>cis</i>‐4‐oxoretinoic acid

Abstract

Abstract A mixture of all‐ trans ‐retinoic acid and iodine in heptane was irradiated. Two oxidation products were isolated by high performance liquid chromatography and identified as all‐ trans ‐ and 13‐ cis ‐4‐oxoretinoic acid by nuclear magnetic reasonance, ultra violet, Infrared spectroscopy, and mass spectral analysis. Under the same conditions, but without light, a mixture of all‐ trans ‐ and 13‐ cis ‐retinoic acid resulted. The corresponding methyl esters were obtained when methyl all‐ trans ‐retinoate was used in place of all‐ trans ‐retinoic acid.