Photchemical Degradation of Flavins—iii. Hydroxyethyl and Formylmethyl Analogs of Riboflavin*

The anaerobic photolysis of the flavins containing hydroxyethyl and formythmethyl side‐chains in place of the ribityl group of riboflavin has been studied employing spectro‐photmetry, thin‐layer chromatography and other mehtods. Both flavins are shown to decompose, in part, directly to lumichrome. Acetaldehyde arises from the hudoxyethyl by the flavin nucleus as has been observed previously for riboflavin. The side‐chain of the hydroxyethylflavin, is shown to be oxidized to the formylmethyl group. Formylmethylflavin is converted in part to lumichrome and unknown products from the side‐chain and in part to a reduced flavin. Formaldehyde could not be detected among the products. Possible mechanisms are discussed briefly.