Abstract Alcohols and ethers that do not normally photoadd to flavins do so in the presence of EDTA to produce covalent attachment of an alkyl group at C (4a). Thus, irradiation of an aerated solution containing both EDTA and t-butanol resulted in rapid formation of an air- stable, reduced flavin, FlH-C (4a) CH 2 C (CH 3) 2 OH. Similar results were also obtained with ethanol, 1-propanol, 2-propanol, pinacol, poly (ethylene glycol), and dioxane, but not ...