Enol intermediates in photoreduction and type I cleavage reactions of aliphatic aldehydes and ketones

Several unstable simple enols including ethenol (vinyl alcohol) and 2-propenol (the enol of acetone) are observed by CIDNP spectroscopy during photoreduction of aliphatic aldehydes and ketonesandType I cleavage of cx-hydroxyketones. They are formed by disproportionation reactions of cx-hydroxy alkyl radicals and tautomerize to the stable keto forms. The NMR parameters of the enols are discussed. For the 2-propanol-acetone system deuterium substitution reveals the relative rate constants of disproportionation and combination of the 1-hydroxy-1-methylethyl radical.