ETHANOL-DEPENDENT OXYGEN-CONSUMPTION AND ACETALDEHYDE FORMATION DURING VANADYL OXIDATION BY H2O2

Sequential addition of vanadyl sulfate to a phosphate-buffered solutio n of H2O2 released oxygen only after the second batch of vanadyl. Etha nol added to such reaction mixtures progressively decreased oxygen rel ease and increased oxygen consumption during oxidation of vanadyl by H 2O2. Inclusion of ethanol after any of the three batches of vanadyl re sulted in varying amounts of oxygen consumption, a property also share d by other alcohols (methanol, propanol and octanol). On increasing th e concentration of ethanol, vanadyl sulfate or H2O2, both oxygen consu mption and acetaldehyde formation increased progressively. Formation o f acetaldehyde decreased with increase in the ratio of vanadyl:H2O2 ab ove 2:1 and was undetectable with ethanol at 0.1 mM. The reaction mixt ure which was acidic in the absence of phosphate buffer (pH 7.0), rele ased oxygen immediately after the first addition of vanadyl and also i n presence of ethanol soon after initial rapid consumption of oxygen, with no accompanying acetaldehyde formation. The results underscore th e importance of some vanadium complexes formed during vanadyl oxidatio n in the accompanying oxygen-transfer reactions.