The Effect of Carboxylic Acids on the Rate of Autoxidation of Secondary Alcohols

Abstract

When an alcohol was oxidized in the presence of carboxylic acids, the rate constant of autoxidation, kI 2kD112, remarkably decreased and the extentof retardation was in dependent of the acidity of carboxylic acid except p-nitrobenzoic acid. The k/(2k)1'2 of autoxidation of 1-phenylethanol in the presence of0. 10 mol/l of any substituted benzoic acids presented the identical value, but extremely small value in the presence of p-nitrobenzoic acid. The k/(2k) 2 ofautoxidation of 1-phenylethanol in the presence of nitrobenzene was smaller thanthat in the absence of nitrobenzene.
The k/(2k)112 of autoxidation of an alcoholin the presence of phthalic acid, which subjected to form an intramolecular hydrogenThond, was greater than that in the presence of isophthalic acid, which was difficult to form an intramolecular hydrogen-bond.
The k/(2k)112 of hydroperoxyl radical in the autoxidation of 1, 4-cyclohexadiene decreased by the additionof acetic acid. When an aichohol was oxidized in the presence of 0. 20 mol/l 1, 2, 3, 4ttrahydro-1-naphthylhydrOperOxide, k I(2k) 2 was not affected by acetic acid.
It was suggested that carboxylic acids deactivated the hydroperoxylor a-hydroxyperoxyl radicals due to hydrogen-bonding but not alkylperoxyl radical. And it was presumed that a nitro group took part in the chain reaction and decreased the k/(2k) 2 in the autoxidation of alcohols.