The rate of oxidation of tertiary amines by aqueous hydrogen peroxide is in
creased in the presence of acetonitrile due to the formation of a reactive
intermediate. The active oxidant, presumably peroxyacetimidic acid, was qua
ntified by a photometric method. Activation parameters of the acetonitrile-
assisted and non-assisted oxidations are given in the temperature range 20
to 40 degreesC. The increased rate of the assisted oxidation is explained b
y the low enthalpy of activation although the entropy of activation is more
negative due to a highly ordered transition state.