Studies On Oxidation Of Benzylidene Derivatives

Abstract

Perfumery compounds isoeugenol and isosafrole can be oxidized to their aldehydes, vanillin and heliotropin respectively. The aldehydes obtained are very useful and commercially valuable products. Apart from their importance as perfumery compounds, they form important intermediates in the Pharmaceuticals and pesticide industries.

Liquid phase oxidation of isosafrole using different oxidizing agents were tried. Sodium dichromate as oxidizing agent in aqueous acetic acid was found to be most suitable because of its higher yields and mild reaction conditions. This reaction was taken up for detailed study.

Since the kinetic study of dichromate oxidation in aqueous acetic acid medium of isosafrole has not been mentioned in the literature, various parameters like isosafrole, dichromate and acetic acid concentrations were studied. The experiments were conducted at different temperatures to estimate the activation energy of the reaction. The effect of added salts like manganese sulfate, manganese acetate and cobaltous acetate has also been studied. For all the experiments the change in isosafrole concentration was observed.

The rate of reaction increases with increase in isosafrole concentration. The order of the reaction with respect to isosafrole concentration is found to be one. The rate of reaction increases with increase in initial sodium dichromate concentration. The reaction is found to be half order in dichromate ion concentration.

The rate of reaction increases with increase in acetic acid concentration with an order two. The atmospheric oxygen does not affect the reaction rate suggests that the reaction may not be free radical reaction.

The rate of reaction increases with increase in temperature. The activation energy was found to be equal to 14.59 kcal/mol.