ANTIOXIDANT ACTION OF SODIUM DIETHYLDITHIOCARBAMATE - REACTION WITH HYDROGEN-PEROXIDE AND SUPEROXIDE RADICAL

The oxidation of sodium diethyldithiocarbamate (DDC) by hydrogen perox ide or superoxide radicals has been investigated. Hydrogen peroxide ox idizes DDC, leading to the formation of a hydrated form of disulfiram, a dimer of DDC having a disulfide group. In equimolar conditions, the overall process appears as a first-order reaction (k = 0.025 +/- 0.00 5 s(-1)), the first step being a second-order reaction (k = 5.0. +/- 0 .1mol(-1). 1. s(-1)). No radical intermediate was observed in this pro cess. In the presence of an excess of any of the reagents, the hydrate d form of disulfiram transforms into different products corresponding to the fixation of oxygen by sulfur atoms or replacement of C = S grou p by ketone function, in the presence of an excess of hydrogen peroxid e. Superoxide anions (produced by steady-state Co-60 gamma-radiolysis) oxidize DDC, yielding similar products to those obtained with hydroge n peroxide with a maximum oxidation G-value of 0.3 mu mol.J(-1). The r ate constant k(O-2(.-) + DDC) is equal to 900 mol(-1). 1. s(-1).