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The oxidation of organic sulfides (thioethers) plays an important role in biochemical transformations and in the chemistry of the atmosphere and natural waters. Dimethyl sulfide (Me 2 S), generated by oceanic phytoplankton, is an important source of sulfur in the atmosphere [1,2]. Its oxidation in the gas phase to the oxides of sulfur leads to the formation of acid rain [2]. In biosystems the oxidation of methionine, which plays a key role in the transfer of unpaired electrons, leads to the destruction of proteins and peptides [3]. Sulfides are also active components of pesticides and toxic substances the utilization of which requires a search for new effective oxidizing systems.Particularly attractive among the large number of the various reagents used for the oxidation of sulfides [2, 4], both in economic and ecological respects, is hydrogen peroxide. The mechanisms of oxidation of thioethers, particularly dimethyl sulfide, by hydrogen peroxide have been studied well experimentally [2, 5, 6] and by quantum-chemical methods [7,8]. The ab initio calculations in [8] indicate that the slow stage of the reaction includes cleavage of the O-O bond in H 2 O 2 and the formation of an S-O bond.However, the oxidation of sulfides by hydrogen peroxide takes place slowly. One promising way of activating H 2 O 2 is to convert it into peroxo acids [9][10][11]. An effective activator may be boric acid, B(OH) 3 , which in reaction with hydrogen peroxide gives peroxoborates [12]. Recently we showed [13,14] that the monoperoxoborate B(OOH)(OH) 3 -(MPB) and diperoxoborate B(OOH) (OH) 2 2-anions formed at pH 6-13.5 are 2.5 and 100 times respectively more active than hydrogen peroxide in the oxidation of diethyl sulfide.2 0040-5760/11/4701-0002

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