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The oxidation of methyl phenyl sulfide in water and water-alcohol mixtures takes place both by a noncatalytic mechanism and with the participation of hydrogen peroxide as catalyst; in the presence of ammonium hydrocarbonate it takes place by a mechanism involving HCO 4 − as a more active oxidant than hydrogen peroxide (>100 times). In water-alcohol media (ethylene glycol, isopropyl alcohol, tert-butanol) the rate decreases in the order H 2 O > EG > IPA > TBA. The reactivity of organic sulfides varies in the following way: MeSPh ≈ EtSPh << Et 2 S. The results were interpreted from the standpoint of a molecular mechanism of oxidation of the sulfide with H 2 O 2 and HCO 4 − through a polar transition state, containing the HOX molecule (X = H, OH, OR) as acid-base catalyst.Recent interest in investigation of the oxidation of organic sulfides arises from the fact that these processes are regarded as the most satisfactory model of the decomposition of ecotoxicants (pesticides) and the active components of chemical weapons; models of yperite are investigated more often than others [1][2][3][4]. Of great interest from the standpoint of the creation of so-called "green" technologies for protection of the environment are systems based on hydrogen peroxide. In weakly alkaline media they can act as a mild oxidant in the un-ionized form [1,4] and as an effective α-nucleophile in the form of the HO 2 − anion [5]. The problem of the low solubility of organic substrates, important for the development of green technologies, is solved by conducting the nucleophilic oxidation reactions in aqueous solutions of surfactants (micellar catalysis) [6-8] and also in microemulsions [9, 10] and water-alcohol mixtures [1,4,8,11]. In oxidation processes hydrogen peroxide is usually activated by various acids, transforming it into highly reactive peroxy acids. Particularly attractive among the activators are hydrocarbonates as readily obtainable and ecologically safe compounds exhibiting maximum activating effect in a weakly alkaline medium [1,4,7,8,11].The reactivity of a series of sulfides in water-alcohol media [1,4,11] and also in the presence of surfactants [7,8] was recently investigated in the H 2 O 2 /OH -and H 2 O 2 /OH -/HCO 3 − systems. In the present work the kinetics of oxidation of methyl phenyl sulfide (MPS) by hydrogen peroxide was investigated both in the absence and in the presence of ammonium hydrocarbonate as activator in water and in water-alcohol mixtures [30 vol.% of the alcohol: isopropyl alcohol (IPA), tert-butyl alcohol (TBA), and ethylene glycol (EG), at 25°C]. The choice of the given sulfide as subject of investigation was determined by the fact that compared with our previously investigated diethyl sulfide [4, 8] it is a model closer to yperite both in 98 0040-5760/05/4102-0098

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The kinetics and mechanism of the catalysis by ammonium hydrogen carbonate oxidation of methyl phenyl sulfide with hydrogen peroxide has been investigated. Using the classical pseudo-phase model of micellar catalysis, the basic parameters of the catalytic process have been determined: the binding constants of H 2 O 2 , the HCO 4 − anion, and the substrate to the surface of the micelles, and also the second order rate constants for the oxidation of methyl phenyl sulfide in the micellar phase.There is considerable interest in systems based on hydrogen peroxide in the development of universal systems of oxidative nucleophilic action for the decomposition of ecotoxicant substrates [1,2]. This reagent is an a-nucleophile (HOO -) which can be used for the destruction of nerve paralytic toxins [2] and also as a mild oxidant (H 2 O 2 ) for the decomposition of mustard gas and its analogs. These processes are accelerated considerable by the introduction of activators into hydrogen peroxide [3].The hydrogen carbonate catalyzed oxidation of organic sulfides in water and aqueous ethanolic media has been studied previously [4]. It was established that a co-solvent (ethylene glycol, isopropanol, tert-butanol) solved the problem the solubility of the substrate and at the same time led to a decelerated both the catalytic (H 2 O 2 /HCO 3 − ) and non-catalytic (H 2 O 2 ) processes.Consequently aqueous solutions of surface-active substances [5], which on the one hand effectively solubilize the substrate and on the other hand increase the rate as a result of concentration of the reagents on the micellar surface can be examines as and alternative to aqueous alcoholic mixtures.In this work we have studied the kinetic laws of the oxidation of methyl phenyl sulfide (MPS) with hydrogen peroxide (H 2 O 2 ) and the hydrogen peroxocarbonate anion (HCO 4 − ) in aqueous solutions of cetyltrimethylammonium bromide (CTAB).Methyl phenyl sulfide is a model analog for mustard gas both in its hydrophobic properties and reactivity [4]. The micelle forming CTAB is used because cationic detergents are effective catalysts for nucleophilic substitution [6] and oxidation reactions [5]. EXPERIMENTAL35% Aqueous hydrogen peroxide (chemically pure), ammonium hydrogen carbonate (chemically pure), sodium hydrogen phosphate Na 2 HPO 4 ×12H 2 O (chemically pure), CTAB (Merck), recrystallized from an ethanol : ether mixture (1 : 10), and MPS, synthesized by a known method [5], were used in this work.