KINETICS, KINETIC ISOTOPE EFFECTS, AND SUBSTRATE SELECTIVITY OF ALKYLBENZENE OXIDATION IN AQUEOUS-SOLUTIONS OF PERMANGANATE .3. REACTIONS IN THE PRESENCE OF CL- IONS

The kinetics of toluene and toluene-d(8) oxidation in the KMnO4/HClO4- H2O-Cl- system at [HClO4] = O - 0.4 mol/l and substrate selectivity in the benzene-toluene-o-, m-, p-xylene-pseudocumeme series in 0.327 mol /l HClO4 are studied by the kinetic distribution method. It is establi shed that in the presence of chloride ions and [H+] > 0.02 mol/l, the chlorination (k(Cl)) occurs along with the arene oxidation with MnO4-( k) and HMnO4(k(0)) to form chlorotoluenes (ortho/para = 3.2). The kine tic equation (-d[Arh]/d tau) = (k(-)[MnO4-] + k(0)[HMnO4] + k(Cl)[Cl-] [H+])[ArH] is fulfilled under the conditions when [ArH] much less than [Cl-] much less than [KMnO4]. Relative contributions of different rea ction routes are estimated. The chlorination reaction is first-order w ith respect to Cl- and H+ and zero-order with respect to Mn(VII), and the kinetic isotope effect is equal to 1.0. The substrate selectivity correlates with the basicity of ArH. The data obtained agree with the mechanism of electrophilic chlorination; the active particle H2OCl+ at tacks the arene ring to form a sigma-complex at the slow stage of the reaction.