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The ozonation reactions of benzo and dibenzo derivatives of pyrrole, furan, and thiophene in ace tic acid solution have been studied. Peroxide compounds have been detected as the products. The mechanism of ozone interaction with these hetarenes has been proposed. The kinetics of ozonolytic reactions of benzo logues of five membered aromatic heterocycles (hetarenes) have been investigated. The reaction of ozone with the hetarenes obeys the bimolecular rate law and has the first order in each reactant. The effective rate constants and experimental stoichiometric coefficients for ozone have been found.

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The use of transition metal salts in the liquid phase oxidation of methylbenzenes with ozone in acetic acid has been analyzed using a number of examples [1][2][3]. However, the ozonation of alkylbenzenes in the pres ence of transition metals is poorly understood [4]. In this study, we examined the oxidation of ethylbenzene and cumene with ozone in acetic acid in the presence of transition metals activated by strong acid additives [5,6]. EXPERIMENTALThe oxidation of alkylbenzenes was performed in a sealed, thermostated glass reactor equipped with a high speed turbine stirrer and a bubbler of 3 mm in diameter. The reactor was charged with 0.05 L of gla cial acetic acid and calculated amounts of alkylben zene, catalyst, and strong acid, and an ozone-air mix ture (4 × 10 -4 mol/L of ozone) was fed. At a stirrer speed of 29.2 rps and a gas mixture flow rate of 6.0 × 10 -3 L/s, the oxidation occurred in the kinetic region.The concentration of ozone in the gas phase was determined spectrophotometrically according to absorption in the range of 254-259 nm, the concen tration of Co(III) in the reaction mixture was found photometrically by measuring the optical density with a KFK 2 instrument (λ = 315 nm, a 30 mm cell), and that of Mn(III) and product peroxides was determined by iodimetric titration. Changes in the concentration of ethylbenzene and its oxidation products were mon itored via gas-liquid chromatography using a flame ionization detector on a 2 m × 2 mm column packed with Chromaton N AW DMCS as a support coated with the polyethylene glycol adipate stationary phase in an amount of 15% of the support weight; cumene and dimethylphenylcarbinol (DMPC) were deter mined on a 3 m × 2 mm column packed with 5% SE 30 coated Inerton AW DMCS . The concentration of the product benzoic acid was determined as described in [7]. The procedures for determining the rate con stants of the ozone reaction with alkylbenzenes and the transition metals are described in [8]; those for the oxidized metal form with alkylbenzenes are given in [9]. RESULTS AND DISCUSSION Oxidation of Ethylbenzene in the Presence of Manganese(II) AcetateIt was previously shown that the ozonation of eth ylbenzene in acetic acid is accompanied by the destruction of the aromatic ring (formation of ozo nides) and is characterized by an extremely low selec tivity of formationl of the alkyl group oxidation prod ucts, which include methylphenylcarbinol (MPC), acetophenone (AP), traces of benzaldehyde, and, in the case of deep oxidation, benzoic acid (BA). The side chain oxidation selectivity depends on the sever ity of oxidation and does not exceed 18% [5].Taking into account that Mn(II) salts are ineffec tive as catalysts for ozonation in acetic acid [2,3], in this work, we focused on studying the possibility of using Mn(II) acetate in the ozone enhanced oxida tion of ethylbenzene in the СН 3 СООН-H 2 SO 4 sys tem. The results (Fig. 1) show that the use of Mn(II) acetate and sulfuric acid makes it possible to preclude to a significant extent the degradation of the a...