V. D. Komissarov

On the mechanism of phenol ozonolysis

The mechanisms of liquid-phase phenol ozonation are revised. A new mechanism in which a significant role is played by free-radical reactions is suggested for this process.

Kinetics of the Reactions of Ozone with Substituted Ethylenes

The rate constants of second-order reactions of ozone with 22 substituted ethylenes in CCl4 solutions at 293 K were determined using the stopped-flow method. An analysis of the experimental results and published data demonstrated that the structure dependence of olefin reactivity can be described in terms of either the Taft equation or the Swain equation.

Kinetics of the Reaction of Ozone with tert-Butanol

The kinetics of tert-butanol (ROH) oxidation by ozone in CCl4 and H2O solutions at 295 K is studied by spectrophotometry under batch conditions. The rate-limiting step of the process in both solvents is the reaction of ozone with the monomeric form of ROH. In H2O, the hydrated molecules of ROH and ozone react with each other. In CCl4, the association of ROH molecules, which changes the kinetics and mechanism of the process, should be taken into account. The reaction kinetic parameters and the dimerization constant of ROH in CCl4 are determined.

Kinetics of Polyol Oxidation by Ozone in Aqueous Solutions

Spectrophotometry is applied to study the oxidation of ethylene glycol, triethylene glycol, glycerol, etriol, pentaerithritol and mannitol by ozone in aqueous solutions at 277–304 K. Rate constants and activation parameters of the reaction are measured. It is proposed that the oxidation of these alcohols by ozone occurs via the same mechanism. The formation of an intermediate complex is a rate-limiting step in the case of diols; the decomposition of the complex is a rate-limiting step for tri- to hexatomic alcohols.

Kinetics of oxidation of diols by ozone in aqueous solution

The kinetics of the oxidation of diols by ozone was investigated by a spectrophotometric method in the temperature interval of 277–304 K. The activation parameters of the reaction were determined.

Quantitative description of the effect of solvent on kinetics of benzophenone oxide decay

The effect of solvent on rate constants of benzophenone oxide decay was investigated by flash photolysis. A quantitative description of this dependence in the terms of the Koppel-Palm equation suggests that all types of the solvation (non-specific electrostatic and polarizational, specific electrophilic and nucleophilic) strongly affect the reactivity of benzophenone oxide. Besides, strengthening of any effect leads to a decrease of the observed rate constant.

Kinetics, mechanism, and products of the reaction of diphenylcarbonyl oxide with carboxylic acids

The kinetics of the reactions of acetic, benzoic, formic, oxalic, malic, tartaric, trifluoroacetic, and hydrochloric acids with diphenylcarbonyl oxide Ph2COO was studied. The carbonyl oxide Ph2COO was generated by flash photolysis of diphenyldiazomethane Ph2CN2 in solutions of acetonitrile and benzene at 295 K. The apparent rate constants of the reaction range from 4.6·108 for (COOH)2 in MeCN to 7.5·109 L mol–1 s–1 for acetic acid in a benzene solution. The reaction mechanism was proposed, according to which at the first stage the carbonyl oxide is reversibly solvated by the solvent. Then the solvated carbonyl oxide reacts with the acid molecule by the mechanism of insertion at the O—H bond.

Flash Photolysis of Diphenyldiazomethane in the Presence of Organic Sulfides

The flash photolysis of diphenyldiazomethane in acetonitrile, benzene, and n-decane solutions saturated with air resulted in the formation of diphenyl carbonyl oxide Ph2COO which decayed in combination reactions. In the presence of organic sulfides, the transfer of the terminal oxygen atom of Ph2COO to the sulfur atom was observed. The kinetics of this reaction was studied. The absolute rate constants (k6, dm3 mol–1 s–1) of the reactions of Ph2COO with sulfides at 295 K (acetonitrile as a solvent) varied from 4.1 × 102 (Me2S) to 8.1 × 104 (Ph2S). The solvent effect on the reaction kinetics and product composition was studied. The mechanism of the process was discussed.

Solvent effects on the absorption spectrum and recombination kinetics of diphenylcarbonyl oxide

The absorption spectra and rate constants of diphenylcarbonyl oxide recombination in a series of solvents and their binary mixtures were determined by flash photolysis. An increase in the solvent polarity causes hypsochromic shift of the maximum in the absorption spectrum of Ph2COO. The analysis of the solvent effect on the recombination rate constant in terms of the four-parameter Koppel—Palm equation shows that the reactivity of carbonyl oxide depends on both specific and non-specific solvations. Quantum chemical B3LYP/6-31G(d) calculations of H2COO and PhHCOO carbonyl oxides as well as the complexes of H2COO with acetonitrile and ethylene in different media were performed using a polarized continuum model.