Oxidation of olefins with alkanesulfoperacids

Alkanesulfonic peracids RSO₄H effectively oxidize olefins to the corresponding epoxides. The kinetics and mechanism of this reaction are studied. It was shown that both the monomer and dimer form of the peracid act as oxidizing agents. The dependence of the weight constant of the reaction of monomer RSO₄H with substituted acyclic olefins on the structure of the latter is described by the Taft equation. A linear correlation is established between log k₂ and the inductive constants of the substituents on the oxygen atom in the peracid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 333–337, February, 1991.     

Quantum-chemical modeling of the detachment of hydrogen atoms by the sulfate radical anion

Nonempirical quantum-chemical calculations of the transition states of reactions between the sulfate radical anion and organic compounds of various classes were performed, and the activation energies of the corresponding reactions were calculated. A correlation dependence between the calculated activation energies and the strength of substrate C-H bonds was found. The polarized continuum model COSMO was used to study the influence of solvents on the kinetics of the reactions.     

Diffusion-controlled recombination of peroxide radicals in polyatomic esters

Pulse photolysis measurements of rate constants for the decay of peroxide radicals of seven polyatomic esters show that the reaction is diffusion-controlled for esters with 2 cP. The Smoluchowsky equation is suggested to calculate 2k_t for esters with short alkyl radicals.

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. , - , 2 . 2k_t .

     

Kinetics of the reaction of decanesulfoperacid with SO2 in the presence of water

A study has been made of the kinetics of the oxidation of SO₂ by decanesulfoperacid in the presence of water in a medium of CH₃CN. Retardation of the process by acids has been observed, the retarding effect decreasing with decreasing strength of acid. A mechanism for the reaction has been suggested which explains the experimental results obtained.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 546–548, March, 1991.     

Medium effect on the decay kinetics of benzophenone oxide

The rate constants of benzophenone oxide decay measured at 25°C by flash photolysis (FPh) strongly depend on the nature of the solvent [2k=(2.6±0.3)×10⁷ L mol⁻¹ s⁻¹ in CH₃CN, and (2.0±0.2)×10⁹ L mol⁻¹ s⁻¹ in pentane].     

Chemiluminescent Method for Determination of Rate Constants for Reactions of Triplet Aromatic Nitrenes

It has been shown that the chemiluminescence accompanying the deoxygenation of nitrosobenzenes with triphenylphosphine can be used to measure the rate constants of reactions of the intermediates triplet nitrenes with the system components nitroso compounds and triphenylphosphine.     

Kinetics and mechanism of the nitrosobenzene deoxygenation by trivalent phosphorous compounds

The reaction of aryl nitroso compounds with organic phosphines and phosphites in aerated media is a convenient non-photolytic procedure to generate aromatic nitroso oxides. The reaction rate constants and activation parameters of the key (for the proposed method of nitroso oxide generation) reaction of nitrosobenzene with tripenyl phosphite or para-substituted phosphines (4-RC₆H₄)₃P (R = MeO, Me, H, F), as well as that of para-methoxynitrosobenzene with triphenylphosphine in acetonitrile were determined by kinetic spectrophotometry and chemiluminescence. A significant transfer of the electron density to the nitroso compound occurs in the transition state of the reaction as was revealed using the Hammett correlation analysis and DFT calculations in the M06L/6-311+G(d,p) approximation. The introduction of the electron-donor substituent MeO into the para-position of PhNO decreases the reactivity of the nitroso compound by two orders of magnitude. The reactivity of triphenyl phosphite in the oxygen atom transfer reaction is lower by two orders of magnitude compared to that of triphenylphosphine. In the case of the reactions of PhNO with phosphines, the apparent rate constant depends on the oxygen content in the reaction medium.     

Antioxidant Activity of Methano- and Cyclopentenofullerenes

Kinetics and Catalysis - The rate constant of the reaction of methano- and cyclopentenofullerenes (С60R) with a peroxyl radical (PhCH(OO?)CH3) was measured in a model system of the...     

Rate Constants of the Interaction of 2-Thio-6-Aminouracil with Peroxyl Radicals

Kinetics and Catalysis - It was shown that 2-thio-6-aminouracil (TAU) is an inhibitor of the radical-chain oxidation of ethylbenzene and methyl oleate. The reactivity of structurally different...