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.     

Effect of the medium on the decomposition rate of di-t-butyl trioxide

Using the chemiluminescence method, the effect of the medium on the overall rate constant of the thermal decomposition of di-tert-butyl trioxide has been studied. In all solvents investigated the decomposition occurs in accordance with a first order rate law. The effect of solvent on the rate constant (0°C) is analyzed.     

Effect of medium on the rate constant of decomposition of di(tert-butyl)trioxide

It was found that the medium affects the rate constant of the thermal decomposition of di(tert-butyl)trioxide. In all solvents studied, the decomposition occurred according to the first-order law. The effect of the solvent on the rate constant was analyzed within the framework of the Koppel-Palm equation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1167–1168, June, 1995.The authors are grateful to O. N. Makarova for help in this work.This study was financially supported by the Russian Foundation for Basic Research (Grant No. 93-03-5231).     

Inversion of the Deactivation Efficiency of Excited States upon Selective Photoexcitation of the Uranyl Ion Complex with D-Tryptophan in Aqueous and Methanol Solutions

High Energy Chemistry - The quenching of fluorescence (FL) of uranyl ion $${\text{UO}}_{2}^{{2 + }}$$ and tryptophan Trp during their selective intracomplex photoexcitation in aqueous and methanol...     

Photochemical and Photophysical Processes of N-Deacetyllappaconitine and Its Monohydrobromide in Aqueous Solutions

Chemistry of Natural Compounds - The photophysical and photochemical processes of N-deacetyllappaconitine (DAL) and its hydrobromide (DAL·HBr) in aqueous solutions were investigated. Their...     

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.     

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.     

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 .

     

On the mechanism for the photooxidation of aromatic azides containing a secondary N–H bond: A sequence of intramolecular transformations with the formation of heterocyclic oximes

During the photooxidation of aromatic azides containing a secondary N–H bond at the para-position, a sequence of intramolecular transformations of nitroso oxides led to the formation of heterocyclic oximes along with the corresponding nitroso and nitro compounds.