Voltammetric study of reactions of triphenylphosphite ozonide

The electrochemical characteristics of reduction of triphenylphosphite ozonide at a stationary platinum electrode were determined in acetonitrile at between –30 and –11°C. The feasibility of employing voltammetric methods to investigate the reactions of phosphite ozonides was demonstrated in a model study of the kinetics of the thermal decomposition of (C₆H₅O)₃PO₃ and its reaction with triphenylphosphite.Institute of Organic Chemistry, Urals Branch, Russian Academy of Sciences, 450054 Ufa. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 84–86, January, 1992.     

Chemiluminescence in the thermal decomposition of di(tert-butyl) trioxide

Intense chemiluminescence (CL) in the visible and IR regions arising during the thermal decomposition of di(tert-butyl) trioxide has been observed. The decomposition rate constants have been determined. The emitter of CL in the IR region is singlet oxygen, that of CL in the visible region is triplet excited acetone. Kinetic and spectral data and thermochemical and MNDO calculations point to a homolytic mechanism of decomposition. The formation of the CL emitters occurs in the reactions of radicals that arise upon the decay of di(tert-butyl) trioxide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2056–2059, December, 1993.     

Oxidation of diazo compounds by triphenyl phosphite ozonide. Quenching of singlet oxygen by diazo compounds

The reaction of triphenyl phosphite ozonide with various types of diazo compounds results in their oxidation, which is accomplished by singlet oxygen (¹O₂) evolved during thermal decomposition of the ozonide. A decrease in the ionization potential of the substrate results in an increase in the overall rate constant of quenching of¹O₂. In the case of 9-diazofluorene, the main channel of¹O₂ quenching is physical quenching.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1567–1571, September, 1994.The work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 93-03-5231).     

Heterogeneous decomposition ofp-methoxy- andp-methyl-dibenzoyl peroxides by a montmorillonite amine intercalate

A kinetic study of the heterogeneous thermal decomposition ofp-MeO-DBP andp-Me-DBP catalysed by the montmorillonite benzidine intercalate has been made. The kinetics of decomposition were observed to follow a three-halves order reaction with respect to the peroxides. The activation parameters in heterogeneous media have lower values compared with the corresponding values in homogeneous ones. The relationships between H ^* and S ^* were plotted and show two converging straight lines which indicate that both electron donating and withdrawing substituents on the peroxide enhance the rate of decomposition under these conditions.     

Catalyst Development for the Synthesis of Ozonides and Tetraoxanes Under Heterogeneous Conditions: Disclosure of an Unprecedented Class of Fungicides for Agricultural Application

The catalyst H_3+xPMo_12−x⁺⁶Mo_x⁺⁵O₄₀ supported on SiO₂ was developed for peroxidation of 1,3- and 1,5-diketones with hydrogen peroxide with the formation of bridged 1,2,4,5-tetraoxanes and bridged 1,2,4-trioxolanes (ozonides) with high yield based on isolated products (up to 86 and 90 %, respectively) under heterogeneous conditions. Synthesis of peroxides under heterogeneous conditions is a rare process and represents a challenge for this field of chemistry, because peroxides tend to decompose on the surface of a catalyst . A new class of antifungal agents for crop protection, that is, cyclic peroxides: bridged 1,2,4,5-tetraoxanes and bridged ozonides, was discovered. Some ozonides and tetraoxanes exhibit a very high antifungal activity and are superior to commercial fungicides, such as Triadimefon and Kresoxim-methyl. It is important to note that none of the fungicides used in agricultural chemistry contains a peroxide fragment.     

Free-radical chain decomposition of ozone initiated by di(tert-butyl) trioxide

Di(tert-butyl) trioxide in a solution of CFCl₃ (Freon-11) at –23 °C exists in equilibrium with the tert-butoxyl and tert-butylperoxyl radicals virtually without irreversible decomposition. The above radicals decompose ozone to dioxygen with a high effective rate constant, which is proprotional to the square root of the Bu^tOOOBu^t concentration. The kinetic scheme describing the found relationships was proposed.     

Gold/Acid‐Co‐catalyzed Direct Microwave‐Assisted Synthesis of Fused Azaheterocycles from Propargylic Hydroperoxides

The gold–acid‐co‐catalyzed synthesis of nine series of fused azaheterocycles with structural diversity starting from the same synthons as readily available propargylic hydroperoxides and aromatic amines has been achieved. The overall tandem process consists in a gold‐catalyzed hydroperoxide rearrangement/Michael reaction followed by a final acid‐catalyzed cyclization.     

Induced decomposition of di(tert-butyl)trioxide

Thermal decomposition of di(tert-butyl)trioxide (Bu^tOOOBu^t) in a wide range of concentrations was studied by visible and IR chemiluminescence. Induced decomposition of Bu^tOOOBu^t caused by its reaction with the peroxy radicals formed in the solvent (CH₂Cl₂) was found and investigated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 924–927, May, 1997.     

Effect of the solvent on the kinetics of thermal decomposition of acetylcyclohexylsulfonyl peroxide

The kinetics of the decomposition of acetylcyclohexylsulfonyl peroxide (ACSP) in CCl₄, benzene, toluene, ethylbenzene, cumene, acetonitrile, ethanol, and 2-propanol in an atmosphere of O₂ were studied at 40–70 °C. The rate constants (k ₀) and activation parameters of the monomolecular decomposition of ACSP were determined. A linear dependence between logA ₀ and activation energyE ₀ (compensation effect) was established. The dependence ofk ₀ on the nature of a solvent is described by the four-parameter Koppel-Palm equation. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 935–937, May 1997.     

The kinetics of acid-catalyzed decomposition of decanepersulfonic acid

The kinetics of thermal decomposition of decanepersulfonic acid (RSO₂OOH, R=C₁₀H₂₁) in CCl₄ in the presence of cyclohexanesulfonic and trifluoroacetic acids at 323–343 K was studied. The reaction has an autocatalytic character. The kinetics of consumption of the persulfonic acid is described by the equation-d[RSO₂OOH]/dt=k ₁[RSO₂OOH]+k ₂[RSO₂OOH]·[HX]. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 202–203, January, 1999.     

Kinetics of the thermal decomposition of dinitramide

The kinetic regularities of the thermal decomposition of dinitramide in aqueous solutions of HNO₃, in anhydrous acetic acid, and in several other organic solvents were studied. The rate of the decomposition of dinitramide in aqueous HNO₃ is determined by the decomposition of mixed anhydride of dinitramide and nitric acid (N₄O₆) formed in the solution in the reversible reaction. The decomposition of the anhydride is a reason for an increase in the decomposition rates of dinitramide in solutions of HNO₃ as compared to those in solutions in H₂SO₄ and the self-acceleration of the process in concentrated aqueous solutions of dinitramide. The increase in the decomposition rate of nondissociated dinitramide compared to the decomposition rate of the N(NO₂)₂ ⁻ anion is explained by a decrease in the order of the N−NO₂ bond. The increase in the rate constant of the decomposition of the protonated form of dinitramide compared to the corresponding value for neutral molecules is due to the dehydration mechanism of the reaction. For Part 1, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 41–47, January, 1998.     

The influence of detergentless microemulsion on the kinetics of hydrolysis of di(p-nitrophenyl) methylphosphonate catalyzed by amines

The influence of the detergentless water/oil microemulsion formed in then-hexane-water-2-propanol system on the kinetics of the hydrolysis of di(p-nitrophenyl) methylphosphonate under the conditions of general base catalysis by primary, secondary, and tertiary aliphatic amines was investigate. The leveling of the catalytic rate constants and basicities of the amines was found for this reaction in a microemulsion. The catalytic rate constants for the amines containing hydrophilic groups increase in microemulsions as compared to those in an aqueous medium, while the catalytic constants for the amines containing hydrophobic groups decrease. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1339–1342, July, 1998.     

Scope, kinetics, and mechanistic aspects of aerobic oxidations catalyzed by ruthenium supported on alumina

The Ru/Al(2)O(3) catalyst was prepared by modification of the preparation of Ru(OH)(3).n H(2)O. The present Ru/Al(2)O(3) catalyst has high catalytic activities for the oxidations of activated, nonactivated, and heterocyclic alcohols, diols, and amines at 1 atm of molecular oxygen. Furthermore, the catalyst could be reused seven times without a loss of catalytic activity and selectivity for the oxidation of benzyl alcohol. A catalytic reaction mechanism involving a ruthenium alcoholate species and beta-hydride elimination from the alcoholate has been proposed. The reaction rate has a first-order dependence on the amount of catalyst, a fractional order on the concentration of benzyl alcohol, and a zero order on the pressure of molecular oxygen. These results and kinetic isotope effects indicate that beta-elimination from the ruthenium alcoholate species is a rate-determining step.     

催化裂解低碳烷烃制备碳纳米管薄膜

碳纳米管性质奇特、用途广泛[1]。目前制备碳纳米管薄膜的方法主要有电弧放电法[2]、催化裂解[3]、及真空过滤碳纳米管悬浮液制备“巴基管纸”(Buckypaper)[4]等。本文采用镀镍基板催化裂解低碳烷烃法制备碳纳米管薄膜,考察了镀膜时间、蚀刻和氨水处理等条件对碳纳米管薄膜产物形貌的影响。1　实验部份1 1　镀膜与后处理采用离子溅射法在硅酸盐基板上镀镍,镀镍电流7 5mA,镀镍时间分别为2min、15min、30min、45min或60min;对镀镍基板再进行蚀刻(蚀刻电流7 5mA,蚀刻时间2min)或用氨水浸泡处理(含NH325%,超声振荡30min),然后烘干备用。1 …     

Kinetics of thermal decomposition of nickel sulfate hexahydrate

The paper describes the kinetics of all the recorded steps of thermal decomposition of nickel sulfate hexahydrate in air. The thermal decomposition of the salt in air led to NiO at about 1060 K. The kinetic parameters, the activation energyE and the preexponential factorA, and the thermodynamic parameters, the entropy, enthalpy and free energy of activation were evaluated for the dehydration and decomposition reactions. Tentative reaction mechanisms are suggested for each step of the thermal decomposition.