Influence of γ-irradiation on the kinetics of heat release during the interaction of an aqueous solution of HNO3 with aliphatic hydrocarbons

The influence of preliminary γ-irradiation and γ-irradiation during hte oxidation process on the kinetics of heat release in the systemsn-decane—aqueous solution of HNO₃ and a solution of tributyl phosphate in a kerosene—aqueous solution of HNO₃ was studied. The preliminary γ-irradiation of the system at 43°C increases the initial rate of the process (k ₁). The increase is proportional to the irradiation dose at doses up to 150kGy, then the increase ink ₁ is retarded, and the further course of the process becomes practically independent of the irradiation dose. The effect of γ-irradiation during the oxidation depends on the temperature of the system: at temperatures lower than 80 °C, γ-irradiation increases the rate of heat release, whereas at higher temperatures, γ-irradiation decreases the rate of heat release. The effects observed were explained by the competition of NO₂ accumulation due to the radiolysis of nitric acid and processes of the addition of NO₂ to unsaturated hydrocarbons produced by the radiolysis of the organic phase. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1116–1120, June, 1998.     

The features of hydrogen ignition over Pt and Pd foils at low pressures

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On third Poisson structure of KdV equation

The third Poisson structure of the KdV equation in terms of canonical free fields and the reduced WZNW model is discussed. We prove that it is diagonalized in the Lagrange variables which were used before in the formulation of 2d gravity. We propose a quantum path integral for the KdV equation based on this representation.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 103, No. 3, pp. 461–466, June, 1995.     

Synthesis, Structure, and Chemical Properties of N-Substituted 2(3)-Imino-2,3-dihydrofuran-3(2)-ones. (Review)

Published data on the synthesis, structure, and chemical properties of N-substituted 2(3)-imino-2,3-dihydrofuran-3(2)-ones to 2002 are reviewed     

Nitration equilibrium of water-soluble carboxycellulose

Maximum and minimum values of the equilibrium constants for nitration of hydroxyl groups in water-soluble carboxycellulose (WSCC) have been estimated. Electronegative substituants and elements of the cellulose structure in the WSCC molecule substantially lower the equilibrium constants for nitration compared with those for polyatomic aliphatic alcohols.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2254–2258, October, 1991.     

Ultrafast singlet excited-state polarization in electronically asymmetric ethyne-bridged bis[(porphinato)zinc(II)] complexes

The excited-state dynamics of two conjugated bis[(porphinato)zinc(II)] (bis[PZn]) species, bis[(5,5'-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethyne (DD) and [(5,-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5',-15'-ethynyl-10',20'-bis(heptafluoropropyl)porphinato)zinc(II)]ethyne (DA), were studied by pump-probe transient absorption spectroscopy and hole burning techniques. Both of these meso-to-meso ethyne-bridged bis[PZn] compounds display intense near-infrared (NIR) transient S(1)-->S(n) absorptions and fast relaxation of their initially prepared, electronically excited Q states. Solvational and conformational relaxation play key roles in both DD and DA ground- and excited-state dynamics; in addition to these processes that drive spectral diffusion, electronically excited DA manifests a 3-fold diminution of S(1)-->S(0) oscillator strength on a 2-20 ps time scale. Both DD and DA display ground-state and time-dependent excited-state conformational heterogeneity; hole burning experiments show that this conformational heterogeneity is reflected largely by the extent of porphyrin-porphyrin conjugation, which varies as a function of the pigment-pigment dihedral angle distribution. While spectral diffusion can be seen for both compounds, rotational dynamics driving configurational averaging (tau approximately 30 ps), along with a small solvational contribution, account for essentially all of the spectral changes observed for electronically excited DD. For DA, supplementary relaxation processes play key roles in the excited-state dynamics. Two fast solvational components (0.27 and 1.7 ps) increase the DA excited-state dipole moment and reduce concomitantly the corresponding S(1)-->S(0) transition oscillator strength; these data show that these effects derive from a time-dependent change of the degree of DA S(1)-state polarization, which is stimulated by solvation and enhanced excited-state inner-sphere structural relaxation.     

Kinetics of thermal decomposition of dinitramide

Kinetic regularities of thermal decomposition of dinitramide in aqueous and sulfuric acid solutions were studied in a wide temperature range. The rate of the thermal decomposition of dinitramide was established to be determined by the rates of decomposition of different forms of dinitramide as the acidity of the medium increases: first, N(NO₂)⁻ anions, then HN(NO₂)₂ molecules, and finally, protonated H₂N(NO₂)₂ ⁺ cations. The temperature dependences of the rate constants of the decomposition of N(NO₂)⁻ (k _an) and HN(NO₂)₂ (k′_ac) and the equilibrium constant of dissociation of HN(NO₂)₂ (K _a) were determined:k _an=1.7·10¹⁷ exp(−20.5·10³/T), s⁻¹,k′_ac=7.9·10¹⁶ exp(−16.1·10³/T), s⁻¹, andK _a=1.4·10 exp(−2.6·10³/T). The temperature dependences of the decomposition rate constant of H₂N(NO₂)₂ ⁺ (k _d) and the equilibrium constant of the dissociation of H₂N(NO₂)₂ ⁺ (K _d) were estimated:k _d=10¹² exp(−7.9·10³/T), s⁻¹ andK _d=1.1 exp(6.4·10³/T). The kinetic and thermodynamic constants obtained make it possible to calculate the decomposition rate of dinitramide solutions in a wide range of temperatures and acidities of the medium. In this series of articles, we report the results of studies of the thermal decomposition of dinitramide performed in 1974–1978 and not published previously. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2129–2133, December, 1997.     

Nitrogen Trichloride Decomposition in the Presence of Molecular Hydrogen: I. Promotion of Nitrogen Trichloride Decomposition by Molecular Hydrogen Additives Near the Lower Self-Ignition Limit

The promotion of the branched-chain decomposition of nitrogen trichloride by molecular hydrogen additives at room temperature and 20 torr manifests itself in a decrease in the induction period and the acceleration of reactant consumption with an increase in the hydrogen concentration in the NCl₃+ H₂+ He mixtures. The emission spectrum of the H₂+ NCl₃flame contains the intense bands of NCl (b ¹⁺– X ^3–, = 1 – 0, = 0 – 1, and = 0 – 0, where is the vibrational quantum number) and the bands of a hydrogen-free compound. The latter bands can be assigned to electronically excited NCl ₂radicals formed in the H + NCl₃reaction. The calculations restrict the number of elementary reactions favoring promotion. The promotion effect in the system studied should be due to the side reaction of linear branching. The occurrence of the H + NCl₃reaction via two pathways (NHCl + 2Cl and NCl ₂+ HCl) ensures the qualitative agreement between the experimental data and calculation.     

Anisotropy time dependence of photoexcited C60 and C70 in transient grating experiments. Solvent effect

Anisotropy time dependence of photoexcited C₅₀ and C₇₀ has been measured by picosecond transient grating techniques at room temperature in various solvents. The monoexponential anisotropy decay was observed for the C₆₀ molecule and biexponential anisotropy decay was observed for the C₇₀ molecule. Both for the C₆₀ and for the C₇₀ molecules anisotropy time decay is very fast. The data obtained were analyzed in terms of the rotational reorientation of fullerene molecules in solvents. Hynes-Kapral-Weinberg theory reasonably explains the observed reorientation times of fullerenes molecules. The dielectric friction effect on the C₇₀ rotational reorientation on the short axis is reported.