摘要:

AbstractThe Modified Simplex Method (MSM) coupled with contour diagrams is used to determine the rate constants of a kinetic scheme involving three sequential second order processes.Reaction between glutathione and the dithiocarbamate fungicide tetramethylthiuram disulfide produces the oxidized form of glutathione which is then reduced in the presence of NADPH. The concentration of the reducing agent is monitored as a function of time. In the absence of simplifying assumption a closed form solution of the rate equations does not exist. Computed curves of NADPH concentration versus time were generated using the software SIMULCIN.The rate constant values are optimized by the MSM procedure to obtain the best agreement between calculated and experimental data. The significance, validity limits of the estimated rate constants and the relevance of thesein vitrodata to previousin vivostudies are discussed.

ISSN:0538-8066    

DOI:10.1002/kin.550201102

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe Taylor dispersion technique has been used to measure the diffusion coefficients of nine compounds in dilute solution in isopropanol at 300 K. These compounds correspond, by the difference of a single hydrogen atom, to nine free radicals, for which the rate constants for bimolecular (termination) reactions have been previously measured under the same conditions by e.s.r. Comparison of the two sets of results show the termination reactions to be essentially diffusion‐controlled, and, assuming no activation‐energy effect, interaction parameters for the termination reactions are calculated and discus

ISSN:0538-8066    

DOI:10.1002/kin.550201103

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe rate of reaction between NO and HNO3and the rate of thermal decomposition of HNO3have been measured by FTIR spectroscopy. The measurements were made in a teflon lined batch reactor having a surface to volume ratio of 14 m−1. During the experiments, with initial HNO3concentrations between 2 and 12 ppm and NO concentrations between 2 and 30 ppm, a reactant stoichiometry of unity and a first order NO and HNO3dependence were confirmed. The observed rate constant for the reaction\documentclass{article}\pagestyle{empty}\begin{document}$${\rm HNO}_{\rm 3} + {\rm NO} \longrightarrow {\rm HNO}_{\rm 2} + {\rm NO}_2$$\end{document}at 22°C and atmospheric pressure was determined to 1.1 (±0.3) 10−5ppm−1min−1. At atmospheric pressure, HNO3decomposes into NO2and other products with a first order HNO3dependence and with a rate constant of 2.0 (±0.2) 10−3min−1. The apparent activation energy for the decomposition is 13

ISSN:0538-8066    

DOI:10.1002/kin.550201104

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe relative rate technique has been used to determine the rate constants for the reaction of chlorine atoms with a series of oxygenated organic species. Experiments were performed at 295 ± 2 K and atmospheric pressure of synthetic air or nitrogen. The decay rates of the organic species were measured relative to that of ethane orn‐butane. Using rate constants of 5.7 × 10−11cm3molecule−1s−1, and 2.25 × 10−10cm3molecule−1s−1for the reaction of Cl with ethane andn‐butane respectively the following rate constants were derived, in units of 10−11cm3molecule−1s−1: propane, (16.0 ± 0.4);i‐butane, (15.1 ± 0.9)n‐pentane, (31.0 ± 1.6);n‐hexane, (34.5 ± 2.3); cyclohexane, (36.1 ± 1.5); methanol, (4.57 ± 0.40); ethanol, (8.45 ± 0.91);n‐propanol, (14.4 ± 1.2);t‐butylalcohol, (3.26 ± 0.19); acetaldehyde, (8.45 ± 0.79); propionaldehyde, (11.3 ± 0.9); dimethylether, (20.5 ± 0.8); diethylether, (35.6 ± 2.8); and methyl‐t‐butylether, (16.6 ± 1.2). Quoted errors represent 2σ, and do not include any errors due to uncertainties in the rate constants used to place our relative measurements on an absolute basis. The results are discussed with respect to the mechanis

ISSN:0538-8066    

DOI:10.1002/kin.550201105

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe reactions of poly(4‐vinylbiphenyl) (denoted as PVB) polymers and biphenyl molecules with solvated electrons in the 2‐methyltetrahydrofuran (MTHF) solvent have been studied at 100–120 K by electron‐pulse radiolysis. The formation of PVB polymer anions as well as biphenyl anions was observed by the electron‐pulse irradiation of the MTHF‐PVB(or biphenyl) solution. The anions are formed by two processes; a rapid formation during the pulse irradiation (<20 ns) and a slow formation after the pulse irradiation. The slow formation is due to a diffusion‐controlled reaction between solutes, such as PVB and biphenyl, and solvated electrons. It was found that the reaction efficiency, expressed in monomer unit, of PVB polymers is 1/27 of that of biphenyl molecules. The reaction radius for the electron capture reaction of PVB polymers is estimated as 200–370 A, which is much larger than the gyration radius (107 A) of polymer coils i

ISSN:0538-8066    

DOI:10.1002/kin.550201106

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe 147 nm photolysis of 3,3 dimethylbut‐1‐ene leads mainly to the formation of very hot (≅375 kJ/mol) α,α‐dimethallyl radicals. On the other hand, that of 3‐methyl‐cis‐andtrans‐pentene‐2, as well as that of 2,3‐dimethylbut‐1‐ene is a source of very hot α,β‐dimethallyl radicals. These allylic radicals are coolled down using pressure and are allowed to combine with available methyl radicals. From the formation of various C6H12products, it is concluded that the very hot α,α‐ radical isomerizes towards the α,β‐structure at low pressures andvice versa. The equilibrium constant of the following process has been evaluated to be 1.72 ± 0.30.\documentclass{article}\pagestyle{empty}\begin{document}$${\rm CH}_3{\rm C}({\rm CH}_3){\rm CHCH}_2 ^ * \Leftrightarrow {\rm CH}_2 {\rm C}({\rm CH}_{

ISSN:0538-8066    

DOI:10.1002/kin.550201107

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA kinetic study of the reactions of H atoms with CH3SH and C2H5SH has been carried out at 298 K by the discharge flow technique with EPR and mass spectrometric analysis of the species. The pressure was 1 torr. It was found:k1= (2.20 ± 0.20) × 10−12for the reaction H + CH3SH (1) andk2= (2.40 ± 0.16) × 10−12for the reaction H + C2H5SH (2). Units are cm3molecule−1s−1. A mass spectrometric analysis of the reaction products and a computer simulation of the reacting systems have shown that reaction (1) proceeds through two mechanisms leading to the formation of CH3S + H2(1a) and CH

ISSN:0538-8066    

DOI:10.1002/kin.550201108

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550201101

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY