Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Polish Journal of Chemistry

1 2009

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: methyl mercaptan

Sortuj według:

Ogranicz wyniki do:

Theoretical Analysis of the Kinetics of the Reaction of Methyl Mercaptan with Nitrogen Dioxide in the Gas Phase

Brudnik B., Wójcik-Pastuszka D., Jodkowski J. T.

Polish Journal of Chemistry

2009

Vol. 83, nr 6

1203-1221

In this study a theoretical analysis of the kinetics and thermochemistry of the gas phase reaction between methyl mercaptan and nitrogen dioxide is presented. The molecular properties (optimized geometries, vibrational levels, and rotational constants) of the reactants and products were derived from ab in itio calculations. The relative total energies of the molecular structures taking part in the reaction kinetics were examined at the G3 level. The rate constants of the elementary steps and their dependence on temperature were evaluated using transition-state theory and a version of the statistical adiabatic channel model. The mechanism of the reaction CH3SH + NO2 is complex and the first elementary step is related to hydrogen abstraction. The derived analytical expressions for the rate constants k1a = 7.9 x 10–15 x (T/300)1.90 x exp(–8190/T) and k1b = 6.0 x 10–13 x (T/300)1.94 x exp(–16290/T) cm3 molecule–1 s–1 de scribe the kinetics of the hy - drogen abstraction reactions CH3SH + NO2 rightwards arrow CH3S + HNO2 (1a) and CH3SH + NO2 rightwards arrow CH2SH + HNO2 (1b), respectively, in the temperature range of 200–500 K. The CH3S and CH2SH radicals formed can undergo subsequent radical-radical (2a–c) and radical-NO2 (3a,b) recombination reactions with rates determined by the high-pressure limiting rate constant, expressed as k2a,Y(CH3S + CH3S) = 4.0×10–11×(T/300)0.20, k2b,infinity(CH3S + CH2SH) = 1.2×10–10×(T/300)0.15, k2c,infinity(CH2SH + CH2SH) = 6.7×10–11×(T/300)0.19, k3a,infinity(CH3S + NO2) = 1.3×10–11×(T/300)0.19, and k3b,infinity(CH2SH + NO2) = 2.6×10–11×(T/300)0.23 cm3 molecule–1 s–1. Values of the calculated rate constants are in good agreement with available results of kinetic measurements.