Experimental and theoretical studies of the reaction of the OH radical with alkyl sulfides: 2. Kinetics and mechanism of the OH initiated oxidation of methylethyl and diethyl sulfides; observations of a two channel oxidation mechanism

M. B. Williams, P. Campuzano-Jost, A. J. Pounds, Anthony J Hynes

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13 Citations (Scopus)

Abstract

A pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to measure rate coefficients for the OH initiated oxidation of methylethyl sulfide (MES) and diethylsulfide (DES). In the absence of oxygen and at low sulfide concentrations we measure rate coefficients that are independent of pressure and temperature. At high sulfide concentrations and a temperature of 245 K, we observed the equilibration of MESOH and DESOH adducts over the pressure range 100-600 Torr. In the presence of O 2 the observed rate coefficients show a dependence on the O 2 partial pressure. We measured the dependence of the overall rates of oxidation on the partial pressure of O 2 over the temperature range 240-295 K and at 200 and 600 Torr total pressures. All observations are consistent with oxidation proceeding via a two channel oxidation mechanism involving abstraction and addition channels, analogous to that observed in the OH initiated oxidation of dimethylsulfide (DMS). Structures and thermochemistry of the MESOH and DESOH adducts were calculated and all results compared to those for DMS. Calculated bond strengths of adducts increase with alkyl substitution but are comparable to that of the DMSOH adduct and are consistent with experimental observations.

Original languageEnglish (US)
Pages (from-to)4370-4382
Number of pages13
JournalPhysical Chemistry Chemical Physics
Volume9
Issue number31
DOIs
StatePublished - 2007

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Sulfides
sulfides
adducts
Oxidation
oxidation
Kinetics
kinetics
Pulsed lasers
Partial pressure
partial pressure
pulsed lasers
coefficients
Thermochemistry
thermochemistry
Photolysis
laser induced fluorescence
Temperature
temperature
photolysis
Substitution reactions

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Atomic and Molecular Physics, and Optics

Cite this

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title = "Experimental and theoretical studies of the reaction of the OH radical with alkyl sulfides: 2. Kinetics and mechanism of the OH initiated oxidation of methylethyl and diethyl sulfides; observations of a two channel oxidation mechanism",
abstract = "A pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to measure rate coefficients for the OH initiated oxidation of methylethyl sulfide (MES) and diethylsulfide (DES). In the absence of oxygen and at low sulfide concentrations we measure rate coefficients that are independent of pressure and temperature. At high sulfide concentrations and a temperature of 245 K, we observed the equilibration of MESOH and DESOH adducts over the pressure range 100-600 Torr. In the presence of O 2 the observed rate coefficients show a dependence on the O 2 partial pressure. We measured the dependence of the overall rates of oxidation on the partial pressure of O 2 over the temperature range 240-295 K and at 200 and 600 Torr total pressures. All observations are consistent with oxidation proceeding via a two channel oxidation mechanism involving abstraction and addition channels, analogous to that observed in the OH initiated oxidation of dimethylsulfide (DMS). Structures and thermochemistry of the MESOH and DESOH adducts were calculated and all results compared to those for DMS. Calculated bond strengths of adducts increase with alkyl substitution but are comparable to that of the DMSOH adduct and are consistent with experimental observations.",
author = "Williams, {M. B.} and P. Campuzano-Jost and Pounds, {A. J.} and Hynes, {Anthony J}",
year = "2007",
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T2 - 2. Kinetics and mechanism of the OH initiated oxidation of methylethyl and diethyl sulfides; observations of a two channel oxidation mechanism

AU - Williams, M. B.

AU - Campuzano-Jost, P.

AU - Pounds, A. J.

AU - Hynes, Anthony J

PY - 2007

Y1 - 2007

N2 - A pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to measure rate coefficients for the OH initiated oxidation of methylethyl sulfide (MES) and diethylsulfide (DES). In the absence of oxygen and at low sulfide concentrations we measure rate coefficients that are independent of pressure and temperature. At high sulfide concentrations and a temperature of 245 K, we observed the equilibration of MESOH and DESOH adducts over the pressure range 100-600 Torr. In the presence of O 2 the observed rate coefficients show a dependence on the O 2 partial pressure. We measured the dependence of the overall rates of oxidation on the partial pressure of O 2 over the temperature range 240-295 K and at 200 and 600 Torr total pressures. All observations are consistent with oxidation proceeding via a two channel oxidation mechanism involving abstraction and addition channels, analogous to that observed in the OH initiated oxidation of dimethylsulfide (DMS). Structures and thermochemistry of the MESOH and DESOH adducts were calculated and all results compared to those for DMS. Calculated bond strengths of adducts increase with alkyl substitution but are comparable to that of the DMSOH adduct and are consistent with experimental observations.

AB - A pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to measure rate coefficients for the OH initiated oxidation of methylethyl sulfide (MES) and diethylsulfide (DES). In the absence of oxygen and at low sulfide concentrations we measure rate coefficients that are independent of pressure and temperature. At high sulfide concentrations and a temperature of 245 K, we observed the equilibration of MESOH and DESOH adducts over the pressure range 100-600 Torr. In the presence of O 2 the observed rate coefficients show a dependence on the O 2 partial pressure. We measured the dependence of the overall rates of oxidation on the partial pressure of O 2 over the temperature range 240-295 K and at 200 and 600 Torr total pressures. All observations are consistent with oxidation proceeding via a two channel oxidation mechanism involving abstraction and addition channels, analogous to that observed in the OH initiated oxidation of dimethylsulfide (DMS). Structures and thermochemistry of the MESOH and DESOH adducts were calculated and all results compared to those for DMS. Calculated bond strengths of adducts increase with alkyl substitution but are comparable to that of the DMSOH adduct and are consistent with experimental observations.

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