Title

Overall rate constant measurements of the reaction of hydroxy- and chloroalkylperoxy radicals derived from methacrolein and methyl vinyl ketone with nitric oxide

Abstract

The overall rate constants of the reactions of NO with hydroxy- and chloroalkylperoxy radicals, derived from the OH- and Cl-initiated oxidation of methacrolein and methyl vinyl ketone, respectively, were directly determined for the first time using the turbulent-flow technique and pseudo-first-order kinetics conditions with high-pressure chemical ionization mass spectrometry for the direct detection of peroxy radical reactants. The individual 100 Torr, 298 K hydroxyalkylperoxy + NO rate constants for the methacrolein [(0.93 ± 0.12) (2σ) × 10-11 cm3 molecule-1 s-1] and methyl vinyl ketone [(0.84 ± 0.10) × 10-11 cm3 molecule-1 s-1] systems were found to be identical within the 95% confidence interval associated with each separate measurement, as were the chloroalkylperoxy + NO rate constants for both methacrolein [(1.17 ± 0.11) × 10-11 cm3 molecule-1 s-1] and methyl vinyl ketone [(1.14 ± 0.14) × 10-11 cm3 molecule-1 s-1]. However, the difference in the rate constants between the hydroxyperoxy + NO and chloroalkylperoxy + NO systems was found to be statistically significant, with the chloroalkylperoxy + NO rate constants about 30% higher than the corresponding hydroxyalkylperoxy + NO rate constants. This substitutent effect was rationalized via a frontier molecular orbital model approach.

Publisher

American Chemical Society

Publication Date

2-1-2007

Publication Title

Journal of Physical Chemistry A

Department

Chemistry and Biochemistry

Document Type

Article

DOI

10.1021/jp0665574

Language

English

Format

text

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