Kinetics and mechanism for the oxidation of 1,1,1-trichloroethane

✍ Scribed by Linda Nelson; Imelda Shanahan; Howard W. Sidebottom; Jack Treacy; Ole J. Nielsen

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 734 KB
• Volume: 22
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550220603

✦ Synopsis

Abstract

The reaction mechanisms for oxidation of CH~3~CCl~2~ and CCl~3~CH~2~ radicals, formed in the atmospheric degradation of CH~3~CCl~3~ have been elucidated. The primary oxidation products from these radicals are CH~3~CClO and CCl~3~CHO, respectively. Absolute rate constants for the reaction of hydroxyl radicals with CH~3~CCl~3~ have been measured in 1 atm of Argon at 359, 376, and 402 K using pulse radiolysis combined with UV kinetic spectroscopy giving 𝓀(OH + CH~3~CCl~3~) = (5.4 ± 3) 10^−12^ exp(−3570 ± 890/RT) cm^3^ molecule^−1^ s^−1^. A value of this rate constant of 1.3 × 10^−14^ cm^3^ molecule^−1^ s^−1^ at 298 K was calculated using this Arrhenius expression. A relative rate technique was utilized to provide rate data for the OH + CH~3~ CCl~3~ reaction as well as the reaction of OH with the primary oxidation products. Values of the relative rate constants at 298 K are: 𝓀(OH + CH~3~CCl~3~) = (1.09 ± 0.35) × 10^−14^, 𝓀(OH + CH~3~CClO) = (0.91 ± 0.32) × 10^−14^, 𝓀(OH + CCl~3~CHO) = (178 ± 31) × 10^−14^, 𝓀(OH + CCl~2~O) < 0.1 × 10^−14^; all in units of cm^3^ molecule^−1^ s^−1^. The effect of chlorine substitution on the reactivity of organic compounds towards OH radicals is discussed.