Kinetic Study of the Reaction of the CFCl₂CH₂O Radical with O₂

Abstract

The 2-fluoro-2,2-dichloroethoxy radical, CFCl2CH2O, is an intermediate in the mechanism of the tropospheric degradation of CFCl2CH3 (HCFC-141b), a chlorofluoromethane replacement in some large-scale industrial applications. In this work, the reaction of CFCl2CH2O with O2 was investigated at 10−35 Torr and 251−341 K by UV flash photolysis and time-resolved mass spectrometry. CFCl2CH2O2 radicals were formed from the photolysis of CFCl2CH3/N2/O2 mixtures. The CFCl2CH2O radical is a product of the reactions of CFCl2CH2O2 with Cl and ClO and the self-reaction. The rate of formation and decay of CFCl2CH2O was followed by observations of the fragment ion CClCH2O+. The rate coefficient of the reaction of CFCl2CH2O with O2, determined from CHCl2CH2O decay in excess O2 by both pseudo-first-order analysis and nonlinear regression, can be expressed as (2.4 ± 0.5) × 10-15 exp[−(944 ± 55)/T] cm3 molecule-1 s-1. The half-life for removal of CFCl2CH2O radicals from the atmosphere by the title reaction is 6 ms in the mid-troposphere and 1 s in the mid-stratosphere.