Kinetics and mechanism of the reaction of perfluoro propyl vinyl ether (PPVE, C₃F₇OCH=CH₂) with OH: assessment of its fate in the atmosphere.

Abstract

Absolute rate coefficients for the reaction between OH radicals and perfluoro propyl vinyl ether (PPVE) were obtained using the technique of pulsed laser photolysis with the detection of OH radicals by laser induced fluorescence. Rate coefficients were measured over a range of temperatures (212-298 K) and at either 50 or 200 Torr bath-gas (N2 or N2/O2). The temperature dependence of the rate coefficient is given by k1(212-298 K) = (4.88 ± 0.49) × 10(-13) exp[(564 ± 10)/T] cm(3) molecule(-1) s(-1) with a value at room temperature of (3.4 ± 0.3) × 10(-12) cm(3) molecule(-1) s(-1). No pressure dependence was observed, indicating that the reaction is at the high pressure limit under atmospheric conditions. The accuracy of the rate coefficient obtained was enhanced by on-line optical absorption measurements of PPVE at 184.95 nm using a value of σ(184.95 nm) = (5.64 ± 0.28) × 10(-18) cm(2) molecule(-1) determined in this work. An atmospheric lifetime of a few days for PPVE was calculated. Extensive quantum chemical calculations as a complement to the experimental work are presented in order to determine its probable tropospheric degradation mechanism.