Rate constants for the reactions of OH radicals with CH3OCF2CHF2, CHF2OCH2CF2CHF2, CHF2OCH2CF2CP3, and CF3CH2OCF2CHF2 over the temperature range 250-430 K

The OH reaction rate constants have been measured for CH3OCF2CHF2, CHF2OCH2 CF2CHF2, CHF2OCH2CF2CF3 and CF3CH2OCF2CHF2 over the temperature range 250-4 30 K, Kinetic measurements have been carried out using the flash photolysis , laser photolysis, and discharge flow methods, combined respectively with the laser-induced fluorescence technique to monitor the OH radical concentr ations. The influence of impurities contained in the samples of fluorinated ethers has been investigated by means of sample purification using gas chr omatography. No sizable effect of impurities was found on the measured rate constants of these fluorinated ethers, if the purified samples were used i n the kinetic measurements. The Arrhenius rate constants have been determin ed from the respective kinetic data as k(CH3OCF2CHF2), = 2.60 x 10(-12) exp [-(1420 +/- 170)/T], k(CHF2OCH2CF2CHF2)= 2.49 x 10(-12) exp[-(1500 +/- 170) /T], k(CHF2OCH2CF2CF3)= 2.14 x 10(-12) exp[-(1580 +/- 170)/T], and k(CF3CH2 OCF2CHF2) = 1.49 x 10(-12) exp[-(1520 +/- 170)/T] cm(3) molecule(-1) s(-1), where the quoted errors represent the 95% confidence level and included sy stematic errors. Uncertainty factors at 298 K (with the formulation of the NASA panel for data evaluation(14)) for these fluorinated ethers were 1.1.