KINETICS AND MECHANISM FOR THE ATMOSPHERIC OXIDATION OF 1,1,2-TRIFLUOROETHANE (HFC-143)

The rate constant for the reaction of the hydroxyl radical with 1,2,2- trifuoroethane has been determined over the temperature range 278-323 K using a relative rate technique. The results provide a value of k(OH + CH2FCHF2) = 2.65 x 10(-12) exp(-1542 +/- 500/T) cm(3) molecule(-1) s(-1) based on k(OH + CH3CCl3) = 1.2 x 10(-12) exp(-1400 +/- 200/T) cm (3) molecule(-1) s(-1) for the rate constant of the reference reaction . The chlorine atom initiated photooxidation of CH2CHF2 was investigat ed from 255 to 330 K and as a function of O-2 pressure at 1 atmosphere total pressure using Fourier transform infrared spectroscopy. The maj or carbon-containing products were CHFO and CF2O suggesting that the a lkoxy radicals CH2FCF2O and CHF2CHFO, formed in the reaction, react pr edominantly by carbon-carbon bond cleavage. The results indicate that formation of CHF2CFO from the reaction of CHF2CHFO radicals with O-2 w ill be unimportant under all atmospheric conditions. (C) 1995 John Wil ey & Sons, Inc.