Rates of reaction for cyclopropane and difluoromethoxydifluoromethane with hydroxyl radicals

The rates of reaction, Arrhenius preexponential factors, and activation energies of cyclopropane and difluoromethoxydifluoromethane, CHF2OCHF2 (HFOC-134), reacting with hydroxyl radical were measured by a relative method. Using ethane as the reference, eight measurements in the range from 25 to 186 degreesC yielded an Arrhenius fit of k = (6.82 +/- 1.5) x 10(-12)e(-(1335+/-90)/T) cm(3) molecule(-1) s(-1) for the reaction of cyclopropane with hydroxyl radical. Measurements were repeated using CH3CHF2 (FC-152a) instead of ethane as the reference. Both measurements agreed within 3%. Nine measurements in the range from 0 to 191 degreesC were made of HFOC-134 using CF3CHF2 (FC-125) as the reference. The result was k = (1.29 +/- 0.5) x 10(-12)e(-(1895+/-100)/T) cm(3) molecule(-1) s(-1) for HFOC-134. Preexponential factors for these two reactions are shown to be consistent with values predicted from a wide range of observed values for OH abstraction reactions. The rate constant results are compared to previously published values for these same compounds obtained by both relative and absolute methods.