Hydrogen abstraction from toluene by methyl radicals and the pressure dependence of the recombination of methyl radicals

Abstract

Using dimethylzinc, dimethylmercury, and trimethylbismuth as sources of methyl radicals, values of k1/k21/2[Formula: see text]have been calculated from 338 to 610 °C over the pressure range 4.5–204 mm. M is predominantly toluene. The observed pressure dependence of reaction [2] is in agreement with that found when M = benzene, but is somewhat greater, and the fall-off occurs at higher pressures, than for ethane dissociation. However, reasonable agreement is obtained if it is assumed that the efficiency of toluene as a third body in reaction [2] is about 1/10th that of ethane.Extrapolation to infinite pressure, where it is assumed that E2 = 0and A2 = 1013.34 cm3 mole−1 s−1, gives E1 = 8.0 ± 0.3 kcal mole−1 and A1 = 1011.07 cm3 mole−1 s−1.