REACTIONS OF METHYL RADICALS .2. HYDROGEN ABSTRACTION FROM METHYL TRIFLUOROACETATE

Hydrogen abstraction from CF3COOCH3 and CH3COCH3 by CH3 radicals has been studied in the temperature range 117-244°. The rate constants, based on the value of 1013 34 cm3 mol-1 s-1 for the recombination of CH3 radicals, are given by (k in cm3 mol-1 s-1 and E in J mol-1): CF3COOCH3 is less susceptible to attack by CH3 radicals than by CF3 radicals by a factor of 2-8 at 400 K, due mainly to a difference in A factors, since the activation energies of the two reactions are almost identical. These results can be rationalized in terms of intermolecular polar repulsion between the CF3radical and CF3COOCH3. © 1979 ASEG.