The Reactions of Methyl Radicals. II. The Abstraction of Hydrogen Atoms from Paraffins

The reactions of methyl radicals formed by the photolysis of acetone and deutero-acetone with nine paraffins have been studied from 25°C to 340°C. If the combination of methyl radicals requires no activation energy, then the activation energies found for the abstraction of hydrogen atoms are as follows: ethane, 10.4; n-butane, 8.3; 2-methyl propane, 7.6; n-pentane, 8.1; 2,2-dimethyl propane, 10.0; n-hexane, 8.1; 2,3-dimethyl butane, 6.9 and 7.8; 2,3,4-trimethyl pentane, 7.9; 2,2,3,3-tetra-methyl butane, 9.5 (all values in kcal). The collision theory steric factors of these reactions are all less than 10−3.