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.