COMPETITIVE UNIMOLECULAR DECOMPOSITION PROCESSES IN CHEMICALLY ACTIVATED SYSTEMS. 3-HEXYL RADICAL.

A general formulation of the rates of competitive unimolecular reactions is given and various relationships between the rates, and between the energetics, of competing processes are described. The relative and absolute rates of decomposition, C-C-C-C.-C-C to .CH3C5H10-1 to .C2H5 C4H8-1, were measured at pressures from 0.004 to 90 mm Hg for vibrationally excited 3-hexyl radicals, chemically activated by the addition of hydrogen atoms to trans-3-hexene at 300C. Use of a quantum-statistical model for k sub E in the general relations provides good theoretical agreement with the experimental data at all pressures. The results can also be used to lead to either of two alternative conclusions that D-null CH3-H - D-null C2H5-H is 5.4 kcalmole, or that the difference in critical energies for addition of methyl to pentene-1, Em-null, and of ethyl to butene-1, Ee-null is Em-null -Ee-null -0.4 kcal. In the second paper, evidence is presented that triplet methylene radicals may, under certain conditions, insert into C-H bonds.