ChemInform Abstract: Production and Decomposition of Highly Excited 2‐Butyl Radicals by the Addition of Hot Hydrogen Atoms to But‐2‐ene. Cross Section for the Addition Reaction

Abstract

Highly excited 2-butyl radicals have been generated by addition of hot hydrogen atoms to but-2-ene. Atoms of initial energy 130 kJ mol−1 and 161 kJ mol−1 were produced by photolysis of H2S. Rates of decomposition of the highly excited 2-butyl radicals were monitored by analysis of stabilization and decomposition products, and the extent of energy-loss of the hydrogen atoms in nonreactive collisions assessed by measuring the effect of added xenon on product yields. A model involving the cross-section for the addition reaction, energy transfer in nonreactive collisions between hydrogen atoms and but-2-ene, RRKM rate constants for decomposition of excited 2-butyl radicals, and collisional energy transfer from the radicals, has been used to calculate product yields for comparison with experimental values. It is concluded that the cross-section for addition of hydrogen atoms of energy about 130 kJ mol−1 to but-2-ene is 0.055 ± 0.028 nm2. This value is compatible with the A factor for the thermal addition reaction.