Kinetics and mechanisms of unimolecular gas-phase reactions of 2-methylpropane radical-ions at times as short as 20 picoseconds and at longer times

Abstract

The rates of loss of methyl radical and of methane from 2-methylpropane, 2-methyl[2-²H]propane, and 2-[²H₃]methyl[1,1,1,3,3,3-²H₆]propane following field ionisation (FI) have been determined over a time range extending from 20 ps to 1 ns and at times of the order of microseconds. These kinetic results are in qualitative agreement with the predictions of the statistical theory (QET). The loss of methane specifically involves 1,3 hydrogen transfer. The loss of CH₄ from (CH₃)₃CD⁺_˙ is faster than the loss of CD₄ from (CD₃)₃CH⁺_˙ at times of the order of 10 ps by a factor of 2, whereas at times of the order of microseconds the loss of CD₄ is the faster reaction.