Concerted HO 2 elimination from α-aminoalkylperoxyl free radicals: Experimental and theoretical evidence from the gas-phase NH 2 •CHCO 2 - O 2 reaction

Abstract

We have investigated the gas-phase reaction of the α-aminoacetate (glycyl) radical anion (NH 2 •CHCO 2 -) with O 2 using ion trap mass spectrometry, quantum chemistry, and statistical reaction rate theory. This radical is found to undergo a remarkably rapid reaction with O 2 to form the hydroperoxyl radical (HO 2 •) and an even-electron imine (NHCHCO 2 -), with experiments and master equation simulations revealing that reaction proceeds at the ion-molecule collision rate. This reaction is facilitated by a low-energy concerted HO 2 • elimination mechanism in the NH 2CH(OO •)CO 2 - peroxyl radical. These findings can explain the widely observed free-radical-mediated oxidation of simple amino a..