Reactions of hydroxyl and hydroxyl-d with hydrogen peroxide and hydrogen peroxide-d2

Abstract

The reactions OH + H{sub 2}O{sub 2} {yields} products (k{sub 1}) and OD + D{sub 2}O{sub 2} {yields} products (k{sub 3}) were studied in the temperature range 273-410 K. The obtained Arrhenius expressions are as follows: k{sub 1} = (2.76 {plus minus} 0.80) {times} 10{sup {minus}12} exp((-110 {plus minus} 60)/T) and k{sub 3} = (1.75 {plus minus} 0.30) {times} 10{sup {minus}12} exp((-320 {plus minus} 20)/T) cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}. The indicated errors are 2{sigma}, including estimated systematic errors. The rate coefficients were independent of the buffer gas (He, N{sub 2}, or SF{sub 6}) used and the pressure (50-500 Torr) employed. The measured kinetic isotope effect, k{sub 1}/k{sub 3}, ranges from 2.7 at 410 K to 3.5 at 273 K. The values of the rate coefficients for OH + D{sub 2}O{sub 2} {yields} products (k{sub 2}) at 273 K and OD + H{sub 2}O{sub 2} {yields} products (k{sub 4}) at 298 K were the same as those of k{sub 3} at 273 K and k{sub 1} at 298 K, respectively. The possible exchange reaction such as OD + H{sub 2}O{sub 2} {yields} OH + HOOD is unimportant, with an upper limit of 2 {times} 10{sup {minus}15} cm{sup 3} molecule{supmore » {minus}1} s{sup {minus}1} for the rate coefficient at 273 K. Bond energy-bond order (BEBO) calculations using a linear five-particle transition state for a H-abstraction reaction do not yield results that agree with experiments. Transition-state theory calculations using a five-particle nonlinear transition state, (HO)-O-H-O-H, yield results in reasonable agreement with the data.« less