Theoretical study on the gas phase reaction of acrylonitrile with a hydroxyl radical

Abstract

The mechanism and kinetics of the reaction of acrylonitrile (CH₂CHCN) with hydroxyl (OH) has been investigated theoretically. This reaction is revealed to be one of the most significant loss processes of acrylonitrile. BHandHLYP and M05-2X methods are employed to obtain initial geometries. The reaction mechanism conforms that OH addition to CC double bond or C atom of –CN group to form the chemically activated adducts, 1-IM1(HOCH₂CHCN), 2-IM1(CH₂HOCHCN), and 3-IM1(CH₂CHCOHN) via low barriers, and direct hydrogen abstraction paths may also occur. Temperature- and pressure-dependent rate constants have been evaluated using the Rice–Ramsperger–Kassel–Marcus theory. The calculated rate constants are in good agreement with the experimental data. At atmospheric pressure with N₂ as bath gas, 1-IM1(OHCH₂CHCN) formed by collisional stabilization is the major product in the temperature range of 200–1200 K. The production of CH₂CCN and CHCHCNviahydrogen abstractions becomes dominant at high temperatures (1200–3000 K).