Theoretical study on the atmospheric reaction mechanism and kinetics of 2-isopropoxyethanol initiated by OH radical

Abstract

By using the CCSD(T)/6–311++G(d,p)//BH&HLYP/6–311++G(d,p) method, the gas-phase H-abstraction reactions of 2-isopropoxyethanol (2-iPE) with OH radical were studied theoretically for the first time. Over the temperature range of 220–360 K, the rate constants were evaluated by employing the conventional transition state theory (CTST) and a modified three-parameter Arrhenius expression of k(T) = 3.18 × 10⁻²⁷× T^4.7 × exp.(3127/T) was proposed. Our calculational results revealed that the initial H-abstraction channels mainly occurred from C1, C2 and C3 atoms, forming radical intermediates IM1, IM2 and IM3, with the order of reaction activity being IM2 > IM3 > IM1. Further investigation on the atmospheric loss processes of these radical intermediates gave the major products of isopropyl formate and HCHO and secondary product of 2-hydroxyethyl acetate. Our theoretical investigations are in good agreement with the experimental observations. Furthermore, the atmospheric lifetime of 2-iPE initiated by OH radical and the potential environmental and health impacts of products were evaluated.