A Computational Perspective on the Chemical Reaction of HFO-1234zc with the OH Radical in the Gas Phase and in the Presence of Mineral Dust

Abstract

The gas phase and heterogeneous reaction on mineral dust aerosols of trace gases could significantly affect the tropospheric oxidation capacity and aerosol composition of the atmosphere. In this work, the OH radical-initiated oxidation of a hydrofluoroolefin, HFO-1234zc, and subsequent reaction of favorable intermediates with other reactive species, such as O2, HO2, and NO x (x = 1–2) radicals, were studied, and the role of mineral dust in the form of silicate clusters on the reaction mechanism and rate constant was studied. In the gas phase, OH radical addition to HFO-1234zc is kinetically more favorable than the H-atom abstraction reaction. The calculated reaction energy barrier and thermochemical parameters show that both the initial reactions are more feasible on silicate clusters. Thus, silicates can act as chemical sinks for trapping of hydrofluoroolefins (HFOs). It is found that both gas-phase and heterogeneous reactions are responsible for the transformation of HFOs into fluorinated compounds in the atmosphere. Further, the results show that the ozone creation potential of HFO-1234zc is low, and few of the products are harmful to aquatic organisms. This study provides new insights on the formation of toxic pollutants from the oxidation of HFO-1234zc, which may have significant implications in the troposphere.

Reactions of Anthropogenic Gas CHF2OCH2CF2CHF2 (HFE-356pcf3): Climatic Influences and Formation of Carbonyl Intermediates

“…The adverse effects of fully halogenated chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) on stratospheric ozone depletion led to the adoption of the Montreal Protocol, which phased out these compounds globally. − Recently, oxygenated hydrofluorocarbons (HFOCs), such as hydrofluoroethers (HFEs) − and hydrofluoroalcohols (HFAs), − and hydrofluoroolefins (HFOs) − have emerged as promising new generation ozone-friendly alternatives as they meet various industrial and commercial needs. However, these compounds have high radiative efficiency due to the presence of the C–F bond and are, therefore, strong fluorinated greenhouse gases (GHGs). − In addition, there is growing interest in the possibility that atmospheric oxidation of HFOCs and HFOs produces short-chain perfluorocarboxylic acids − or carbonyl intermediates. − Thus, the environmental impact of these molecules is the subject of active discussion.…”