Unraveling the Autoxidation Mechanisms of Limonene, α-Pinene, and β-Pinene: A Computational Study with Reactivity Prediction Models.

The hydrogen shift reactions of peroxy radicals derived from the ȮH-initiated oxidation of three atmospherically important monoterpenes, limonene, α-pinene, and β-pinene, have been studied. The Bell-Evans-Polanyi relationship (BEPR), Marcus cross relationship (MCR), and Robert-Steel relationship (RSR) are employed to study the factors that contribute to the kinetics of the H-shift reactions. Our results show distinct kinetic behaviors based on the size of the transition-state ring, the functional group present at the H atom abstraction site, and the type of carbon-centered radical formed.

Tailoring the mechanistic pathways and kinetics of OH-addition reaction of sulfoxaflor and its ecotoxicity assessment.

Sulfoxaflor is one of the widely used insecticides in agricultural lands to protect crops from insects. Due to its persistent nature, sulfoxaflor is identified as an environmental pollutant. In the present work, the mechanism and kinetics of sulfoxaflor degradation initiated by OH radical addition reaction are studied by using quantum chemical calculations.

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.

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 O, HO, and NO ( = 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.

Conformation-dependent antioxidant properties of β-carotene.

The antioxidant capacity of β-carotene has been studied in terms of H-atom abstraction reactions using quantum chemical methods. These oxidation reactions are studied for the all- as well as 15,15'- isomers (15) of β-carotene, as the latter is only ∼10 kJ mol less stable than the all- isomer in the gas phase and about 9 kJ mol less stable in aqueous solution. Hydrogen abstraction from the rotamers obtained through C-C single and double bond rotations has been shown to play an important role in determining the antioxidant capacity of β-carotene.

Mechanism, Kinetics, and Ecotoxicity Assessment of ·OH-Initiated Oxidation Reactions of Sulfoxaflor.

The ·OH-initiated reaction mechanism and kinetics of sulfoxaflor were investigated by using electronic structure calculations. The possible hydrogen atom and cyano group abstraction reaction pathways were studied, and the calculated thermochemical parameters show that the hydrogen atom abstraction from the C7 carbon atom is the more favorable reaction pathway. The subsequent reactions for the favorable intermediate () with other atmospheric reactive species, such as O, HO, HO·, and NO· ( = 1, 2), were studied in detail.