Experimental and Computational Investigations of the Tropospheric Photooxidation Reactions of 1,1,1,3,3,3-Hexafluoro-2-Methyl-2-Propanol Initiated by OH Radicals and Cl Atoms

Abstract

The gas-phase kinetics for the reactions of OH radicals and Cl atoms with 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol (HF2M2P) were measured at temperatures between 268 and 363 K using the relative rate experimental technique. Methane and acetonitrile were used as reference compounds to measure the rate coefficients of the title reactions. For the reactions of HF2M2P with OH radicals and Cl atoms, the rate coefficients were measured to be ( 7.07 ± 1.21) × 10 −15 and (2.85 ± 0.54) × 10 −14 cm 3 molecule −1 s −1 , respectively, at 298 K. The obtained Arrhenius expressions for the reactions of HF2M2P with OH radicals and Cl atoms are k HF2M2P + OH Exp − (268 − 363 K) = (7.84 ± 0.75) × 10 −14 exp [−(717 ± 59)/T] and k HF2M2P + Cl Exp − (268 − 363 K) = (3.21 ± 0.45) × 10 −12 exp [−(1395 ± 83)/T] cm 3 molecule −1 s −1 .In addition to the experimental measurements, computational kinetic calculations were also performed for the title reactions at the M06-2X/MG3S//M06-2X/6-31 + G(d,p) level of theory using advanced methods such as the canonical variational transitionstate theory coupled with small curvature tunneling corrections at temperatures between 200 and 400 K. Theoretical calculations reveal that the H-abstraction from the CH 3 group is a more favorable reaction channel than that from the OH group. Thermochemistry, branching ratios, cumulative atmospheric lifetime, global warming potential, acidification potential, and photochemical ozone creation potential of HF2M2P were calculated in the present investigation.

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

“…The M06-2X method is known to be a more reliable method to calculate the energetics, thermochemistry, and kinetics of atmospheric chemical reactions. Previous studies from many research groups − and our group − showed that the results obtained from the M06-2X method are comparable with the available experimental results.…”

Auxiliary Therapeutic Role of Cholinergic Agents: Mechanistic Insights into the Antioxidant Behavior of Alzheimer’s Disease Drugs

“…The kinetics of the corresponding reactions, representing the antioxidant property of each of the investigated drugs, which includes the reactants, transition states, complexes, and the products of the reaction with hydroperoxyl radicals, was investigated with the Minnesota hybrid meta functional M06-2X in conjugation with the 6-31+G­(d,p) basis set. M06-2X was employed because of its greater reliability in comparison with the B3LYP functional in kinetic calculations. − In fact, the M06-2X method was specially developed for thermochemistry and kinetic study of chemical reactions and since then has been used extensively for studying H-abstraction reactions. − The rate constant values obtained from the M06-2X method were comparable to the experimental results in a wide temperature range. Only the CCSD­(T) method with a reasonably good correlation consistent with the triple zeta basis set (like cc-pVTZ) can provide comparable/better results, but such a method could not be used due to the large size of the systems, and therefore, the M06-2X method was followed throughout in the present study.…”