Theoretical studies on atmospheric chemistry of (CF3)2C(OH)CH3: Kinetics, mechanism and thermochemistry of gas phase reactions with OH radicals

Lily, Makroni; Chandra, Asit K.

doi:10.1016/j.jfluchem.2015.04.019

Cited by 13 publications

(14 citation statements)

References 33 publications

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“…Both the experimental and computed rate coefficients for reaction R1 at 298 K are k R1 Exp – 298 K = (7.07 ± 1.21) × 10 –15 and k R1 The – 298 K = 8.34 × 10 –15 cm 3 molecule –1 s –1 , respectively, and show a good agreement. Both these obtained rate coefficients show a good agreement with the previously reported ones by Orkin et al [(7.84 ± 0.12) × 10 –15 cm 3 molecule –1 s –1 ] and Lily and Chandra [7.46 × 10 –15 cm 3 molecule –1 s –1 ] within the error limits. In the studied temperature range, both the measured and computed rate coefficients increase with an increase in temperature.…”

Section: Resultssupporting

confidence: 91%

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

Kumar

Srinivasulu

Vijayakumar³

et al. 2021

J. Phys. Chem. A

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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.

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Section: Resultssupporting

confidence: 91%

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

Kumar

Srinivasulu

Vijayakumar³

et al. 2021

J. Phys. Chem. A

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“…Geometry optimization and vibrational frequency calculations for stable parent molecules, products, intermediate radicals, and transition state structures for the OH radical reaction with CF 2 CHF were performed using the hybrid density functional theory method at the M06-2X level with the 6-311++G(2d,d,p) and aug-cc-pVDZ basis sets as well as the composite CBS-QB3 method . Previous studies showed that reaction pathways and the kinetic analysis of fluorinated alkanes/alkenes can be determined accurately by the use of the M06-2X level of theory. − The activation barrier computed by M06-2X in this study is in satisfactory agreement with CBS-QB3 calculations. The absence of imaginary frequencies is verified to confirm the stable structures for molecules and radicals at their true minima for each respective level of theory.…”

Section: Methodsmentioning

confidence: 99%

Kinetic Analysis of Unimolecular Reactions Following the Addition of the Hydroxyl Radical to 1,1,2-Trifluoroethene

2021

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Fluorinated olefins are valued chemicals in industry, especially as heat transfer fluids in refrigeration applications. As these volatile compounds are widely used, they may be released into the atmosphere, and investigation of their reactions in the atmosphere are therefore of importance. The kinetic analysis of the reaction mechanisms of trifluoroethene (CF 2 CHF) with hydroxyl radicals is studied using computational chemistry at the M06-2X level with the 6-311+ +G(2d,d,p) and aug-cc-pVDZ basis sets as well as the composite CBS-QB3 method. Rate coefficients for the proposed mechanisms are calculated using transition state theory (TST) with tunneling corrections. The calculated rate constants for OH addition to CF 2 CHF are in excellent agreement with experimental values. Kinetic parameters as a function of temperature and pressure are evaluated for the chemically activated formation and unimolecular dissociation of hydroxylfluoroalkyl intermediates. Important forward reactions result in adduct stabilization, H atoms, hydrogen fluoride (HF) via molecular elimination, and formation of fluorinated carbonyl radicals with CF 2 (O) and CHF(O) product channels. Stabilization of initial adducts along with HF elimination are important reaction pathways under high pressure and low temperatures. Important HF eliminations and H atom transfers primarily involve H atoms from the hydroxyl group, as the C−H bonds on or adjacent to carbons with F atoms are stronger and show high barriers to H atom transfer.

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“…1 They are mainly used as pesticides, lubricating agent, fuel additives and as warfare agents. 2 They are also used to synthesize the plasticizers. 3 OP's mechanism of action depend on their binding properties to enzyme acetylcholinesterase at the nerve synapse so as to inhibite the hydrolysis of the neurotransmitter acetylcholine.…”

Section: Introductionmentioning

confidence: 99%

Photodegradation kinetics of organophosphorous with hydroxyl radicals: Experimental and theoretical study

Aydogdu

Hatipoğlu

Eren

et al. 2021

JSCS

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The presence of organophosphorus compounds (OPs) in the environmental counterparts has been an important problem because of their toxicity. In this study, the photocatalytic degradation reactions of the three OPs with hydroxyl radical were investigated by both experimental and quantum chemical methods. Photocatalytic degradation kinetics of organophosphorus compounds were investigated under UV-A irradiation using TiO2 as the photocatalyst. The effects of the initial concentrations on the degradation rate have been examined. There was an observable loss of OPs in the presence of TiO2 photocatalyst under UV-A at 0.2 g TiO2 per 100 mL. The quantum chemical calculations have been carried out by the Density Functional Theory (DFT) at B3LYP/6-31g(d) level. Reaction pathways were modeled to find the most probable mechanism for OPs with the OH radical and to determine the primary intermediates. The rate constants of the eight reaction paths were calculated by the Transition State Theory. CPCM (Conductor-like Polarizable Continuum Model) was used as the solvation model with the intention of understanding the water effect. Theoretical results were in agreement with experimental ones.

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Theoretical studies on atmospheric chemistry of (CF3)2C(OH)CH3: Kinetics, mechanism and thermochemistry of gas phase reactions with OH radicals

Cited by 13 publications

References 33 publications

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

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

Kinetic Analysis of Unimolecular Reactions Following the Addition of the Hydroxyl Radical to 1,1,2-Trifluoroethene

Photodegradation kinetics of organophosphorous with hydroxyl radicals: Experimental and theoretical study

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