Theoretical study of the kinetics and mechanism of the decomposition of trifluoromethanol, trichloromethanol, and tribromomethanol in the gas phase

Abstract

Ab initio calculations at the G2 level were used in a theoretical analysis of the kinetics of unimolecular and water-accelerated decomposition of the halogenated alcohols CX(3)OH (X = F, Cl, and Br) into CX(2)O and HX. The calculations show that reactions of the unimolecular decomposition of CX(3)OH are of no importance under atmospheric conditions. A considerably lower energy pathway for the decomposition of CX(3)OH is accessible by homogenous reactions between CX(3)OH and water. It is shown that CX(3)OH + H(2)O reactions proceed via the formation of intermediate complexes. The mechanism of the reactions appears to be complex and consists of three consecutive elementary processes. The calculated values of the second-order rate constants are of 2.5 x 10(-21), 2.1 x 10(-19), and 1.2 x 10(-17) cm(3)molecule(-1)s(-1) at 300 K for CF(3)OH + H(2)O, CCl(3)OH + H(2)O, and CBr(3)OH + H(2)O, respectively. The theoretically derived atmospheric lifetimes of the CX(3)OH molecules indicate that the water-mediated decomposition reactions CX(3)OH + H(2)O may be the most efficient process of CF(3)OH, CCl(3)OH, and CBr(3)OH loss in the atmosphere.

α‐Fluoroalcohols: Synthesis and Characterization of Perfluorinated Methanol, Ethanol and n‐Propanol, and their Oxonium Salts

“…In addition to the experimental study described above, electronic structure computations were carried out to gain a better understanding of the nature of these perfluoroalcohols. Although numerous theoretical studies have been previously carried out on free gaseous CF 3 OH, very little is known on its condensed‐phase chemistry and, particularly, on the higher perfluoroalcohols. Therefore, extensive calculations were carried out at the G3MP2 level of theory for all three fluoroalcohols both in the gas phase and in aqueous solutions.…”

Will water act as a photocatalyst for cluster phase chemical reactions? Vibrational overtone-induced dehydration reaction of methanediol

“…11 Phillips et al 28 have studied the dechlorination reaction CH 2 Cl(OH) → H 2 CO + HCl and again noted a strong catalytic effect of water in clusters of size n = 1, 2, and 3. Brudnik et al 29 likewise noted barrier lowering for dehalogenation reactions of trichloro-, trifluoro-, and tribromomethanol. In previous works, we have demonstrated substantial lowering of the TS barrier by water complexation for the CH 2 FOH → CH 2 O + HF reaction for clusters containing up to three water molecules.…”

Photoelectrochemical reactors for treatment of water and wastewater: a review

“…These processes present some drawbacks such as the need to continuously add reagents such as H2O2 (Oturan and Aaron 2014) or have applicability at a limited pH range. At the end of the nineties, the electrochemical-based advanced oxidation processes have been proposed as an alternative for producing in situ and continuously the oxidant species during the electrolysis, the electron being the main reagent involved (Brillas et al 2009;Panizza and Cerisola 2009;Vasudevan and Oturan 2014;Sirés et al 2014;Martínez-Huitle et al 2015;Moreira et al 2017). These characteristics make electrochemical advanced oxidation processes gaining great interest in the scientific community since degradation and mineralisation yields can reached higher than 99% for a wide range of organic pollutant and organic load represented by a chemical oxygen demand below 100 g-O2 L -1 (Lahkimi et al 2007;Alcántara et al 2009;Mousset et al 2013Mousset et al , 2014aSirés et al 2014;dos Santos et al 2015dos Santos et al , 2017Shukla and Oturan 2015;Ganzenko et al 2018).…”