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J Phys Chem A

Title:		OH Radical and Chlorine Atom Kinetics of Substituted Aromatic Compounds: 4-chlorobenzotrifluoride (p-ClC(6)H(4)CF(3))
Author(s):		Chattopadhyay A; Bedjanian Y; Romanias MN; Eleftheriou AD; Melissas VS; Papadimitriou VC; Burkholder JB;
Address:		"Chemical Sciences Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, Colorado 80305-3327, United States. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States. Institut de Combustion, Aerothermique, Reactivite et Environnement (ICARE), CNRS 45071 Orleans Cedex 2, France. Center for Energy and Environment, Institut Mines-Telecom Nord Europe, Universite Lille, F-59000 Lille, France. Laboratory of Photochemistry and Chemical Kinetics, Department of Chemistry, University of Crete, Vassilika Vouton, 70013, Heraklion, Crete, Greece. Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece"
Journal Title:		J Phys Chem A
Year:		2022
Volume:		20220809
Issue:		32
Page Number:		5407 - 5419
DOI:		10.1021/acs.jpca.2c04455
ISSN/ISBN:		1520-5215 (Electronic) 1089-5639 (Linking)
Abstract:		"The mechanisms for the OH radical and Cl atom gas-phase reaction kinetics of substituted aromatic compounds remain a topic of atmospheric and combustion chemistry research. 4-Chlorobenzotrifluoride (p-chlorobenzotrifluoride, p-ClC(6)H(4)CF(3), PCBTF) is a commonly used substituted aromatic volatile organic compound (VOC) in solvent-based coatings. As such, PCBTF is classified as a volatile chemical product (VCP) whose release into the atmosphere potentially impacts air quality. In this study, rate coefficients, k(1), for the OH + PCBTF reaction were measured over the temperature ranges 275-340 and 385-940 K using low-pressure discharge flow-tube reactors coupled with a mass spectrometer detector in the ICARE/CNRS (Orleans, France) laboratory. k(1)(298-353 K) was also measured using a relative rate method in the thermally regulated atmospheric simulation chamber (THALAMOS; Douai, France). k(1)(T) displayed a non-Arrhenius temperature dependence with a negative temperature dependence between 275 and 385 K given by k(1)(275-385 K) = (1.50 +/- 0.15) x 10(-14) exp((705 +/- 30)/T) cm(3) molecule(-1) s(-1), where k(1)(298 K) = (1.63 +/- 0.03) x 10(-13) cm(3) molecule(-1) s(-1) and a positive temperature dependence at elevated temperatures given by k(1)(470-950 K) = (5.42 +/- 0.40) x 10(-12) exp(-(2507 +/- 45) /T) cm(3) molecule(-1) s(-1). The present k(1)(298 K) results are in reasonable agreement with two previous 296 K (760 Torr, syn. air) relative rate measurements. The rate coefficient for the Cl-atom + PCBTF reaction, k(2), was also measured in THALAMOS using a relative rate technique that yielded k(2)(298 K) = (7.8 +/- 2) x 10(-16) cm(3) molecule(-1) s(-1). As part of this work, the UV and infrared absorption spectra of PCBTF were measured (NOAA; Boulder, CO, USA). On the basis of the UV absorption spectrum, the atmospheric instantaneous UV photolysis lifetime of PCBTF (ground level, midlatitude, Summer) was estimated to be 3-4 days, assuming a unit photolysis quantum yield. The non-Arrhenius behavior of the OH + PCBTF reaction over the temperature range 275 to 950 K is interpreted using a mechanism for the formation of an OH-PCBTF adduct and its thermochemical stability. The results from this study are included in a discussion of the OH radical and Cl atom kinetics of halogen substituted aromatic compounds for which only limited temperature-dependent kinetic data are available"
Keywords:
Notes:		"PubMed-not-MEDLINEChattopadhyay, Aparajeo Bedjanian, Yuri Romanias, Manolis N Eleftheriou, Angeliki D Melissas, Vasilios S Papadimitriou, Vassileios C Burkholder, James B eng 2022/08/10 J Phys Chem A. 2022 Aug 18; 126(32):5407-5419. doi: 10.1021/acs.jpca.2c04455. Epub 2022 Aug 9"