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Titolo:
Rate coefficients and mechanistic analysis for the reaction of hydroxyl radicals with 1,1-dichloroethylene and trans-1,2-dichloroethylene over an extended temperature range
Autore:
Yamada, T; El-Sinawi, A; Siraj, M; Taylor, PH; Peng, JP; Hu, XH; Marshall, P;
Indirizzi:
Univ Dayton, Res Inst, Environm Sci & Engn Grp, Dayton, OH 43469 USA Univ Dayton Dayton OH USA 43469 ronm Sci & Engn Grp, Dayton, OH 43469 USA Univ N Texas, Dept Chem, Denton, TX 76203 USA Univ N Texas Denton TX USA 76203 N Texas, Dept Chem, Denton, TX 76203 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY A
fascicolo: 32, volume: 105, anno: 2001,
pagine: 7588 - 7597
SICI:
1089-5639(20010816)105:32<7588:RCAMAF>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
RATE CONSTANTS; NITROUS-ACID; OH RADICALS; TETRACHLOROETHYLENE; KINETICS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Taylor, PH Univ Dayton, Res Inst, Environm Sci & Engn Grp, 300 Coll Pk, Dayton, OH 43469 USA Univ Dayton 300 Coll Pk Dayton OH USA 43469 ayton, OH 43469 USA
Citazione:
T. Yamada et al., "Rate coefficients and mechanistic analysis for the reaction of hydroxyl radicals with 1,1-dichloroethylene and trans-1,2-dichloroethylene over an extended temperature range", J PHYS CH A, 105(32), 2001, pp. 7588-7597

Abstract

Rate coefficients are reported for the gas-phase reaction of the hydroxyl radical (OH) with 1,1-dichloroethylene (k(1)) and trans- 1,2-dichloroethylene (k(2)) over an extended temperature range at 740 +/- 10 Torr in a He bath gas. Absolute rate measurements were obtained using a laser photolysis/laser-induced fluorescence (LP/LIF) technique under slow flow conditions. Rate measurements for k(1) exhibited complex behavior with negative temperature dependence at temperatures below 640 K, a rapid falloff in rate between 650 and 700 K, and positive temperature dependence from 700 to 750 K. The simple Arrhenius equation adequately describes the data below 640 K and above700 K and is given (in units of cm(3) molecule(-1) s(-1)) by k(1)(291-640 K) = (1.81 +/- 0.36) x 10(-12) exp(511 +/- 71)/T and k(1)(700-750 K) = 3.13x 10(-10) exp(-5176/T). Rate measurements for k2 also exhibited complex behavior with a near-zero or slightly negative temperature dependence below 500 K and a near-zero or slightly positive temperature dependence above 500 K. The modified Arrhenius equation adequately describes all of the data andis given (in units of cm(3) molecule(-1) s(-1)) by k(2)(293-720 K) = (9.75+/- 1.14) x 10(-18) T1.73 +/- 0.05 exp(727 +/- 46)/T. Error limits are 2 sigma values. The room-temperature values for k(1) and k(2) are within +/-2 sigma of previous data using different techniques. The rate measurements were modeled using, QRRK theory. OH addition to the unsubstituted carbon followed by adduct stabilization describes the low-temperature measurements fork(1). Analysis of equilibration in this system yields a C-O bond dissociation enthalpy of 32.8 +/- 1.5 kcal mol(-1) at 298 K, a value confirmed by abinitio calculations. OH addition followed by Cl elimination described the experimental data for k(2). Ab initio based transition state calculations for the H atom abstraction channel indicated that this mechanism is consistent with the rate measurements for k(1) above 700 K. The H abstraction channel for k(2) could not be observed because of the presence of a more rapid Cl elimination channel at elevated temperatures. H abstraction is predicted to be the dominant reaction channel for both k(1) and k(2) at flame temperatures.

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Documento generato il 29/09/20 alle ore 10:30:20