Kinetics of the gas-phase reaction of OH with chlorobenzene.
The kinetics of the reaction of hydroxyl radicals with chlorobenzene was studied experimentally using a pulsed laser photolysis/pulsed laser induced fluorescence technique over a wide range of temperatures, 298-670 K, and at pressures between 13.33 and 39.92 kPa. The bimolecular rate constants demonstrate different behavior at low and high temperatures. At room temperature, T = 298.8 +/- 1.5 K, the rate constant is equal to (6.02 +/- 0.34) x 10(-13) cm3 molecule(-1) s(-1); at high temperatures (474-670 K), the rate constant values are significantly lower and have a positive temperature dependence that can be described by an Arrhenius expression k1(T) = (1.01 +/- 0.35) x 10(-11) exp[(-2490 +/- 170 K)/T] cm3 molecule(-1) s(-1). This behavior is consistent with the low-temperature reaction being dominated by reversible addition and the high-temperature reaction representing abstraction and addition-elimination channels. The potential energy surface of the reaction was studied using quantum chemical methods, and a transition state theory model was developed for all reaction channels. The temperature dependences of the high-temperature rate constants obtained in calculations using the method of isodesmic reactions for transition states (IRTS) and the CBS-QB3 method are in very good agreement with experiment, with deviations smaller than the estimated experimental uncertainties. The G3//B3LYP-based calculated rate constants are in disagreement with the experimental values. The IRTS-based model was used to provide modified Arrhenius expressions for the temperature dependences of the rate constant for the abstraction and addition-elimination (Cl replacement) channels of the reaction.
Bryukov
Mikhail G
MG
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Knyazev
Vadim D
VD
Gehling
William M
WM
Dellinger
Barry
B
D002722:Chlorobenzenes / Q000737:chemistry*; D006256:Hazardous Waste; D006358:Hot Temperature; D017665:Hydroxyl Radical / Q000737:chemistry*; D017745:Incineration; D007700:Kinetics; D008956:Models, Chemical; D044367:Phase Transition; D010782:Photolysis
D002722:Chlorobenzenes; D006256:Hazardous Waste; D017665:Hydroxyl Radical; C031294:chlorobenzene