Experimental and Computational Investigation on the Gas Phase Reaction of p-Cymene with Cl Atoms

Abstract

The rate coefficient for the gas-phase reaction of Cl atoms with p-cymene was determined as a function of temperature (288-350 K) and pressure (700-800 Torr) using the relative rate technique, with 1,3-butadiene and ethylene as reference compounds. Cl atoms were generated by UV photolysis of oxalyl chloride ((COCl)2) at 254 nm, and nitrogen was used as the diluent gas. The rate coefficient for the reaction of Cl atoms with p-cymene at 298 K was measured to be (2.58 ± 1.55) × 10(-10) cm(3) molecule(-1) s(-1). The kinetic data obtained over the temperature range 288-350 K were used to derive an Arrhenius expression: k(T) = (9.36 ± 2.90) × 10(-10) exp[-(488 ± 98)/T] cm(3) molecule(-1) s(-1). Theoretical kinetic calculations were also performed for the title reaction using canonical variational transition state theory (CVT) with small curvature tunneling (SCT) between 250 and 400 K. The calculated rate coefficients obtained over the temperature range 250-400 K were used to derive an Arrhenius expression: k(T) = 5.41 × 10(-13) exp[1837/T] cm(3) molecule(-1) s(-1). Theoretical study indicated that addition channels contribute maximum to the total reaction and H-abstraction channels can be neglected. The atmospheric lifetime (τ) of p-cymene due to its reactions with various tropospheric oxidants was estimated, and it was concluded that the reactions of p-cymene with Cl atoms may compete with OH radicals in the marine boundary layer and in coastal urban areas where the concentration of Cl atoms is high.

Cl Atom Initiated Photo-oxidation of Mono-chlorinated Propanes To Form Carbonyl Compounds: A Kinetic and Mechanistic Approach

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Gas Phase Kinetics of 2,2,2-Trifluoroethylbutyrate with the Cl Atom: An Experimental and Theoretical Study

“…The quoted errors are two least-squares standard deviations and include uncertainties associated with the reported rate coefficients of the both reference reactions. Indicated errors are determined using the error propagation method, which we have discussed in detailed in our recent studies . Cuevas et al studied the rate coefficients of Cl atoms with ethyl acetate over the temperature range of 265–383 K using pulsed laser photolysis-resonance fluorescence technique (PLP-RF) at pressures between 20 and 200 Torr and they have found that there is no pressure dependence within the given uncertainty ranges.…”

Experimental and Theoretical Investigations on the Reaction of 1,3-Butadiene with Cl Atom in the Gas Phase

“…Rate coefficients for the reaction of 1,3-butadiene with Cl atom were measured over the temperature range 269–363 K using relative rate method. The complete experimental setup and the details were given in our earlier publications, − and only a brief and necessary description is given here. All the experiments were performed in a double walled Pyrex chamber of volume 1250 cm 3 .…”