Diode laser probes of vinyl radical kinetics: The reaction of C2H3 with HCl and DCl

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Abstract
A tunable diode laser probe is used to measure the rate of reaction of vinyl radicals with HCl and DCl at room temperature. Rate constants for reaction with HCl and DCl are (1.3±0.3)×10− 1 2 and (7.8±1.6)×10− 1 3 cc/molecule s, respectively. These rate constants are about five orders of magnitude faster than the estimated rate constant for reaction of vinyl radicals with H2, and potential reasons for these differences are considered within the context of the BSBL (bond strength–bond length) model of atom abstraction reactions. The rate constant for reaction of C2H3 with O2 is determined to be (1.0±0.4)×10− 1 1 cc/molecule s, in excellent agreement with a previous determination. Finally, the temperature dependence of the vinyl radical + HCl rate constant is reported. The rate constant is found to decrease by approximately 33% over the temperature range of 278–370 K. This change, however, is within the experimental error of the measured rate constants. From these measurements, an activation energy of −840±1400 (2σ) cal/mol is obtained.