A Kinetic and Mechanistic Study of the Reaction of Cl Atoms with Acrolein:  Temperature Dependence for Abstraction Channel

Rate coefficients for the reaction CH 2 CHCHO + Cl → P (1) at different temperatures (260−333 K) have been determined using a discharge flow-mass spectrometric technique (DF-MS) at low total pressure. k (1) was found to be pressure-independent at T = 298 K in the pressure range 0.5−3 Torr. The temperature dependence of the reaction rate constant has been determined under pseudo-first-order kinetic conditions in excess of acrolein over Cl atoms, with no significant changes in the rate constant. At room temperature and 1 Torr, products of both abstraction (1a) and addition (1b) channels have been detected. The branching ratio for abstraction channel at 298 K and 1 Torr was determined as 0.83 ± 0.13 and led to HCl and CH 2 CHCO* radical. The temperature dependence of this abstraction channel has also been studied, giving the Arrhenius expression k (1a) = (5.4 ± 2.0) × 10 -10 exp{(−748 ± 110)/ T } cm 3 molecule -1 s -1 in the temperature range 260−333 K. The results obtained are related to previous studies, and the mechanism of reaction is discussed.