Rate coefficients for the CH(X2Π) + CHX3 (X = Cl and Br) reactions and the propensity of the reactions of CH with halomethanes

Abstract

Methylidyne (CH) was generated in the ultraviolet multiphoton photolysis of CHCl3 and CHBr3 and detected with laser-induced fluorescence (LIF) via the A2Δ − X2Π (0,0) transition. The time-resolved LIF intensity recorded at varying pressures of CHCl3 and CHBr3 has given the overall rate coefficients for the reactions of CH with CHCl3 and CHBr3. The near gas kinetic rates indicate that CH inserts into the C − Cl and C − Br bonds. The correlation between the rate coefficients for the CH + CHnX4−n (X = F, Cl, and Br) reactions and the heats of reactions for H-, Cl-, Br-elimination is elucidated by the Evans − Polanyi principle.