Theoretical investigation of the mechanism and kinetics of the CH 3 NH 2 +O( 3 P) reaction

We present the kinetics and mechanism of the reaction of O (³P) with CH₃NH₂. Geometries of all the stationary points involved in the reaction have been investigated at the B3LYP/6-311+G (d, p) level. We report the potential energy surface for all of the possible pathways by the Gaussian-2 G3B3 method. This is the first time one has gained a conclusive insight into the detailed mechanism and kinetics for this reaction. Using the Rice–Ramsperger–Kassel-Marcus (RRKM) theory, we have computed the rate constants for channels leading to several products over the temperature range 298–440 K. The main reaction channel is found to be addition of an oxygen atom to CH₃NH₂ followed by migration of an H atom from N to O atoms and loss of H₂O, which agrees with experimental results (Slagle, Dudich, and Gutman (1979) J. Phys. Chem., 83). As experimental data are available for this reaction, we are able to conclude that our thermal rate constants are in agreement over a wide range of temperatures.