On The Importance Of The Reaction CH₂+N₂ → HCN+NH As A Precursor For Prompt No Formation

The rate of the reaction CH₂+ N₂is modeled by transition state (RRKM) theory in order to evaluate its importance as a candidate precursor for so-called “prompt” NO formation in flame fronts. The transition state parameters are based on the best available thermochemical and kinetic data, assuming a “tight” complex. The rate constant predicted by the model for the triplet ground state has the form k= 8 x10^-12 exp(- 18,000/T) cm³/molecule-sec. Nearly identical results were obtained for the singlet first excited state, assuming a zero activation energy for the addition of CH₂to N₂. These rate constants are a factor of 675–85 smaller than the experimental values reported for the reaction CH + N₂ in the temperature range 1500–2000 K. Thus the reaction of CH₂ with N₂is unlikely to be an important precursor of prompt NO formation.