Kinetics of the Fast Reaction between Nitrogen Dioxide and Fluorine

Abstract

The rate of the reaction between nitrogen dioxide and fluorine to form nitryl fluoride has been measured at 27.7, 50.4, and 70.2°. Light absorption by nitrogen dioxide was used to follow the reaction. By using a 22‐liter Pyrex flask and by going to low concentrations of reactants, between 0.5 and 20×10⁻⁸ moles cc⁻¹, the rate of this fast reaction was reduced to a convenient value. The rate was found to be first order in each reactant, and it showed no dependence on nitryl fluoride. The proposed mechanism is $$\begin{array}{c}{\mathrm{NO}}_2+{\mathrm{F}}_2\to {\displaystyle {lim}^{k_1}}{\mathrm{NO}}_2\mathrm{F}+\mathrm{F}\mathrm{\hspace{0.17em}(}\mathrm{slow}\mathrm{),}\\ {\mathrm{NO}}_2+\mathrm{F}+\mathrm{M}\to {\displaystyle {lim}^{k_2}}{\mathrm{NO}}_2\mathrm{F}+\mathrm{M}\mathrm{\hspace{0.17em}(}\mathrm{fast}\mathrm{).}\end{array}$$ The empirical second order rate constant is k₁, that of an elementary bimolecular reaction. If the rate constant is written as Ae^−E/RT then A is 1.6×10¹² cc moles⁻¹ sec⁻¹ and E is 10.5 kcal.