Optimization of the photochemical generation of trifluoronitromethane, CF3NO2, and a refined purification technique

The gas-phase photochemical generation of CF3NO2 from CF3I and NO2 was found to be equilibrium limited. The formation of CF3NO2 is favored at low pressure and high temperature, where the concentration of the reactive species NO2 is the greatest, and unfavored at high pressure and low temperature, where the concentration of N2O4 is greatest. The results from varying the stoichiometric ratio of reactants, pressure, temperature, and reaction time in an attempted scale-up of this reaction are consistent with the reaction being equilibrium limited. The best reaction conditions allowed the generation of only 1–3 g of CF3NO2 per batch reaction in an approximate 16-L vessel. As long as reaction conditions are chosen so that all of the starting CF3I is consumed, caustic scrubbing affords a significantly faster, less expensive, and more practical purification method than those previously published.