Polyfluoroalkyl derivatives of nitrogen. Part XXXIII. The kinetics of the reaction between trifluoronitrosomethane and tetrafluorethylene to form perfluoro-2-methyl-1,2-oxazetidine

Abstract

The kinetics of the reaction between trifluoronitrosomethane and tetrafluoroethylene to give perfluoro-2-methyl-1,2-oxazetidine have been studied for both the gaseous and liquid phase reactions, with mixture compositions in the range 1 : 5 to 5 : 1 trifluoronitrosomethane:tetrafluoroethylene. The gas-phase reaction has been studied at temperatures between 110 and 150° with total initial pressures in the range 125–500 Torr and, with 1,1,2-trichloro-trifluoroethane as solvent, the liquid-phase reaction has been examined between –35 and 80° over a four-fold variation in the initial total concentration of reactants. The reaction is a homogeneous bimolecular reaction in both phases, and the respective second-order rate constants are given by the Arrhenius equations: k(l mol^–1 s^–1)=(3·85 ± 0·78)× 10⁷ exp –(16,200 ± 250/RT), k(l mol^–1 s^–1)=(3·27 ± 0·54)× 10⁶ exp –(13,215 ± 90/RT). It is suggested that the abnormally low pre-exponential factors obtained reflect the formation of the transition state in a specifically orientated collision process, and that the nature of this transition state is similar to those obtained in Diels–Alder addition reactions.