KINETICS OF REACTION OF HYDROGEN IODIDE WITH 1,1-DIFLUOROETHYLENE

The gas-phase reaction of hydrogen iodide with 1,1-difluoroethylene produces 1,1-difluoro-l-iodoethane, 1,1-difluoroethane, and iodine. l,l-Difluoro-2-iodoethane rarely is observed, and never below 230˚. The activation energy for consumption of 1,1-difluoroethylene is 27.2 ± 0.7 kcal/mole, and the preexponential factor is 1.5 × 108 l.(mol sec). These values are close to those for the reaction of hydrogen iodide with ethylene. The predominant orientation of hydrogen iodide addition is in keeping with an ion-pair model of the transition state. Calculations based on a point-dipole transition-state model lead to the incorrect prediction that the hydrogen iodide addition is anti-Markovnikov. In the reaction of hydrogen iodide with fluoroethylene, silicon tetrafluoride is produced at both 175 and 305˚. Apparently hydrogen fluoride is the product of a side reaction. © 1969, American Chemical Society. All rights reserved.