Theoretical Prediction of the Thermochemistry and Kinetics of Reactions of CF20 with Hydrogen Atom and Water

A theoretical investigation of transition states and reaction products for reaction of carbonyl difluoride (CF20) with H atoms and water has been conducted. Bond-additivity-corrected (BAC) MP4 calculations have been used to obtain the thermochemistry of equilibrium and transition state structures. R R W m a s t e r equation as well as bimolecular-QRRK analysis of the H atom reaction manifold has been compared with available experimental rate constants and shows excellent agreement. The major reaction pathway is through attack on the oxygen, followed by chemically activated 1,2-elimination of HF. Analysis of carbonyl difluoride reaction with water indicates that the primary reaction is through a concerted reaction to form fluoroformic acid (FCO(0H)) and HF. Calculated rate constants for CF20 with water are considerably slower than reaction with H atoms, and even in hydrocarbon flames, where the water concentration is high, the H atom reaction should dominate. Reaction with OH was found not to be competitive with the other two processes and proceeds to FC02 + HF