Potential energy surface for unimolecular dissociations and rearrangements of the ground state of [C2H3FO] systems

Abstract

The potential energy surface (PES) of systems in its electronic ground state has been investigated [C 2 H 3 FO] using density functional theory method, at the B3LYP/6-311]]G(d,p) level. Ten stable intermediates, including acetyl Ñuoride (1), Ñuoroacetaldehyde (9), 1-Ñuorovinyl alcohol (4), 2-Ñuorovinyl alcohol, carbenes and Ñuorooxiranes, have been located. Most stationary points on the PES corresponding to the molecular elimination and rearrangement channels from these intermediates have been identiÐed. Ketene ( 8) is found to be the predominant product in the unimolecular dissociations of 1, 4, 9 and Ñuorooxirane (6). The most probable channels for ketene formation from acetyl Ñuoride are 1 ] 8 and 1 ] 4 ] 8. In the reactions of both and radicals, both these processes are energetically feasible for the thermal reactants and CH 3 CO~Fh ence should lead to a spontaneous emission of vibrationally hot HF. The present PES characterises the reaction to be a capture-limited associationÈelimination reaction with a very high and CH3 CO~] Fp ressure-independent rate coefficient. In addition to its direct decomposition to ketene, 9 can give rise to stable rearrangement products, viz., 2-Ñuorovinyl alcohol (12) and 6. Fluorooxirane (6) decomposes to ketene through its isomerisation to 9 as intermediate and the present study provides an explanation for the non-observation of this intermediate.