Physical Chemistry Chemical Physics vol:1 issue:6 pages:1013-1024
date:Univ Louvain, Dept Chem, B-3001 Louvain, Belgium; Ho Chi Min City Univ Technol, Fac Chem Engn, Ho Chi Min City, Vietnam
The potential energy surface (PES) of [C2H3FO] systems in its electronic ground state has been investigated using density functional theory method, at the B3LYP/6-311+ + G(d,p) level. Ten stable intermediates, including acetyl fluoride (1), fluoroacetaldehyde (9), 1-fluorovinyl alcohol (4), 2-fluorovinyl alcohol, carbenes and fluorooxiranes, have been located. Most stationary points on the PES corresponding to the molecular elimination and rearrangement channels from these intermediates have been identified. Ketene (8) is found to be the predominant product in the unimolecular dissociations of 1, 4, 9 and fluorooxirane (6). The most probable channels for ketene formation from acetyl fluoride are 1 --> 8 and 1 --> 4 --> 8. In the reactions of both CH3CO. and F-. radicals, both these processes are energetically feasible for the thermal reactants and hence should lead to a spontaneous emission of vibrationally hot HF. The present PES characterises the CH3CO. + F-. reaction to be a capture-limited association-elimination reaction with a very high and pressure-independent rate coefficient. In addition to its direct decomposition to ketene, 9 can give rise to stable rearrangement products, viz., 2-fluorovinyl 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.