The gas phase acidities of fluorinated acetones. An ion cyclotron resonance investigation of the role of fluorine substituents in the stabilization of planar carbanions

Abstract

The gas phase acidities of a series of fluorinated acetones and acetylfluoride have been determined. The results obtained are interpreted in terms of a model for fluorine substituents in planar carbanions in which fluorine exerts an overall stabilizing influence on enolate ions, but also has a component in the interaction which is destabilizing via a repulsive interaction between fluorine lone pair electrons and the carbanion centre. Comparisons with solution phase acidities are made and the validity of the model for fluorine substituents discussed.