Fluorinated anions

Abstract

Each of my four main areas of work is concerned with the formation and further reactions of organic fluorinated anions. a) We have investigated the fluoride ion induced reactions of 2H-pentafluoropropene with some perfluoro-aromatic compounds, forming a series of aryl substituted carbon acids and their corresponding carbanions. Also included is a study of an unusual product that was formed with pentafluoronitrobenzene as the aromatic substrate. b) Some fluorinated dienes have been generated from the fluoride ion induced reactions of dimethylacetylenedicarboxylate with a series of cyclic fluorinated alkenes. With perfluorocyclohexene, a variable temperature n.m.r. investigation indicated that one of the products was fluxional at room temperature. Products derived from, perfluorocyclopentene were then further reacted with mono- and bi-functional nucleophiles forming some new products including some interesting polycyclic compounds. c) We have studied the fluoride ion induced reactions of malononitrile and phenylsulphonylacetonitrile with a range of polyfluorinated aromatic and heteroaromatic systems. This study has yielded a series of stable fluorinated organic caesium salts which could be crystallised. Acidification of these salts yielded a series of conjugate acids and some acidity measurements were made. Analysis of n.m.r. data has shed some light on the n.m.r. consequences of tautomerisation which was observed in some of the conjugate acids. A highly unusual carbon-13 n.m.r. concentration effect was studied for several pyrimidyl salts in perdeuteroacetone solution. d) The reaction of bifunctional carbon acids with fluorinated dienes has been used to develop a route to new pentadienyl anions, cyclopentadienes, and cyclopentadienyl anions. FAB mass spectroscopy has proved to be an important tool in the study of our anionic species. Some unusual thermal isomerisation behaviour of the new cyclopentadienes has also been observed and investigated.