Interactions between amines and aromatic fluoro derivatives. 19F NMR Investigation in [2H8]toluene

Abstract

¹⁹ F NMR chemical shifts of some nitro-fluorobenzenes and of 2-fluoropyridine are recorded in [²H₈]toluene in the presence of variable amounts of amines(butylamine, piperidine and aniline). The Fluorine resonances are shifted upfield by addition of the amine, except for addition of aniline to the solution of 2,4-dinitrofluorobenzene. The shift differences in ¹⁹F spectra are related to an association between the amine and fluoroderivative, mainly involving hydrogen bonding interactions. The data on the apparent stability of the observed complexes are related to the catalystic behaviour of amines in some aromatic nucleophilic substitutions.