19F nuclear magnetic resonance studies of aromatic compounds. Part I. The effect of solvents on the chemical shift of fluorine nuclei in para-substituted fluorobenzenes, 4-substituted 4′-fluoro-trans-stilbenes, and 4-substituted 3′-fluoro-trans-stilbenes

Abstract

Solvent effects upon ¹⁹F shielding in some aryl fluorides are examined. A criterion is established which, it is believed, enables solvents and reference to be chosen so that interactions other than those due to ‘reaction fields’ are minimised. The reaction field model appears to work satisfactorily for 4-substituted 3′- and 4′-fluoro-trans-stilbenes, but breaks down for para-substituted fluorobenzenes.