Dependence of the furan-2-carbaldehyde conformational equilibrium on solvent dielectric constant: direct evidence from pulsed (Fourier transform) nuclear magnetic resonance

Abstract

Low temperature pulsed (Fourier transform) n.m.r. measurements on very dilute solutions of furan-2-carbaldehyde in trichlorofluoromethane and carbon disulphide, and on a concentrated solution in deuteriodichloromethane, demonstrate the sensitivity to changes in solution dielectric constant of the position of the conformational equilibrium between syn- and anti-forms. A previous estimate of the position of the equilibrium in non-polar solvents is close to the results found in the present study.