Solvent Effects in Nuclear Magnetic Resonance. II. Critical Examination of the Reaction Field

Abstract

The reaction‐field concept is examined quantitatively using nuclear magnetic spectroscopy by determining the magnetic shielding constants of three protons within the same molecule as a function of dielectric constant: the results are based on the fact that the magnetic shielding constant of a bonded proton depends linearly on the effective electric field along the bond axis. It is shown that (1) the reaction field must take on different values at different points in the molecule, and (2) the calculated reaction field's dependence on ε for a dipole in a spherical or spheroidal cavity does not adequately describe the experimental reaction field's dependence on ε.