Nuclear Magnetic Resonance Studies of Sulfur Compounds. III. The Substituent and Solvent Effect on Magnetic Nonequivalence of the Methylene Protons of Phenyl Phenacyl and Phenyl Benzyl Sulfoxides

Abstract

The magnetic nonequivalences between the ceminal protons of phenyl phenacyl sulfoxides and phenyl benzyl sulfoxides have been measured in a variety of solvents. A clear correlation observed between the electron withdrawal power of substituent and V_A-V_B is discussed by considering the geometry of these protons with respect to the S-O bond. It is suggested that reaction field effects, specific solvent-solute interactions, as well as the electronic character of substituents are responsible for the observed change in magnetic nonequivalence. It is also suggested that, by a careful consideration of solvent effects, it is possible to make an assignment of these protons, a method for which has not hitherto been proposed for acyclic systems.