ABSTRACT
O nuclear magnetic resonance (NMR) spectroscopy is an important method for assessment of numerous structural problems in organic chemistry. This chapter reviews the effect of intramolecular and intermolecular hydrogen bonding on O NMR chemical shifts including hydrogen-bonding solvent interactions from a historical viewpoint. It describes intramolecular hydrogen-bonding studies involving NH and OH proton donors on the O NMR data for carbonyl groups that are currently ongoing in our laboratories. An extensive O NMR study of acetophenones and benzylaldehydes by Fiat and coworkers in 1981 showed the importance of intramolecular hydrogen-bonding effects. Substituent and steric effects were thought to be one order of magnitude smaller than the observed intramolecular hydrogen-bonding effects based on the O NMR data of the analogous o-methoxy substituted compounds. Solvent effect studies by O NMR spectroscopy hold considerable promise for study of solute-solvent interactions, including detection of intramolecular hydrogen bonding by the lack of appreciable solvent effects.
