PYRIDINE-INDUCED SOLVENT SHIFTS IN NUCLEAR MAGNETIC RESONANCE SPECTRA OF HYDROXYLIC COMPOUNDS

Proton chemical shifts for a wide variety of structurally different compounds containing the hydroxyl function have been measured in deuteriochloroform and pyridine-d5 The solvent shifts (Δ = δCDCl. — δC) observed are rationalized in terms of specific solute-solvent complexes between pyridine molecules and the polar hydroxyl function in the solute molecules. It is found that in saturated cyclic systems, protons occupying positions 1,3-diaxial, vicinal, or geminal to a hydroxyl function are deshielded. In phenolic systems, protons ortho to a hydroxyl function experience much larger deshielding effects than protons in the meta or para positions. Pyridine-induced solvent shifts can therefore be extremely useful in establishing both the location and stereochemical nature of protons situated in the vicinity of hydroxyl functions. © 1968, American Chemical Society. All rights reserved.