Hydration of Aza-aromatic Aldehydes. II. Solvent Effect on the Equilibrium Constants of the Hydration

Article abstract of DOI:10.1246/bcsj.54.466

The equilibrium constants for the hydration reaction of 4-pyridinecarbaldehyde were determined in several solvents by 1H-NMR spectroscopic measurements.The hydration reactions were sensitive in the nature of the solvents.In strong donor solvents such as hexamethylphosphoric triamide, pyridine, and dimethyl sulfoxide, formation of the hydrate is far more favorable than in water or other poor donor solvents.Thus the stabilization of the product by hydrogen bond formation is assumed to favor the reaction.Polarity of the solvent does not explain the solvent effect, even if it is supposed to affect the equilibria secondarily.