Intramolecular hydrogen bond and molecular conformation. Part 2.—Effect of pressure and temperature on the IR spectra of some hydroxy ketones

The effects of temperature and pressure on the intramolecular hydrogen bonds of some aliphatic hydroxy ketones have been studied in dilute solutions by FTIR spectroscopy. Differences in enthalpy, ΔH, and in partial molar volume, ΔV, between the intramolecularly hydrogen-bonded and hydrogen-bond-free conformers were obtained from an analysis of the OH stretching bands as functions of temperature and pressure. The effect of solvation on ΔH and ΔV has been discussed using a dielectric model combined with molecular mechanics calculations. How the intramolecular hydrogen bonds are influenced by the configuration and substituents of molecules has been discussed in terms of the observed ΔH values.