Intramolecular hydrogen bond and molecular conformation. Part 1.—Effect of pressure and temperature on the infrared spectra of 4-hydroxy-4-methylpentan-2-one (diacetone alcohol) in dilute solutions

Abstract

Infrared spectra of 4-hydroxy-4-methylpentan-2-one in dilute solutions in carbon tetrachloride and in carbon disulfide have been measured at various pressures and temperatures. The overlapping OH stretching bands of the intramolecularly hydrogen-bonded OH and hydrogen-bond-free OH were resolved by least-squares fitting. From the temperature and pressure dependence of the band intensities, changes in the enthalpy, entropy and partial molar volume due to a break of an intramolecular hydrogen bond have been obtained. Both the changes in the enthalpy and in the partial molar volume are fairly well reproduced by a dielectric model of solvation combined with molecular mechanics calculations.