SOLVENT EFFECTS ON INFRARED SPECTROSCOPIC AND CALORIMETRIC CHARACTERISTICS OF ALIPHATIC-KETONES IN BINARY SOLVENT MIXTURES

Solution enthalpies of n-hexane, acetone, butan-2-one and octan-2-one in a series of tetrachloromethane-acetonitrile mixtures and the carbon yl stretching absorption frequencies in the IR spectra of these ketone s were determined. It was found that over the whole range of concentra tions (varying from neat tetrachloromethane up to neat acetonitrile) t he solvation enthalpy of these compounds can be obtained additively fr om the contributions of the alkyl and carbonyl fragments. The solvent effect on the solvation enthalpy of the carbonyl group was found to be satisfactorily correlated with the corresponding IR frequency shifts of the C=O group. It was also found that the sensitivities of the carb onyl IR frequencies to the solvent composition are different for vario us ketones. From both IR and calorimetric data, the preferential solva tion parameters were evaluated. The differences between the IR spectro scopic and calorimetric data are discussed. (C) 1998 John Wiley & Sons , Ltd.