Infrared study of 6-methylcoumarin in binary solvent mixtures.

The infrared absorption spectra of the carbonyl stretching vibrations of 6-methylcoumarin (6MC) have been investigated in CCl4/ROH mixtures (CCl4/C2H5OH, CCl4/n-C3H7OH, CCl4/i-C3H7OH, and CCl4/t-C5H11OH). Two types of carbonyl stretching vibration bands for 6MC are found with the change of the mole fraction of the aprotic solvent CCl4(X CCl4 in binary solvent mixtures. The dependencies of the frequencies of carbonyl stretching vibrations upsilon(C=O) on X CCl4 allow a distinction and assignment of all species resulting from the solvent-solute interactions. Linear correlations between the upsilon(C=O) of each species and X CCl4 are found. The influence on the transformation of some species caused by the self-associated alcohols is discussed.