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 CCl 4/ROH mixtures (CCl 4/C 2H 5OH, CCl 4/ n-C 3H 7OH, CCl 4/ i-C 3H 7OH, and CCl 4/ t-C 5H 11OH). Two types of carbonyl stretching vibration bands for 6MC are found with the change of the mole fraction of the aprotic solvent CC l 4 ( X CC l 4 ) in binary solvent mixtures. The dependencies of the frequencies of carbonyl stretching vibrations υ(C O) on X CC l 4 allow a distinction and assignment of all species resulting from the solvent–solute interactions. Linear correlations between the υ(C O) of each species and X CC l 4 are found. The influence on the transformation of some species caused by the self-associated alcohols is discussed.