INFRARED STUDY OF HEXAHYDROPHTHALIC ANHYDRIDE, HALOGENATED PHTHALIC ANHYDRIDES, HALOGENATED MALEIC-ANHYDRIDE AND STYRENE-MALEIC ANHYDRIDE COPOLYMER IN SOLVENT MIXTURES

The v(C=O)2 modes for carboxylic acid anhydrides decrease in frequency as the solvent solubility parameter value increases. The vout-of-phase(C=O)2 mode for anhydrides decreases more in frequency than the vin-phase(C=O)2 mode in going from CCl4 solution to CHCl3 solution, indicating that it is more difficult for the vin-phase(C=O)2 mode to vibrate than it is for the vout-of-phase(C=O)2 mode in the same solvent system. Solute/solvent interaction induces a change in the Fermi resonance interaction between v(C=O)2 and combination and/or overtones of lower-lying fundamentals as the mole % solvent 1/solvent 2 changes.