Study On Solvent Effects Of Conjugated Carbonyl Compounds By FTIR

The frequency of the carbonyl stretching vibrations (v(C=O)) of two conjugated carbonyl compounds:acetophenone and ethyl methylacrylate in single and binary solvent systems was measured by FTIR to investigate the solvent effects in organic solvents.In the single solvent system, the v(C=O) of each solute were correlated with solvent parameters. And the applicability of these solvent scales was discussed. Solvent acceptor number (AN), Dimroth and Reichardt's parameter Et(30) and Schleyer's linear free energy equation (LFE)(G) were included as the single solvent parameters. It showed the results of correlation between v(C=O) and G was better, and next was the one between v(C=O) and AN. The correlation between v(C=O) and the value of ET(30) were feebleness.The multi-parameters were the revised KBM equation by Buckingham and the version of Bekarek, Katritzky's equation, Krygowski & Fawcett equation, Catalan's equation, Swain's two-solvent parameter equation, KAT equation and the theory linear solvation energy relationships (TLSER). It showed that the Swain's two-solvent parameter equation gives better agreements than any other equations else. And correlation improvement of KBM equation has been obtained on account of the addition of a cross-term which was proposed by Bekarek. Although the correlation of TLSER equation is weak in the present study, the ease in interpreting chemically properties for compounds for which the solvatochromic or other solvent parameters are not readily available made it a promising approach in solvent effects investigation.Four types of binary solvent systems:apolar/apolar, apolar/dipolar, apolar/protic and dipolar/protic have been discussed in detail to explore the interaction between solutes and solvent mixtures. Studies suggested that, apolar solvent mixtures can be seen as ideal solvent mixtures; hydrogen bonding has a predominant influence on solvent-induced IR band shifts; various degrees of preferential solvation appears in all binary systems; no apparent synergistic influence on the carbonyl vibration has been detected for binary solvent mixtures composed of HBA and HBD solvents.