Solvent Effects on the Stability Constants of the Molecular Complexes of Chloranil with Benzoic and Salicylic Acids

F.C. College, Diamond Harbour, 24-Parganas (S)-743 331 Department of Chemistry, University of Kalyani, Kalyam-741 235 Manuscript received 6 July 1995, revised 28 February 1996, accepted 8 March 1996 In order to explore the role of solvents on the molecular complexes, the stability or the formation constants of the molecular complexes of chloranil with benzoic and salicylic acids have been determined in different solvents. The stability constants of the complexes are high indicating fairly stable complex formation resulting from both specific (i.e. chemical) and non-specific (i.e. physical) interactions. The formation constants for the benzoic acid complexes are higher in aromatic solvents but lower in aliphatic solvents but the reverse has been found to be true in case of salicylic acid complexes. The intramolecular hydrogen bonding in case of salicylic acid may be the reasons for the changes in chemical and physical interactions. The correlations of ∆GS°of the complexes against (ԑ — 1)/(2ԑ + 1) and ∆GS° against ET (30) (solvent polarity) have been attempted to understand the role of solvents with limited success