Thermodynamic Consideration of the Charge Transfer Interaction of the Donor: Acceptor Type between Chloranilic Acid and Haloperidol

Abstract

The thermodynamic parameters of the charge transfer complex between chloranilic acid and haloperidol were studied. Haloperidol in pure form and in dosage form was assayed in this study. The method was based on charge transfer complex formation between the drug, which acted as an n-donor, and chloranilic acid, which acted as a p acceptor in a non aqueous solvent. The complex stoichiometry was found to be 1 : 2 (haloperidol : chloranilic acid) with the maximum absorption band at a wavelength of 576 nm. The complex obeyed Beer’s law. The thermodynamic parameters investigated included stability constant, molar absorptivity, free energy change, enthalpy, and entropy. The method was successfully applied in the analysis of commercially available haloperidol tablets without interference from its excipients, with good precision and reproducibility, compared with the official assay method (non aqueous titration) described for haloperidol in the compendium.