CALORIMETRIC AND INFRARED SPECTROPHOTOMETRIC STUDY OF ETHAMBUTOL DIHYDROCHLORIDE

The binary phase diagram of [S,S(+)]-ethambutol dihydrochloride, a chemotherapeutic drug, and its [R,R(-)]-enantiomer, has been determined by IR spectroscopy, X-ray podwer diffraction and differential scanning calorimetry, the equimolecular mixture of [S,S(+)]/[R,R(-)] corresponds to a racemic compound. The infrared spectra of enantiomers and racemic compound differ especially in the finger print region. The solid-solid transition and fusion enthalpies and entropies for the optically active compounds and the corresponding racemic compound have been determined. The stability of the racemic compound has been evaluated on the basis of free energy of formation. In this paper the results of calorimetric and spectroscopic analyses for the determination of enantiomeric purity of ethambutol dihydrochloride have been reported.