Spectroscopic studies of isonicotinoyl-, nicotinoyl-, and piconoylhydrazines with chloranil

Isonicotinoyl-, nicotinoyl-, and piconoylhydrazines form molecular complexes with chloranil at pH 9. The composition and stability of these complexes have been studied spectrophotometrically. The results indicate that all complexes were of the 1:1 type and their stabilities depend on the position of the substituent group in the pyridine ring. The method of complexation was used to determine parts per million amounts of INH, NH, PH, and isoniazid tablets in solution spectrophotometrically.