Spectroscopic studies on the proton transfer reactions of 4-hydroxy-2-oxo-1,2-dihydroquinolin-3-carbonitrile with different amines in acetonitrile

摘要

Proton transfer reactions between 4-hydroxy-2-oxo-1,2-dihydroquinolin-3-carbonitrile (HQC) and propylamine (PA), triethylamine (TEA) and piperidine (Pip) have been studied spectro-photometrically in acetonitrile as a polar solvent. The molecular compositions of the formed complexes (I, II, and III) were determined using Job's and photometric titration methods. Minimum-maximum absorbances' method has been applied to estimate the formation constants of the formed complexes (K_(PT)). It has been found that KPT reached higher value for HQC-TEA complex than PA and Pip ones. On the basis of the rapidity of the PT-reactions, a simple and accurate spectro-photometric method for determination of HQC was proposed. Beer's law was obeyed in the concentration range 0.19 to18.60 μg mL~(?1) with excellent correlation coefficients. The recovery percentages ranged from 99.63 to 99.99%. The solid complexes were synthesized and characterized using i.r., NMR spectroscopy and elemental analyses.