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E-Journal of Chemistry
Volume 6, Issue 4, Pages 1181-1187
http://dx.doi.org/10.1155/2009/375684

Spectral and Electrochemical Studies of Phenazopyridine

P. Vijaybhaskar and A. Ramachandraiah

Department of Chemistry, National Institute of Technology Warangal, Warangal-506004, Andhra Pradesh, India

Received 3 March 2009; Accepted 4 April 2009

Copyright © 2009 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The spectral and voltammetric behavior of phenazopyridine (1) in aqueous buffers of varied pH is presented. Spectrophotometry, cyclic voltammetry, differential pulse polarography and coulometry were utilized to study its proton and electron transfer characteristics. Relevant thermodynamic and electrochemical data such as pKa, charge transfer co-efficient (αna), forward rate constant (k0f,h), etc., have been evaluated. An excellent electroanalytical method of assaying of 1 has been developed in differential pulse polarography at pH = 8. Molecular modeling on various acid-base conjugates of 1 and their several conformers has been carried out to arrive at the thermodynamic and conformational issues to correlate the spectral and electrochemical observations.