Pulse radiolysis study of 2,6-pyridine dicarboxylic acid in aqueous solutions

Abstract

The reactions of primary species of water radiolysis viz.e aq −, H-atom and OH radicals and some one electron reductants with 2,6-pyridine dicarboxylic acid were studied at various pHs. The rate constants for these reactions were determined and the values were found to be in the range of 0.3−1 × 10 10 dm 3 mol −1 s −1. Spectral, kinetic, redox and acid-base properties of the transient species were also studied. The transient species formed by e aq − reaction have absorption maxima around 300 and 390 nm. The pk a values of the semireduced species were determined to be 2.1 and 5.4. These species were found to be strong reductants. The species produced by H-atom reaction was also able to reduce methyl viologen but to a lesser extent indicating that only a part of the species produced by H-atom reaction are reducing in nature. OH radicals react by addition to the pyridine ring. The transient spectra have absorption maxima around 350 and 500 nm. pK a values of the OH adducts were determined to be 2.1 and 4.5.