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|Title:||Synthesis, characterization and electrochemical behaviour of some substituted 3-arylazo-8-aldehydo-4-methylcoumarins at dropping mercury and glassy carbon electrodes|
|Abstract:||A series of 3-arylazo-8-aldehydo-4-methylcoumarins have been synthesized in excellent yields (80-90%) and their structures established on the basis of IR, 1H NMR and elemental analysis. Their purity has been ascertained by chromatographic resolution using acetic acid-toluene (6:4, v/v) as eluent. The electrochemical reduction of 3-arylazo-8-aldehydo-4- methylcoumarins have been studied over a wide pH range at dropping mercury and glassy carbon electrodes. All the compounds found to exhibit well-defined, diffusion-controlled irreversible wave. They give two-electron wave corresponding to the reduction of azo group. On the basis of cyclic voltammetry, coulometry, spectrophotometry, number of protons involved in the rate-determining step, the number of electrons in the reduction and product identification, a plausible reduction mechanism is suggested. Kinetic parameters, i.e. charge-transfer coefficient (αn) and forward rate constant (Kof,h) have also been calculated. The pK values are calculated by polarographic and spectrophotometric method.|
|Appears in Collections:||IJC-B Vol.42B(02) [February 2003]|
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