Article ID Journal Published Year Pages File Type
560969 Egyptian Journal of Basic and Applied Sciences 2016 10 Pages PDF
Abstract

•Square wave.•DME.•Azo compounds.•Betadiketones.

The mostly advanced polarographic mode of measurement, square wave (SW), was applied for studying reduction of for 2,2-Dimethyl-1,3-dioxan-4,6-dione (Meldrum acid) and its 5-phenyl-azo substituent in 40% v/v ethanolic universal buffer (pH~ 2–12). At more negative potentials, a 2e pH-dependent wave (dEp/dpH = 31 mv) was assigned to one carbonyl group, while at more positive potentials a 4e pH-dependent wave (dEp/dpH = 71 mv) was assigned to the azomethine group. Based on the polarographic data and acid-base pKa values were determined spectrophotometrically. The reduction mechanism pathway was suggested. The azomethine group proved to be in the azo form since the nitro group of the p-NO2 derivative is reduced at a more negative potential than the azomethine linkage. Fair Ep-σ correlation was obtained with positive p values (~0.2–0.3), indicating that the substituents facilitate the reduction process at the dropping electrode.

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