Coulometric–potentiometric titration of bases and acids in γ-butyrolactone Original Research Article

The coulometric generation of hydrogen ions by the anodic oxidation of esters of gallic acid (methyl, ethyl, propyl and octyl gallate), hydroquinone, ascorbic acid, 2,3,4-trihydroxybenzoic acid, tiron and hydrogen dissolved in palladium in γ-butyrolactone is described. The current–potential curves recorded for these depolarizers, titrated bases, indicator and solvent used showed that the investigated depolarizers were oxidized at more negative potentials than the oxidation potential of the titrated base and other components in the solution. The generated hydrogen ions were used for the titration of organic bases (triethylamine, N,N′-diphenylguanidine, piperidine and quinoline) with visual and potentiometric end-point detection. The current efficiency was 100%. The coulometric generation of bases (m-cresolate ions) by the cathode reduction of m-cresol in γ-butyrolactone (GBL) is described. The current efficiency was 100%.