Analytical utility of 2-halopyridinium salts-II Acidimetric determination of thiol groups.
2-Chloro-1-methylpyridinium iodide reacts rapidly and quantitatively with thiol groups in the presence of excess of triethylamine to give the 2-alkyl(aryl)thio-1-methylpyridinium iodide and an equimolar amount of hydrogen chloride which is trapped by the triethylamine. The excess of triethylamine is back-titrated with hydrochloric acid, with Bromothymol Blue as indicator.
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Department of Chemical Technology, Lodz University, 18 Nowotki Street, 91-416 Lodz, Poland.