Benzothiazoline Converts SO2 to Sulfuric Acid en Route to Benzothiazole

Abstract

By a new sustainable strategy, sulfur dioxide (SO2) was converted at room temperature into sulfuric acid by taking advantage of the spontaneous aerial oxidation of benzothiazoline into benzothiazole. 2-(4-Methoxyphenyl)benzothiazoline (HL) was reacted with SO2 at room temperature, and the adduct upon reaction with aerial oxygen produced 2-(4-methoxyphenyl)benzothiazolium bisulfate. The same strategy was applied on [CdL2] and [ZnL2] and found to work better than neat benzothiazoline. Bunte salt, S-(2-((pyridin-1-ium-2-ylmethyl)amino)phenyl) thiosulfate, was obtained upon reacting SO2 with 2-(pyridin-2-yl)-2,3-dihydrobenzothiazole which is an important clue for the intermediates involved in the S-oxygenation of SO2 bound on electron rich centers. This sustainable route offers a new avenue of utilizing the suicidal reaction of benzothiazoline into benzothiazole in the activation of SO2 with the help of aerial oxygen.