Oxyhalogen-sulfur chemistry: Oxidation of taurine by chlorite in acidic medium

The reaction between chlorite and the aminosulfonic acid, taurine, has been studied in neutral to acidic pH. The stoichiometry of the reaction was deduced as 3ClO(2)(-) + H2NCH2CH2SO3H + 3H(+) --> Cl(H)NCH2CH2SO3H + 2ClO(2) + 2H(2)O. The formation of chlorotaurine is rapid and is followed by a slower accumulation of chlorine dioxide. The chlorotaurine disproportionates at low pH to give dichlorotaurine and taurine. There is no appreciable reaction between chlorine dioxide and any of the amine species in solution. The reaction is characterized by an induction period during which the reactive species HOCl and H(OH)NCH2CH2SO3H are formed. This is followed by the autocatalytic production of chlorotaurine and chlorine dioxide. The autocatalysis is mediated through the formation of the intermediate Cl2O2, which is typical of the reactions of chlorite. One notable result obtained in this study was that the C-S bond in taurine does not cleave even when subjected to a strong oxidizing agent, HOCl.