OXYHALOGEN-SULFUR CHEMISTRY - OXIDATION OF 2-AMINOETHANETHIOLSULFURICACID BY IODATE IN ACIDIC MEDIUM

The oxidation of 2-aminoethanethiolsulfuric acid, AETSA, by iodate has been studied in highly acidic media. The reaction is very slow and sh ows some clock-reaction characteristics in which iodine is formed afte r some induction period. The oxidation of AETSA involves the oxidation of only one of the sulfur atoms to SO42-. The other sulfur atom remai ns attached to the carbon chain as a sulfonic acid (taurine). The stoi chiometry of the reaction is: IO3- + H2NCH2CH2S-SO3H + H2O --> H2NCH2C H2SO3H + I- + SO42- + 2H(+). The reaction of I-2 and AETSA was found t o be slow and autoinhibitory as the I- formed combines with the remain ing I-2 to form the relatively unreactive triiodide ion, I-3(-). The s econd-order rate constant for the reaction between I-2 and AETSA was d etermined as 16.7 +/- 2.3 M-1 s(-1).