Kinetics and mechanism of the reaction of aqueous sulfite with N-chloroalanylalanylalanine

The rate of the reaction of aqueous sulfite with the N‐chloropeptide N‐chloroalanylalanylalanine has been studied as a function of pH, temperature, and ionic strength. The results of this work suggest that the mechanism of the reaction involves the interaction of the neutral chloramine with the three ionic forms of sulfite, SO 3−2, HSO 3−, and H2SO3, with the rate of reaction increasing rapidly with increasing protonation. The estimated second‐order rate constants for each ionic species as a function of temperature are \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm H}_{\rm 2} {\rm SO}_{\rm 3} } \hfill & {k_1 \, = \,2.00\, \times \,10^8 \,{\rm exp}\left( {{{ - 1544} \mathord{\left/ {\vphantom {{ - 1544} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right){\rm min}^{ - 1} } \hfill \\ {{\rm HSO}_{\rm 3}^ - } \hfill & {k_2 \, = \,4.35\, \times \,10^4 \,{\rm exp}\left( {{{ - 1170} \mathord{\left/ {\vphantom {{ - 1170} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right){\rm min}^{ - 1} } \hfill \\ {\,\,{\rm SO}_{\rm 3}^{ - 2} } \hfill & {k_3 \, = 1.58\, \times \,10^{12} \,{\rm exp}\left( {{{ - 12,660} \mathord{\left/ {\vphantom {{ - 12,660} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right){\rm min}^{ - 1} } \hfill \\ \end{array} $$\end{document} where the activation energies are in units of cal/mol.