James Pyott Johnston

The interaction of N-bromo-N-sodiobenzenesulphonamide (bromamine B) with p-nitrophenoxide ion

By using the interaction with p-nitrophenol as a mechanistic probe it has been established that solutions of N-bromo-N-sodiobenzenesulphonamide (bromamine B) in dilute alkali contain two reactive brominating species, the conjugate acid (PhSO2NHBr) and hypobromous acid; formation of the latter can be suppressed by the addition of the parent sulphonamide. These solutions are fully described by a system of four equilibria: three are proton transfer reactions, for which pKa values have been obtained, and the fourth is the alkaline hydrolysis of the conjugate acid, for which an equilibrium constant has been estimated from model experiments with sodium 3-(N-bromophenylsulphonamido)propanesulphonate. These data have been used to establish a species distribution diagram and the predictive value of this has been tested.