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

Abstract

Box Forest Hall No. 2, Newcastle upon Tyne NE12 9TS By using the interaction with p-nitrophenol as a mechanistic probe it has been established that solutions of Nbromo-N-sodiobenzenesulphonamide (bromamine B) in dilute alkali contain two reactive brominating species, the conjugate acid (PhS0,NHBr) 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 pK, 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 -bromophenylsu1phonamido)propanesulphonate. These data have been used to establish a species distribution diagram and the predictive value of this has been tested.THE chemistry of N-chloro-N-sodiosulphonamides in aqueous solution is reasonably well understood. Recent kinetic studies have established that the reactivity of weakly alkaline solutions of N-chloro-N-sodiotoluene-9-sulphonamide (chloramine T) towards $-cresol,l succinimide,2 and sulphides 3,4 is due to the presence of the conjugate acid, +-MeC,H,SO,NHCl, and/or the disproportionation product, +-MeC,H4S0,NCl, ; hypochlorite was not implicated. Both the dissociation 6 and disproportionation G ~7 constants for N-chlorot oluene-$-sulphonamide have been measured. Surprisingly, almost no information is available on the composition and properties of corresponding solutions of the N-bromo-N-sodiosulphonamides.We are interested in the potential of N-halogenosulphonamide ion as a nucleophile in aqueous solution and have recently described the reactions of the N-chlorospecies with ethylene oxide and propanesultone.8 As essential groundwork for an extension of our nucleophilicity studies to N-bromosulphonamide ion it was decided to investigate the composition of aqueous alkaline solutions of an N-bromo-N-sodiosulphonamide using some convenient organic substrate as a kinetic probe. This work is described in the present paper. EXPERIMENTALReage&.-Reagents used mere of the highest grade commonly available. P-Nitrophenol and toluene-p-sulphonamide were crystallised from toluene and aqueous ethanol (50y0), respectively, before use. Bromamine B (1) was prepared from the sulphonamide, bromine, and aqueous sodium hydroxide by a published p r o c e d ~r e . ~ Repeated recrystallisation from dilute aqueous sodium hydroxide (10-3~) and drying in VUGUO (P,O,) gave the sesquihydrate (Found:

PdCl2 Catalyzed and Uncatalyzed N-Oxidation of Naratriptan with Alkaline Chloramine-T: Delineation of Reaction Mechanisms and Kinetic Modelings

“…Further, Hardy and Jhonston [29] have made detailed calculations on the relative concentrations of the reactive species in alkaline bromamine-B solutions and reported that HOBr is also the predominant species in alkaline medium. Since N-haloamines have similar properties and hence one can expect similar equilibrium for alkaline CAT solutions also as shown below, …”

Kinetics and Mechanistic Chemistry of Sodium N-Halobenzenesulfonamides Oxidative Decolorization of Azo Dye Acid Orange 10 in Acid Medium: Spectrophotometric Approach

“…Since organic N-haloamines have analogous chemical properties, it is predicted that identical equilibria exist in aqueous acidic and basic solutions of these compounds [25][26]. Chloramine-B and bromamine-B act as oxidizing agents in acidic and alkaline media [27][28][29] with a two electron change per mole giving benzenesulfonamide (BSA) and NaCl or NaBr. The redox potential of CAT-PTS couple is pH dependent [25] and decreases with increase in pH of the medium (E redox 1.138 V, 1.778 V, 0.614 V and 0.5 V at pH 0.65, 7.0, 9.7 and 12, respectively).…”

Conversion of imidazoles to imidazolones with chloramine-B: kinetic and mechanistic study

“…The redox potential of CAB/BSA is pH dependent and decreases with increases in pH of the medium. Chloramine-B behaves as a strong electrolyte [19] in aqueous solutions and depending upon the pH of the medium it furnishes following types of reactive species in solutions [19][20][21] (Scheme 2).…”