Historically, reaction rates for the formation of disinfection byproducts through bromination of aromatic compounds were almost exclusively accredited to the species HOBr. However, it has more recently been discovered that several inorganic brominating agents (BrCl, Br2, BrOCl, and Br2O) in equilibrium with HOBr can have a significant impact on bromination rates. We examined rates of bromination of anisole and bromoanisole regioisomers (as model DBP precursors) in solutions of NaBr and free available chlorine. Time course experiments were conducted at 20.00 (�0.02 �C) under pseudo-first-order conditions, in which total free bromine was generated in excess ([HOBr]T/  [parent anisole] = 12) via oxidation of bromide by free chlorine.Key independent variables such as pH, bromide concentration, and chloride concentration were examined for their effects on the rates of bromination. Gas chromatography with mass spectrometry and electron capture detection was used to monitor the loss of parent compound and formation of products.As solution pH increased, rates of bromination decreased significantly. Our results suggest that bromination rates of anisole and its brominated products decrease with increasing bromine substitution. Our findings also provide insight into changes in selectivity toward specific brominating agents with changes in anisole structure.

Reactivity of anisole and bromoanisole regioisomers toward brominating agents in solutions of NaBr + free available chlorine

247th National Meeting (2014)

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