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<p>Despite decades of research on the formation of toxic disinfection by-products (DBPs) during water disinfection with chlorine, considerable uncertainties remain regarding the formation mechanism of toxic DBPs from phenolic precursors. Here we report the use of a series of synthesized ethylparabens containing stable isotope (<sup>13</sup>C) labels at different positions of the molecule to ascertain DBP formation mechanisms from phenols, including those of regulated chloroacetic acids and recently identified α,β-unsaturated dialdehydes and dicarboxylic acids. Our results highlight the involvement of four general ring cleavage pathways. Three of the DBP formation pathways involve carbons originating from the aromatic ring, while the fourth pathway involves the substituent carboxylic ester carbon in the formation of dichloroacetic acid and C<sub>4</sub>-dicarboxylic acids. Quantitative comparison of the <sup>13</sup>C-labelled DBPs enabled further assessment of the contribution from each of these distinct pathways, providing novel insights into ring cleavage reaction mechanisms that have eluded previous DBP investigations.</p>

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Stable isotope labelling to elucidate ring cleavage mechanisms of disinfection by-product formation during chlorination of phenols

  • 期刊论文

  • 发表日期：

    2025年1月9日

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  • Zhuoyue Zhang,
  • Keith P. Reber,
  • Neechi Okwor,
  • Priyansh D. Gujarati,
  • Matthew Vollmuth,
  • Lijin Zhang,
  • Daniel L. McCurry,
  • John D. Sivey,
  • Carsten Prasse

摘要

Despite decades of research on the formation of toxic disinfection by-products (DBPs) during water disinfection with chlorine, considerable uncertainties remain regarding the formation mechanism of toxic DBPs from phenolic precursors. Here we report the use of a series of synthesized ethylparabens containing stable isotope (13C) labels at different positions of the molecule to ascertain DBP formation mechanisms from phenols, including those of regulated chloroacetic acids and recently identified α,β-unsaturated dialdehydes and dicarboxylic acids. Our results highlight the involvement of four general ring cleavage pathways. Three of the DBP formation pathways involve carbons originating from the aromatic ring, while the fourth pathway involves the substituent carboxylic ester carbon in the formation of dichloroacetic acid and C4-dicarboxylic acids. Quantitative comparison of the 13C-labelled DBPs enabled further assessment of the contribution from each of these distinct pathways, providing novel insights into ring cleavage reaction mechanisms that have eluded previous DBP investigations.