Nitrogen Incorporation during Breakpoint Chlorination and the Formation of Dichloroacetonitrile and Higher-Carbon Nitrogenous Disinfection Byproducts

:precursor = 5:1 mol:mol). Liquid chromatography-high-resolution mass spectrometry analyses identified higher-carbon N-DBPs from the breakpoint chlorination of aniline and phenol, such as chloro(hydroxy)anilines and (chloro)benzoquinone (di)imines. Specifically, ammonia-nitrogen was incorporated into the aromatic moieties as amine and benzoquinone (di)imine groups, which can be attributed to trichloramine reactions based on kinetic modeling and experimental evidence. Some of the higher-carbon N-DBPs may also serve as important intermediates in DCAN formation. These findings advance the understanding of N-DBP formation mechanisms in breakpoint chlorination and highlight new classes of higher-carbon N-DBPs.