Abstract
Non-target chemical analysis of drinking water revealed the presence of two new disinfectant by-product (DBP) groups in the UK, halogenated-hydroxycyclopentenediones and halogenated-methanesulfonic acids. We unequivocally identified 2,2,4-tribromo-5-hydroxycyclopent-4-ene-1,3-dione (TBHCD), and quantified it together with dibromomethanesulfonic acid at 122±34 and 326±157 ng L-1 in London drinking water, respectively (N=21). We found TBHCD to be photolabile and unstable in tap water and at alkaline pH. Furthermore, spectral and computational data for TBHCD and three other halogenated-hydroxycyclopentenediones indicated they could act as a source of radicals and form other DBPs as a result. Importantly, TBHCD was calculated to have a 14.5 kcal mol-1 lower C-Br bond dissociation enthalpy than the N-Br bond of N-bromosuccinimide, a common radical substitution reagent used in organic synthesis. TBHCD was mutagenic in Salmonella/microsome assays using strains TA98, TA100 and TA102. This work reveals the unique features, activity and toxicity of trihalogenated hydroxycyclopent-4-ene-1,3-diones, prompting a need to more comprehensively assess their risks.
Supplementary materials
Title
Supplementary Information
Description
The details of the instruments used for the characterization of the compound after synthesis are reported, as well as the details of X-ray Christal structure of 2,2,4-tribromo-5-hydroxycyclopent-4-ene-1,3-dione characterization and the cartesian coordinates of optimized structure for bond dissociation enthalpies and energies calculations. Supplementary figures and tables are included below.
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