Chlorination of Phenols Revisited: Unexpected Formation of α,β-Unsaturated C<sub>4</sub>-Dicarbonyl Ring Cleavage Products

Prasse, Carsten; Gunten, Urs von; Sedlak, David L.

doi:10.1021/acs.est.9b04926

Cited by 71 publications

(52 citation statements)

References 97 publications

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“…Driving this difference was the higher relative abundance of RND efflux pump genes in public water- versus private well water-supplied showerheads (Mann–Whitney U test, p = 6.85 × 10 –14 ) (Figure b). RND efflux pump genes have been shown to be enriched by the presence of disinfectants in other studies. , A possible explanation for this difference is that the treatment process for municipal water generates toxic compounds during the disinfection process, such as chlorinated phenols, that favor survival of bacteria with inherently robust efflux systems to prevent intracellular damage. − Disinfectants have also been shown to impact biofilm detachment, a process that could impact the transmission of ARGs . This difference between public water- and private well water-supplied showerheads could also be related to the higher relative abundances of mycobacteria in the public water-supplied communities, given prevalence of ARGs in the Mycobacterium genus and the significant association of ARGs with mycobacterial relative abundances.…”

Section: Resultsmentioning

confidence: 98%

Structure and Functional Attributes of Bacterial Communities in Premise Plumbing Across the United States

Webster

McFarland

Gebert

et al. 2021

Environ. Sci. Technol.

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Microbes that thrive in premise plumbing can have potentially important effects on human health. Yet, how and why plumbing-associated microbial communities vary across broad spatial scales remain undetermined. We characterized the bacterial communities in 496 showerheads collected from across the continental United States. The overall community structure, determined by 16S rRNA gene amplicon sequencing, revealed high levels of bacterial diversity. Although a large fraction of the observed variation in community composition could not be explained, differences in bacterial community composition were associated with water supply (private well water vs public municipal water), water source (groundwater vs surface water), and associated differences in water chemistry (pH and chlorine). Most notably, showerheads in homes supplied with public water had higher abundances of Blastomonas, Mycobacterium, and Porphyrobacter, while Pseudorhodoplanes, Novosphingobium, and Nitrospira were more abundant in those receiving private well water. We conducted shotgun metagenomic analyses on 92 of these samples to assess differences in genomic attributes. Public water-sourced showerheads had communities enriched in genes related to lipid and xenobiotic metabolisms, virulence factors, and antibiotic resistance. In contrast, genes associated with oxidative stress and membrane transporters were over-represented in communities from private well water-sourced showerheads compared to those supplied by public water systems. These results highlight the broad diversity of bacteria found in premise plumbing across the United States and the role of the water source and treatment in shaping the microbial community structure and functional potential.

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Section: Resultsmentioning

confidence: 98%

Structure and Functional Attributes of Bacterial Communities in Premise Plumbing Across the United States

Webster

McFarland

Gebert

et al. 2021

Environ. Sci. Technol.

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“…The ubiquitous water disinfectants free chlorine (i.e., HOCl + OCl – ) and monochloramine (NH 2 Cl) induce oxidation reactions that can transform contaminants and produce disinfection byproducts (DBPs) . HOCl and NH 2 Cl quickly oxidize Br – and I – to produce other electrophilic halogen species (e.g., HOBr and HOI). , Researchers examining electrophilic substitution often focus on reactions directly involving the most abundant halogen species [e.g., hypohalous acids (HOX), where X = Cl, Br, or I]. , However, reaction models that include only the electrophiles that are prevalent in chlor(am)inated water sometimes fail to accurately predict product distributions and the effects of halide ion concentration, disinfectant concentration, and pH on reaction rates (see examples in Figures S1–S3). − …”

Section: Introductionmentioning

confidence: 99%

Exotic Electrophiles in Chlorinated and Chloraminated Water: When Conventional Kinetic Models and Reaction Pathways Fall Short

Rose

Lau

Prasse

et al. 2020

Environ. Sci. Technol. Lett.

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Halogenation and oxidation of organic matter in chlorinated and chloraminated water are typically attributed to the most abundant electrophiles present. This interpretation sometimes fails to explain laboratory observations, including halogenation kinetics and product distributions. Exotic electrophiles, species commonly overlooked in the environmental literature, can help to resolve these discrepancies. Herein, we review evidence demonstrating the significance of lesser-studied electrophilic chlorinating (Cl2 and Cl2O), brominating (BrCl, BrOCl, and Br2O), and iodinating (H2OI+ and ICl) agents in chlor(am)inated water. The evidence includes reaction rate dependencies on [Cl–], [H+], and [HOCl] that cannot be attributed to the reactivity of hypohalous acids or hypohalites alone. For example, enhancement of chlorination and bromination rates by Cl– implicates Cl2 and BrCl, respectively, as active halogenating agents. Herein, we discuss a new method for quantifying the sensitivity of halogenation to rate enhancement by Cl–. We also discuss complexities that Cl– can impart on iodination kinetics. In addition, we highlight recent insights into radical-mediated reaction pathways and unexpected organic electrophiles in chlorinated water. Finally, we discuss practical implications, identify research needs, and offer recommendations to improve the design of future halogenation experiments. Overall, this review aims to spur new research into underappreciated electrophiles in chlor(am)inated water.

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“…We suggested a direct interaction of avonoids with hypochlorous acidavonoid chlorinations and a decrease of effective HOCl concentration in erythrocyte suspensions. It is known that the reaction of HOCl with phenolic compounds occurs through an electrophilic attack on an aromatic carbon at the ortho-and para-positions to yield chlorine-substituted products [35,36]. Our theoretical calculation demonstrates possible sites for electrophilic attack in the avonoid molecules (negatively charged C atoms, Fig.…”

Section: Discussionmentioning

confidence: 78%

Comparative Analysis of Molecular Properties and Reactions With Oxidants for Quercetin, Catechin and Naringenin

Заводник¹,

Veiko²,

Лапшина³

2021

Preprint

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Flavonoids, a large group of secondary plant phenolic metabolites, are important natural antioxidants and regulators of cellular redox balance. The present study addressed the evaluation of the electronic properties of some flavonoids belonging to different classes: quercetin (flavonols), catechin (flavanols), and naringenin (flavanones) and their interactions with oxidants in the model systems of DPPH reduction, flavonoid autoxidation and chlorination. According to our ab initio calculations, the high net negative excess charges of the C rings and the small positive excess charges of the B rings of quercetin, catechin, and naringenin make these parts of flavonoid molecules attractive for electrophilic attack. The 3’-OH group of the B-ring of quercetin has the highest excess negative charge and the lowest energy of hydrogen atom abstraction for the flavonoids studied. The apparent reaction rates (M-1s-1, 20 ºC) and the activation energies (kJ/mol) of DPPH reduction are 4000±1000 and 23.0±2.5 in the case of quercetin, 1100±200 and 32.5±2.5 in the case of catechin, respectively. The stoichiometry of the DPPH – flavonoid reaction was 1:1. The activation energies (kJ/mol) of quercetin and catechin autoxidations were 50.8±6.1 and 58.1±7.2, respectively. Naringenin was not oxidized by the DPPH radical and air oxygen (autoxidation) and the flavonoids studied effectively prevented HOCl-induced hemolysis due to direct scavenging of hypochlorous acid (flavonoid chlorination). The best antioxidant quercetin has the highest value of HOMO energy, the planar structure and the optimal electron orbital delocalization on all phenolic rings due to C2=C3 double bond in the C ring (absent in catechin and naringenin).

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Chlorination of Phenols Revisited: Unexpected Formation of α,β-Unsaturated C₄-Dicarbonyl Ring Cleavage Products

Abstract: Chlorination of phenols revisited: unexpected formation of α,β-unsaturated c4-dicarbonyl ring cleavage products. Environmental Science and Technology.

Cited by 71 publications

References 97 publications

Structure and Functional Attributes of Bacterial Communities in Premise Plumbing Across the United States

Structure and Functional Attributes of Bacterial Communities in Premise Plumbing Across the United States

Exotic Electrophiles in Chlorinated and Chloraminated Water: When Conventional Kinetic Models and Reaction Pathways Fall Short

Comparative Analysis of Molecular Properties and Reactions With Oxidants for Quercetin, Catechin and Naringenin

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Chlorination of Phenols Revisited: Unexpected Formation of α,β-Unsaturated C4-Dicarbonyl Ring Cleavage Products

Abstract: Chlorination of phenols revisited: unexpected formation of α,β-unsaturated c4-dicarbonyl ring cleavage products. Environmental Science and Technology.

Cited by 71 publications

References 97 publications

Structure and Functional Attributes of Bacterial Communities in Premise Plumbing Across the United States

Structure and Functional Attributes of Bacterial Communities in Premise Plumbing Across the United States

Exotic Electrophiles in Chlorinated and Chloraminated Water: When Conventional Kinetic Models and Reaction Pathways Fall Short

Comparative Analysis of Molecular Properties and Reactions With Oxidants for Quercetin, Catechin and Naringenin

Contact Info

Product

Resources

About

Chlorination of Phenols Revisited: Unexpected Formation of α,β-Unsaturated C₄-Dicarbonyl Ring Cleavage Products