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Bavarostat (EKZ-001) is a selective inhibitor of histone deacetylase 6 (HDAC6) that contains a

1-Iodoalkynes and 1,3-diynes are versatile chemical intermediates and pharmaceutically valuable ingredients. In this study, copper mediated on-DNA alkyne iodination and Cadiot-Chodkiewicz coupling are developed for the first time. This generates diverse, systematic, and unprecedented topographic structural features, which could be invaluable as molecular recognition agents for drug discovery in DEL screening.

Acetaminophen is widely used to treat mild to moderate pain and to reduce fever. Under the worldwide COVID-19 pandemic, this over-the-counter pain reliever and fever reducer has been drastically consumed, which makes it even more abundant than ever in municipal wastewater and drinking water sources. Chlorine is the most widely used oxidant in drinking water disinfection, and chlorination generally causes the degradation of organic compounds, including acetaminophen. In this study, a new reaction pathway in the chlorination of acetaminophen, i.e., oxidative coupling reactions via acetaminophen radicals, was investigated both experimentally and computationally. Using an ultraperformance liquid chromatograph coupled to an electrospray ionization-triple quadrupole mass spectrometer, we detected over 20 polymeric products in chlorinated acetaminophen samples, some of which have structures similar to the legacy pollutants "polychlorinated biphenyls". Both C-C and C-O bonding products were found, and the corresponding bonding processes and kinetics were revealed by quantum chemical calculations. Based on the product confirmation and intrinsic reaction coordinate computations, a pathway for the formation of the polymeric products in the chlorination of acetaminophen was proposed. This study suggests that chlorination may cause not only degradation but also upgradation of a phenolic compound or contaminant.

Many of the diseases that plague society today are driven by a loss of protein quality. One method to quantify protein quality is to measure the protein folding stability (PFS). Here, we present a novel mass spectrometry (MS)-based approach for PFS measurement, iodination protein stability assay (IPSA). IPSA quantifies the PFS by tracking the surface-accessibility differences of tyrosine, histidine, methionine, and cysteine under denaturing conditions. Relative to current methods, IPSA increases protein coverage and granularity to track the PFS changes of a protein along its sequence. To our knowledge, this study is the first time the PFS of human serum proteins has been measured in the context of the blood serum (in situ). We show that IPSA can quantify the PFS differences between different transferrin iron-binding states in near

Toxic and odorous iodophenols are commonly identified as disinfection by-products (DBPs) in drinking water. Herein, ng/L levels of iodophenols were identified in river water, wastewater treatment plant effluent, and medical wastewater, with the simultaneous identification of μg/L to mg/L levels of iodide (I

Snow with large specific surface area and strong adsorption capacity can effectively adsorb atmospheric pollutants, which could/might lead to the increase of disinfection by-product (DBP) precursors in surface water. In this study, the contents and characteristics of dissolved organic matter (DOM) in meltwater were investigated, and DBP formation and the DBP-associated cytotoxicity index during chlorination of meltwater was first explored. Overall, meltwater exhibited high nitrogen contents. Meltwater-derived DOM was mainly composed of organics with low molecular weights, low aromaticity, and high unsaturated degrees. DBP formation potentials and cytotoxicity indexes in chlorinated meltwater were positively correlated with air quality index and were significantly impacted by snowfall stages. The trihalomethane and haloacetic acid yields from meltwater were relatively low, while yields of highly cytotoxic DBPs, especially halonitromethanes (6.3-10.8 μg-HNMs/mg-DOC), were significantly higher than those of surface water (1.7 μg-HNMs/mg-DOC). Notably, unsaturated nonaromatic organic nitrates in meltwater were important precursors of halonitromethanes. The actual monitoring results showed that snowfall significant increased the haloacetaldehydes and nitrogenous DBP formation levels of surface water. Considering increased DBP formation and DBP-associated toxicity, it was demonstrated that DOM derived from snowfall in atmosphere-polluted areas could deteriorate surface water quality and pose potential risks to drinking water.

Over 2 billion people globally lack access to safely managed drinking water. In contrast to the household-level, manually implemented treatment products that have been the dominant strategy for gaining low-cost access to safe drinking water, passive chlorination technologies have the potential to treat water and reduce reliance on individual behavior change. However, few studies exist that evaluate the performance and costs of these technologies over time, especially in small, rural systems. We conducted a nonrandomized evaluation of two passive chlorination technologies for system-level water treatment in six gravity-fed, piped water systems in small communities in the hilly region of western Nepal. We monitored water quality indicators upstream of the treatment, at shared taps, and at households, as well as user acceptability and maintenance costs, over 1 year. At baseline, over 80% of tap samples were contaminated with

Batteries using fluoride anions as the carrier might possess high capacity and energy density. Especially, the fluoride shuttle battery (FSB), which uses a fluoride-ion-conductive liquid electrolyte and operates at room temperature, has been reported previously and is deemed a solution to the global energy and environmental crises. Although several electrolyte solutions have been synthesized, and the fluorination/defluorination reactions of various active materials have been evaluated, no subsequent FSBs using those electrolyte solutions have been reported. In this study, two metal species, Bi and Pb, which have different fluorination/defluorination mechanisms in the electrolyte solution composed of alkylammonium fluoride and an ionic liquid, were used as the positive and negative active materials for the FSB. The fluorination/defluorination mechanisms at each electrode during the reactions were explained by in situ electrochemical atomic force microscopy (EC-AFM) measurements. Differences in the morphological changes by two existing mechanisms, direct fluorination and dissolution–deposition, were clarified with evidence. Furthermore, the charge/discharge process of the FSB, with the electrolyte solution combining the active materials, was demonstrated, and the cycling performance and capacity fading mechanism were discussed based on the characteristic morphological change of the active materials at their interface with the electrolyte solution obtained by in situ EC-AFM measurements., 電解液を用いたフッ化物シャトル型蓄電池の電極反応メカニズムを実証 --リチウムイオン電池の性能を凌駕する革新型蓄電池の開発を目指して--. 京都大学プレスリリース. 2022-09-29.

1,1′-Bi-2-naphthol (BINOL)-derived chiral bifunctional sulfide and selenide catalysts that possess a hydroxy group are known to be effective catalysts for enantioselective bromolactonizations. When applied to asymmetric iodolactonizations of 4-pentenoic acids, these catalysts yield chiral γ-butyrolactone products that are important compounds in medicinal chemistry. Although chiral bifunctional selenides have shown good catalytic performances in enantioselective iodolactonizations, reactions with BINOL-derived chiral sulfide catalysts unexpectedly gave iodolactonization products in nearly racemic forms. The roles of chalcogenide moieties and hydroxy groups on bifunctional catalysts were investigated, and the importance of both a selenide moiety and a hydroxy group on chiral bifunctional selenide catalysts to achieve enantioselective iodolactonizations was clarified. An optimized chiral bifunctional selenide catalyst was applied to the asymmetric synthesis of chiral γ-butyrolactones and phthalides. Furthermore, the utility of chiral bifunctional selenides was also demonstrated in the catalytic enantioselective desymmetrizing iodolactonization of α,α-diallyl carboxylic acids., Chemical & pharmaceutical bulletin, 70(9), pp. 599-604; 2022

Chitosan exhibits moderate antimicrobial properties. Here, we enhanced the antimicrobial properties of chitosan through alkylation and chlorination and evaluated the effect of alkylation on chitosan's hydrophobicity, bacterial attachment, chlorination, biocidal property, and stability. First, chitosan films were prepared through casting and were then immersed in a hexanal solution of different concentrations. The aldehyde groups of hexanal reacted with the amino group in chitosan through a Schiff base reaction. Next, the hexanal-modified chitosan films were soaked in 10 % bleach to form N-halamine. The results demonstrated that the surface became more hydrophobic, and chitosan films with increased hexanal-grafting concentrations exhibited less bacterial attachment. However, the degree of chlorination decreased as the degree of alkylation increased, further reducing the diameter of the zone of inhibition. Nevertheless, all chlorinated samples could kill ~5 log of Staphylococcus aureus and Escherichia coli within 30 min. Unlike previous results for chlorinated chitosan, in this study, alkylation before chlorination enhanced antibacterial properties and bactericidal ability and decelerated the degradation of chlorinated samples. The results of a systematic evaluation indicated that a hexanal-grafting concentration of approximately 80 mM maintains the equilibrium of the various properties of chitosan. Alkylated and chlorinated chitosan has considerable potential application as mask filter layers.

The short-chain per- and polyfluorinated alkyl substances (PFAS), introduced to replace the legacy PFAS compounds, turned out to be as toxic and harmful as their longer-chain predecessors and even harder to sequester from contaminated water sources. In this work, molecular dynamics (MD) simulations are employed to investigate the adsorption mechanism of GenX, a representative compound for short-chain PFAS, on a polycationic hydrogel with various extents of fluorination in its backbone and cross-linkers. Simulations indicate that the presence of fluorinated segments next to cationic groups in the polymer gel structure provides the most efficient environment for GenX adsorption. The combination of electrostatic and hydrophobic interactions offered by the cationic-fluorophilic segments amplifies the binding of GenX molecules compared to polymer segments with nonfluorinated cationic or noncationic fluorinated segments. Moreover, such a gel demonstrates high selectivity toward GenX against its hydrogenated analogue.

Breakpoint chlorination is applied to remove ammonia in water treatment. Trichloramine (NCl

Although700 disinfection by-products (DBPs) have been identified to date, most DBPs in drinking water are still unknown. Identifying unknown DBPs is an important step for improving drinking water quality because known DBPs do not fully account for the adverse health effects noted in epidemiologic studies. Using gas chromatography high-resolution mass spectrometry, six chloro- and bromo-halocyclopentadienes (HCPDs) were identified in chlorinated and chloraminated drinking water

The electrophilic halogenation of arenes is perhaps the simplest method to prepare aryl halides, which are important structural motifs in agrochemicals, materials, and pharmaceuticals. However, the nucleophilicity of arenes is weakened by the electron-withdrawing substituents, whose electrophilic halogenation reactions usually require harsh conditions and lead to limited substrate scopes and applications. Therefore, the halogenation of arenes containing electron-withdrawing groups (EWGs) and complex bioactive compounds under mild conditions has been a long-standing challenge. Herein, we describe Brønsted acid-catalyzed halogenation of arenes with electron-withdrawing substituents under mild conditions, providing an efficient protocol for aryl halides. The hydrogen bonding of Brønsted acid with the protic solvent 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) enables this transformation and thus solves this long-standing problem.

Though chlorine is a cost-effective disinfectant for water and wastewaters, the bacteria surviving after chlorination pose serious public health and environmental problems. This review critically assesses the mechanism of chlorine disinfection as described by various researchers; factors affecting chlorination efficacy; and the re-growth potential of microbial contaminations in treated wastewater post chlorination to arrive at meaningful doses for ensuring health safety. Literature analysis shows procedural inconsistencies in the assessment of chlorine tolerant bacteria, making it extremely difficult to compare the tolerance characteristics of different reported tolerant bacteria. A comparison of logarithmic reduction after chlorination and the concentration-time values for prominent pathogens led to the generation of a standard protocol for the assessment of chlorine tolerance. The factors that need to be critically monitored include applied chlorine doses, contact time, determination of chlorine demands of the medium, and the consideration of bacterial counts immediately after chlorination and in post chlorinated samples (regrowth). The protocol devised here appropriately assesses the chlorine-tolerant bacteria and urges the scientific community to report the regrowth characteristics as well. This would increase the confidence in data interpretation that can provide a better understanding of chlorine tolerance in bacteria and aid in formulating strategies for effective chlorination.

Disinfectants are added to swimming pools to kill harmful pathogens. Although liquid chlorine (sodium hypochlorite) is the most commonly used disinfectant, alternative disinfection techniques like electrochemically generated mixed oxidants or electrochemically generated chlorine, often referred to as salt water pools, are growing in popularity. However, these disinfectants react with natural organic matter and anthropogenic contaminants introduced to the pool water by swimmers to form disinfection byproducts (DBPs). DBPs have been linked to several adverse health effects, such as bladder cancer, adverse birth outcomes, and asthma. In this study, we quantified 60 DBPs using gas chromatography-mass spectrometry and assessed the calculated cytotoxicity and genotoxicity of an indoor community swimming pool before and after switching to a salt water pool with electrochemically generated chlorine. Interestingly, the total DBPs increased by 15% upon implementation of the salt water pool, but the calculated cytotoxicity and genotoxicity decreased by 45% and 15%, respectively. Predominant DBP classes formed were haloacetic acids, with trichloroacetic acid and dichloroacetic acid contributing 57% of the average total DBPs formed. Haloacetonitriles, haloacetic acids, and haloacetaldehydes were the primary drivers of calculated cytotoxicity, and haloacetic acids were the primary driver of calculated genotoxicity. Diiodoacetic acid, a highly toxic iodinated DBP, is reported for the first time in swimming pool water. Bromide impurities in sodium chloride used to electrochemically generate chlorine led to a 73% increase in brominated DBPs, primarily driven by bromochloroacetic acid. This study presents the most extensive DBP study to-date for salt water pools.

Chlorine disinfection of saline wastewater effluents rich in bromide and iodide forms relatively toxic brominated and iodinated disinfection byproducts (DBPs). Ultrasonication is a relatively new water treatment technology, and it is less sensitive to suspended solids in wastewaters. In this study, we examined the effects of ultrasonication (in terms of reactor type and combination mode with chlorination) on the DBP formation and toxicity in chlorinated primary and secondary saline wastewater effluents. Compared with the chlorinated wastewater effluent samples without ultrasonication, ultrasonic horn pretreatment of the wastewater effluent samples reduced the total organic halogen (TOX) levels in chlorination by ∼30%, but ultrasonic bath pretreatment of the wastewater samples did not significantly change the TOX levels in chlorination, which might be attributed to the higher energy utilization and decomposition extent of organic DBP precursors in the ultrasonic horn reactor. Moreover, the TOX levels in the chlorinated samples with ultrasonic horn pretreatment (USH-chlorination), simultaneous treatment (chlorination+USH) and subsequent treatment (chlorination-USH) were also significantly reduced, with the maximum TOX reductions occurring in the samples with ultrasonic horn pretreatment. A toxicity index was calculated by weighting and summing the levels of total organic chlorine, total organic bromine and total organic iodine in each treated sample. The calculated toxicity index values of the chlorinated wastewater effluent samples followed a descending rank order of "chlorination""chlorination+USH""chlorination-USH""USH-chlorination", with the lowest toxicity occurring in the samples with ultrasonic horn pretreatment. Then, a developmental toxicity bioassay was conducted for each treated sample. The measured toxicity index values of the chlorinated wastewater samples followed the same descending rank order.

Although the health benefits of swimming are well-documented, health effects such as asthma and bladder cancer are linked to disinfection by-products (DBPs) in pool water. DBPs are formed from the reaction of disinfectants such as chlorine (Cl) or bromine (Br) with organics in the water. Our previous study (Daiber et al., Environ. Sci. Technol. 50, 6652; 2016) found correlations between the concentrations of classes of DBPs and the mutagenic potencies of waters from chlorinated or brominated swimming pools and spas. We extended this study by identifying significantly different concentrations of 21 individual DBPs in brominated or chlorinated pool and spa waters as well as identifying which DBPs and additional DBP classes were most associated with the mutagenicity of these waters. Using data from our previous study, we found that among 21 DBPs analyzed in 21 pool and spa waters, the concentration of bromoacetic acid was significantly higher in Br-waters versus Cl-waters, whereas the concentration of trichloroacetic acid was significantly higher in Cl-waters. Five Br-DBPs (tribromomethane, dibromochloroacetic acid, dibromoacetonitrile, bromoacetic acid, and tribromoacetic acid) had significantly higher concentrations in Br-spa versus Cl-spa waters. Cl-pools had significantly higher concentrations of Cl-DBPs (trichloroacetaldehyde, trichloromethane, dichloroacetic acid, and chloroacetic acid), whereas Br-pools had significantly higher concentrations of Br-DBPs (tribromomethane, dibromoacetic acid, dibromoacetonitrile, and tribromoacetic acid). The concentrations of the sum of all 4 trihalomethanes, all 11 Br-DBPs, and all 5 nitrogen-containing DBPs were each significantly higher in brominated than in chlorinated pools and spas. The 8 Br-DBPs were the only DBPs whose individual concentrations were significantly correlated with the mutagenic potencies of the pool and spa waters. These results, along with those from our earlier study, highlight the importance of Br-DBPs in the mutagenicity of these recreational waters.

Water disinfection is an essential process that provides safe water by inactivating pathogens that cause waterborne diseases. However, disinfectants react with organic matter naturally present in water, leading to the formation of disinfection by-products (DBPs). Multi-analyte methods based on mass spectrometry (MS) are preferred to quantify multiple DBP classes at once however, most require extensive sample pre-treatment and significant resources. In this study, two analytical methods were developed for the quantification of 32 regulated and unregulated DBPs. A purge and trap (PT) coupled with gas chromatography mass spectrometry (GC-MS) method was optimized that automated sample pre-treatment and analyzed volatile and semi-volatile compounds, including trihalomethanes (THMs), iodinated trihalomethanes (I-THMs), haloacetonitriles (HANs), haloketones (HKTs) and halonitromethanes (HNMs). LOQs were between 0.02-0.4 µg/L for most DBPs except for 8 analytes that were in the low µg/L range. A second method with liquid chromatography (LC) tandem mass spectrometry (MS/MS) was developed for the quantification of 10 haloacetic acids (HAAs) with a simple clean-up and direct injection. The LC-MS/MS direct injection method has the lowest detection limits reported (0.2-0.5 µg/L). Both methods have a simple sample pre-treatment, which make it possible for routine analysis. Hyperchlorination and uniform formation conditions (UFC) formation potential tests with chlorine were evaluated with water samples containing high and low TOC. Hyperchlorination formation potential test maximized THMs and HAAs while UFC maximized HANs. Ascorbic acid was found to be an appropriate quencher for both analytical methods. Disinfected drinking water from four water utilities in Alberta, Canada were also evaluated.

In this study, the formation of iodinated trihalomethanes (I-THMs) was systematically evaluated and compared for three treatment processes - (i) chlorination, (ii) monochloramine, and (iii) dichloramination - under different pH conditions. The results demonstrated that I-THM formation decreased in the order of monochloraminationdichloraminationchlorination in acidic and neutral pH. However, the generation of I-THMs increased in the dichloraminationchlorinationmonochloramination order in alkaline condition. Specifically, the formation of I-THMs increased as pH increased from 5 to 9 during chlorination and monochloramination processes, while the maximum I-THM formation occurred at pH 7 during dichloramination. The discrepancy could be mainly related to the stability of the three chlor (am) ine disinfectants at different pH conditions. Moreover, in order to gain a thorough insight into the mechanisms of I-THM formation during dichloramination, further investigation was conducted on the influencing factors of DOC concentration and Br

In the race to deliver clean water to communities through potable water reuse, disinfection and water quality assessment are and will continue to be fundamental factors. There are over 700 disinfection byproducts (DBPs) in water; evaluating each compound is practically impossible and very time consuming. A bioanalytical approach could be an answer to this challenge. In this work, the response of four major classes of DBPs toward mitochondrial membrane potential (ΔΨm) and cytoplasmic adenosine triphosphate (C-ATP) was investigated with human carcinoma (HepG2) cells. Within 90 min of cell exposure, only the haloacetic acid (HAA) mixture caused a cytotoxic response as measured by C-ATP. All four groups (haloacetonitriles (HANs), trihalomethanes (THMs), nitrosamines (NOAs), and HAAs) responded well to ΔΨm, R

Halogenated disinfection byproducts (DBPs) are an unintended consequence of drinking water disinfection, and can have significant toxicity. XAD resins are commonly used to extract and enrich trace levels of DBPs for comprehensive, nontarget identification of DBPs and also for in vitro toxicity studies. However, XAD resin recoveries for complete classes of halogenated DBPs have not been evaluated, particularly for low, environmentally relevant levels (ng/L to low µg/L). Thus, it is not known whether levels of DBPs or the toxicity of drinking water might be underestimated. In this study, DAX-8/XAD-2 layered resins were evaluated, considering both adsorption and elution from the resins, for extracting 66 DBPs from water. Results demonstrate that among the 7 classes of DBPs investigated, trihalomethanes (THMs), including iodo-THMs, were the most efficiently adsorbed, with recovery of most THMs ranging from 50%-96%, followed by halonitromethanes (40%-90%). The adsorption ability of XAD resins for haloacetonitriles, haloacetamides, and haloacetaldehydes was highly dependent on the individual species. The adsorption capacity of XAD resins for haloacetic acids was lower (5%-48%), even after adjusting to pH 1 before extraction. Recovery efficiency for most DBPs was comparable with their adsorption, as most were eluted effectively from XAD resins by ethyl acetate. DBP polarity and molecular weight were the two most important factors that determine their recovery. Recovery of trichloromethane, iodoacetic acid, chloro- and iodo-acetonitrile, and chloroacetamide were among the lowest, which could lead to underestimation of toxicity, particularly for iodoacetic acid and iodo-acetonitrile, which are highly toxic.

Disinfection by-products (DBPs), formed from the reactions of disinfectants with natural organic matter and halides in drinking water, were considered to be cytotoxic and genotoxic, and might trigger various cancers. The relatively low concentration of DBPs in finished water (low µg/L or even ng/L levels) and the interference from water matrix inhibited in situ determination of DBPs. Moreover, the further formation and degradation of DBPs by disinfectants during the holding time (several hours to several days) from sample collection to analysis could adversely affect the determination of DBPs. To obtain accurate, precise and reliable data of DBP occurrence and formation, robust and reliable sample preservation is indispensable. However, the commonly used quenching agents (e.g., sodium sulfite, sodium thiosulfate, and ascorbic acid) for sample preservation can decompose reactive DBPs by reductive dehalogenation. This study evaluated the performance of N-acetylcysteine (NAC) and glutathione (GSH) as quenching agents for the analysis of halogenated DBPs by investigating the stoichiometry of the disinfectant-quenching agent reaction, the formation of DBPs during chlor(am)ination of NAC or GSH, and the effects of NAC or GSH on the stability of 18 individual DBPs and total organic halogen (TOX). Based on the results of this study, NAC and GSH were considered to be ideal quenching agents for the analysis of most DBPs and TOX, except halonitromethanes.

Water-borne pathogenic bacteria are always the top priority to be removed through disinfection process in water treatment due to their threat to human health. It was necessary to develop novel disinfection methods since the conventional chlorine disinfection was inefficient in inactivating chlorine-resistant bacteria, inducing the viable but non-culturable (VBNC) bacteria and forming disinfection by-products (DBPs). In this study, the inactivation of four model strains including Gram-negative (G

A survey was conducted at eight U.S. drinking water plants, that spanned a wide range of water qualities and treatment/disinfection practices. Plants that treated heavily-wastewater-impacted source waters had lower trihalomethane to dihaloacetonitrile ratios due to the presence of more organic nitrogen and HAN precursors. As the bromide to total organic carbon ratio increased, there was more bromine incorporation into DBPs. This has been shown in other studies for THMs and selected emerging DBPs (HANs), whereas this study examined bromine incorporation for a wider group of emerging DBPs (haloacetaldehydes, halonitromethanes). Moreover, bromine incorporation into the emerging DBPs was, in general, similar to that of the THMs. Epidemiology studies that show an association between adverse health effects and brominated THMs may be due to the formation of brominated emerging DBPs of heath concern. Plants with higher free chlorine contact times before ammonia addition to form chloramines had less iodinated DBP formation in chloraminated distribution systems, where there was more oxidation of the iodide to iodate (a sink for the iodide) by the chlorine. This has been shown in many bench-scale studies (primarily for iodinated THMs), but seldom in full-scale studies (where this study also showed the impact on total organic iodine. Collectively, the THMs, haloacetic acids, and emerging DBPs accounted for a significant portion of the TOCl, TOBr, and TOI; however, ∼50% of the TOCl and TOBr is still unknown. The correlation of the sum of detected DBPs with the TOCl and TOBr suggests that they can be used as reliable surrogates.

UV/peroxymonosulfate (UV/PMS) advanced oxidation process has attracted significant attention for removal of micropollutants in water. However, during practical water treatment applications, the PMS treatment must be performed before the UV treatment to achieve full contact. In this study, sulfamethoxazole (SMX) was selected as the target micropollutant. Four different operational approaches, including UV alone, PMS alone, simultaneous UV/PMS and sequential PMS-UV, were compared for their differences in SMX removal and disinfection by-product (DBP) formation potentials during chlorine-driven disinfection. Among the four approaches, UV/PMS and PMS-UV achieved over 90% removal efficiencies for SMX without substantial differences. For raw water, the trichloronitromethane (TCNM) formation potential after treatment with PMS-UV was lower than that after UV/PMS treatment. The time interval over which the PMS-UV process was conducted had little effect on the final removal efficiency for SMX. However, a brief (5 min) pre-PMS treatment significantly reduced the TCNM formation potential and the genotoxicity from DBPs. The formation risk for TCNM during chlorination increased markedly with increasing PMS dosages, and the appropriate dosage under these experimental conditions was suggested to be 0.5-1.0 mmol/L. Under alkaline conditions, PMS-UV treatment can enhance SMX degradation as well as dramatically reduced the formation potentials for haloketones, haloacetonitriles and halonitromethanes. This study suggests that proper optimization of UV/PMS processes can remove SMX and reduce its DBP formation.

An analytical workflow for the analysis of olefins in gasoline that combines selective bromination and comprehensive two-dimensional (2D) gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) with discovery-based analysis is reported. First, a standard mix containing

The formation of disinfection byproducts (DBPs) during UV/chlorine treatment, especially nitrogenous DBPs, is not well understood. This study investigated the formation mechanisms for dichloroacetonitrile (DCAN) from typical amino compounds during UV/chlorine treatment. Compared to chlorination, the yields of DCAN increase by 88-240% during UV/chlorine treatment from real waters, while the yields of DCAN from amino compounds increase by 3.3-5724 times. Amino compounds with electron-withdrawing side chains show much higher DCAN formation than those with electron-donating side chains. Phenylethylamine, l- phenylalanine, and l-phenylalanyl-l-phenylalanine were selected to represent amines, amino acids, and peptides, respectively, to investigate the formation pathways for DCAN during UV/chlorine treatment. First, chlorination of amines, amino acids, and peptides rapidly forms

The world is not on track to meet Sustainable Development Goal 6.1 to provide universal access to safely managed drinking water by 2030. Removal of priority microbial contaminants by disinfection is one aspect of ensuring water is safely managed. Passive chlorination (also called in-line chlorination) represents one approach to disinfecting drinking water before or at the point of collection (POC), without requiring daily user input or electricity. In contrast to manual household chlorination methods typically implemented at the point of use (POU), passive chlorinators can reduce the user burden for chlorine dosing and enable treatment at scales ranging from communities to small municipalities. In this review, we synthesized evidence from 27 evaluations of passive chlorinators (in 19 articles, 3 NGO reports, and 5 theses) conducted across 16 countries in communities, schools, health care facilities, and refugee camps. Of the 27 passive chlorinators we identified, the majority (22/27) were solid tablet or granular chlorine dosers, and the remaining devices were liquid chlorine dosers. We identified the following research priorities to address existing barriers to scaled deployment of passive chlorinators: (i) strengthening local chlorine supply chains through decentralized liquid chlorine production, (ii) validating context-specific business models and financial sustainability, (iii) leveraging remote monitoring and sensing tools to monitor real-time chlorine levels and potential system failures, and (iv) designing handpump-compatible passive chlorinators to serve the many communities reliant on handpumps as a primary drinking water source. We also propose a set of reporting indicators for future studies to facilitate standardized evaluations of the technical performance and financial sustainability of passive chlorinators. In addition, we discuss the limitations of chlorine-based disinfection and recognize the importance of addressing chemical contamination in drinking water supplies. Passive chlorinators deployed and managed at-scale have the potential to elevate the quality of existing accessible and available water services to meet "safely managed" requirements.

Metathesis reactions represent powerful synthetic tools that have been used in a number of fields from the synthesis of natural product to functional material preparation. However, the C–H metathes...

C-H functionalization via functional group metathesis is extremely rare. A protocol of remote site-selective C-H iodination of 2-aryl benzoic acid derivatives via formal C(sp

In this study, we report the formation and cancer risk estimation of trihalomethanes (THMs) emanating from ‘ex-situ’ chlorination of shallow hand-dug well water obtained from a peri-urban area of Mufulira District, Zambia. The aim of the study was to evaluate the potential cancer risks for people in this area where chlorine water disinfection at the household level is commonly practiced. Water samples from 13 randomly selected hand-dug wells (4–8 m deep) were collected and analyzed for pH, turbidity, and dissolved organic carbon before chlorination. Then another set of water samples from the same 13 wells was chlorinated using the methods commonly practiced in this area, consistent with WHO recommended doses. The chlorination degradation products, THMs, trichloromethane, bromodichloromethane (CHCl2Br), dibromochloromethane (CHClBr2), and tribromomethane, were determined at three different times of 60, 180, and 300 min after chlorination, while residual chlorine was determined immediately after chlorination and at 60 and 1,440 min after chlorination. THMs were determined using gas chromatography (GC), while residual chlorine was determined colorimetrically. Then cancer risk estimation from ingestion, inhalation, and dermal routes was carried out. All water samples from the 13 wells showed elevated amounts of THMs, which also increased with increasing contact time. For instance, the concentrations of THMs at 60 min after chlorination ranged from 24.3 ± 2.0 to 61.3 ± 1.0 μg/L, while at 180 and 300 min, ranged between 85.6 ± 4.3–146.9 ± 2.5 μg/L and 188.1 ± 7.1–250.1 ± 7.1 μg/L, respectively. It was observed that tribromomethane was not detected at all in all samples, while CHCl2Br and CHClBr2 were only detected at 180 and 300 min post chlorination. The lifetime cancer risk estimation results showed negligible risk at 60 min post chlorination. However, at 180 and 300 min post chlorination, the results were far above negligible, but within the regulatory US EPA limits. The overall risk, however, could not be ignored, given a multiplicity of exposure to various other contaminants, raising concerns over additivity and synergistic interactive effects, particularly for non-cancer hazard indices.

The high specific capacity of alkalic metal (Li, Na, and K) anodes has drawn widespread interest; however, the practical applications of alkalic metal anodes have been hampered by dendrite growth and interfacial instability, resulting in performance deterioration and even safety issues. Here, we describe a simple method for building tunable fluoride-based artificial solid-electrolyte interphase (SEI) from the fluorination reaction of alkali metals with a mild organic fluorinating reagent. Comprehensive characterization by advanced electron microscopes shows that the LiF-based artificial SEI adopts a crystal-glass structure, which enables efficient Li ion transport and improves structural integrity against the volume changes that occur during Li plating/stripping. Compared with bare Li anode, the ones with artificial SEI exhibit decreased voltage hysteresis, enhanced rate capability, and prolonged cycle life. This method is also applied to generate fluoride-based artificial SEI on Na and K metal anodes that brings significant improvement in battery performance.

Nonheme iron halogenases are unique enzymes in nature that selectively activate an aliphatic C-H bond of a substrate to convert it into C-X (X = Cl/Br, but not F/I). It is proposed that they generate an FeIII(OH)(X) intermediate in their catalytic cycle. The analogous FeIII(OH) intermediate in nonheme iron hydroxylases transfers OH• to give alcohol product, whereas the halogenases transfer X• to the carbon radical substrate. There remains significant debate regarding what factors control their remarkable selectivity of the halogenases. The reactivity of the complexes FeIII(BNPAPh2O)(OH)(X) (X = Cl, Br) with a secondary carbon radical (R•) is described. It is found that X• transfer occurs with a secondary carbon radical, as opposed to OH• transfer with tertiary radicals. Comprehensive computational studies involving density functional theory were carried out to examine the possible origins of this selectivity. The calculations reproduce the experimental findings, which indicate that halogen transfer is not observed for the tertiary radicals because of a nonproductive equilibrium that results from the endergonic nature of these reactions, despite a potentially lower reaction barrier for the halogenation pathway. In contrast, halogen transfer is favored for secondary carbon radicals, for which the halogenated product complex is thermodynamically more stable than the reactant complex. These results are rationalized by considering the relative strengths of the C-X bonds that are formed for tertiary versus secondary carbon centers. The computational analysis also shows that the reaction barrier for halogen transfer is significantly dependent on secondary coordination sphere effects, including steric and H-bonding interactions.

This paper evaluates the performance of a low-cost technology in rural Benin (West Africa) that locally produces chlorine (sodium hypochlorite) and then injects it into the community water tanks. Thirty-one water tanks were selected in cooperation with local authorities to receive electro-chlorinator devices (WATA™). Water samples were tested at two points: before chlorination and at the most distant terminal after chlorination. Residual chlorine control tests and microbiology control tests were performed. Water samples that tested positive for the presence of microorganisms were analyzed at a laboratory when possible. The water provided to the community was not always chlorinated, and over half of the tanks lacked access to chlorine powder. Among the sites using the technology, 30% (9/31) of them had structural problems that prevented the existing system from performing adequately. Furthermore, 60% of the water samples collected before chlorination were positive for microbiological contamination. All samples collected from systems where proper chlorination was taking place tested negative for microbiological contamination. However, the water from six tanks presenting structural problems continued to be distributed to the population despite contamination. The average residual chlorine level analyzed at the most distant terminal fountain was 0.29±0.2 mg/L, which is within the country's reference level 0.1–0.8 mg/L. The installation of water-chlorinator devices (WATA™) produces water without microbiological contamination and with chlorine levels within the WHO's recommended values. However, the success of the technology depends on the pre-existing structure of the water tank.

An efficient chlorination reaction of in situ generated (β-diazo-α,α-difluoroethyl)phosphonates has been achieved with hydrochloric acid as a chlorine source under mild and operationally convenient conditions. The reaction does not need any catalyst and tolerates a wide scope of substrates, which affords the (β-chlorodifluoroethyl)phosphonate products in good to excellent yields. This reaction represents the first example of the halogenation of difluoroalkyl diazo compounds, and also provides an easy way for the synthesis of difluoromethylenephosphonate-containing compounds.

Herein, we report a study on the reactivity of three 1,3-diarylimidazolium-based fluoride reagents, with a general formula of [IPrH][F(HF)$_n$] (n = 0, 1, or 2), that tackle the challenges of limited solubility, hygroscopicity, instability, and laborious preparation procedures of nucleophilic fluoride reagents. Fluorination of 4-tert-butylbenzyl bromide reveals that trifluoride [IPrH][F(HF)$_2$] is the most selective reagent. Microwave-assisted activation coupled with the addition of sterically hindered amine DIPEA or alkali metal fluorides increases the rate of fluorination with [IPrH][F(HF)$_2$], making it an excellent reagent for the fluorination of various organic substrates. The scope of substrates includes benzyl bromides, iodides, chlorides, aliphatic halides, tosylates, mesylates, α-haloketones, a silyl chloride, acyl and sulfuryl chlorides, and a nitroarene. The exceptional stability of the air-stable and nonhygroscopic [IPrH][F(HF)$_2$] reagent is illustrated by its convenient synthesis and detailed experimental regeneration protocol using hydrofluoric acid without organic solvents.

Among halogenated molecules, those containing chlorine atoms are fundamental in many areas such as pharmaceuticals, polymers, agrochemicals and natural metabolites. Despite the fact that many reactions have been developed to install chlorine on organic molecules, most of them rely on toxic and hazardous chlorinating reagents as well as harsh conditions. In an attempt to move towards more sustainable approaches, photoredox catalysis and electrocatalysis have emerged as powerful alternatives to traditional methods. In this review, we collect the most recent and significant examples of visible-light- or current-mediated chlorination published in the last five years.

The aromatic side-chains of phenylalanine, tyrosine, and tryptophan interact with their environments via both hydrophobic and electrostatic interactions. Determining the extent to which these contribute to protein function and stability is not possible with conventional mutagenesis. Serial fluorination of a given aromatic is a validated method in vitro and in silico to specifically alter electrostatic characteristics, but this approach is restricted to a select few experimental systems. Here, we report a group of pyrrolysine-based aminoacyl-tRNA synthetase/tRNA pairs (tRNA/RS pairs) that enable the site-specific encoding of a varied spectrum of fluorinated phenylalanine amino acids in E. coli and mammalian (HEK 293T) cells. By allowing the cross-kingdom expression of proteins bearing these unnatural amino acids at biochemical scale, these tools may potentially enable the study of biological mechanisms which utilize aromatic interactions in structural and cellular contexts.

Sulfadiazine (SDZ) is a typical persistent sulfonamide antibiotic, which has been widely detected in natural drinking water sources. The degradation of SDZ by UV/Oxone (potassium monopersulfate compound) was explored in this study. The results showed that Cl

Identifying disinfection byproducts (DBPs) with high health risk is an unresolved challenge. In this study, six members of a new class of aromatic nitrogenous DBPs─2-chloroaniline, 2-bromoaniline, 2,4-dichloroaniline, 2-chloro-4-bromoaniline, 4-chloro-3-nitroaniline, and 2-chloro-4-nitroaniline─are reported as DBPs in drinking water for the first time. Haloanilines completely degraded within 1 h in the presence of chlorine (1 mg/L), while about 20% remained in the presence of chloramine (1 mg/L) after 120 h. Haloanilines showed high stability in the absence of disinfectants, with30% degradation at pH 5-9 over 120 h. Eight haloanilines were determined in chloraminated finished water and tap water at total concentrations of up to 443 ng/L. The most abundant was 2-bromoaniline, with a median concentration of 104 ng/L. The cytotoxicity of eight haloanilines and regulated trichloromethane and dichloroacetic acid (DCAA) was evaluated using Hep G2 cell assay. The EC

The development of a rational strategy for achieving site-selective C4-H halogenation of indoles is an appealing yet challenging task. Herein, we disclose a Pd(II)-catalyzed transient directing group (TDG)-assisted methodology for realizing C4 chlorination/bromination of indoles employing glycine as the TDG and NFSI as a bystanding oxidant. The use of inexpensive and commercially available CuX

Aims: Kinetic study of iodination of propanone in different acidic medium by using colorimeter. Background: The kinetic experimentation of iodination of propanone has been done in presence of different acid such as sulphuric acid, hydrochloric acid and acetic acid. The rate law of the iodination of propanone in acidic medium is determined by observing the disappearance of the brownish yellow colour of iodine in aqueous solution. Objective: Preparation of standard solution, Determination of absorbance of iodine solution at λmax= 480 nm, Kinetic study of iodination of propanone at different acidic medium. Method: The kinetic analysis of this reaction has been investigated by colorimetry. The extent of the reaction has been monitored by measuring the absorbance of reaction mixture after a suitable time interval. Result: The rate law expression has been determined to be rate = k [propanone]0 0.728 [acid] 0. The rate of iodination of propanone in the presence of different acidic medium is in the order of H2SO4 > HCl > CH3COOH. Conclusion: The rate of the reaction has been found to be independent of the concentration of iodine, i.e., a zero-order reaction with respect to iodine; however, it depended upon the concentration of propanone and the acidic catalyst. In this experimental technique, the consumption of chemicals is minimal.

Nitrogenous aromatic halogenated disinfection byproducts (DBPs) in drinking water have received considerable attention recently owing to their relatively high toxicity. In this study, a new group of nitrogenous aromatic halogenated disinfection byproducts, halophenylacetamides (HPAcAms), were successfully identified for the first time in both the laboratory experiments and realistic drinking water. The formation mechanism of HPAcAms during chlorination of phenylalanine in the presence of Br

This study investigated the efficiency and feasibility of ultraviolet (UV)-assisted photolysis of synthetic dye containing textile raw wastewater effluent. For a said purpose, in-house developed UV/Chlorine/Br process was followed in the presence of activated carbon (AC) which additionally facilitate the dye adsorption. In UV/Chlorine process Cl

Primary alkyl halides have broad utility as fine chemicals in organic synthesis. The direct halogenation of alkenes is one of the most efficient approaches for the synthesis of these halides. Internal alkenes, in particular mixtures of isomers from refineries, constitute readily available and inexpensive feedstock and are the most attractive starting materials for this synthesis. However, the hydrohalogenation of alkenes generally affords branched alkyl halides; there are no catalytic methods to prepare linear alkyl halides directly from internal alkenes, let alone from a mixture of alkene isomers. Here we report the remote oxidative halogenation of alkenes under palladium catalysis via which both terminal and internal alkenes yield primary alkyl halides efficiently. Engineering pyridine-oxazoline ligands by introducing a hydroxyl group is essential for achieving excellent chemo- and regioselectivity. The catalytic system is also good for the mixture of alkene isomers generated from dehydrogenation of alkanes, providing a window to investigate the high-value utilization of inexpensive alkanes.

Chlorinated disinfectants are widely used in hospitals, COVID-19 quarantine facilities, households, institutes, and public areas to combat the spread of the novel coronavirus as they are effective against viruses on various surfaces. Medical facilities have enhanced their routine disinfection of indoors, premises, and in-house sewage. Besides questioning the efficiency of these compounds in combating coronavirus, the impacts of these excessive disinfection efforts have not been discussed anywhere. The impacts of chlorine-based disinfectants on both environment and human health are reviewed in this paper. Chlorine in molecular and in compound forms is known to pose many health hazards. Hypochlorite addition to soil can increase chlorine/chloride concentration, which can be fatal to plant species if exposed. When chlorine compounds reach the sewer/drainage system and are exposed to aqueous media such as wastewater, many disinfection by-products (DBPs) can be formed depending on the concentrations of natural organic matter, inorganics, and anthropogenic pollutants present. Chlorination of hospital wastewater can also produce toxic drug-derived disinfection by-products. Many DBPs are carcinogenic to humans, and some of them are cytotoxic, genotoxic, and mutagenic. DBPs can be harmful to the flora and fauna of the receiving water body and may have adverse effects on microorganisms and plankton present in these ecosystems. Supplementary Information The online version contains supplementary material available at 10.1007/s11356-021-18316-2.

Despite advances in the development of complex culture technologies, the utility, survival, and function of large 3D cell aggregates, or spheroids, are impeded by mass transport limitations. The incorporation of engineered microparticles into these cell aggregates offers a promising approach to increase spheroid integrity through the creation of extracellular spaces to improve mass transport. In this study, we describe the formation of uniform oxygenating fluorinated methacrylamide chitosan (MACF) microparticles via a T-shaped microfluidic device, which when incorporated into spheroids increased extracellular spacing and enhanced oxygen transport via perfluorocarbon substitutions. The addition of MACF microparticles into large liver cell spheroids supported the formation of stable and large spheroids (500 μm in diameter) made of a heterogeneous population of immortalized human hepatoma (HepG2) and hepatic stellate cells (HSCs) (4 HepG2/1 HSC), especially at a 150:1 ratio of cells to microparticles. Further, as confirmed by the albumin, urea, and CYP3A4 secretion amounts into the culture media, biological functionality was maintained over 10 days due to the incorporation of MACF microparticles as compared to controls without microparticles. Importantly, we demonstrated the utility of fluorinated microparticles in reducing the number of hypoxic cells within the core regions of spheroids, while also promoting the diffusion of other small molecules in and out of these 3D in vitro models.

We have designed and synthesized 3,6,13,16-tetrapropylporphycene for the first time as its alkyl analogue from ethyl 4-propyl-1