-
The Science of the Total Environment Nov 2022Thermal spas are gaining more and more popularity among the population because they are used for recreational purposes. Disinfecting these baths without losing the...
Thermal spas are gaining more and more popularity among the population because they are used for recreational purposes. Disinfecting these baths without losing the health benefits poses a challenge for swimming pool operators. Previous studies have mainly focused on regulated chlorinated DBPs in freshwater pools with no bromide or seawater pools with very high bromide content. Thermal water pools have a low bromide content and in combination with chlorine can lead to chlorinated, brominated and mixed halogenated DBP species. The occurrence of brominated and mixed halogenated DBPs in these types of pools is largely unexplored, with very few or limited studies published on regulated DBPs and even fewer on emerging DBP classes. In the field of swimming pool water disinfection, apart from extensive studies in the field of drinking water disinfection, only a few studies are known in which >39 halogenated and 16 non-halogenated disinfection by-products, including regulated trihalomethanes (THM) and haloacetic acids (HAA), were investigated in swimming pool water. Calculated bromine incorporation factor (BIF) demonstrated that even small amounts of bromide in swimming pool water can lead to a large shift in DBP species towards brominated and mixed halogenated DBPs. Dihaloacetonitriles (DHANs) accounted for >50% of the calculated cytotoxicity and genotoxicity on average. Comparison of the target analysis with the TOX showed that a major part of the measured TOX (69% on average) could be explained by the regulated classes THMs, HAAs, and the unregulated class of HANs. This study aims to help operators of swimming pools with bromide-containing water to gain a better understanding of DBP formation in future monitoring and to fill the knowledge gap that has existed so far on the occurrence of DBPs in thermal water pools.
Topics: Chlorine; Disinfectants; Disinfection; Drinking Water; Halogenation; Swimming Pools; Trihalomethanes; Water Pollutants, Chemical; Water Purification
PubMed: 35843322
DOI: 10.1016/j.scitotenv.2022.157338 -
Chemical Society Reviews Sep 2021The enzymatic generation of carbon-halogen bonds is a powerful strategy used by both nature and synthetic chemists to tune the bioactivity, bioavailability and... (Review)
Review
The enzymatic generation of carbon-halogen bonds is a powerful strategy used by both nature and synthetic chemists to tune the bioactivity, bioavailability and reactivity of compounds, opening up the opportunity for selective C-H functionalisation. Genes encoding halogenase enzymes have recently been shown to transcend all kingdoms of life. These enzymes install halogen atoms into aromatic and less activated aliphatic substrates, achieving selectivities that are often challenging to accomplish using synthetic methodologies. Significant advances in both halogenase discovery and engineering have provided a toolbox of enzymes, enabling the ready use of these catalysts in biotransformations, synthetic biology, and in combination with chemical catalysis to enable late stage C-H functionalisation. With a focus on substrate scope, this review outlines the mechanisms employed by the major classes of halogenases, while in parallel, it highlights key advances in the utilisation of the combination of enzymatic halogenation and chemical catalysis for C-H activation and diversification.
Topics: Catalysis; Halogenation; Synthetic Biology
PubMed: 34368824
DOI: 10.1039/d0cs01551b -
The Journal of Organic Chemistry Oct 2021F-fluorination is an important and growing field in organic synthesis that has attracted many chemists in the recent past. Here we present our own, biased perspective...
F-fluorination is an important and growing field in organic synthesis that has attracted many chemists in the recent past. Here we present our own, biased perspective with a focus on our own chemistry that evaluates recent advances in the field and provides our opinion on the challenges for the development of new chemistry, so that it may have an impact on imaging. We hope that the manuscript will provide a useful guide to chemists to develop reliable and robust reaction chemistry suitable for radiofluorination to have a real impact on human health.
Topics: Halogenation; Humans
PubMed: 34428043
DOI: 10.1021/acs.joc.1c01474 -
Angewandte Chemie (International Ed. in... Mar 2016At last count, nearly 5000 halogenated natural products have been discovered. In approximately half of these compounds, the carbon atom to which the halogen is bound is... (Review)
Review
At last count, nearly 5000 halogenated natural products have been discovered. In approximately half of these compounds, the carbon atom to which the halogen is bound is sp(3) -hybridized; therefore, there are an enormous number of natural products for which stereocontrolled halogenation must be a critical component of any synthesis strategy. In this Review, we critically discuss the methods and strategies used for stereoselective introduction of halogen atoms in the context of natural product synthesis. Using the successes of the past, we also attempt to identify gaps in our synthesis technology that would aid the synthesis of halogenated natural products, as well as existing methods that have not yet seen application in complex molecule synthesis. The chemistry described herein demonstrates yet again how natural products continue to provide the inspiration for critical advances in chemical synthesis.
Topics: Biological Products; Halogenation; Stereoisomerism
PubMed: 26833878
DOI: 10.1002/anie.201506388 -
Chemosphere Aug 2016Monitoring total bromine and bromide concentrations in soils is significant in many environmental studies. Thus fast analytical methodologies that entail simple sample...
Monitoring total bromine and bromide concentrations in soils is significant in many environmental studies. Thus fast analytical methodologies that entail simple sample preparation and low-cost analyses are desired. In the present work, the possibilities and drawbacks of low-power total reflection X-ray fluorescence spectrometry (TXRF) for the determination of total bromine and bromide contents in soils were evaluated. The direct analysis of a solid suspension using 20 mg of fine ground soil (<63 μm) gave a 3.7 mg kg(-1) limit of detection for bromine which, in most cases, was suitable for monitoring total bromine content in soils (Br content range in soils = 5-40 mg kg(-1)). Information about bromide determination in soils is also possible by analyzing the Br content in water soil extracts. In this case, the TXRF analysis can be directly performed by depositing 10 μL of the internal standardized soil extract sample on a quartz glass reflector in a measuring time of 1500 s. The bromide limit of detection by this approach was 10 μg L(-1). Good agreement was obtained between the TXRF results for the total bromine and bromide determinations in soils and those obtained by other popular analytical techniques, e.g. energy dispersive X-ray fluorescence spectrometry (total bromine) and ionic chromatography (bromide). As a study case, the TXRF method was applied to study bromine accumulation in two agricultural soils fumigated with a methyl bromide pesticide and irrigated with regenerated waste water.
Topics: Bromides; Bromine; Soil; Soil Pollutants; Spectrometry, X-Ray Emission
PubMed: 27179429
DOI: 10.1016/j.chemosphere.2016.04.136 -
ACS Nano Aug 2013Graphene derivatives containing covalently bound halogens (graphene halides) represent promising two-dimensional systems having interesting physical and chemical... (Review)
Review
Graphene derivatives containing covalently bound halogens (graphene halides) represent promising two-dimensional systems having interesting physical and chemical properties. The attachment of halogen atoms to sp(2) carbons changes the hybridization state to sp(3), which has a principal impact on electronic properties and local structure of the material. The fully fluorinated graphene derivative, fluorographene (graphene fluoride, C1F1), is the thinnest insulator and the only stable stoichiometric graphene halide (C1X1). In this review, we discuss structural properties, syntheses, chemistry, stabilities, and electronic properties of fluorographene and other partially fluorinated, chlorinated, and brominated graphenes. Remarkable optical, mechanical, vibrational, thermodynamic, and conductivity properties of graphene halides are also explored as well as the properties of rare structures including multilayered fluorinated graphenes, iodine-doped graphene, and mixed graphene halides. Finally, patterned halogenation is presented as an interesting approach for generating materials with applications in the field of graphene-based electronic devices.
Topics: Absorption; Animals; Bromine; Chlorine; Electrons; Fluorine; Graphite; Halogens; Humans; Materials Testing; Nanostructures; Nanotechnology; Polymethyl Methacrylate; Semiconductors; Spectrum Analysis, Raman; Stress, Mechanical; Thermodynamics; Tissue Engineering; Vibration
PubMed: 23808482
DOI: 10.1021/nn4024027 -
Molecules (Basel, Switzerland) May 2022In nature, living organisms produce a wide variety of specialized metabolites to perform many biological functions. Among these specialized metabolites, some carry... (Review)
Review
In nature, living organisms produce a wide variety of specialized metabolites to perform many biological functions. Among these specialized metabolites, some carry halogen atoms on their structure, which can modify their chemical characteristics. Research into this type of molecule has focused on how organisms incorporate these atoms into specialized metabolites. Several families of enzymes have been described gathering metalloenzymes, flavoproteins, or S-adenosyl-L-methionine (SAM) enzymes that can incorporate these atoms into different types of chemical structures. However, even though the first halogenation enzyme was discovered in a fungus, this clade is still lagging behind other clades such as bacteria, where many enzymes have been discovered. This review will therefore focus on all halogenation enzymes that have been described in fungi and their associated metabolites by searching for proteins available in databases, but also by using all the available fungal genomes. In the second part of the review, the chemical diversity of halogenated molecules found in fungi will be discussed. This will allow the highlighting of halogenation mechanisms that are still unknown today, therefore, highlighting potentially new unknown halogenation enzymes.
Topics: Bacteria; Fungi; Genome, Fungal; Halogenation; Halogens
PubMed: 35630634
DOI: 10.3390/molecules27103157 -
Proceedings of the National Academy of... Apr 2010High level ab initio calculations at the MP2/cc-pVTZ, CCSD(T)/cc-pVTZ, and CASSCF(6,6)/cc-pVTZ levels were performed to investigate geometries and energies of...
High level ab initio calculations at the MP2/cc-pVTZ, CCSD(T)/cc-pVTZ, and CASSCF(6,6)/cc-pVTZ levels were performed to investigate geometries and energies of superelectrophilic diprotonated, and dimethylated molecular chlorine (Cl2) and bromine (Br2) dications. Diprotonated chlorine and diprotonated bromine dications 3a and 6a, respectively, were found to be lowest energy minima. The isomeric dications, 3b and 6b, are also minima on the potential energy surfaces but they are significantly less stable than the structures 3a and 6a by 33.6 and 30.9 kcal/mol, respectively. On the basis of computed G2 energies, proton affinities and related thermodynamic parameters were also calculated. Dications 3a and 6a have substantial kinetic barriers for deprotonation. Their homolytic dissociation are however facile. Dimethylated molecular chlorine and bromine dications 3g and 6g, respectively, were also found to be global energy minima. These vicinal dihalonium or the corresponding protosolvated species are expected to form either in the superacidic media or in the gas phase.
Topics: Bromine; Cations; Chemistry; Chlorine; Gases; Kinetics; Methylation; Models, Chemical; Protons; Temperature; Thermodynamics
PubMed: 20351253
DOI: 10.1073/pnas.1001603107 -
Organic Letters Apr 2018A simple, user-friendly, metal-free protocol for the regioselective anti-Markovnikov hydrofluorination of olefins using readily available and inexpensive reagents has...
A simple, user-friendly, metal-free protocol for the regioselective anti-Markovnikov hydrofluorination of olefins using readily available and inexpensive reagents has been developed. This new approach displays a broader scope than previously reported methodologies and has been applied to the late-stage fluorination of a complex molecule, giving rise to a fluorosteroid derivative. The stereochemistry of the process has also been studied in some detail.
Topics: Alkenes; Halogenation; Metals; Molecular Structure
PubMed: 29624064
DOI: 10.1021/acs.orglett.8b00681 -
British Medical Journal Apr 1964
Topics: Fluoridation; Fluoride Poisoning; Halogenation; Toxicology
PubMed: 14102781
DOI: 10.1136/bmj.1.5387.907-c