Search

The purity of drinking water is an important issue of the human life quality. Water disinfection has saved millions people from the diseases spread with water. However, that procedure has a certain drawback due to formation of toxic organic disinfection products. Establishing the structures of these products and the mechanisms of their formation and diminishing their levels in drinking water represent an important task for chemistry and medicine, while mass spectrometry is the most efficient tool for the corresponding studies. The current review throws light upon natural and anthropogenic sources of the formation of disinfection by-products (DBPs) and the mechanisms of their formation related to the structural peculiarities and the presence of functional groups. In addition to chlorination, bromination is discussed since it is used quite often as an alternative method of disinfection, particularly, for the purification of swimming pool water. The benefits of the contemporary GC/MS and LC/MS methods for the elucidation of DBP structures and study of the mechanisms of their formation are discussed. The reactions characteristic for various functional groups and directions of transformation of certain classes of organic compounds in conditions of aqueous chlorination/bromination are also covered in the review., Author(s): D. M. Mazur [sup.1] , A. T. Lebedev [sup.2] Author Affiliations: (1) grid.14476.30, 0000 0001 2342 9668, Organic Chemistry Department, Moscow State University, , 119991, Moscow, Russia (2) grid.462706.1, [...]

We studied the reactions of 4-tert-butyl-4'-methoxydibenzoylmethane (avobenzone), the most common UV filter in formulations of sunscreens, under the conditions of disinfection. Three chlorinated compounds were identified as the main products. Their structures were confirmed by high-performance liquid chromatography-tandem mass spectrometry (HPLC--[MS.sup.2]) with accurate mass measurements and by gas chromatography-mass spectrometry (GC/MS). It was reliably proved, that the substitution involved the double bond of the enolic form of the diketone, rather than the activated aromatic ring, leading to the formation of 2-chloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione and 2,2-dichloro-1-(4tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione as the main products. The third identified product was 2-chloro-1-(4-methoxyphenyl)ethanone. Keywords: UVA filter, avobenzone, water chlorination, GC--MS, HPLC--[MS.sup.2], INTRODUCTION Creams designed for protecting human skin against UV rays contain substances absorbing or reflecting UV radiation [1-3]. Because sunscreen formulations should be photostable, various combinations of the respective components [...]

This study determined and monitored the halogenated disinfection by-products (DBP) of natural waters used to produce drinking water for the City of Casablanca, Morocco. The natural water physicochemical parameters were first monitored to characterize these waters; chlorine requirements were determined by plotting the break point curve. Then waters were synthesized in a laboratory, based on the results of previous analyses. The break point curves of these synthetic waters were also determined. To assess the consequences of chlorination, monitoring tests determined the trihalomethane (THM) and the halogenated organic compounds (COX) out before and after coagulation. Results for natural waters showed a correlation between total organic carbon (TOC), the THM contents and type as well as the COX formed following chlorination. Results thus showed that coagulation before chlorination helped reduce the formation of disinfection byproducts. Key words: surface water, disinfection, chlorination, coagulation, trihalomethane, THM, halogenated organic compound, COX. Cette etude visait la determination et le suivi des sous-produits de desinfection (SPD) halogenes des eaux naturelles servant a la production d'eau potable de la ville de Casablanca au Maroc. Dans un premier temps, un suivi des parametres physicochimiques des eaux naturelles a ete effectue dans le but de caracteriser ces eaux, pour lesquelles la demande en chlore a ete determinee a partir du tracage de la courbe de point de rupture (<< break point >>). Dans un deuxieme temps, des eaux ont ete synthetisees au laboratoire, sur la base des resultats des analyses effectuees precedemment. Ces eaux synthetiques ont fait l'objet, elles aussi, de la determination des courbes de point de rupture. Afin d'evaluer les consequences de la chloration, des tests de suivi des trihalomethanes (THM) et des composes organohalogenes (COX), avant et apres coagulation ont ete effectues. Les resultats obtenus pour les eaux naturelles ont montre une correlation entre le carbone organique total (COT), la teneur et la nature des THM et les COX formes suite a la chloration. Aussi, les resultats ont montre que la coagulation avant chloration permet de reduire la formation de SPD. Mots-cles: eau de surface, desinfection, chloration, coagulation, trihalomethane, THM, compose organohalogeene, COX., Introduction Au Maroc, l'alimentation en eau potable se fait en majoritee par les eaux de surface. Le tableau 1 illustre d'ailleurs la repartition geographique des ressources en eaux de surface [...]

The reaction of copper-mediated chlorination of phenol rings under mild conditions at room temperature which involves the ligand 1,7-bis(2-hydroxyphenyl)-2,6-diaza-4-hydroxylheptane ([H.sub.3]L1) with CuC[l.sub.2] in acetonitrile is reported.

This study investigates the interaction of natural organic matter with iron oxide (goethite) on chlorine decay, disinfection by-product (DBP) formation, and DBP compound speciation [total trihalomethanes (TTHM4) and haloacetic acids (HAA5)]. Batch experiments were conducted with goethite, multiple finished drinking waters, variable chlorine dose, and fixed pH 8. The overall objective was to assess natural organic matter (NOM) adsorption onto goethite and its effect on chlorine decay and DBP formation. Chlorine consumption always increased in the presence of goethite and is attributed to an increase in the reactivity and/or modification of adsorbed NOM. Adsorbed NOM also led to an overall increase in TTHM4, however, HAA5 formation was suppressed during the first 2 h. Chloroform was identified as the increasing species and dichloracetic acid was identified as the suppressed species. This study clearly shows that goethite, which is the predominant iron oxide of pipe deposits, alters both chlorine decay and DBP formation and should be considered when assessing water treatment plant operations and DBP monitoring site selection. CE Database subject headings: Halogen organic compounds; Water distribution systems; Disinfection; Chlorine; Iron.

The covalent modification of Si surfaces through a two-step chlorination-methylation method is described to introduce kinetically stable C[H.sub.3]-Si bonds onto Si(111) surfaces. The results have provided strong evidence that the energetics of chemically modified Si interfaces can be fixed with respect to pH and have shown that the band-edge energies of Si can be tuned independently of pH-derived variations in the electrochemical potential of the solution redox species.

The potential of 'Sphingobium indicum' (S.indicum) B90A for transforming [beta]- and [delta]- hexachlorocyclohexane (HCH) is reconfirmed. It is demonstrated that LinB is responsible for the transformation of [beta]-HCH to pentachlorocyclohexanol and tetrachlorocyclohexanediol in 'S. indicum' B90A and that LinB also acts on delta-HCH, analogously forming the respective pentachlorocyclohexanol and tetrachlorocyclohexanediol intermediates.

Long-term (e.g., 5--15 years) groundwater concentration versus time records were compiled from 47 near-source zone monitoring wells at 23 chlorinated solvent sites (52 total records). Chlorinated volatile organic compound (CVOC) concentrations decreased significantly in most of the 52 temporal records, with a median reduction in concentration of 74%. A statistical method based on a Mann--Kendall analysis also showed that most sites had statistically significant decreasing concentration trends over time. Median point decay rate constants ([k.sub.point]) values were calculated for nine sites containing tetrachloroethene (PCE); 13 sites containing trichloroethene (TCE); two sites containing cis-1,2-dichloroethene (DCE); and six sites containing 1,1,1-trichloroethane (TCA). The TCA sites had the highest [k.sub.point] values (0.34/year) followed by PCE, DCE, and TCE (0.23/year, 0.16/year, and 0.11/year, respectively) (equal to decay half-lives of 2.0, 3.0, 4.3, and 6.1 years, respectively). If the median point decay rates from these sites are maintained over a 20 year period, the resulting reduction in concentration will be similar to the reported reduction in source zone concentrations achieved by active in situ source remediation technologies (typical project length: 1-2 years). DOI: 10.1061/(ASCE)0733-9372(2006)132:6(653) CE Database subject headings: Attenuation; Chlorination; TCE; PCE; Ground-water pollution; Water treatment.

This paper deals with the optimization of accelerated solvent extraction (ASE) for the analysis of the polychlorinated dibenzo-p-dioxins, benzo-p-furans (PCDD/Fs), mixed bromine/chlorine-dibenzo-p-dioxins, and benzo-p-furans (so-called MXDD/Fs) in solid samples. Previous theoretical studies have shown that these compounds exhibit similar electronic properties. It is reasonable to assume that there is little difference in the behavior, formation, and toxicity of PCDD/Fs and MXDD/Fs. Indeed, for most of the cases, the affinity is defined by these weak interactions. Only eight native standards are available for the MXDD/Fs; hence, the use of similar compounds (native and (13) [C.sub.12]-1abeled), such as PCDD/ Fs, is required to optimize and to validate experimental methods. This would allow conclusions to be applied for the MXDD/Fs without extended studies involving complex synthesis methods. Experimental design methodology was used to evaluate the influence of five parameters (temperature, pressure, static time, number of cycles, and solvent nature) on the polyhalogenated dibenzodioxin and -furan (PXDD/Fs) extractions in different materials. The extraction profiles and the optimal operating conditions were determined for each matrix from the modeling of extraction performance. The two following effects, the relative peak area and the co-extracted matrix (CEM), were screened in this study. The temperature of extraction was found to be the most important parameter. ASE offers automation and appears to be as efficient as Soxhlet or Soxtet; however, a major benefit was that a 4-fold decrease in extraction time was obtained. Results suggest that extraction efficiency was quantitative with extraction times as low as 15 min for all congeners at 130[degrees]C with a mixed solvent (n-hexane/acetone (1/1)). Under these operating conditions, the CEM and the degradation of the highly brominated compounds were minimized. The analysis of some real life samples from municipal solid waste incinerators showed significant amounts of PXDD/Fs.

Risk issues become complicated when scientific evidence concerning a potential environmental exposure is equivocal; particularly when many argue that the public health benefits of a policy action outweigh any potential negative health effects. Chlorinated drinking water, and chlorinated disinfection byproducts (CDBPs) that are formed during the disinfection process, represent a useful case-study for examining these complications. We conduct a media analysis of chlorinated drinking water stories in the Canadian print media from 1977 to 2000. We examine media presentations of science compared to framings by scientists, regulators, the chlorine industry, water utility representatives, and non-governmental organizations of the CDBP issue based on key informant interviews. We argue that there are two main framings of the debate, each of which are powerful in constructing risk perceptions. On the one hand, many frame the debate as a `voluntary' risk: we choose chlorine disinfection to protect against microbial risks with a possible adverse consequence of that protection. On the other hand, others frame the issue as an `involuntary' risk: chlorine disinfection was a `choice' imposed by public health and water utility officials; a choice that carries a potential cancer risk, and alternative disinfection technologies are advocated. We demonstrate these different frames by examining metaphorical constructs of water, chlorine and cancer contained within them. Keywords: Canada; Risk communication; Media frames; Metaphors; Chlorinated drinking water; Cancer

In this paper, a Fourier transform infrared (FT-IR) spectroscopic method for detection of chlorinated aromatic compounds in soils was developed. The sensing device of this method was based on an infrared hollow waveguide, the inner surface of which was coated with a hydrophobic film. Vaporized chlorinated aromatic compounds from soils were trapped onto the hydrophobic film of the hollow waveguide sampler following detection by FT-IR spectrometry. The extraction process in this method was similar to the headspace solid-phase microextraction (HSSPME) in principle. Means of increasing the speed of transfer of the vaporized organic species to the sampler were also studied. Results indicated that, with a negative pressure on the end of the sampler, the speed of transfer increased significantly. Vapor pressures of the analytes were used as an indication to test the limitation of this method in the analysis of organic compounds in soils. Results showed that analytes with vapor pressures lower than 12 Torr could be detected quantitatively. The typical R-square of the regression on the concentration and IR signals was around 0.99 and the typical detection limits were in the range of hundreds of parts per billion.

The use of solid-phase microextraction with poly(dimethylsiloxane) (PDMS)-coated glass fibers for the extraction and analysis of hydrophobic organic analytes is increasing. The literature on this topic is characterized by large discrepancies in partition coefficients and an uncertainty of whether highly hydrophobic analytes are retained by absorption into the fiber coating or by adsorption to the fiber surface. We applied a new method, which minimizes the impact of experimental artifacts, to determine PDMS water partition coefficients of 17 hydrophobic analytes including chlorinated benzenes, PCBs, PAHs, and p,p'-DDE. These partition coefficients are several orders of magnitude higher than some reported values. Two observations strongly suggest that the retention of hydrophobic organic substances is governed by partitioning into the PDMS coating. (1) The partition coefficients are proportional with octanol/water partition coefficients. (2) The fluorescence of fluoranthene was observed to be homogeneously distributed within the polymer coating when studied by means of fluorescence microscopy. Implications of these findings for the application of solid-phase microextraction with respect to potential detection limits, with respect to biomimetic extraction, and with respect to measurements in multicompartment systems are discussed.

A study was conducted to examine the dechlorination of perchloroethylene in an upflow anaerobic sludge blanket reactor which was incorporated with a perchloroethylene-degrading bacterium Dehalospirillum multivorans. Immunological and analytical methods were utilized in investigating the dechlorinating performance of the upflow anaerobic sludge blanket reactor with the said bacterium. Results revealed the bacterium grew in microcolonies which were located at the centers of the granules obtained from the reference 1 reactor.

Iron complexes catalyze the activation of 1:1 HOOH HCl that facilitates the chlorohydroxylation of olefins and chlorination of hydrocarbons through (HCl) (L(x)FeIV(OH)Cl), an intermediate formed through a Fenton process. This intermediate, which is more reactive than HOCl, reacts with olefin substrates and saturated hydrocarbons in a highly efficient manner and in selective substrate solutions to yield chlorohydroxo and chloro derivatives.

Readily available materials with the formula R(sub f)CH2OCX double bond CYZ facilitate the synthesis of perfluorovinyl ethers. The protection of the fluorinated double bonds by chlorination is the vital reaction step. The method enables the preparation of perfluorovinyl ethers with long or short perfluoroalkyl groups. The use of perfluoro 2-butyltetrahydrofuran and hexafluoropropylene oxide oligomers as solvents reduces the chances of fragmentation.

Solvent effect highly influences the chemoselectivity of the free radical chlorination of cyclopropane. Internal pressure of the solvent is related to the ratio between ring-opened and hydrogen-abstraction products. Gas and condensed-phase chlorination of cyclopropane differ due to the solvent pressure effect of the phase. Results obtained from extrapolation techniques are in good agreement with the experimental data.

An investgation of the long-term rate and pathway dechlorination of Aroclor 1254 by sediment microorganisms from the Hudson river is discussed. Comparisons were made between polychlorinated biphenyl (PCB)-enriched and non-enriched sediments of their rate, extent and pathway of dechlorination over a 24-month period. Results indicate that highly chlorinated congeners could still be present even after the successful bioremediation of PCBs by dechlorination.

The synthesis and isolation of the elusive fullerene cage ([C.sub.2v]-[C.sub.72]) is described. The [C.sub.2v]-[C.sub.72] cage is captured by in situ chlorination to form [C.sub.72][Cl.sub.4] and the chlorination pattern and resulting stability of [C.sub.72][Cl.sub.4] are discussed.

Bicyclic C-fused chlorinated tetrahydrofuro[3,2-c]azetidin-2-ones are prepared by a general route involving Staudinger reaction of allylic/propargylic imidates with dichloroketene followed by highly diastereoselective CuCl/PMDETA-catalyzed 5-exo-trig/dig chlorine atom transfer radical cyclization. Synthetic application of the side chain chlorine atom of the products is shown by its substitution in one of the products with azide followed by azide-alkyne click reaction with phenylacetylene to obtain a 1,2,3-triazolyltetrahydrofuro[3,2-c]azetidin-2-one.

A novel reductive dehalogenase (RDase) involved in the dechlorination of highly chlorinated phenols from Desulfitobacterium hafniense strain PCP-1 cultivated in the presence of 2,4,6-trichlorophenol is partially purified. CprA3 is shown to be the first RDase with high affinity toward pentachlorophenol (PCP) and with high ortho-dechlorinating activity toward PCP and other highly chlorinated phenols.

Pd[(OAc).sub.2]-catalyzed aromatic C-H chlorination is analyzed and dinuclear Pd(III) complexes are proposed as intermediated. Kinetic data obtained during catalysis and structural information of relevant intermediates is used for proposing a Pd[(II).sub.2]/Pd[(III).sub.2] catalysis cycle for Pd[(OAc).sub.2]-catalyzed aromatic C-H chlorination.

Computational methods were applied to study the mechanism of the chlorination reaction of SyrB2, a representative [alpha]-ketoglutarate dependent halogenase. CASPT2 calculations for the spin state splittings in the oxoferryl species supported the conclusion that once the [Fe.sup.IV]=O intermediate is formed, the reaction proceeds on the quintet potential energy surface.

A manganese porphyrin mediated reaction of different unactivated alkanes with sodium hypochlorite as the chlorine source was performed to obtain alkyl chlorides as major products with only trace amounts of oxygenation products. The regioselectivity and the preference for C[H.sub.2] groups in the aliphatic C-H bond chlorination could be attributed to nonbonded interactions between the alkyl groups on the substrates and the aryl groups of the manganese porphyrin.

A new [C.sub.1]-symmetric non-IPR hollow isomer, [super #23863][C.sub.78], was captured as [super #23863][C.sub.78][Cl.sub.8] and then subjected to a regioselective substitution reaction with benzyl hydroperoxide to obtain [super #23863][C.sub.78](OOC[H.sub.2][C.sub.6][H.sub.5])[Cl.sub.7]. The differences observed in in C-Cl bond length, intermediate stability, and steric effects of the involved molecules accounted for the chemical regioselectivity of the substitution reaction.

The halogenase gene prnA from pyrrolnitrin biosynthesis was introduced into Streptomyces coeruleorubidus to perform an efficient in situ chlorination of the uridyl peptide antibotic pacidamycin. The installed chlorine provided a selectably functionalizable handle enabling synthetic modification of the natural product using mild cross-coupling conditions in crude aqueous extracts of the culture broth.

Chiral short-chain [alpha]-chloroaldehydes are prepared staring from enantiomerically pure amino acids in a three-step approach, thus giving a practical synthetic alternative for known organocatalytic [alpha]-chlorination procedures. The latter aldehydes are useful starting materials for the stereoselective Staudinger synthesis of (3S,4S)-4-[(1S)-1-chloroalkyl]azetidin-2-ones in high diastereomeric ratios, which are used as chiral building blocks for preparing azetidines and pyrrolidines.

Two bacterial strains capable of degrading persistent chlorinated organophosphorus (OP) flame retardants, tris(2-chloroethyl) phosphate (TCEP) and tris(1,3-dichloro-2-propyl) phosphate (TDCPP), are isolated and identified. The strains are useful for the bioremediation of environments contaminated with these compounds.

Several molecular dynamics simulations are conducted to explain the [Cl.sup.+] etching taking place on a Si(100) surface. The thickness of the chlorinated reaction layer thus formed on the surface is shown to be completely dependent on the energy of the system.

The first example of a reagent controlled organocatalytic enantioselective chloroactonization reaction is reported. Various N-chlorinated hydantoins as the terminal chlorenium source is used to cyclize several 4-aryl pentenoic acids in the presence of 0.1 equiv of [(DHQD).sub.2]PHAL.

The article discusses a new approach, which can be used for the total synthesis of the antimitotic bicyclic peptide celogentin C. The various chemical shifts taking place in the process are shown to be highly temperature and concentration dependent.

Application of [H.sub.2][O.sub.2] in conjunction with SO[Cl.sub.2] as a highly reactive reagent for the direct oxidative conversion of thiol derivatives to the corresponding sulfonyl chlorides with high purity through oxidative chlorination is described. The same reaction with amines could be used to generate corresponding sulfonamides in excellent yields within short duration of reaction times.

Several techniques are simultaneously applied to explain the characterization and synthesis of the various catena-phosphorous cations. These cations are shown to contain numerous phosphinophosphonium bonds, which are found to exhibit a strong coordinate nature.

Genome annotation of the chlorinated ethene-respiring 'Dehalococcoides ethenogenes' strain 195 has shown the presence of a complete nitrogenase operon. The results from gene expression and [super 15][N.sub.2]-isotope measurements have confirmed that strain 195 is capable of fixing atmospheric dinitrogen when a defined fixed-nitrogen source such as ammonium is unavailable.

The analysis of the J-based configuration analysis method in chlorinated hydrocarbons and chlorohydrins is described along with the development of a spectroscopic database that has facilitated the configurational assignment of these structures. Certain diastereomeric subclasses of 4,5-dichloro-2,3-epoxyhexane-1-ols have displayed a propensity to undergo ring-opening reactions at C-3 with concomitant inversion of configuration at the neighboring C-Cl at C4, implicating the intermediacy of chloronium ions.

The literature data for the partial rate factors and (ln) for [S.sub.E]Ar processes are compared to theoretical reactivity parameters to rationalize the reactivity and regioselectivity of the electrophilic chlorination, nitration, and alkylation of benzene derivatives. The observed variations of electron density at the different arene ring positions and the experimental partial rate factors for the chlorination and nitration reactions are attributed to strong steric influences on the reaction rates for substitutions involving the bulky benzyl moiety.

Comparative studies on 42 human outbreak strains that represented nine distinct Escherichia coli O157:H7 genetic lineages were performed to understand their relative resistance to chlorine treatment. Identifications of E. coli O157:H7 strains with enhanced resistance to chlorine decontamination and analysis of their transcriptomic response to oxidative stress might help to better understand the survival strategy of this human enteric pathogen on fresh produce during minimal processing.

A four-step synthesis method is described for cis-3,5-disubstituted morpholines from enantiomerically pure amino alcohols, where the key step is a Pd-catalyzed carboamination reaction between ethanolamine derivative and an aryl or alkenyl bromide. The morpholine products are generated as single stereoisomers and this method has provided access to fused bicyclic morpholines as well as 2,3- and 2,5-disubstituted products.

The sequential treatment of optically active terminal propargylic alcohols with n-BuLi/[(HCHO).n] and regioselective chlorination has produced optically active 4-chloro-2-butyn-1-ols. The subsequent reaction of the optically active 4-chloro-2-butyn-1-ols with the corresponding Grignard reagents under the catalysis of CuCN has produced the optically active secondary 2,3-allenols.

Muironolide A, a new chemical entity with an unprecedented chlorinated hexahydro-1H-isoindolone skeleton, is isolated from the same marine sponge, Phorbas sp. that has also provided phorboxazoles A and B. Muironolide A is the first macrolide bearing an esterified trichloromethyl carbinol and is produced by a cyanobacterium that has also made phorbasides.

New 3'-terminal deoxyribonucleoside-loading reagents having a silyl-type linker are developed. A new reaction of chlorination of cytosine base is described by using 1,3-dichloro-5,5-dimethylhydantoin.

The addition of chlorine atoms to conjugated cores is shown to be general, effective route for designing n-type air-stable organic semiconductors. The calculations and cyclic voltammetry measurements in solution have shown that the chloro-functionalized molecules have a slightly smaller HOMO-LUMO gap and a lower LUMO level than the fluoro-containing molecules.

A nucleophilic multiple chlorinations of chiral epoxides that stereospecifically incorporated halogen atoms into oxygenated molecular scaffolds are used to perform synthesis of polychlorinated hydrocarbon motifs in enantiomerically pure forms. The new reagent system that form [sp.sup.3]C-Cl bonds in terms of selectivity and reactivity could be applied as the multiple chlorination method to various internal alkenyl-substituted epoxides.