Sample records for bromamines

  1. Correction: Benchmark thermochemistry of chloramines, bromamines, and bromochloramines: halogen oxidants stabilized by electron correlation. (United States)

    Trogolo, Daniela; Arey, J Samuel


    Correction for 'Benchmark thermochemistry of chloramines, bromamines, and bromochloramines: halogen oxidants stabilized by electron correlation' by Daniela Trogolo et al., Phys. Chem. Chem. Phys., 2015, 17, 3584-3598.

  2. Formation and reactivity of inorganic and organic chloramines and bromamines during oxidative water treatment. (United States)

    Heeb, Michèle B; Kristiana, Ina; Trogolo, Daniela; Arey, J Samuel; von Gunten, Urs


    The formation and further reactions of halamines during oxidative water treatment can be relevant for water quality. In this study, we investigated the formation and reactivity of several inorganic and organic halamines (monochloramine, N-chloromethylamine, N-chlorodimethylamine, monobromamine, dibromamine, N-bromomethylamine, N,N-dibromomethylamine, and N-bromodimethylamine) by kinetic experiments, transformation product analysis, and quantum chemical computations. Kinetic model simulations were conducted to evaluate the relevance of halamines for various water treatment scenarios. Halamines were quickly formed from the reaction of chlorine and bromine with ammonia or organic amines. Species-specific second-order rate constants for the reaction of chlorine and bromine with ammonia, methyl- and dimethylamine were in the order of 106-108 M-1s-1. The formed halamines were found to be reactive towards phenolic compounds, forming halogenated phenols via electrophilic aromatic substitution (phenol and resorcinol) or quinones via electron transfer (catechol and hydroquinone). At near neutral pH, apparent second-order rate constants for these reactions were in the order of 10-4-10-1 M-1s-1 for chloramines and 101-102 M-1s-1 for bromamines. Quantum chemical computations were used to determine previously unknown aqueous pKa values, gas phase bond dissociation energies (BDE) and partial atomic charges of the halamines, allowing a better understanding of their reactivities. Kinetic model simulations, based on the results of this study, showed that during chlorination inorganic and organic chloramines are the main halamines formed. However, their further reactions with organic matter are outcompeted kinetically by chlorine. During ozonation, mainly inorganic bromamines are formed, since ozone quickly oxidizes organic amines. The further reactions of bromamine are typically outcompeted by ozone and thus generally of minor importance. The use of peracetic acid for saline

  3. Benchmark thermochemistry of chloramines, bromamines, and bromochloramines: halogen oxidants stabilized by electron correlation. (United States)

    Trogolo, Daniela; Arey, J Samuel


    Chloramines, bromamines, and bromochloramines are halogen-containing oxidants that arise from the reaction of hypohalous acids with ammonia in water. Although relevant to both water disinfection chemistry and biochemistry, these molecules are difficult to study in the laboratory, and their thermochemical properties remain poorly established. We developed a benchmark level ab initio calculation protocol, termed TA14, adapted from the Weizmann theory and Feller-Peterson-Dixon approaches to determine the molecular structures and thermochemical properties of these compounds. We find that the halamine molecules are bound largely, and in some cases entirely, by electron correlation forces. This presumably explains their high reactivity as electrophilic oxidants. We provide computed heats of formation at 0 K (ΔfH(0)(0 K)) and at 298 K (ΔfH(0)(298 K)) and Gibbs free energies of formation at 298 K (ΔfG(0)(298 K)) for the 9 inorganic chloramines, bromamines, bromochloramines in gas phase. Based on comparisons to previous theoretical and experimental data for a set of 11 small molecules containing N, O, H, Cl, and Br, we propose uncertainties ranging from 1 to 3 kJ mol(-1) for computed thermodynamic properties of the halamines. Reported thermochemical data enable the determination of equilibrium constants for reactions involving halamines, opening possibilities for more quantitative studies of the chemistry of these poorly understood compounds.

  4. Taurine Bromamine: Reactivity of an Endogenous and Exogenous Anti-Inflammatory and Antimicrobial Amino Acid Derivative

    Directory of Open Access Journals (Sweden)

    Luiza De Carvalho Bertozo


    Full Text Available Taurine bromamine (Tau-NHBr is produced by the reaction between hypobromous acid (HOBr and the amino acid taurine. There are increasing number of applications of Tau-NHBr as an anti-inflammatory and microbicidal drug for topical usage. Here, we performed a comprehensive study of the chemical reactivity of Tau-NHBr with endogenous and non-endogenous compounds. Tau-NHBr reactivity was compared with HOBr, hypochlorous acid (HOCl and taurine chloramine (Tau-NHCl. The second-order rate constants (k2 for the reactions between Tau-NHBr and tryptophan (7.7 × 102 M−1s−1, melatonin (7.3 × 103 M−1s−1, serotonin (2.9 × 103 M−1s−1, dansylglycine (9.5 × 101 M−1s−1, tetramethylbenzidine (6.4 × 102 M−1s−1 and H2O2 (3.9 × M−1s−1 were obtained. Tau-NHBr demonstrated the following selectivity regarding its reactivity with free amino acids: tryptophan > cysteine ~ methionine > tyrosine. The reactivity of Tau-NHBr was strongly affected by the pH of the medium (for instance with dansylglycine: pH 5.0, 1.1 × 104 M−1s−1, pH 7.0, 9.5 × 10 M−1s−1 and pH 9.0, 1.7 × 10 M−1s−1, a property that is related to the formation of the dibromamine form at acidic pH (Tau-NBr2. The formation of singlet oxygen was observed in the reaction between Tau-NHBr and H2O2. Tau-NHBr was also able to react with linoleic acid, but with low efficiency compared with HOBr and HOCl. Compared with HOBr, Tau-NHBr was not able to react with nucleosides. In conclusion, the following reactivity sequence was established: HOBr > HOCl > Tau-NHBr > Tau-NHCl. These findings can be very helpful for researchers interested in biological applications of taurine haloamines.

  5. The role of heme oxygenase-1 in down regulation of PGE2 production by taurine chloramine and taurine bromamine in J774.2 macrophages. (United States)

    Olszanecki, R; Kurnyta, M; Biedroń, R; Chorobik, P; Bereta, M; Marcinkiewicz, J


    Taurine chloramine (TauCl) and taurine bromamine (TauBr), products of myeloperoxidase halide system, exert anti-inflammatory properties. TauCl was demonstrated to inhibit the production of a variety of pro-inflammatory mediators including cyclooxygenase-2 (COX-2) dependent production of prostaglandin E(2) (PGE(2)). Recently we have demonstrated that both major leukocyte haloamines, TauCl and TauBr, induced expression of HO-1 in non-activated and LPS-activated J774.2 macrophages. In this study, we have shown that TauCl and TauBr, at non-cytotoxic concentrations, inhibited the production of (PGE(2)) without altering the expression of COX-2 protein, in LPS/IFN-gamma stimulated J774.2 cells. The inhibitory effect of TauCl and TauBr was reversed by chromium III mesoporhyrin (CrMP), an inhibitor of HO-1 activity. Our data suggest that HO-1 might participate in anti-inflammatory effects of TauCl/TauBr possibly by inhibition of COX-2 activity and decrease of PGE(2) production.

  6. Oxidation of Amitriptyline by Bromamine-T in Acidic Buffer Medium: A Kinetic and Mechanistic Approach


    Chandrashekar; R. T. Radhika; B. M. Venkatesha; S. Ananda; Shivalingegowda; T. S. Shashikumar; H. Ramachandra


    The kinetics of the oxidation of amitriptyline (AT) by sodium N-bromotoluene sulphonamide (C6H5SO2NBrNa) has been studied in an acidic buffer medium of pH 1.2 at 303 K. The oxidation reaction of AT was followed spectrophotometrically at maximum wavelength, 410 nm. The reaction rate shows a first order dependence each on concentration of AT and concentration of sodium N-bromotoluene sulphonamide. The reaction also shows an inverse fractional order dependence at low or high concentration of HCl...

  7. A study of substituent effect on the oxidative strengths of sodium ...

    Indian Academy of Sciences (India)


    phonamide (NBBS, bromamine-B) and N-bromo-4- methylbenzenesulphonamide (NB4MBS, bromamine-. T).4,5 In fact, the kinetics of oxidation of D-fructose and D-glucose by these oxidants have also been car- ried out under identical conditions and analysed. Carbohydrates comprise one of the largest classes.

  8. Kinetics of oxidation of acidic amino acids by sodium N ...

    Indian Academy of Sciences (India)


    Keywords. Acidic amino acids; bromamine-B; oxidation kinetics, acid medium. 1. Introduction. The chemistry of aromatic sulphonyl haloamines has evoked considerable interest, as they are sources of halonium cations, hypohalite species, and N-anions which act both as bases and nucleophiles. The prominent members of ...

  9. A sensitive and selective assay for chloramine production by myeloperoxidase. (United States)

    Dypbukt, Jeannette M; Bishop, Cynthia; Brooks, Wendy M; Thong, Bob; Eriksson, Håkan; Kettle, Anthony J


    We describe a new assay for the chlorination activity of myeloperoxidase and detection of chloramines. Chloramines were detected by using iodide to catalyze the oxidation of either 3,3',5,5'-tetramethylbenzidine (TMB) or dihydrorhodamine to form strongly absorbing or fluorescent products, respectively. With TMB as little as 1 muM taurine chloramine could be detected. The sensitivity of the dihydrorhodamine assay was about 10-fold greater. The chlorination activity of myeloperoxidase was measured by trapping hypochlorous acid with taurine and subsequently using iodide to promote the oxidation reactions of the accumulated taurine chloramine. A similar approach was used to detect hypochlorous acid production by stimulated human neutrophils. Iodide-dependent catalysis distinguished N-chloramines from N-bromamines. This allows for discrimination between heme peroxidases that generate either hypochlorous acid or hypobromous acid. The assay has distinct advantages over existing assays for myeloperoxidase with regard to sensitivity, specificity, and its ease and versatility of use.

  10. Kinetic model for predicting the concentrations of active halogen species in chlorinated saline cooling waters

    Energy Technology Data Exchange (ETDEWEB)

    Lietzke, M. H.; Haag, W. R.


    A kinetic model for predicting the composition of chlorinated water discharged from power plants using fresh water for cooling was previously reported. The model has now been extended to be applicable to power plants located on estuaries or on the seacoast where saline water is used for cooling purposes. When chloride is added to seawater to prevent biofouling in cooling systems, bromine is liberated. Since this reaction proceeds at a finite rate there is a competition between the bromine (i.e., hypobromous acid) and the added chlorine (i.e., hypochlorous acid) for halogenation of any amine species present in the water. Hence not only chloramines but also bromamines and bromochloramines will be formed, with the relative concentrations a function of the pH, temperature, and salinity of the water. The kinetic model takes into account the chemical reactions leading to the formation and disappearance of the more important halamines and hypohalous acids likely to be encountered in chlorinated saline water.

  11. Kinetics of bromochloramine formation and decomposition. (United States)

    Luh, Jeanne; Mariñas, Benito J


    Batch experiments were performed to study the kinetics of bromochloramine formation and decomposition from the reaction of monochloramine and bromide ion. The effects of pH, initial monochloramine and bromide ion concentrations, phosphate buffer concentration, and excess ammonia were evaluated. Results showed that the monochloramine decay rate increased with decreasing pH and increasing bromide ion concentration, and the concentration of bromochloramine increased to a maximum before decreasing gradually. The maximum bromochloramine concentration reached was found to decrease with increasing phosphate and ammonia concentrations. Previous models in the literature were not able to capture the decay of bromochloramine, and therefore we proposed an extended model consisting of reactions for monochloramine autodecomposition, the decay of bromamines in the presence of bromide, bromochloramine formation, and bromochloramine decomposition. Reaction rate constants were obtained through least-squares fitting to 11 data sets representing the effect of pH, bromide, monochloramine, phosphate, and excess ammonia. The reaction rate constants were then used to predict monochloramine and bromochloramine concentration profiles for all experimental conditions tested. In general, the modeled lines were found to provide good agreement with the experimental data under most conditions tested, with deviations occurring at low pH and high bromide concentrations.

  12. Characterization of vanadium bromoperoxidase from Macrocystis and Fucus: reactivity of vanadium bromoperoxidase toward acyl and alkyl peroxides and bromination of amines. (United States)

    Soedjak, H S; Butler, A


    Vanadium bromoperoxidase (V-BrPO) has been isolated and purified from the marine brown algae Fucus distichus and Macrocystis pyrifera. V-BrPO catalyzes the oxidation of bromide by hydrogen peroxide, resulting in the bromination of certain organic acceptors or the formation of dioxygen. V-BrPO from F. distichus and M. pyrifera have subunit molecular weights of 65,000 and 74,000, respectively, and specific activities of 1580 units/mg (pH 6.5) and 1730 units/mg (pH 6) for the bromination of monochlorodimedone, respectively. As isolated, the enzymes contain a substoichiometric vanadium/subunit ratio; the vanadium content and specific activity are increased by addition of vanadate. V-BrPO (F. distichus, M. pyrifera, and Ascophyllum nodosum) also catalyzes the oxidation of bromide using peracetic acid. In the absence of an organic acceptor, a mixture of oxidized bromine species (e.g., hypobromous acid, bromine, and tribromide) is formed. Bromamine derivatives are formed from the corresponding amines, while 5-bromocytosine is formed from cytosine. In all cases, the rate of the V-BrPO-catalyzed reaction is much faster than that of the uncatalyzed oxidation of bromide by peracetic acid, at pH 8.5, 1 mM bromide, and 2 mM peracetic acid. In contrast to hydrogen peroxide, V-BrPO does not catalyze formation of dioxygen from peracetic acid in either the presence or absence of bromide. V-BrPO also uses phenylperacetic acid, m-chloroperoxybenzoic acid, and p-nitroperoxybenzoic acid to catalyze the oxidation of bromide; dioxygen is not formed with these peracids. V-BrPO does not catalyze bromide oxidation or dioxygen formation with the alkyl peroxides ethyl hydroperoxide, tert-butyl hydroperoxide, and cuminyl hydroperoxide.

  13. One-electron reduction of N-chlorinated and N-brominated species is a source of radicals and bromine atom formation. (United States)

    Pattison, David I; O'Reilly, Robert J; Skaff, Ojia; Radom, Leo; Anderson, Robert F; Davies, Michael J


    Hypochlorous (HOCl) and hypobromous (HOBr) acids are strong bactericidal oxidants that are generated by the human immune system but are implicated in the development of many human inflammatory diseases (e.g., atherosclerosis, asthma). These oxidants react readily with sulfur- and nitrogen-containing nucleophiles, with the latter generating N-halogenated species (e.g., chloramines/bromamines (RR'NX; X = Cl, Br)) as initial products. Redox-active metal ions and superoxide radicals (O(2)(•-)) can reduce N-halogenated species to nitrogen- and carbon-centered radicals. N-Halogenated species and O(2)(•-) are generated simultaneously at sites of inflammation, but the significance of their interactions remains unclear. In the present study, rate constants for the reduction of N-halogenated amines, amides, and imides to model potential biological substrates have been determined. Hydrated electrons reduce these species with k(2) > 10(9) M(-1) s(-1), whereas O(2)(•-) reduced only N-halogenated imides with complex kinetics indicative of chain reactions. For N-bromoimides, heterolytic cleavage of the N-Br bond yielded bromine atoms (Br(•)), whereas for other substrates, N-centered radicals and Cl(-)/Br(-) were produced. High-level quantum chemical procedures have been used to calculate gas-phase electron affinities and aqueous solution reduction potentials. The effects of substituents on the electron affinities of aminyl, amidyl, and imidyl radicals are rationalized on the basis of differential effects on the stabilities of the radicals and anions. The calculated reduction potentials are consistent with the experimental observations, with Br(•) production predicted for N-bromosuccinimide, while halide ion formation is predicted in all other cases. These data suggest that interaction of N-halogenated species with O(2)(•-) may produce deleterious N-centered radicals and Br(•).