- The mechanism of monochloramine disproportionation under acidic conditions
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Monochloramine is a widely employed agent in water treatment technologies. However, its utilization has some drawbacks like the transformation of the active species into the undesired dichloramine. Although it is more pronounced in acidic solutions, the f
- Fehér, Péter Pál,Purgel, Mihály,Lengyel, Adrienn,Stirling, András,Fábián, István
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p. 16713 - 16721
(2019/11/19)
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- AQUEOUS SOLUTIONS CONTAINING CHLORAMINE WHICH ARE FREE FROM DI-AND TRICHLOROAMINE, AS WELL AS FROM AMMONIA
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The combination of N-chlorotaurine, preferably in the form of sodium salt, and ammonium chloride in aqueous solution absent a buffer is a powerful antiseptic preparation sufficiently stable for use in topical treatment of infections, inflammation and oozing tissue deficiencies. The outstanding microbicidal properties of the preparation are founded in the formation of monochloramine, which is distinguished by the absence, or substantial absence, of dichloramine and trichloramine.
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Page/Page column 3-4
(2008/12/04)
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- Method and apparatus for producing synergistic biocide
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An apparatus and methods to produce synergistic mixtures (or combinations) of haloamines to control growth of microorganisms in aqueous systems are disclosed. The apparatus and methods to produce synergistic mixtures entails producing a batch quantity of a haloamine and converting part of the haloamine to a second haloamine species to form the synergistic mixture.
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Page/Page column 6-7
(2008/06/13)
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- Electrochemical behavior of chloramines on the rotating platinum and gold electrodes
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Electroreduction of chloramines (mono-, di-, and trichloramine) in 1 M NH4Cl solutions of different pH was investigated at the rotating platinum and gold electrodes. It was found that all chloramines are present in the solution in nonprotonated forms and give well-formed one-step or two-step current-potential waves. The final products of reduction are ammonium (or ammonia) and chloride ions. Monochloramine is reduced in a single two-electron irreversible wave. Hydrazine is not an intermediate in monochloramine reduction. Dichloramine reduction generally proceeds in two two-electron steps (via monochloramine). Below pH 4.3 a kinetic current due to the protonated dichloramine reduction (single four-electron wave) is in force, appearing as an increase of the height of the first step on lowering pH. Due to this process below pH 2.5 only one four-electron reduction wave is observed. Trichloramine reduction occurs in two steps: two-electron trichloramine to dichloramine reduction and four-electron dichloramine reduction. In strong acidic solutions the kinetic current due to the protonated trichloramine reduction has to be taken into account. A reaction mechanism common for all chloramines was proposed with [NXCl·] as an intermediate (X = H2, HCl, and Cl2 for mono-, di-, and trichloramine, respectively). The rate-determining step does not involve proton transfer.
- Piela, Barbara,Wrona, Piotr K.
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p. E255-E265
(2008/10/08)
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- BICYCLIC NONANE AND DECANE COMPOUNDS HAVING DOPAMINE RECEPTOR AFFINITY
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Described herein are D4 receptor-selective compounds of the general formula: STR1 wherein: A and B are independently selected, substituted or unsubstituted, unsaturated 5-or 6-membered, homo-or heterocyclic rings;X 1 is selected from O, S, SO, SO 2, CH. sub.2, C=O, CH--OH, CH--N(C 1-4 alkyl) 2, C= CHCl, and C=CHCN;X 2---is selected from N= , CH. sub.2--, CH= and C(O)--;n is 1 or 2; R 1 is selected from H and the α-carbon side chain of an amino acid;R 2 and R 3 are selected independently from H, OH,--NH 2,--C(O)NH 2 =O, =S,halo, cyano, C 1-9 alkyl, C 1-9 alkoxy, C 1-4 alkylS--, C 1-4 alkylSO--, C 1-4 alkylSO 2--, phenoxy, benzyloxy and piperonyloxy; andH* is in either the R-or the S-configuration,and acid addition salts, solvates and hydrates thereof.Their use as ligands for dopamine receptor identification and in a drug screening program, and as pharmaceuticals to treat indications in which the D4 receptor is implicated, such as schizophrenia, is also described.
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- BICYCLIC NONANE AND DECANE COMPOUNDS HAVING DOPAMINE RECEPTOR AFFINITY
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Described herein are D4 receptor-selective compounds of the general formula: STR1 wherein: A and B are independently selected, optionally substituted, saturated or unsaturated 5-or 6-membered, homo-or heterocyclic rings;X 1 is selected from CH 2, O, NH, S, C=O, CH--OH, CH--N(C 1-4 alkyl) 2, C=CHCl, C= CHCN, N-C 1-4 alkyl, N-acetyl, SO 2 and SO;X. sub.2---is selected from N=, CH 2--, CH=, C(O)--, O--, and S--;n is 1 or 2;R 1 is selected from H and an amino acid side chain;R 2 is selected from H, OH, C 1-9 alkyl, C 1-9 alkoxy, and benzyloxy; andR 3 is selected from H, OH, halo, cyano, C 1-4 alkyl, C 1-4 alkoxy, phenoxy, benzyloxy, =O, =S, C 1-4 alkylsulfonyl, C 1-4 alkylsulfonyl, C 1-4 alkylthio, amino, and aminocarbonyl;and acid addition salts, solvates and hydrates thereof. Their use as ligands for dopamine receptor identification and in a drug screening program, and as pharmaceuticals to treat indications in which the D4 receptor is implicated, such as schizophrenia, is also described.
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- Non-metal redox kinetics: Oxidation of bromide ion by nitrogen trichloride
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Bromide ion reacts with NCl3 to generate NBrCl2 with the rate expression d[NCl3]/dt = 12[Br-][NCl3] (M s-1 at 25.0°C, μ = 0.50 M). The NBrCl2 intermediate subsequently reacts with Br- to give N2, Br2, and Cl- with the rate expression -d[NBrCl2]/dt = (0.05 + 5.3[Br-])[NBrCl2]. The overall stoichiometry from pH 3.2 to 6.5 corresponds to 2NCl3 + 6Br- → N2 + 3Br2 + 6Cl-. Rate constants for NCl3 reactions show extreme sensitivity to nucleophilic strength with SO32- > CN- > I- ? Br-. Aqueous absorption spectra are determined for NCl3 with maxima at 336 nm (∈ 190 M-1 cm-1) and 220 nm (∈ 5320 M-1 cm-1) and for NBrCl2 with a maximum at 228 nm (∈ 4800 M-1 cm-1). Spectral bands for NCl3, NBrCl2, NBr2Cl, and NBr3 shift systematically with the number of bromine atoms from 220 to 256 nm. The rate constants for the reactions of NHCl2 with Br2, HOBr, and Br- are much larger than that for the reaction of NCl3 with Br-.
- Gazda, Michael,Kumar, Krishan,Margerum, Dale W.
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p. 3536 - 3542
(2008/10/08)
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- Non-metal redox kinetics: Reactions of trichloramine with ammonia and with dichloramine
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Trichloramine reacts with excess NH3 and base (B) with the rate expression -d[NCl3]/dt = 2kB[B][NH3][NCl3], based on the overall stoichiometry 2NCl3 + 3NH3 + 3OH- → 3NH2Cl + N2 + 3Cl- + 3H2O. The reaction is general-base assisted with kB values (M-2 s-1, 25.0°C, μ = 0.50 M) of 4.46 × 103 for OH-, 3.3 × 103 for PO43-, and 22 for NH3. A water path with kH2O = 2.2 M-1 s-1 and an acidic phosphate path for H2PO4- (kHB = 450 M-2 s-1) are also found. The rate-determining step in the proposed mechanism is a Cl+ transfer between NCl3 and NH3 to give HNCl2 and NH2Cl. This is followed by N2 formation in a rapid base-assisted reaction between NCl3 and HNCl2 with the rate expression -d[NCl3]/dt = kB′[B][HNCl2][NCl3], based on the stoichiometry NCl3 + HNCl2 + 3OH- → N2 + 2HOCl + 3Cl- + H2O. Values of kB′ (M-2 s-1, 25.0°C, μ = 0.50 M) are 2.92 × 104 for HPO42- and greater than 4 × 107 for OH-. The HOCl released in the formation of N2 reacts with excess NH3 to give more NH2Cl, which accounts for the overall stoichiometry of 1.5 NH2Cl formed per NCl3. The reaction between NCl3 and HNCl2 is of critical importance in the explanation of breakpoint chlorination processes.
- Yiin, Boudin S.,Margerum, Dale W.
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p. 2135 - 2141
(2008/10/08)
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- Non-metal redox kinetics: Reactions of sulfite with dichloramines and trichloramine
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Pulsed-accelerated-flow (PAF) and stopped-flow techniques are used to study the kinetics of HNCl2 and CH3NCl2 reactions with sulfite. Pseudo-first-order rate constants with excess sulfite at p[H+] 3.7-6.4 are measured from 35-45000 s-1 (25.0°C, μ = 0.50). Acid suppresses the rate because SO3H- is much less reactive than SO32-. The rate expression is -d[RNCl2]/dt = k1[RNCl2][SO32-], where k1 (M-1 s-1) is 5.8 × 106 for HNCl2 and 2.4 × 107 for CH3NCl2. The initial nitrogen product is RNHCl, which reacts further with sulfite. Trichloramine reactions with sulfite are measured by the PAF method under second-order conditions with unequal concentrations (25.0°C, μ = 0.50) from p[H+] 3.8 to 4.6. The rate expression is -d[NCl3]/dt = (k1[SO32-] + k2[SO3H-])[NCl3], where k1 is 4.5 × 109 M-1 s-1 and k2 is 1.4 × 107 M-1 s-1. The initial nitrogen product is HNCl2, which reacts further with sulfite. A Cl+-transfer mechanism is proposed for all the reactions with sulfite to give ClSO3- as an initial product that hydrolyzes to give Cl- and SO42-. The relative reactivities of active chlorine species with SO32- are NCl3 ? HNCl2 ? NH2Cl ? OCl-, where the NCl3 and HNCl2 reactions are suppressed by acid whereas the NH2Cl and OCl- reactions are acid assisted.
- Yiin, Boudin S.,Margerum, Dale W.
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p. 1942 - 1948
(2008/10/08)
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- Non-metal redox kinetics: Oxidation of iodide by hypochlorous acid and by nitrogen trichloride measured by the pulsed-accelerated-flow method
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The very rapid reaction between HOCl and I- is general-acid- (HA-) assisted. The proposed mechanism is HOCl + I- ?k-1k1 HOClI- HOClI- →k0 HO- + ICl HOClI- + HA →kHA H2O + ICl + A- ICl + 2I- →fast I3- + Cl- where a stability constant (k1/k-1 = 220 M-1) is determined for the HOClI- intermediate from kinetic data and the limiting rate constant at high [H+] is k1 = 4.3 × 108 M-1 s-1. Values for third-order rate constants (with the general form k1kHA/(k0 + k-1) (M-2 s-1) at 25.0°C, μ = 0.1) are evaluated for H3O+ (3.5 × 1011), CH3COOH (3.2 × 1010), and H2PO4- (2.6 × 1010) and give a Br?nsted α value of 0.11, which indicates a small degree of proton transfer in the transition state. For the H2O path, k0k1/(k0 + k-1) = 1.4 × 108 M-1 s-1. The reaction between trichloramine and iodide exhibits saturation kinetics due to the formation of NCl3I- (K1 = 6 × 103 M-1), which undergoes first-order decomposition (k2 = 1.5 × 104 s-1 at 25.0°C and μ = 0.1) to HNCl2 and ICl. Acids do not affect the rate of NCl3I- decomposition. For these two studies first-order rate constants fall in the range of 10 000-142 000 s-1 and are measured by pulsed-accelerated-flow spectroscopy.
- Nagy, Julius C.,Kumar, Krishan,Margerum, Dale W.
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p. 2773 - 2780
(2008/10/08)
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- Kinetics and mechanisms of the base decomposition of nitrogen trichloride in aqueous solution
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The rate expression for the base decomposition of nitrogen trichloride is -d[NCl3]/dt = 2(k0 + k1[OH-] + kHB[HB][OH-] + k2[OH-]2)[NCl3], based on the stoichiometry 2NCl3 + 6OH- → N2 + 3OCl- + 3Cl- + 3H2O. Values of the rate constants (25.0 °C μ = 0.5) are 1.6 × 10-6 s-1 for k0, 8 M-1 s-1 for k1, and 890 M-2 s-1 for k2. The specific-base/general-acid-catalyzed path gives kHB values (M-2 s-1) of 2.1 × 103 for H2PO4-, 7.6 × 102 for B(OH)3, 65 for HCO3-, and 128 for HPO42-. In the proposed mechanism Cl2NClOH- is a common reactive intermediate that can react with acids (H3O+, HB, and H2O with a Br?nsted α value of 0.48) to form HNCl2 and HOCl or it can react with an additional OH- to release OCl-. The HNCl2 so formed reacts rapidly with a second NCl3 to give products. Kinetics data allow an equilibrium constant of 1.6 × 108 M-1 (25.0°C, μ = 0.5) to be calculated for the reaction NHCl2 + HOCl ? NCl3 + H2O.
- Kumar, Krishan,Shinness, Roger W.,Margerum, Dale W.
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p. 3430 - 3434
(2008/10/08)
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- Contribution a l'etude de la reaction d' oxydation de l'ammoniaque par l'hypochlorite de sodium :reactions de formation et de degradation des chloramines
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Reactions of sodium hypochlorite (OCl(1-)) with ammonia in aqueous solution have been studied at 20 deg C.Depending upon the conditions of solution pH, reactant concentrations, temperature and initial reactant ratios R = 0/0, chloramines (mono, di or trichloramine) together with a variety of degradation products (N2 or oxides of nitrogen) were produced.With an adjusted excess of ammonia, the reaction conditions were sufficiently stationnary to permit the determination of equilibrium constants for the hydrolysis of the different chloramines and for the disproportionation of NH2Cl and NHCl2.For reactions in basic medium and with an excess of oCl(1-), a comparison of observed reaction behavior with equilibrium theory leads to the assumption that the degradation of NHCl2 produced OCl(1-).The degradation process appeared very complex; one product detected by HPLC gave a UV spectrum in the same wave length range as that of NH2Cl.
- Rizk-Ouaini, Rosette,Ferriol, Michel,Gazet, Josette,Saugier-Cohen Adad, Marie-Therese
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p. 512 - 521
(2007/10/02)
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- Tetrazole derivatives, anti-ulcer composition containing the same and method for treating ulcers
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Tetrazole derivatives of the formula: STR1 wherein R1 is an optional defined substituent; A is sulfur or a lower alkylene-thio; l is 0 or 1; B is a lower alkylene; R2 is hydroxy, a lower alkoxy, or a group: STR2 wherein R3 and R4 are optional defined substituents, or the R3 and R4 may combine together with the nitrogen atom to which they are joined to form a defined heterocyclic group, and a pharmaceutically acceptable salt thereof, which have prophylactic or therapeutic activities against peptic and/or duodenal ulcers and also anti-inflammatory activity and are useful as an anti-ulcer or anti-inflammatory drug; processes for the preparation of the tetrazole derivatives; and pharmaceutical composition containing said tetrazole derivatives.
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- Kinetics and mechanisms of the decomposition of dichloramine in aqueous solution
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The reaction of hypochlorous acid with dichloramine is general base catalyzed: NHCl2 + HOCl + B→B NCl3 + OH- + HB+. Base assists proton removal from NHCl2 as the nitrogen attacks the chlorine of HOCl. Values of the third-order rate constants (kB, M-2 s-1 at 25.0°C) are 1.6 × 104 for HPO42-, 1 × 105 for OCl-, 6 × 106 for CO32-, and 3.3 × 109 for OH-. The trichloramine formed reacts with dichloramine to generate more hypochlorous acid and hence speeds the decomposition. One postulated reaction is NHCl2 + NCl3 + 3OH- → N2 + 3Cl- + 2HOCl + H2O, but side reactions produce other oxidized nitrogen products as well. The decomposition of NHCl2 is 5 orders of magnitude slower in neutral solutions that contain ammonium ion, because HOCl reacts rapidly with NH3 and hence HOCl is not available to form NCl3. Even traces of NH3 interrupt these coupled reactions and inhibit the decomposition. In ammoniacal solutions, NH2Cl is produced from NHCl2 (25% yield) by two pathways. One of these is first order in NHCl2 and first order in NH4+ with a second-order rate constant of 3 × 10-5 M-1 s-1. The other is first order in NHCl2 and first order in OH- with a second-order rate constant of 150 M-1 s-1.
- Hand, Vincent C.,Margerum, Dale W.
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p. 1449 - 1456
(2008/10/08)
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- TETRAZOLE DERIVATIVES, AND ANTI-ULCER COMPOSITION CONTAINING THE SAME
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Tetrazole derivatives of the formula: STR1 wherein R 1 is a lower alkykl, phenyl or a group of the formula:--S(O) l--A--(X) m--R 3, and R 2 is hydrogen, a lower alkyl, phenyl or a cycloalkyl when R 1 is the group--S(O) l--A--(X) m--R 3, or R 2 is a group of the formula:--B--CO--R 4 when R 1 is a lower alkyl or phenyl and a pharmaceutically acceptable salt thereof, which have prophylactic or therapeutic activities against peptic and/or duodenal ulcers and are useful as an anti-ulcer drug; processes for the preparation of the tetrazole derivatives; and pharmaceutical composition containing said tetrazole derivatives.
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- Dichloroamino acid derivatives useful as potent germicidal and fungicidal agents
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Dichloroamino acid derivatives other than α-dichloroamino acids are prepared from chlorination of corresponding amino acids, and are found to be potent germicidal and fungicidal agents.
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- Tetrahydronaphthoxazoles
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Compounds having the structure: STR1 are novel and useful as antiallergic agents. The compounds are formulated with a pharmaceutical carrier for oral, parental, inhalational, or rectal means of administration.
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