- Kinetics and mechanistic investigation into the degradation of naproxen by a UV/chlorine process
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In this study, UV irradiation combined with chlorine (UV/chlorine) was used to degrade naproxen (NPX), a typical non-steroidal anti-inflammatory drug (NSAID) widely used for the treatment of symptoms associated with inflammation, in water. Compared with UV irradiation alone and direct chlorination, the UV/chlorine process shows a synergistic effect on NPX degradation. The effects of different factors, including the chlorine dose, solution pH, and the presence of Cl-, HCO3- or humic acid (HA), on NPX degradation in the UV/chlorine process were investigated. The results indicated that the degradation of NPX followed pseudo-first-order kinetics in all cases, and the rate constant increased as the chlorine dose increased and decreased as the pH increased. The effects of the water matrix on UV/chlorine treatment were species-dependent. The NPX degradation rate was inhibited by the presence of HCO3- and HA but significantly improved by Cl-. LC/MS/MS analysis indicated that NPX decomposition in the UV/chlorine process was associated with decarboxylation, demethylation and hydroxylation. These results indicate that the UV/chlorine process is a promising technology for the treatment of water polluted by emerging contaminants, such as NPX. However, UV/chlorine can notably enhance the formation of disinfection by-products compared to direct chlorination, which should be carefully considered when integrating this process into drinking water treatment schemes.
- Gao, Yu-Qiong,Gao, Nai-Yun,Chu, Wen-Hai,Yang, Qin-Lin,Yin, Da-Qiang
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- Thermally induced oxidative decarboxylation of copper complexes of amino acids and formation of strecker aldehyde
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In the Maillard reaction, independent degradations of amino acids play an important role in the generation of amino-acid-specific products, such as Strecker aldehydes or their Schiff bases. Such oxidative decarboxylation reactions are expected to be enhan
- Nashalian, Ossanna,Yaylayan, Varoujan A.
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p. 8518 - 8523
(2015/04/22)
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- Hydrolysis of N-(2,2,2-trichloroethyl)arenesulfonamides
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The direction of alkaline hydrolysis of N-(2,2,2-trichloro-1-R-ethyl)arenesulfonamides depends on the R substituent in the α-position with respect to the nitrogen atom. Substituents R having an n-donor heteroatom X promote cleavage of the C-N and C-X bonds to release the corresponding sulfonamide. Alkaline hydrolysis of N-(1-aryl-2,2,2-trichloroethyl)arenesulfonamides occurs chemoselectively at the trichloromethyl group. This reaction can be regarded as a preparative route to N-arylsulfonyl-α-arylglycines.
- Rozentsveig,Levkovskaya,Mirskova,Kashik
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p. 1760 - 1764
(2007/10/03)
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- Metabolism of trichloroethylene and chloral hydrate by the Japanese medaka (Oryzias latipes) in vitro
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Trichloroethylene (TRI), a common groundwater contaminant, is readily metabolized by mammals to produce chloral hydrate (CH), trichloroacetic acid (TCA), and trichloroethanol (TCOH). Cytochrome P450 (CYP) and other enzymes are responsible for formation of these metabolites, which are implicated in TRI's toxicity and carcinogenicity. To establish the validity of the Japanese medaka (Oryzias latipes) as an alternate test species for TRI, we examined the metabolism of TRI and CH, as well as CYP expression, in medaka liver preparations. Trichloroethylene was incubated with medaka microsomal protein, and metabolites were extracted and analyzed using gas chromatography. Microsome-mediated metabolism of TRI was observed, and a K(m) value for TRI oxidation of 540 μM and a V(max) value of 213 pmol/min·mg-1 protein were obtained. Conversion of TRI to CH, TCA, and TCOH was found with medaka hepatic subcellular fractions. In addition, a sex difference in hepatic microsomal TRI metabolism, specific CYP content, and ethoxyresorufin O- deethylase activity was noted. The lower specific activity of preparations from the livers of female medaka is compensated for by increased total protein in the larger liver mass of the female. Immunochemical analysis showed that CYP1A was readily detectable in medaka liver, but CYP2E1 was present at very low levels. These data suggest that TRI metabolism in medaka liver preparations mimics that observed in mammalian systems and supports their use as an alternative test species in the evaluation of the toxicity of TRI.
- Lipscomb, John C.,Confer, Patricia D.,Miller, Michael R.,Stamm, Steven C.,Snawder, John E.,Bandiera, Stelvio M.
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p. 325 - 332
(2007/10/03)
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- Thermochemistry of carbonyl reactions. 6. A study of hydration equilibria
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The hydration of carbonyl compounds, along with hemiketal and ketal or hemiacetal and acetal formation, has been studied both experimentally and theoretically. The heats of hydrolysis of some acetals and ketals were determined calorimetrically. Equilibrium constants for hydrate, hemiacetal, and acetal formation were determined via NMR spectroscopy, and heats of reaction were obtained from the change in equilibrium constants with temperature. Calculations of the hydration energies were made using a set of theoretical models through MP2/6-311++G**// HF/6-31G* for formaldehyde, acetaldehyde, acetone, cyclopropanone, and cyclobutanone and through MP2/6-31G**/ /HF/6-31G* for crotonaldehyde, bicyclo[1.1.1]pentan-2-one, cyclohexanone, 7-norbornanone, methyl acetate, chloral, and fluoral. Additional calculations were carried out using the CBS-4 theoretical model. The energies of hemiacetalization and acetalization also were calculated for formaldehyde, acetaldehyde, and acetone. The origin of the changes in hydration energies was analyzed using group transfer reactions of formaldehyde with an alkane to give the substituted carbonyl compound and of formaldehyde hydrate with an alkane to give the substituted carbonyl hydrate.
- Wiberg, Kenneth B.,Morgan, Kathleen M.,Maltz, Henry
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p. 11067 - 11077
(2007/10/02)
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- A Theoretical and Experimental Investigation of Vicinal Tricarbonyl Systems and Their Hydrates
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The conformational preference of the vinyl vicinal tricarbonyl reagent (VTC) and related triketones have been examined in the context of ab initio molecular orbital theory in order to better understand the properties of these reactive polyelectrophiles.The preferred conformation of the VTC methyl ester has been calculated to have the glyoxal unit twisted almost perpendicular to the plane of the ester unit.These results support the recent conclusions of Schreiber and co-workers on the activity of FK-506 and related compounds for inhibition of the rotamase enzyme.The origin of the enhanced reactivity has been examined via an analysis of the charge density distribution of the triketones and the corresponding hydrates.Electrostatic stabilization appears to be the main driving force for the stability of the hydrates.The energy of hydration for VTC has been calculated to be similar to that of activated aldehydes such as fluoral and chloral.Experimental values are also presented for the energy of hydration of chloral and VTC in acetone solution.
- Henke, Susan L.,Hadad, Christopher M.,Morgan, Kathleen M.,Wiberg, Kenneth B.,Wasserman, Harry H.
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p. 2830 - 2839
(2007/10/02)
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- REACTION OF TRICHLOROETHYLENE WITH N,N-DICHLOROARENESULFONAMIDES IN THE PRESENCE OF LEWIS ACIDS
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The reaction of N,N-dichloroarenesulfonamides with trichloroethylene in the presence of ionic catalyst (SnCl4 and AlCl3) leads to N-(2,2,2-trichloroethyliden)-arenesulfonamides and the products of the subsequent conversion, namely, N-(2,2,2-trichloro-1-arenesulfonamidoethyl)arenesulfonamides and N-(2,2,2-trichloro-1-hydroxyethyl)arenesulfonamides.
- Mirskova, A. N.,Drozdova, T.I.,Levkovskaya, G. G.,Kalikhman, I. D.,Voronkov, M. G.
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p. 681 - 685
(2007/10/02)
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- Derivatives of chloral
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The present invention relates to a chloral derivative having the general formula STR1 in which Y' is a polysaccharide consisting of a chain of anhydroglucose, modified anhydroglucose or uronic acid units as substituent group and in which R is selected from --H, --COCH2 OH, --[(CH2)n 0]χ --H in which n is 2 to 5 and χ is 1 to 7; --CH2 OSO2 X' or --CH2 COOX' in which X' is NH4 or a single equivalent of a non-toxic metallic cation, --(CH2)n H where n is 1 to 7, --(CH2)n (OH)χ Y where Y is --H or --CH3 n is 1 to 7, χ is 1 to 12 and the --OH groups are attached to any or all of the carbon atoms by substitution and wherein when Y1 is a chain of unmodified anhydroglucose units, these units have the following configurations: α-D-glucopyranosyl units having a predominantly 1-4 linkage β-D-glucopyranosyl units having a predominantly 1-4 linkage and/or β-D-glucopyranosyl units having a predominately 1-4 linkage when C6 is a carboxylic acid group.
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- Method for purifying a dehydrochlorination mixture
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A method is provided for making substantially pure 1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene by dehydrochlorinating 1,1,1-trichloro-2,2-bis(4-hydroxyphenyl)ethane with a methanol solution of potassium hydroxide, followed by purifying the crude reaction product with a mixture of a hot aromatic solvent and a polar solvent, such as methanol.
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