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Showing 1 to 20 of 37 for “"second order rate"”.
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Primary Photoproducts and the Mechanism of Ligand Substitution in the Photochemistry of Dinuclear Metal Carbonyls
… observed for both primary photoproducts. The second-order rate constant for radical recombination was measured and determined to be (8.0 (+OR-) 0.6) x 10('8) M('-1) s('-1). The second-order rate constant for CO recapture was found to be (4.4 (+OR-) 0.4) x 10('3) M('-1) s('-1).
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HIGH TEMPERATURE KINETICS OF PRECIPITATION AND DISSOLUTION OF FERROUS-CARBONATE
… The precipitation kinetics fit an empirical second order rate law with an activation energy of (9.31 $\pm$ 1.47) $\times$ $10\sp4$ J/mole, indicating surface reaction control. The dissolution kinetics fit an empirical second order rate law more closely than a first order rate law; however, …
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Bromamine Decomposition and Cyanogen Bromide Formation in Drinking Water From Monobromamine and Formaldehyde
… a fast equilibrium reaction. The equilibrium and second order rate constants are 2.5 x 105 M-1 and 6.3 x 104 M-1s-1, respectively. (Abstract shortened by UMI.).
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Kinetics and Speciation of Brominated Disinfection by -Products During Ozonation
… This new method determined the reaction rates of HOBr with phenolic compounds, one of the major chemical components in natural organic matters (NOM). The apparent second-order rate constants increased with pH between 4.0 and 8.5 suggesting that a major reaction pathway is the reaction …
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Substitution and redox reactions of heptarhenium cluster derivatives
The second-order rate constants for the reactivity of (Re$\sb7$C(CO)$\sb{21}$Rh(CO)$\sb2$) $\sp{2-}$ towards phosphorus donors were determined. In order to correlate the results to electronic and/or steric effects, steric profiles relating log k$\sb2$ to an intrinsic reactivity $(\alpha),$ an …
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Chemical probes for the study of mitochondrial oxidative stress
… of nitrones with the Zincke reaction was demonstrated for the first time. The capability of spin traps iv-vi to trap methyl radicals was demonstrated using EPR spectroscopy. Two novel selective uncoupling molecules (SUMs), DNP-SUM vii and FCCP-SUM viii, were designed to react with H2O2 and …
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Mechanism-Guided Studies of Brønsted Acid and Base Organocatalysis
… absence of chiral phosphoric acid catalysts. In order to gain mechanistic insight into the asymmetric Mannich reaction, a structurally homologous series of N-Boc imines and BINOL-derived phosphoric acid and thiophosphoric acid catalysts were synthesised. The degree of asymmetric catalysis was …
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A novel diazonium-sulfhydryl reaction in the inactivation of yeast alcohol dehydrogenase by diazotized 3-aminopyridine adenine dinucleotide
… Diazonium-sulfhydryl reactions were demonstrated for a number of diazonium derivatives with cysteine, homocysteine, glutathione and mercaptoethanol at 0-4° and neutral pH. Second order rate constants were determined in reactions of these sulfhydryl compounds with diazotized …
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The Mechanisms, Products, and Kinetics of Triclosan-Free Chlorine Reactions
… to play a significant role in the kinetics. The second order rate constant for the reaction between phenolate-triclosan and HOCl was found to be 5.40 (±1.82) Ã 103 M⁻¹s⁻¹. Three chlorinated triclosan intermediates were tentatively identified based on mass spectral analysis. Additionally, …
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Active Center Studies on Bacterial Luciferase: Modification of the Enzyme With 2,4-Dinitrofluorobenzene
… the mixed-function oxidation of a long-chain saturated aldehyde and FMNH(,2) to yield the carboxylic acid, FMN and blue-green light. The enzyme is inactivated by 2,4-dinitrofluorobenzene (FDNB) with an observed second-order rate constant (k(,2(obs))) of 157 M('-1) min('-1) at pH 7.0, 25(DEGREES); …
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Kinetics and Mechanism of the Reaction of 4,4'-Dimethoxythio Benzophenone With Grignard Reagents
… in ether at 25.0(DEGREES)C was found to be first order in thioketone and first order in Grignard, with a second-order rate constant of 0.047 (+OR-) 0.002 s('-1)M('-1). The mechanism proposed to account for the products of the reaction involves slow thiophilic addition of Grignard to thioketone, …
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Searching for ribozymes with new and improved properties
… variants isolated by in vitro selection. The rate of the most efficient ribozyme identified was 30-fold faster than that of the most efficient ribozyme used to build the pool, with a second order rate enhancement approaching 100°- fold.
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GROWTH MECHANISMS OF COMPLEX ORGANICS IN THE GAS PHASE AND ON METAL NANOPARTICLES GENERATED BY A LASER VAPORIZATION PROCESS
… neutrals with different aromatic cations, in order to infer the possible mechanisms of formation of PAHs and PANHs in different environments such as interstellar media under different ionizing conditions. Furthermore, this technique is used to probe structures, address the thermochemistry, and …
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The UV/H2O2 advanced oxidation process in UV disinfection units : removal of selected phosphate esters by hydroxyl radical
… of phosphate esters through hydroxyl radical generated by the UV/H202 process applied at a UV disinfection unit was selected for evaluation. The second-order rate constants of the reactions of two phosphate esters, Tri(2-butoxyethyl) phosphate (TBEP) and Tri-2-chloroethyl phosphate (TCEP) , with …
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Kinetic studies of the mechanism of transimination
… basic than aniline) is subject to catalysis by a second molecule of the amine, by carboxyanions and by tertiary amines. Plots of second order rate constants against catalyst concentration are curved, indicating a change in rate limiting step from proton transfer to some other step. The …
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Mechanistic Studies in Tellurium Chemistry
… common two-electron process. Both systems obey a second-order rate law. The percentage of water in the mixed solvent used plays a role in deciding the rate-determining step of the reaction. A mechanism for the above reactions is suggested. The reduction of p-EtOPhTeCl₃ by chromous and vanadous …
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Experimental Studies of the Heterogeneous Kinetics of OH Radicals with terbuthylazine, Adsorbed on Self- Synthesized SiO2 Particles, in a Temperature Controlled Aerosol Smog Chamber
… around 160 nm) were used as carrier particles in order to avoid any influence of agglomeration. The experimental results of second order rate constants showed a lower value than previous work on Aerosil 200 particles (Palm et al., 1997). However, results from this work correspond to the …
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Selective Oxidations by Iron(III) Porphyrins and Iron(III) Corroles
… water, amounts of oxygen source, and substrate scope. The optimal conditions were determined for iron(III) porphyrin/ corrole-catalyzed sulfoxidations with PhI(OAc)<sub>2</sub> as the mild oxygen source. Competitive catalytic oxidation of substituted thioanisoles versus thioanisole by …
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Cytochrome c peroxidase : its role in nitrosative stress and purification as a GST-fusion protein
… species formed is compound I. An estimate of the second-order rate constant for the reaction of peroxynitrite with CCP at pH 7.0 is 6.9 ± 2.2 \ 10 5 M -1 s -1 . We propose that the end product of the reaction of CCP with peroxynitrite is nitrite and not the NO 2 · radical, since excess nitrite …
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Mechanisms of Methoxide Ion Substitution and Acid- Catalyzed Z/E Isomerization of N-Methoxyimines
The second order rate constants for nucleophilic substitution by methoxide of (Z)- and (E)-O-methylbenzohydroximoyl fluorides [C6H4C(F)=NOCH3] with various substituents on the phenyl ring [p-OCH3 (1h, 2h), p-CH3 (1g, 2g), p-Cl (1f, 2f), p-H (1e, 2e), (3,5)-bis-CF3 (1i, 2i)] in 90:10 DMSO:MeOH have …
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