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1.
Kinetics of oxidation of disodium ethylene-diamine-tetraacetic, acid (EDTA) by bromamine-B (BAB) and bromamine-T (BAT) was
investigated at 30°C in acetate buffer of pH 5. The oxidation behaviour is similar, with a first-order dependence of rate
on [oxidant] and fractional orders in [EDTA] and [H+]. The influence of the reaction products, halide ions, ionic strength and dielectric constant of medium on the rate has been
studied. A possible mechanism is suggested. 相似文献
2.
The kinetics of oxidation of a typical dipeptide glycylglycine (GG) by bromamine-T have been studied in HClO4 medium at 40°C. The rate shows first-order dependence on [BAT]0 and is fractional order in [GG]0 which becomes independent of [substrate]0 at higher [GG]0. At [H+ ] > 0.02mol dm−3, the rate is inverse fractional in [H+ ] but is zero order at lower [H+ ] (≤0.02 mol dm−3). Variation in ionic strength or dielectric constant of the medium had no significant effect on the rate. The solvent-isotope
effect was measured and
= 1.45. Proton inventory studies have been made. The reaction has been studied at different temperatures (308-323 K) and activation
parameters have been computed. 相似文献
3.
R. C. Hiremath R. V. Jagadeesh Puttaswamy S. M. Mayanna 《Journal of Chemical Sciences》2005,117(4):333-336
Chloramphenicol (CAP) is an antibiotic drug having a wide spectrum of activity. The kinetics of oxidation of chloramphenicol
by 1-chlorobenzotriazole (CBT) in HClO4 medium over the temperature range 293–323 K has been investigated. The reaction exhibits first-order kinetics with respect
to [CBT]o and zero-order with respect to [CAP]o. The fractional-order dependence of rate on [H+] suggests complex formation between CBT and H+. It fails to induce polymerization of acrylonitrile under the experimental conditions employed. Activation parameters are
evaluated. The observed solvent isotope effect indicates the absence of hydride transfer during oxidation. Effects of dielectric
constant and ionic strength of the medium on the reaction rate have been studied. Oxidation products are identified. A suitable
reaction scheme is proposed and an appropriate rate law is deduced to account for the observed kinetic data. 相似文献
4.
Oxidation of acetylacetone (AA) by bromamine-B (BAB) in HC1 medium (0.1 to 0.6 mol dm−3) at constant ionic strength has been investigated at 40°C. The rate is first order in [BAB]0 and fractional order each in [AA]0 and [H+]. The reaction is also catalysed by chloride ion. Michaelis-Menten type of kinetics is observed. Decrease in dielectric constant
of medium increases the rate. A solvent isotope effect κ′H2O/κ′D2O = 0.96 has been noted. Activation parameters for the rate limiting step have been computed. The mechanism involves the enol
form of the diketone. 相似文献
5.
The kinetics of the oxidation of five catecholamines viz., dopamine (A), L-dopa (B), methyldopa (C), epinephrine (D) and norepinephrine
(E) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in presence of HClO4 was studied at 30±0.1 °C. The five reactions followed identical kinetics with a first-order dependence on [CAT]
o
, fractional-order in [substrate]
o
, and inverse fractional-order in [H+]. Under comparable experimental conditions, the rate of oxidation of catecholamines increases in the order D>E>A>B>C. The
variation of ionic strength of the medium and the addition of p-toluenesulfonamide or halide ions had no significant effect
on the reaction rate. The rate increased with decreasing dielectric constant of the medium. The solvent isotope effect was
studied using D2O. A Michaelis-Menten type mechanism has been suggested to explain the results. Equilibrium and decomposition constants for
CAT-catecholamine complexes have been evaluated. CH3C6H4SO2NHCl of the oxidant has been postulated as the reactive oxidizing species and oxidation products were identified. An isokinetic
relationship is observed with β=361 K, indicating that enthalpy factors control the reaction rate. The mechanism proposed
and the derived rate law are consistent with the observed kinetics. 相似文献
6.
7.
R. N. Zaripov A. A. Mukhametzyanova R. L. Safiullin V. D. Komissarov 《Russian Chemical Bulletin》2000,49(5):819-822
The kinetics of interaction ofn-decanepersulfonic acid with linear, branched, and substituted hydrocarbons was studied. The oxidation ofcyclo-C6H12/C6D12 occurs with a moderate kinetic isotope effect,k
H/k
D=2.2±0.3. A satisfactory correlation between the partial rate constants and the structure of hydrocarbons in terms of the
Okamoto-Brown equation was found.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 822–825, May, 2000. 相似文献
8.
The kinetics of ruthenium(III)-catalyzed oxidation of several arylthioacetic acids by Ce(IV) have been studied. The proposed
mechanism involves the formation of a 1∶1 complex between Ru(III) and arylthioacetic acid, which then reacts with Ce(IV). 相似文献
9.
Swamy Putta Ramachandrappa Rangegowda Ramalingaiah Hulivana 《Transition Metal Chemistry》1999,24(1):52-58
The kinetics of the RuIII-catalyzed oxidation of urea and substituted ureas namely: methylurea, ethylurea and propylurea, to the corresponding hydrazines by sodium N- bromobenzenesulphonamide or bromamine-B (BAB) in HCl medium has been studied at 303K. The reaction rate shows a first order dependence each upon [BAB], [amide] and [RuIII] and is dependent on [H+]. Addition of halide ions and benzenesulphonamide do not significantly affect the rate. Proton inventory studies were made in H2O-D2O mixtures for urea and methylurea. A Taft linear free energy relationship is observed for the reaction with *=–2.95 and =–0.25, showing that electron-donating groups enhance the rate. An isokinetic relation is observed with =370K, indicating that enthalpy factors control the rate; this result is also confirmed by Exner Criterion which showed a linear plot for the logarithms of rate constants at the highest and lowest temperatures employed. The protonation constant of monobromamine-B has been evaluated and equals 7.5. A mechanism consistent with the observed kinetic data has been proposed. 相似文献
10.
Kinetics of oxidative decarboxylation of arginine, glutamine, histidine and lysine by bromamine-T (BAT) was investigated in
acid and alkaline media at 30° and 20° fespectively. The form of the rate law at low concentrations of HClO4 has been worked out. Proton inventory studies in H2O-D2O mixtures with Arg as a probe have been made. The rate increases in the order: His > Lys > Arg > Glu - NH2. In alkaline media, the rate shows a first order dependence on [BAT]0 and is fractional in [S] and [OH].p-Toluene sulphonamide retards the rate. Mechanisms proposed are consistent with the experimental rate laws. 相似文献
11.
O. A. Luzina M. P. Polovinka N. F. Salakhutdinov G. A. Tolstikov 《Russian Chemical Bulletin》2007,56(6):1249-1251
The condensation of amino acids with (+)-usnic acid involves the 2-positioned acetyl group of the latter and gives derivatives
containing an enamine fragment.
Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1203–1205, June, 2007. 相似文献
12.
The kinetics of oxidation of diazepam (DZ) by 1-chlorobenzotriazole (CBT) has been studied in HClO4 medium in the temperature range of 293–323 K. The reactions followed a first order dependence on [CBT], fractional order
each in [H+] and [DZ]. Activation parameters were evaluated. A negative entropy of activation indicated the involvement of a rigid complex
in the activated state. Variation of reaction rate with dielectric constant and the ionic strength are consistent with a mechanism
involving the decomposition of a dipole in the rate-determining step. Rate equation is derived to account for the observed
kinetic data and the proposed reaction mechanism. 相似文献
13.
14.
15.
Donald M. Kirschenbaum 《Applied biochemistry and biotechnology》1984,9(5-6):489-536
The amino acid analyses of 186 proteins are given as residues per 1000 residues. Additional information as carbohydrate composition,
content of uncomon amino acids, and sources of all proteins are also presented. 相似文献
16.
Isothermal microcalorimetry has been applied as a method for predicting (in)stability of ascorbic acid and several amino acids
that undergo oxidative degradation in aqueous media. The fast and simple method involved the addition of different amounts
of hydrogen peroxide. The appearance of the heat flow curves gave a clear general indication of how stability was influenced.
The accuracy of the microcalorimetric result was investigated by comparing it with an HPLC assay and a good agreement between
the results of both methods was demonstrated. It was also established that susceptibility to oxidative degradation decreases
in the following order: cysteine, methionine, ascorbic acid, tyrosine and tryptophan. 相似文献
17.
Kinetics of oxidation of pantothenic acid (PA) by sodium N‐chloro‐p‐toluenesulfonamide or chloramine‐T (CAT) in the presence of HClO4 and NaOH (catalyzed by OsO4) has been investigated at 313 K. The stoichiometry and oxidation products are same in both media; however, their kinetic patterns were found to be different. In acid medium, the rate shows first‐order dependence on [CAT]o, fractional‐order dependence on [PA]o, and inverse fractional‐order on [H+]. In alkaline medium, the rate shows first‐order dependence each on [CAT]o and [PA]o and fractional‐order dependence on each of [OH?] and [OsO4]. Effects of added p‐toluenesulfonamide and halide ions, varying ionic strength, and dielectric constant of medium as well as solvent isotope on the rate of reaction have been investigated. Activation parameters were evaluated, and the reaction constants involved in the mechanisms have been computed. The proposed mechanisms and the derived rate laws are consistent with the observed kinetics. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 201–210, 2005 相似文献
18.
19.
Ranjana Sharma Mahender Pal 《Phosphorus, sulfur, and silicon and the related elements》2016,191(1):41-47
Kinetic studies on the Cu(II) catalyzed oxidation of mercaptoacetic acid (thioglycolic acid, TGA) by the model electron receptor methylene blue in acidic medium show that the reaction follows a second order kinetics in TGA. The order in methylene blue is unity but at higher [TGA], the order is 3/4. The rate shows an inverse relationship with [H+] and a second order dependence on [Cu(II)]. The reaction conforms to Arrhenius behavior in aqueous medium but resorts to anti-Arrhenius behavior in aqueous methanol and in aqueous acetone media. The reaction involves the in situ participation of nanoparticles which has been confirmed by SEM, XRD, and FTIR techniques. In aqueous medium, cauliflower shaped nanoparticles (44.21–74.33 nm) are obtained but in the presence of acetone and methanol, nanogranules (38.96–70.73 nm) and nanodisks (47.30–72.16 nm), respectively, are produced at 35°C as revealed by SEM images and XRD data. The reaction is characterized by the participation of two transition states in aqueous acetone medium and the kinetics of the reaction, especially the temperature dependence, is governed by the adsorption of methylene blue on copper nanoparticles as influenced by morphology inter alia dielectric constant of the reaction medium. 相似文献
20.
Donald M. Kirschenbaumt 《Applied biochemistry and biotechnology》1982,7(5):343-384
The amino acid analyses of 183 proteins, as residues per 1000 residues, are given. In addition the carbohydrate content and
the content of any noncommon amino acids are also given. The sources of all proteins are presented. 相似文献