ChemInform Abstract: The Effect of Deviations from Pseudo First-Order Conditions on Transient Electrochemical Response as Illustrated by the Protonation of Anthracene Anion Radical by Phenol in N,N-Dimethylformamide

ChemInform ◽  
1987 ◽  
Vol 18 (30) ◽  
Author(s):  
M. F. NIELSEN ◽  
O. HAMMERICH ◽  
V. D. PARKER
Keyword(s):  
Anion Radical ◽  
Order Conditions ◽  
First Order ◽  
Electrochemical Response ◽  
Pseudo First Order

scholarly journals Rate coefficients for the reaction of methylglyoxal (CH<sub>3</sub>COCHO) with OH and NO<sub>3</sub> and glyoxal (HCO)<sub>2</sub> with NO<sub>3</sub>

2011 ◽  
Vol 11 (21) ◽  
pp. 10837-10851 ◽  
Author(s):  
R. K. Talukdar ◽  
L. Zhu ◽  
K. J. Feierabend ◽  
J. B. Burkholder
Keyword(s):  
Relative Rate ◽  
Order Conditions ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
First Order ◽  
No3 Radical ◽  
Pseudo First Order ◽  
Arrhenius Expression ◽  
Coefficient Method

Abstract. Rate coefficients, k, for the gas-phase reaction of CH3COCHO (methylglyoxal) with the OH and NO3 radicals and (CHO)2 (glyoxal) with the NO3 radical are reported. Rate coefficients for the OH + CH3COCHO (k1) reaction were measured under pseudo-first-order conditions in OH as a function of temperature (211–373 K) and pressure (100–220 Torr, He and N2 bath gases) using pulsed laser photolysis to produce OH radicals and laser induced fluorescence to measure its temporal profile. k1 was found to be independent of the bath gas pressure with k1(295 K) = (1.29 ± 0.13) × 10−11 cm3 molecule−1 s−1 and a temperature dependence that is well represented by the Arrhenius expression k1(T) = (1.74 ± 0.20) × 10−12 exp[(590 ± 40)/T] cm3 molecule−1 s−1 where the uncertainties are 2σ and include estimated systematic errors. Rate coefficients for the NO3 + (CHO)2 (k3) and NO3 + CH3COCHO (k4) reactions were measured using a relative rate technique to be k3(296 K) = (4.0 ± 1.0) × 10−16 cm3 molecule−1 s−1 and k4(296 K) = (5.1 ± 2.1) × 10−16 cm3 molecule−1 s−1. k3(T) was also measured using an absolute rate coefficient method under pseudo-first-order conditions at 296 and 353 K to be (4.2 ± 0.8) × 10−16 and (7.9 ± 3.6) × 10−16 cm3 molecule−1 s−1, respectively, in agreement with the relative rate result obtained at room temperature. The atmospheric implications of the OH and NO3 reaction rate coefficients measured in this work are discussed.

Kinetische Untersuchung der Chemilumineszenz von 7-Dimethyl-amino-naphthalin-1.2-dicarbonsäurehydrazid in wäßrig alkalischem Wasserstoffperoxid in Gegenwart von Hämin / Kinetic Investigation of the Chemoluminescence of 7-Dimethyl-amino-naphthalin-1,2-dicarbonic-acid-hydrazid in aqueous alcaline H2O2 in Presence of Hemin

1970 ◽  
Vol 25 (5) ◽  
pp. 484-491 ◽  
Author(s):  
Hans-Friedrich Eicke ◽  
Helmut Fiege ◽  
Karl-Dietrich Gundermann
Keyword(s):  
Temporal Change ◽  
Order Conditions ◽  
Stopped Flow ◽  
Kinetic Investigation ◽  
Reaction Step ◽  
Absorption Change ◽  
First Order ◽  
Light Production ◽  
Pseudo First Order ◽  
Primary Oxidation

The chemoluminescence-system: DNH/NaOHaq/H2O2/hemin was investigated with the help of a “stopped-flow-technique”. By use of an optical cut-off-filter the chemoluminescence- (514 nm), and the absorptionband (325 nm) resp. could be separated which proved impossible with luminol. In this way we could follow the temporal change of chemoluminescence and of absorption of DNH: the latter dropped coutinually with progress of the reaction while the chemoluminescence-intensity passed through a maximum before it decreased according to the same rate law (pseudo first order conditions as for DNH) which governs the absorption change of DNH. The oxidation of DNH is rate-determining and of first order as to DNH, H2O2 and (possibly) NaOH (k1 = 1,5·10-3 s-1-1 M-2). The kinetic interpretation of the chemoluminescence-maxima confirmed this result. The light production occurred in a very fast secondary reaction step (k2 ≫ k1) following the oxidation of the hydrazid and with H2O2 participating. Diazochinone is assumed to be a primary oxidation product.

Kinetics and mechanism of aminolysis of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones

1992 ◽  
Vol 70 (10) ◽  
pp. 2515-2519 ◽  
Author(s):  
Sharifa S. Alkaabi ◽  
Ahmad S. Shawali
Keyword(s):  
Rate Constants ◽  
Activation Parameters ◽  
Order Conditions ◽  
Kinetics And Mechanism ◽  
Hammett Equation ◽  
Third Order ◽  
First Order ◽  
Different Temperatures ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of the reactions of a series of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones 1 with n-butylamine and piperidine were studied spectrophotometrically in dioxane, ethanol, and cyclohexane under pseudo-first-order conditions and at different temperatures. The relation k1(obs) = k2[amine] + k3[amine]2 was found applicable for all reactions studied in either dioxane or ethanol. However, in cyclohexane the n-butylaminolysis of 1 followed only third-order kinetics k1(obs) = k3[n-BuNH2]2. The kinetics of the reaction of 1 with n-butylamine in the presence of catalytic amounts of triethylamine in dioxane followed the equation: k1(obs)k2 = [n-BuNH2] + k3[n-BuNH2]2[Formula: see text] [Et3N]. The rate constants k2 and k3 correlated well with the Hammett equation and the corresponding activation parameters were determined. The results were interpreted in terms of a mechanism involving solvent- and amine-catalyzed processes.

Theoretical Explanation of Nonexponential OH Decay in Reactions with Benzene and Toluene under Pseudo-First-Order Conditions

2008 ◽  
Vol 112 (33) ◽  
pp. 7608-7615 ◽  
Author(s):  
Víctor Hugo Uc ◽  
J. Raúl Alvarez-Idaboy ◽  
Annia Galano ◽  
Annik Vivier-Bunge
Keyword(s):  
Theoretical Explanation ◽  
Order Conditions ◽  
First Order ◽  
Pseudo First Order

scholarly journals Kinetics of Oxidation of Tryptophan by Sodium Hypochlorite

1981 ◽  
Vol 36 (3) ◽  
pp. 359-361 ◽  
Author(s):  
Thomas Rausch ◽  
Frieder Hofmann ◽  
Willy Hilgenberg
Keyword(s):  
Activation Energy ◽  
Reaction Mechanism ◽  
Sodium Hypochlorite ◽  
Arrhenius Plot ◽  
Ph Dependence ◽  
Order Conditions ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Pseudo First Order ◽  
Kinetics Of

AbstractThe oxidation of tryptophan to 3-indoleacetaldehyde with sodium hypochlorite was investigated with 14C labelled DL-tryptophan. The reaction was performed under pseudo first order conditions. From the pH dependence of the reaction it was concluded that only the unprotonated tryptophan is converted to the aldehyde. The activation energy is 35 ± 2.2 (SE) kJ x mol-1 as derived from the Arrhenius plot. Variing the pH between 8.5 and 11.0 and the temperature in the range from 298 K to 318 K did not alter the selectivity of the reaction as confirmed by TLC of the product (purity ≧ 90%). A possible reaction mechanism is proposed.

scholarly journals Kinetics of the reduction of 4-amino and 4-cyanopyridinechlorocobaloximes by iron(II)

2006 ◽  
Vol 71 (12) ◽  
pp. 1311-1321 ◽  
Author(s):  
A. Dayalan ◽  
C. Revathi
Keyword(s):  
Nmr Spectroscopy ◽  
Protonation Constant ◽  
Protonated Form ◽  
Order Conditions ◽  
Hydrogen Ion ◽  
Ion Concentrations ◽  
First Order ◽  
Ir And Nmr Spectroscopy ◽  
Pseudo First Order ◽  
Kinetics Of

Cobaloximes such as trans[Co(dmgH) 2(Py-NH2)Cl] and trans- [Co(dmgH) 2(Py-CN)Cl], where, dmgH = dimethylglyoximato anion, Py-NH 2 = 4-aminopyiridne and Py-CN = 4-cyanopyridine, were prepared and characterized by elemental analysis, UV-VIS, IR and NMR spectroscopy. The kinetics of iron(II) reduction of the complexes were studied spectrophotometrically at 300 nm in 2% (v/v) DMSO-H2O medium at 27?0.1?C and I = 0.25 M (LiClO4) at various hydrogen ion concentrations in the range 2.5 x 10-4 to 5.0x10-2 M under pseudo-first-order conditions using an excess of the reductant. The inverse dependence of rate on [H+] suggests an equilibrium between the protonated and unportonated forms of the complexes, the protonated form reacting slower than the unprotonated form. Computation of the data enabled the evaluation of the rate constants for the protonated and unprotonated from of the complexes, leading to an evaluation of the protonation constant for the complexes. .

Role of a 2,3-bis(pyridyl)pyrazinyl chelate bridging ligand in the reactivity of Ru(ii)–Pt(ii) dinuclear complexes on the substitution of chlorides by thiourea nucleophiles – a kinetic study

2018 ◽  
Vol 42 (15) ◽  
pp. 12557-12569 ◽  
Author(s):  
Rajesh Bellam ◽  
Deogratius Jaganyi ◽  
Allen Mambanda ◽  
Ross Robinson
Keyword(s):  
Kinetic Study ◽  
Order Conditions ◽  
Dinuclear Complexes ◽  
First Order ◽  
Bridging Ligand ◽  
Pseudo First Order ◽  
Methanol Medium

Effect of a bridged ligand on the chloride substitution from hetero bimetallic Ru(ii)–Pt(ii)dichlo complexes by thiourea nucleolus was studied in a methanol medium (I = 0.10 M) under pseudo-first-order conditions.

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