scholarly journals Stopped-Flow Spectrophotometric Studies of the Kinetics of Interaction of Dihydroxyfumaric Acid with the DPPH Free Radical

2010 ◽  
Vol 5 (2) ◽  
pp. 83-87
Author(s):  
Natalia Secara
Keyword(s):  
Free Radical ◽  
Reaction Kinetics ◽  
Rate Constant ◽  
Stopped Flow ◽  
Flow Method ◽  
Reaction Proceeds ◽  
Reaction Orders ◽  
Stoichiometric Reaction ◽  
Two Stages ◽  
Kinetics Of

The reaction of dihydroxyfumaric acid with the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied using the stopped-flow method, in order to describe the reaction kinetics. Dihydroxyfumaric acid reacts very rapidly with DPPH, the reaction being completed in several minutes. This 2-stoichiometric reaction proceeds in two stages, with reaction orders of 1 and 0.76 with respect to DPPH, and 0.5 and 0.3 with respect to DHF, respectively. The rate constant of the two stages of the reaction were found to be 39.1 (L/mol•s) and 0.0012 (s-1) at 20º C and pH 4.0.

Etude du système acridine orange – poly(C) et de son interaction avec les complexes du palladium(II)

1984 ◽  
Vol 62 (9) ◽  
pp. 1681-1686 ◽  
Author(s):  
Robert Ménard ◽  
Miklos Zador
Keyword(s):  
Acridine Orange ◽  
Thermodynamic Parameters ◽  
Rate Constant ◽  
Kinetic Studies ◽  
Stopped Flow ◽  
Flow Method ◽  
Polycytidylic Acid ◽  
Low Concentrations ◽  
C Complex ◽  
Kinetics Of

The complex formed between acridine orange (AO) and polycytidylic acid (poly(C)) was studied by spectrophotometry and spectrofluorometry. The complex was characterized by its stoichiometry, structure, and the thermodynamic parameters of its formation. The results are in agreement with an external aggregation of the protonated dye along the negatively charged poly(C) chain and indicate that approximately two AO molecules are bound per nucleotide unit of poly(C). The kinetics of the reaction between this complex and a Pd(II) complex was studied by the stopped-flow method. The addition of (dien)Pd(II) to the AO–poly(C) complex leads to the dissociation of the latter, due to fixation of the Pd(II) complex to the N3 site of the cytosine base of poly(C). The rate constant for the AO liberation, extrapolated at zero AO concentration, corresponds to the rate constant of Pd(II) fixation on poly(C). This indicates that AO can be used as an indicator for this reaction and allows kinetic studies at very low concentrations (≤ 5 × 10−6 M).

Reaction kinetics of carbon dioxide in aqueous blends of N-methyldiethanolamine and glycine using the stopped flow technique

2016 ◽  
Vol 33 ◽  
pp. 186-195 ◽  
Author(s):  
Abdelbaki Benamor ◽  
Mohammed Jaber Al-Marri ◽  
Majeda Khraisheh ◽  
Mustafa S. Nasser ◽  
Paitoon Tontiwachwuthikul
Keyword(s):  
Carbon Dioxide ◽  
Reaction Kinetics ◽  
Stopped Flow ◽  
Kinetics Of

Kinetics of radical exchange in the reaction of CF3 radicals with tin tetramethyl

1976 ◽  
Vol 54 (10) ◽  
pp. 1617-1623 ◽  
Author(s):  
T. N. Bell ◽  
P. J. Young
Keyword(s):  
Exchange Reaction ◽  
Rate Constant ◽  
Additional Data ◽  
Hydrogen Abstraction ◽  
Arrhenius Parameters ◽  
Abstraction Reaction ◽  
Reaction Proceeds ◽  
Kinetics Of

The reaction of CF3 radicals with SnMe4 leads to hydrogen abstraction and also radical exchange.[Formula: see text]We propose the exchange reaction proceeds via a five coordinate intermediate. The Arrhenius parameters for the exchange reaction are,[Formula: see text]Additional data for the H abstraction reaction[Formula: see text]combined with previous data yields an improved rate constant for abstraction,[Formula: see text]

A Stirred-Flow Reactor for Investigating the Kinetics of Gaseous Reactions: Application to the Decomposition of Di-t-butyl Peroxide

1961 ◽  
Vol 14 (4) ◽  
pp. 534 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams
Keyword(s):  
Excellent Agreement ◽  
Rate Constant ◽  
Flow Reactor ◽  
Reaction Times ◽  
Static Method ◽  
Flow Conditions ◽  
Gaseous Reaction ◽  
Flow Method ◽  
Butyl Peroxide ◽  
Kinetics Of

The uncertainty regarding temperature and flow conditions which attaches to the conventional flow method of determining the rate of a gaseous reaction can be substantially reduced by using a stirred-flow reactor. The reagents, products, and carrier-gas (if any) are mixed sufficiently vigorously for the composition of the gas in the reactor to be virtually uniform. A reactor designed to achieve the required degree of mixing at pressures of about 1 cmHg and reaction times of the order of 1 sec to 1 min is described. The rate constant of the decomposition of di-t-butyl peroxide was determined over the temperature range 430-550 �K. The values derived on the assumption of complete mixing in the reactor were independent of the degree of conversion and in excellent agreement with those obtained by previous authors using the static method.

scholarly journals Diffusion-Limited Reaction Kinetics of a Reactant with Square Reactive Patches on a Plane

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1744
Author(s):  
Changsun Eun
Keyword(s):  
Reaction Kinetics ◽  
Rate Constant ◽  
Spatial Arrangement ◽  
Total Surface Area ◽  
Reaction Model ◽  
Discrete Models ◽  
Diffusion Limited ◽  
Size Number ◽  
Surface Reaction Kinetics ◽  
Kinetics Of

We present a simple reaction model to study the influence of the size, number, and spatial arrangement of reactive patches on a reactant placed on a plane. Specifically, we consider a reactant whose surface has an N × N square grid structure, with each square cell (or patch) being chemically reactive or inert for partner reactant molecules approaching the cell via diffusion. We calculate the rate constant for various cases with different reactive N × N square patterns using the finite element method. For N = 2, 3, we determine the reaction kinetics of all possible reactive patterns in the absence and presence of periodic boundary conditions, and from the analysis, we find that the dependences of the kinetics on the size, number, and spatial arrangement are similar to those observed in reactive patches on a sphere. Furthermore, using square reactant models, we present a method to significantly increase the rate constant by sequentially breaking the patches into smaller patches and arranging them symmetrically. Interestingly, we find that a reactant with a symmetric patch distribution has a power–law relation between the rate constant and the number of reactive patches and show that this works well when the total reactive area is much less than the total surface area of the reactant. Since our N × N discrete models enable us to examine all possible reactive cases completely, they provide a solid understanding of the surface reaction kinetics, which would be helpful for understanding the fundamental aspects of the competitions between reactive patches arising in real applications.

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