scholarly journals Aqueous trifluoroacetic acid as a medium for organic reactions. II. The oxidation of hydrocarbons by manganese(VII)

1978 ◽  
Vol 56 (9) ◽  
pp. 1273-1279 ◽  
Author(s):  
Ross Stewart ◽  
Udo A. Spitzer
Keyword(s):  
Isotope Effect ◽  
Trifluoroacetic Acid ◽  
Reaction Rates ◽  
Acidity Function ◽  
Hydrogen Atoms ◽  
Electrophilic Attack ◽  
Normal Alkanes ◽  
First Order ◽  
Oxidation Of Hydrocarbons ◽  
Mechanism Of Oxidation

The oxidation of 11 alkanes, 4 cycloalkanes, and 10 arenes by potassium permanganate in aqueous trifluoroacetic acid has been studied. The reaction rates are approximately first order in hR, the antilogarithm of the acidity function −HR, and the active oxidant is believed to be MnO3+, either free or complexed. The rate of abstraction of primary, secondary, and tertiary hydrogen atoms in the C5H12 isomers is in the ratio 1:60:2100 and the rate per methylene in normal alkanes increases with increasing chain length. Cyclohexane is the least reactive of the cycloalkanes and the isotope effect in the oxidation of cyclo-C6D12 is 4.3 at 25 °C. The mechanism of oxidation of the aliphatic hydrocarbons is believed to be hydrogen-atom abstraction by MnO3+. The oxidation of arenes C6H5Z has a ρ+ value of −5.29 when appropriate σ+ values of Z are used, and there is no isotope effect when the reaction rates of C6H5CH3, C6H5CD3, and C6D5CD3 are compared. The mechanism of oxidation of the aromatic compounds is believed to be electrophilic attack of MnO3+ at the activated positions of the ring followed by rapid degradation of the ring system.

Oxidation of Hydrocarbons. VII. Kinetics of the Oxidation of Naphthalenes by Ruthenium Tetroxide

1975 ◽  
Vol 53 (19) ◽  
pp. 2865-2868 ◽  
Author(s):  
Udo A. Spitzer ◽  
Donald G. Lee
Keyword(s):  
Isotope Effect ◽  
Bond Cleavage ◽  
Initial Reaction ◽  
Second Order Reaction ◽  
Deuterium Isotope Effect ◽  
Ruthenium Tetroxide ◽  
First Order ◽  
Oxidation Of Hydrocarbons ◽  
Inverse Isotope Effect ◽  
Kinetics Of

The kinetics of the oxidation of naphthalene by ruthenium tetroxide have been investigated. When the reaction was monitored using an absorption band at 385 nm it was possible to detect two processes; the first, a rapid second-order reaction which yielded a ruthenium(VI) moiety, was followed by a much slower first-order decomposition of this intermediate. The initial reaction exhibited an inverse isotope effect when naphthalene-d8 was used as a substrate and was accelerated by the introduction of electron donating substituents. The decomposition of the intermediate was not sensitive to the presence of substituents, but involved carbon–hydrogen bond cleavage as indicated by the occurrence of a primary deuterium isotope effect.

Designing Experiments for Model Identification of the Nitrification Process

1991 ◽  
Vol 24 (6) ◽  
pp. 9-16 ◽  
Author(s):  
P. J. Ossenbruggen ◽  
H. Spanjers ◽  
H. Aspegren ◽  
A. Klapwijk
Keyword(s):  
Mechanistic Model ◽  
Nonlinear Differential Equations ◽  
Model Identification ◽  
Reaction Rates ◽  
Variable Coefficients ◽  
Model Specification ◽  
First Order ◽  
Interactive Behavior ◽  
Batch Tests ◽  
Nitrification Process

A series of batch tests were performed to study the competition for oxygen by Nitrosomonas and Nitrobacter in the nitrification of ammonia in activated sludge. Oxygen uptake rate (OUR) and dynamic (compartment) models describing the process are proposed and tested. The OUR model is described by a Monod relationship and the biogradation process by a set of first order nonlinear differential equations with variable coefficients. The results show a mechanistic model and ten reaction rates are sufficient to capture the interactive behavior of the nitrification process. Methods for model specification, calibrating, and testing the model and the design of additional experiments are described.

The effect of the textile industry dye bath additive EDTMPA on colour removal characteristics by ozone oxidation

2007 ◽  
Vol 55 (10) ◽  
pp. 145-153 ◽  
Author(s):  
T. Ölmez ◽  
I. Kabdaşlı ◽  
O. Tünay
Keyword(s):  
Organic Matter ◽  
Textile Industry ◽  
Reaction Rates ◽  
Textile Dye ◽  
Pseudo First Order Reaction ◽  
Ozone Oxidation ◽  
Reactive Dyeing ◽  
First Order ◽  
Organic Matter Oxidation ◽  
Pseudo First Order

In this study, the effects of the phosphonic acid based sequestering agent EDTMPA used in the textile dye baths on colour and organic matter removal by ozone oxidation was experimentally investigated. Procion Navy HEXL dyestuff that has been commonly used for the reactive dyeing of cellulose fibers was selected as the model component. The organic matter oxidation by ozone was determined to obey the pseudo-first order kinetics as they are treated singly or in combination. COD removal rates obtained from pseudo-first order reaction kinetics showed that oxidation of Navy HEXL alone (0.0947 L/min) was faster than that of EDTMPA (0.0171 L/min) and EDTMPA with dye (0.0155 L/min) at pH 3.0. It was also found that reaction rates of single EDTMPA removal and EDTMPA and dye mixture removal increased as the reaction pH was increased from 3.0 to 10.5.

scholarly journals Excitation of Atomic Hydrogen by Proton Impact in the Presence of a Resonant Laser Field Using the First Order Magnus Approximation

1992 ◽  
Vol 45 (1) ◽  
pp. 47 ◽  
Author(s):  
Bhupat Sharma ◽  
Man Mohan
Keyword(s):  
Laser Beam ◽  
Computer Time ◽  
Dipole Approximation ◽  
Collision Dynamics ◽  
Hydrogen Atoms ◽  
Close Coupling ◽  
First Order ◽  
Resonant Laser ◽  
Atom Interaction ◽  
Transverse Polarisation

We consider proton collisions from hydrogen atoms in the presence of a laser beam (taken in the electric dipole approximation) that resonantly (or nearly resonantly) excites the hydrogen atoms from the Is to the 2p state. The laser beam is linearly polarised with polarisation either parallel (longitudinal) or perpendicular (transverse) to the direction of incidence of the proton. A non-perturbative quasi-energy approach is used to describe the laser-atom interaction, while the first-order Magnus approximation is used to describe the collision dynamics in the presence of the nearly resonant laser beam. We have calculated the integrated cross section o-(2s} for the excitation of the 2s state. It is found that 0-(2s} is small for longitudinal polarisation, as compared with transverse polarisation. We have also compared our field-free results obtained by using the first-order Magnus approximation to that obtained by the close-coupling approximation. Although both methods give excellent results, the former method is quite demanding in terms of computer time.

scholarly journals Reactivity of Phenol and Aniline towards Quinolinium Chloro Chromate: A Comparative Oxidation Kinetic Study

2015 ◽  
Vol 59 ◽  
pp. 81-92
Author(s):  
Seplapatty Kalimuthu Periyasamy ◽  
H. Satham Hussain ◽  
R. Manikandan
Keyword(s):  
Oxidation Kinetic ◽  
Activation Parameters ◽  
Dipole Interaction ◽  
Reaction Rates ◽  
Hydrogen Ion ◽  
Aqueous Acetic Acid ◽  
Acetic Acid Medium ◽  
First Order ◽  
Different Temperatures ◽  
Kinetics Of

The kinetics of Oxidation of Phenol and aniline by quinolinium Chlorochromate (QCC) in aqueous acetic acid medium leads to the formation of quinone and azobenzene respectively. The reactions are first order with respect to both Phenol and aniline. The reaction is first order with respect to quinolinium chlorochromate (QCC) and is catalyzed by hydrogen ion. The hydrogen-ion dependence has the form: kobs = a+b [H+]. The rate of oxidation decreases with increasing dielectric constant of solvent, indicating the presence of an ion-dipole interaction. The reaction does not induced the polymerization of acrylonitrile. The retardation of the rate by the addition of Mn2+ ions confirms that a two electron transfer process is involved in the reaction. The reaction rates have been determined at different temperatures and the activation parameters have been calculated. From the above observations kinetic results a probable mechanism have been proposed.

scholarly journals Extrapolation and interpolation by time-scaling in systems with diffusion-controlled kinetics and first-order reaction rates.

1989 ◽  
Vol 37 (1) ◽  
pp. 47-60
Author(s):  
S.E.A.T.M. van der Zee ◽  
W.H. van Riemsdijk ◽  
J.J.M. van Grinsven
Keyword(s):  
Reaction Rates ◽  
Order Reaction ◽  
Management Tool ◽  
First Order ◽  
Physicochemical Processes ◽  
Time Scaling ◽  
Diffusion Controlled ◽  
Scaling Procedure ◽  
Exposure Variable ◽  
Scaling Rule

The interpolation or extrapolation in time of physicochemical processes from experimental data is often difficult. A theoretically derived time-scaling procedure using an exposure variable of the concentration integrated in time, with at most one adjustable parameter was applied successfully to three systems taken from metallurgical, agricultural and environmental engineering. This scaling rule is potentially useful as a research or management tool for systems that are too complex for mechanistic modelling. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Thiol–disulphide interchange in tubulin: kinetics and the effect on polymerization

2005 ◽  
Vol 389 (2) ◽  
pp. 549-558 ◽  
Author(s):  
P. J. Britto ◽  
Leslie Knipling ◽  
Peter Mcphie ◽  
J. Wolff
Keyword(s):  
Protein Concentration ◽  
Critical Concentration ◽  
Reaction Rates ◽  
High Ionic Strength ◽  
Cd Spectra ◽  
First Order ◽  
Nitrobenzoic Acid ◽  
Cysteine Substitution ◽  
Disulphide Bonds ◽  
Stop Flow

All 20 cysteine residues are accessible to disulphide reagents in the tubulin dimer, whereas only four are accessible in taxol-stabilized microtubules. Reaction rates with disulphide reagents are a function of the reagent, are decreased by G nucleotides, and increased with increase in pH and urea. With transient (stop-flow) kinetics, DTNB [5,5′-dithiobis-(2-nitrobenzoic acid)] and 2,2′-dithiodipyridine progress curves cannot be fitted by the sum of exponential terms based only on classes of cysteines. The mixed disulphide products react further to form both intra- and intermonomer disulphide bonds that can be reversed by reducing agents. With MMTS (methyl methanethiosulphonate) or ODNB (n-octyl-dithio-2-nitrobenzoate), virtually no protein–protein disulphide bonds are formed and the ODNB reaction can be given as the sum of three exponential terms with pseudo-first-order rate constants of 0.206, 0.069 and 0.010 s−1 at pH 6.5, suggesting three classes of thiol reactivities. Limited cysteine substitution leads to only small changes in tryptophan or CD spectra, whereas complete substitution leads to loss of the helix content. MMTS-induced loss of SH groups leads to progressive increases in the critical concentration and loss of polymerization competence that can be reversed by assembly promoters such as higher protein concentration, taxol or high ionic strength. Under such conditions, the substituted tubulin forms protofilament-based structures such as microtubules, open tubules, sheets and/or bundles.

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