THE OXIDATION OF HYDRAZOBENZENE BY AMMONIUM PERSULPHATE IN ACETONITRILE–WATER SOLUTION

1956 ◽  
Vol 34 (9) ◽  
pp. 1154-1162 ◽  
Author(s):  
B. J. P. Whalley ◽  
H. G. V. Evans ◽  
C. A. Winkler
Keyword(s):  
Activation Energy ◽  
Water Solution ◽  
Order Rate Constant ◽  
Second Order ◽  
Radical Mechanism ◽  
Square Root ◽  
Ammonium Persulphate ◽  
Initial Concentration ◽  
Free Radical Mechanism ◽  
Considerable Range

In a given experiment, second order kinetics were displayed during the greater part of the reaction over a considerable range of initial concentrations of reactants. In general, the second order behavior was maintained to greater extent of reaction when hydrazobenzene was in excess. The calculated second order rate constant, k, decreased with increase in initial hydrazobenzene concentration and increased with increase in initial concentration of ammonium persulphate. For different equimolar concentrations of reactants, k was virtually independent of initial concentrations. The value of k was proportional to the square root of the ratio of the initial concentrations of persulphate and hydrazobenzene. The activation energy of the over-all reaction was 16 kcal. per mole. A free radical mechanism appears to account reasonably well for the major experimental observations.

THE REACTIONS OF ACTIVE NITROGEN WITH ETHYLENE AND DEUTERATED ETHYLENES

1966 ◽  
Vol 44 (22) ◽  
pp. 2691-2701 ◽  
Author(s):  
Kenneth D. Foster ◽  
P. Kebarle ◽  
H. B. Dunford
Keyword(s):  
Hydrogen Atom ◽  
Mass Spectrometer ◽  
Rate Constant ◽  
Reaction Times ◽  
Order Rate Constant ◽  
Second Order ◽  
Atomic Nitrogen ◽  
Large Excess ◽  
Active Nitrogen ◽  
Initial Concentration

The reaction of active nitrogen with ethylene and deuterated ethylenes has been investigated by use of a mass spectrometer. The rate of disappearance of atomic nitrogen in the presence of ethylene appears to obey the equation[Formula: see text]where kapp is an apparent second order rate constant and [ethylene]0 is the initial concentration of added ethylene. However, exceptions to this equation are found at 0.6 Torr either for short reaction times or for small concentrations of added ethylene, and apparently for short reaction times at 2.6 Torr when a large excess of ethylene is added. Where the above equation is obeyed, kapp = (3 ± 1) × 10−13 cc molecule−1 s−1. The formation of C2D4 in the reaction of active nitrogen with C2D3H is interpreted as further evidence for the importance of hydrogen atom reactions in intermediate steps of the reaction of active nitrogen with ethylene.

KINETIC STUDIES ON THE FORMATION OF POLYBUTADIENE

1948 ◽  
Vol 26b (8) ◽  
pp. 564-580
Author(s):  
C. A. Winkler ◽  
W. Graham
Keyword(s):  
Nitric Oxide ◽  
Growth Rate ◽  
Benzoyl Peroxide ◽  
Kinetic Studies ◽  
Active Oxygen ◽  
Radical Mechanism ◽  
Square Root ◽  
Gel Formation ◽  
Initial Weight ◽  
Free Radical Mechanism

The growth rate of polybutadiene 'popcorn' is essentially the same in butadiene liquid and vapor, is proportional to the initial weight of seed used, and increases with increased active oxygen content of the seed and with increased temperature. Traces of nitric oxide and larger amounts of benzoyl peroxide and of iodine inhibit the growth of popcorn seed. Air also inhibits the growth. Popcorn formation is initiated in butadiene by benzoyl peroxide; the rate of initiation is increased by rusty iron and water and is a function of benzoyl peroxide concentration and temperature. Studies of 'gel' formation in liquid butadiene containing benzoyl peroxide indicate that the polymerization probably proceeds by a free radical mechanism, the rate being proportional to the square root of the benzoyl peroxide concentration. The growth of polybutadiene 'popcorn' appears to take place by relatively slow reaction of monomer with free radicals formed rapidly by decomposition of hydroperoxides in the seed.

KINETICS AND MECHANISMS OF THE PYROLYSIS OF n-BUTANE: PART I. THE UNINHIBITED DECOMPOSITION

1963 ◽  
Vol 41 (4) ◽  
pp. 838-847 ◽  
Author(s):  
N. H. Sagert ◽  
K. J. Laidler
Keyword(s):  
Activation Energy ◽  
Surface Effect ◽  
Frequency Factor ◽  
Radical Mechanism ◽  
Free Radical Mechanism ◽  
Surface Catalysis ◽  
Initiation Reaction ◽  
Pressure Changes ◽  
Ethyl Radicals ◽  
Kinetics Of

The kinetics of the pyrolysis of n-butane have been studied at temperatures from 520° to 590 °C, and at pressures from 30 to 600 mm Hg; the rate was followed from pressure changes and by gas chromatography. The reaction was accurately of the three-halves order; the activation energy was found to be 59.9 kcal mole−1, and the frequency factor 3.24 × 1015 cc1/2 mole−1/2 sec−1. The reaction is sensitive to surface; packing the vessel and 'conditioning' it usually led to a decrease in rate and an increase in activation energy. The reaction is concluded to be largely homogeneous, and to occur almost entirely by a free-radical mechanism; the initiation reaction is considered to be the dissociation of a butane molecule into two ethyl radicals, in its first-order region, and termination is believed to be the second-order combination of ethyl radicals. The mechanism proposed is shown to account satisfactorily for the observed behavior. The surface effect is attributed to a certain amount of initiation by abstraction, by a surface atom, of a hydrogen atom from butane, and to surface catalysis of the recombination of ethyl radicals.

The kinetics of formation of ruthenium(II) nitrogen complexes

1970 ◽  
Vol 48 (11) ◽  
pp. 1639-1644 ◽  
Author(s):  
Clive M. Elson ◽  
I. J. Itzkovitch ◽  
John A. Page
Keyword(s):  
Activation Energy ◽  
Order Rate Constant ◽  
Second Order ◽  
Kcal Mole ◽  
Potential Reduction ◽  
First Order ◽  
Kinetics Of Formation ◽  
Controlled Potential ◽  
Kinetics Of ◽  
Electrolyte Ph

The formation of nitrogen monomers by the reaction of Ru(NH3)5(H2O)2+ and cis-Ru(NH3)4(H2O)22+ with N2 has been shown to be first order in N2 and second order overall. The formation of bridging N2 dimers by the reaction of the ruthenium(II) pentaammine and tetraammine with the monomers has been shown to be second order overall.The reactions were studied in a H2SO4–K2SO4 electrolyte pH 3.3, μ = 0.30. The ruthenium(II) species were prepared by controlled potential reduction of known ruthenium(III) species at −0.50 V at a Hg cathode. The reactions of the reduced species with N2 or the monomers were followed spectrophotometrically.The second order rate constant at 25 °C and the activation energy for the substrate Ru(NH3)5(H2O)2+ with the respective nucleophiles are: N2, 8.0 × 10−2 M−1 s−1, 22.0 ± 0.1 kcal/mole; Ru(NH3)5N22+, 3.6 × 10−2 M−1 s−1, 19.9 ± 0.5 kcal/mole; Ru(NH3)4(H2O)N22+, 2.7 × 10−2 M−1 s−1, 20.4 ± 0.8 kcal/mole. For the substrate cis-Ru(NH3)4(H2O)22+ the values are: N2, 1.0 × 10−1 M−1 s−1, 20.4 ± 0.2 kcal/mole; Ru(NH3)5N22+, 6.8 × 10−2 M−1 s−1, 18.2 ± 0.1 kcal/mole; Ru(NH3)4(H2O)N22+, 7.2 × 10−2 M −1 s−1, 17.1 ± 0.2 kcal/mole.

Comparative QSAR evidence for a free-radical mechanism of phenol-induced toxicity

2000 ◽  
Vol 127 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Corwin Hansch ◽  
Susan C. McKarns ◽  
Carr J. Smith ◽  
David J. Doolittle
Keyword(s):  
Free Radical ◽  
Radical Mechanism ◽  
Free Radical Mechanism

scholarly journals Preliminary Study on the Use of Ozonation for the Degradation of Dithiocarbamate Residues in the Fruit Drying Process: Mancozeb Residue in Blackcurrant is the Example Used

2013 ◽  
Vol 53 (1) ◽  
pp. 48-52 ◽  
Author(s):  
Piotr Antos ◽  
Anna Kurdziel ◽  
Stanisław Sadło ◽  
Maciej Balawejder
Keyword(s):  
Aqueous Solution ◽  
Ozone Concentration ◽  
Gaseous Phase ◽  
Plant Material ◽  
Water Solution ◽  
Ozone Treatment ◽  
Drying Process ◽  
Initial Concentration ◽  
Preliminary Study ◽  
Treatment Procedures

Abstract In order to reduce the level of dithiocarbamate fungicide mancozeb residues in blackcurrants, two different ozone treatment procedures were evaluated. The first one entailed washing the plant material with an aqueous solution of ozone. This ozone enriched water solution allowed for a 59% reduction of mancozeb residues, compared with the initial concentration. The latter method was based on the utilization of ozone in a gaseous phase combined with a drying process. In that procedure, samples of blackcurrant fruit were exposed to a 19 ppm ozone concentration, and then the blackcurrants were dried. The utilization of ozone in a gaseous phase permitted a 38% reduction of mancozeb residues, in comparison with the initial concentration. As a result of the combination of both processes; ozonation and drying, a 58% reduction of mancozeb residues was achieved.

Kinetic Model of the 1,2-Propanediol Oxidation Reaction in the Presence of 3wt%Pd/α-Al2O3 Catalyst

2021 ◽  
Vol 903 ◽  
pp. 143-148
Author(s):  
Svetlana Cornaja ◽  
Svetlana Zhizhkuna ◽  
Jevgenija Vladiko
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Kinetic Model ◽  
Catalytic Oxidation ◽  
Molecular Oxygen ◽  
Oxidation Reaction ◽  
Main Product ◽  
Oxidation Process ◽  
Water Solution ◽  
Reaction Conditions

Supported 3wt%Pd/α-Al₂O₃ catalyst was tested in selective oxidation of 1,2-propanediol by molecular oxygen. It was found that the catalyst is active in an alkaline water solution. Lactic acid was obtained as the main product of the reaction. Influence of different reaction conditions on 1,2-PDO conversion and oxidation process selectivity was studied. Partial kinetic orders of the reaction with respect to 1,2-propanediol, c0(NaOH), p(O2), n(1,2-PDO)/n(Pd)) were determined and an experimental kinetic model of the catalytic oxidation reaction was obtained. Activation energy of the process was calculated and was found to be about 53 ± 5 kJ/mol.

Dirhodium(II)-Catalyzed Diamination Reaction via a Free Radical Pathway

2021 ◽  
Author(s):  
Zhiying Fan ◽  
Zhifan Wang ◽  
Ruoyi Shi ◽  
Yuanhua Wang
Keyword(s):  
Free Radical ◽  
Bond Formation ◽  
Mechanistic Study ◽  
Radical Mechanism ◽  
Free Radical Mechanism

Unlike C-N bond formation with classical dirhodium(II)-nitrenoids as the key intermediate, dirhodium(II)-catalyzed 1,2-and 1,3-diamination reactions are realized by a free radical mechanism. A mechanistic study revealed that the reactions undergo...

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