Kinetics and Activation Parameters for the Alkaline Aqueous Rearrangement of Trichorfon [O,O-Dimethyl-(2,2,2-Trichloro-1-Hydroxyethyl) Phosphonate] to Dichlorvos [O,O-Dimethyl-O-(2,2-Dichloroethenyl)Phosphate]

2001 ◽  
Vol 36 (3) ◽  
pp. 589-604 ◽  
Author(s):  
Julian M. Dust ◽  
Christopher S. Warren
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Activation Parameters ◽  
Base Catalysis ◽  
Rearrangement Product ◽  
Exponential Factor ◽  
First Order ◽  
Pseudo First Order ◽  
Order Plot ◽  
Kinetics Of

Abstract The kinetics of the alkaline rearrangement of O,O-dimethyl-(2,2,2-trichloro-1- hydroxyethyl)phosphonate, (trichlorfon, 1), the active insecticidal component in such formulations as Dylox, was followed at 25±0.5°C by high pressure liquid chromatography (UV-vis detector, 210 nm). The rearrangement product, O,Odimethyl- O-(2,2-dichloroethenyl)phosphate (dichlorovos, 2), which is a more potent biocide than trichlorfon, undergoes further reaction, and the kinetics, consequently, cannot be treated by a standard pseudo-first-order plot. A two-point van't Hoff (initial rates) method was used to obtain pseudo-first-order rate constants (kѱ) at 25, 35 and 45°C: 2.6 × 10-6, 7.4 × 10-6 and 2.5 × 10-5 s-1, respectively. Arrhenius treatment of this data gave an activation energy (Ea) of 88 kJ·mol-1 with a pre-exponential factor (A) of 5.5 × 109 s-1. Kinetic trials at pH 8.0 using phosphate and tris buffer systems show no buffer catalysis in this reaction and indicate that the rearrangement is subject to specific base catalysis. Estimates are reported for pseudo-first-order half-lives for trichlorfon at pH 8.0 for environmental conditions in aqueous systems in the Corner Brook region of western Newfoundland, part of the site of a recent trichlorfon aerial spray program.

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.

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.

Die Kinetik des Zerfalls von tert. Butylperoxypivalat bei hohen Drücken und Temperaturen / The Kinetics of the Decomposition of tert.Butylperoxypivalate up to High Pressures and Temperatures

1981 ◽  
Vol 36 (12) ◽  
pp. 1371-1377 ◽  
Author(s):  
M. Buback ◽  
H. Lendle
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
High Pressures ◽  
Activation Volume ◽  
Rate Law ◽  
First Order ◽  
Order Rate ◽  
High Pressures And Temperatures ◽  
Kinetics Of

AbstractThe decomposition of tert. butylperoxypivalate dissolved in n-heptane has been measured ir-spectroscopically in optical high-pressure cells up to 2000 bar at temperatures between 65 °C and 105 °C. The reaction follows a first order rate law with an activation energy Ea = 122.3 ±3.0 kJ · mol-1 and an activation volume ⊿V≠ = 1.6 ± 1.0 cm3 mol-1 .

Kinetics of Rubber-Modified Nylon 6

2014 ◽  
Vol 887-888 ◽  
pp. 951-954
Author(s):  
Hong Kai Zhao ◽  
Hong Li Wang
Keyword(s):  
Activation Energy ◽  
Reaction Order ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Exponential Factor ◽  
First Order ◽  
Adiabatic Approach ◽  
Research Findings ◽  
Styrene Butadiene ◽  
Kinetics Of

Kinetic parameters are calculated based on the reactive temperature rise curve measured by adiabatic approach at the temperature of 145 to 160 °C with the catalytic system of NaOH and acyl caprolactam End-capped butadiene-acrylonitrile rubber (CHTBN) or styrene-butadiene rubber (CHTBS). The reaction order is first order, the activation energy is between 72.91−73.16 kJ∙mol−1 and the pre-exponential factor is between 3.22×1011− 3.38×1011 mol1−n∙s−1 in the system of CHTBN/NaOH. While in CHTBS/NaOH, the reaction order is between 1.23-1.34, the activation energy is between 85.55－86.88 kJ∙mol−1 and the pre-exponential factor is between 4.52×1011−5.0 9×1011 mol1−n∙s−1. The adiabatic reaction kinetic model of caprolactam anion was constructed based on the existing research findings, by which the polymerizing reaction is simulated. The coincidence between the simulation results and the experimental data revealed that the model is reasonable and correct.

An Experimental Study of the Coking Process

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Somayeh Ebrahimi ◽  
Jafarsadegh Moghaddas
Keyword(s):  
Activation Energy ◽  
Coke Formation ◽  
Nitrogen Atmosphere ◽  
Fuel Oil ◽  
Effective Parameters ◽  
Pyrolysis Kinetics ◽  
Exponential Factor ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of

The coking process includes two dynamic and isothermal steps. In this process, some factors control the coke formation kinetics. In this research, effects of some important and effective parameters of feed on the quality of petroleum coke were studied. Two hydrocarbon residue feeds; Cracked Fuel Oil (CFO) and Styrene Monomer Tar (SMTAR) were used at 500°C with atmospheric pressure of nitrogen used as an inert gas. Rate of weight loss and gas evolution from these feeds were considered by data of thermal analysis TG (thermogravimetry) and DTG (derivative thermogravimetry). Based on the results, CFO was assigned as the better feed. After selecting better feed, simultaneous thermogravimetry-differential analysis (TG-DTA) was used to study the pyrolysis kinetics of CFO. Samples were heated in a TG-DTA apparatus in nitrogen atmosphere at a temperature range of 37-600°C. The activation energy (Ea) and pre-exponential factor (A) were calculated from the experimental results by using a three stage Arrhenius-type kinetic model and showed that CFO pyrolysis kinetics at temperature ranges 37-285, 320-450 and 467-600°C follows first, second and first order kinetics, respectively. Attentive to temperature increase and reaction progress, activation energy and pre-exponential factor indicated different values at each stage. Also, kinetics of the isothermal step of coke formation was studied during heating of CFO. Samples were reacted in a tube furnace at 450°C and with nitrogen atmosphere. The kinetics of coke formation for petroleum residue was followed by solvent extraction (insolubility in hexane (HI), toluene (TI)) and a development of TI approximate to apparent first order kinetics. The rate constant at this temperature was calculated and it was also observed that the coke formation had been started at a temperature below 450°C.

scholarly journals Kinetics of Hydrodesulfurization of Dibenzothiophene on Sulfided Commercial Co-Mo/γ-Al2O3 Catalyst

2006 ◽  
Vol 3 (1) ◽  
pp. 38 ◽  
Author(s):  
Y.S. Al-Zeghayer ◽  
B.Y. Jibril
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Reaction Temperature ◽  
Reaction Network ◽  
Order Model ◽  
First Order ◽  
Catalytic Sites ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Al2o3 Catalyst

Kinetics of hydrodesulfurization of dibenzothiophene (DBT) has been studied on a commercial CoMo/γ-Al2O3 catalyst at 633 - 683 K and 10 atm. A low DBT concentration typically obtained in hydrodesulfurization operations was used. Pseudo-first-order model was found to fit the experimental data for the consumption of DBT. The activation energy for the conversion of DBT was found to be 51.7 kcal/mol. Biphenyl (BP) and cyclohexylbenzene (CHB) were obtained as dominant products. For the reaction network, both parallel and parallel-sequential routes were explored. The latter was found to give a better description of the BP and CHB distributions. The ratio of BP to CHB depended on the reaction temperature. The values of activation energies of DBT hydrogenolysis to BP (EBP), DBT hydrogenation to CHB (ECHB1) and hydrogenation of BP to CHB (ECHB2) were found to be in a decreasing order of ECHB2 > EBP > ECHB1. The result suggests the presence of different catalytic sites leading to the two products on the catalysts. 

Kinetics of Desulfuration Product Sulphoaluminate Calcium

2010 ◽  
Vol 113-116 ◽  
pp. 1814-1817 ◽  
Author(s):  
Hui Ling Guo ◽  
Jun Lin Xie
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Formation Rate ◽  
Experimental Investigations ◽  
Exponential Factor ◽  
First Order ◽  
First Order Kinetics ◽  
Formation Kinetics ◽  
Competitive Reactions ◽  
Kinetics Of

The formation kinetics of sulphoaluminate calcium was studied by variations of sulfur release with time from SC-132 based on competitive reactions, the generation of sulphoaluminate calcium and the decomposition of CaSO4. Experimental investigations and theoretical derivations show that the formation rate of sulphoaluminate calcium can be described as first-order kinetics at high temperature, and it belongs to the mechanism of random nucleus growth. The apparent activation energy is 456.37 KJ•mol-1 and pre-exponential factor is 1.545×1012.

Thermal and kinetic behaviors of corn stover and polyethylene in catalytic co-pyrolysis

BioResources ◽  
2018 ◽  
Vol 13 (2) ◽  
pp. 4102-4117
Author(s):  
Shaoqing Wang ◽  
Xiaona Lin ◽  
Zhihe Li ◽  
Weiming Yi ◽  
Xueyuan Bai
Keyword(s):  
Activation Energy ◽  
Corn Stover ◽  
Compensation Effect ◽  
Kinetic Studies ◽  
Order Reaction ◽  
Kinetic Compensation Effect ◽  
Exponential Factor ◽  
First Order ◽  
Thermogravimetric Data ◽  
Kinetics Of

Thermal decomposition characteristics and kinetics of high-density polyethylene (HDPE), corn stover (CS), and their blended mixture (1:1 w/w ratio) during non-catalytic and catalytic co-pyrolysis were studied via thermogravimetric analysis (TGA). The results indicated synergetic interactions between the biomass and the plastics during co-pyrolysis as measured by weight loss (ΔW); this effect was attributed to radical interactions during co-pyrolysis. The pyrolysis catalysts with higher nickel loadings (5%, 10%, and 15%) appreciably diminished the solid residue. Kinetic studies indicated that the pyrolysis was a first-order reaction based on the fitted thermogravimetric data. The activation energy (E) and pre-exponential factor (A) ranged between 26.13 kJ/mol to 392.67 kJ/mol and between 156.24 min-1 to 9.19 x 1023 min-1, respectively. There was a kinetic compensation effect (KCE) observed among the two kinetic parameters. The activation energy (E) decreased for each pyrolysis stage with the presence of a catalyst. The results indicated that catalytic co-pyrolysis could provide great potential for reducing the pyrolysis energy input.

A voltammetric study of the kinetics of the hexacyanomanganate(III) disproportionation in acidic medium

1991 ◽  
Vol 69 (12) ◽  
pp. 2112-2116 ◽  
Author(s):  
Guillermo López-Cueto ◽  
Carlos Ubide
Keyword(s):  
Acidic Medium ◽  
Activation Parameters ◽  
Effect Of Temperature ◽  
Disk Electrode ◽  
First Order ◽  
Voltammetric Study ◽  
Half Wave ◽  
Constant Potential ◽  
Pseudo First Order ◽  
Kinetics Of

The fast disproportionation of hexacyanomanganate(III) in acidic medium yields Mn(CN)62− and Mn(H2O)62+. The reaction has been studied by amperometry, with a rotating platinum-disk electrode, at a 1.0 V (vs. SCE) constant potential, in the acidity range 0.01–2.0 M and at temperatures between −5 and 15 °C. A reversible one-electron process takes place with a 0.85 V (vs. SCE) half-wave potential that is not dependent on acidity. The reaction kinetics is pseudo-first order in [Mn(CN)63−] and the rate constant depends on acidity according to the equation: kobs = ka + kb[H3O+] + kc[H3O+]2. At 5 °C and ionic strength 2.0, the determined values of ka, kb, and kc were (2.20 ± 0.08) × 10−3 s−1, (4.9 ± 0.2) × 10−3 s−1 M−1 and (1.40 ± 0.10) × 10−3 s−1 M−2, respectively. A mechanism is proposed where the three terms of kobs are assigned to pathways involving hexacyanomanganate(III) in three different states of protonation. From the effect of temperature the activation parameters, ΔH≠ and ΔS≠, for each pathway are also reported.Key words: hexacyanomanganate(IV), disproportionation, kinetics, amperometry, rotating platinum-disk electrode.

The kinetic study of the addition of tetrachloromethane to styrene in the presence of copper complexes

1987 ◽  
Vol 52 (7) ◽  
pp. 1758-1763 ◽  
Author(s):  
Li Gwang Hun ◽  
Lubomír Nondek
Keyword(s):  
Activation Energy ◽  
Reaction Mechanism ◽  
Kinetic Study ◽  
Copper Complexes ◽  
Catalytic Mechanism ◽  
First Order ◽  
First Order Kinetics ◽  
Experimental Activation Energy ◽  
Pseudo First Order ◽  
Kinetics Of

Kinetics of the addition of tetrachloromethane to styrene catalyzed by copper-amine complexes was studied. The pseudo-first order kinetics in respect to styrene and the catalyst was observed at an excess of tetrachloromethane. The reaction mechanism involving a catalytic cycle compatible with the kinetic observations is proposed. The experimental activation energy, being about 104 kJ mol-1, indicates a catalytic mechanism.

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