Kinetics of the acid-catalysed hydration of prop-2-en-1-ol. Evidence for a free, ion-dipole intermediate in the heterolysis of propane-1,2-diol

1982 ◽  
Vol 35 (11) ◽  
pp. 2221 ◽  
Author(s):  
KP Herlihy
Keyword(s):  
Activation Parameters ◽  
Optically Active ◽  
First Order ◽  
Aqueous Acid ◽  
First Order Kinetics ◽  
Pinacol Rearrangement ◽  
Free Ion ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Good Agreement

Prop-2-en-1-ol in aqueous acid solution gives propane-1,2-diol and propanal. At 100�C the amount of diol in this product ratio is found to decrease from 65% in 1 M HClO4 to 50% in 4 M HClO4. Pseudo-first-order kinetics are found to apply. The values obtained for the activation parameters, Ea and ΔS‡ and for a Hammett acidity plot, are similar to results reported for other alkenes. The relative rates of partitioning between regeneration of the substrate and rearrangement for the pinacol rearrangement of optically active propane-1,2-diol have been calculated previously. When these are compared with product ratios obtained from the hydration of prop-2-en-1-ol, good agreement is found between the respective values if it is assumed that the regenerated substrate has undergone complete racemization of configuration. This is interpreted to be evidence for a short-lived, but free ion-dipole as the intermediate in the heterolysis of propane-1,2-diol.

The kinetics and the mechanism of oxidative decarboxylation of benzilic acid by acidic permanganate (stopped-flow technique) — An autocatalytic study

2004 ◽  
Vol 82 (9) ◽  
pp. 1372-1380 ◽  
Author(s):  
Sairabanu A Farokhi ◽  
Sharanappa T Nandibewoor
Keyword(s):  
Activation Parameters ◽  
Oxidative Decarboxylation ◽  
Two Stage ◽  
First Order ◽  
First Order Kinetics ◽  
Stage Process ◽  
Benzilic Acid ◽  
Reaction Constants ◽  
Kinetics Of ◽  
Good Agreement

The kinetics of the oxidation of benzilic acid by potassium permanganate in an acidic medium were studied spectrophotometrically. The reaction followed a two-stage process, wherein both stages of the reaction followed first-order kinetics with respect to permanganate ion and benzilic acid. The rate of the reaction increased with an increase in acid concentration. Autocatalysis was observed by one of the products, i.e., manganese(II). A composite mechanism involving autocatalysis has been proposed. The activation parameters of the reaction were calculated and discussed and the reaction constants involved in the mechanisms were calculated. There is a good agreement between the observed and calculated rate constants under different experimental conditions.Key words: oxidation, autocatalysis, benzilic acid, two-stage kinetics.

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.

Parameters Effect on Photocatalytic Reduction Kinetics of Bromate in Aqueous Dispersion of TiO2

2013 ◽  
Vol 779-780 ◽  
pp. 1658-1665
Author(s):  
Rong Shu Zhu ◽  
Fei Tian ◽  
Ling Ling Zhang ◽  
Ling Min Yu
Keyword(s):  
Aqueous Dispersion ◽  
Zero Order ◽  
Photocatalytic Reduction ◽  
Reduction Kinetics ◽  
First Order ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Experimental Parameters ◽  
Pseudo First Order ◽  
Kinetics Of

This paper studied the photocatalytic reduction kinetics of bromate in aqueous dispersion of TiO2 and investigated the effects of experimental parameters, including initial concentration of BrO3-, pH, TiO2 dosage, anion and cation. The results indicate that the process of photocatalytic reduction of bromate follows a zero-order kinetics. In all the investigated experimental parameters, the initial bromate concentration, pH and anion have great effect on the photocatalytic reduction kinetics. The processes of photocatalytic reduction of bromate show the pseudo first-order kinetics at initial bromate concentration of 0.39 μmolL-1, pH=5.0, or in presence of HCO3-/CO32-, NO3-, SO42-, respectively.

scholarly journals Kinetics of dechlorination of atrazine using tin (SnII) at neutral pH conditions

2020 ◽  
Vol 3 (1) ◽  
pp. 49
Author(s):  
Vijay Kumar ◽  
Simranjeet Singh
Keyword(s):  
Aqueous Media ◽  
Spectrometric Analysis ◽  
First Order ◽  
Neutral Ph ◽  
First Order Kinetics ◽  
Condi Tions ◽  
Ph Conditions ◽  
Pseudo First Order ◽  
Reaction Constants ◽  
Kinetics Of

Atrazine is a broad spectrum herbicide of triazine family. It is a chlorine-containing molecule and it can persist in environment. Chemical and biochemical techniques are the main techniques used to decompose the chemicals. In pre-sent study, the dechlorination of atrazine (Atr) via reaction with Sn(II) ion under aqueous media at neutral pH condi-tions was studied. The observed dechlorinated metabolite was 4-Ethylamino-6-isopropylamino-[1,3,5]triazin-2-ol. Identification of dechlorinated product of Atr was performed by using spectroscopic (FTIR) and mass (ESI-MS) spectrometric analysis. The kinetics of the dechlorination of Atr was measured by using pseudo-first order kinetics. The observed reaction constants was, kobs = 6.11x10-2 (at 430 mg/ L of Atr), and kobs = 6.14 x10-2 (at 215 mg/ L of Atr). The calculated half-life (t1/2) period was, t1/2 = 0.204 d (at 430 mg/ L of Atr), and t1/2 = 0.205 d (at 215 mg/ L of Atr).

scholarly journals KINETICS OF REACTION BETWEEN MALACHITE GREEN AND HYDROXYL ION IN THE PRESENCE OF REDUCING SUGARS

2015 ◽  
Vol 23 (23) ◽  
pp. 61-72
Author(s):  
Dayo Felix Latona ◽  
Adewumi Oluwasogo Dada
Keyword(s):  
Malachite Green ◽  
Activation Parameters ◽  
Cell Compartment ◽  
First Order ◽  
Rate Determining Step ◽  
First Order Kinetics ◽  
Hydroxyl Ion ◽  
Kinetics Of Reaction ◽  
Kinetics Of ◽  
Sphere Mechanism

The reaction was studied via pseudo-first-order kinetics using a UV-1800 Shimadzu spectrophotometer with a thermostated cell compartment and interfaced with a computer. The reaction showed first order with respect to malachite green and sugar and hydroxyl ion concentrations. However, the reaction was independent of ionic strength and showed no dependence on the salt effect, indicating an inner sphere mechanism for the reaction. There was no polymerization of the reaction mixture with acrylonitrile, indicating the absence of radicals in the course of the reaction. Michaelis-Menten plot indicated the presence of a reaction intermediate in the rate-determining step. The activation parameters of the reaction have been calculated and products were elucidated by FTIR spectroscopy. The stoichiometry of the reaction is 1:1. A mechanism consistent with the above facts has been suggested.

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 Reaction Kinetics of Carbon Dioxide in Aqueous Diethanolamine Solutions Using the Stopped-Flow Technique

2012 ◽  
Vol 19 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Marta Siemieniec ◽  
Hanna Kierzkowska-Pawlak ◽  
Andrzej Chacuk
Keyword(s):  
Carbon Dioxide ◽  
Reaction Kinetics ◽  
Rate Constants ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Stopped Flow ◽  
First Order ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Good Agreement

Reaction Kinetics of Carbon Dioxide in Aqueous Diethanolamine Solutions Using the Stopped-Flow Technique The pseudo-first-order rate constants (kOV) for the reactions between CO2 and diethanolamine have been studied using the stopped-flow technique in an aqueous solution at 293, 298, 303 and 313 K. The amine concentrations ranged from 167 to 500 mol·m-3. The overall reaction rate constant was found to increase with amine concentration and temperature. Both the zwitterion and termolecular mechanisms were applied to correlate the experimentally obtained rate constants. The values of SSE quality index showed a good agreement between the experimental data and the corresponding fit by the use of both mechanisms.

Kinetics of hydrolysis of aromatic mono- and disulfonyl chlorides

1987 ◽  
Vol 65 (9) ◽  
pp. 2263-2267 ◽  
Author(s):  
Przemyslaw Sanecki ◽  
Edward Rokaszewski
Keyword(s):  
Aqueous Acetic Acid ◽  
Polarographic Method ◽  
Acid System ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of Hydrolysis ◽  
Consecutive Reactions ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Hydrolysis Of

A continuous polarographic method of recording instantaneous concentrations of —SO2Cl groups in an aqueous acetic acid system containing CH3CO2Na has been elaborated. Ten model monosulfonyl chlorides underwent hydrolysis according to pseudo-first order kinetics (20% H2O, 80% v.v. CH3CO2H, 0.5 mol × dm−3 CH3CO2Na). Plots of hydrolysis for seven disulfonyl dichlorides with different number of —CH3 groups have been determined. Pseudo-first order rate constants for two consecutive reactions of hydrolysis (k1 and k2) have been computed and the influence of —SO2Cl and [Formula: see text] groups on the reactivity of the second group —SO2Cl has been discussed. The mechanism of nucleophilic substitution has also been discussed.

Oxidation of the mercurous ion by peroxidase

1986 ◽  
Vol 64 (5) ◽  
pp. 969-972 ◽  
Author(s):  
Donald C. Wigfield ◽  
Season Tse
Keyword(s):  
Elemental Mercury ◽  
Order Rate Constant ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Order Rate ◽  
First Order Kinetics ◽  
Cold Vapour ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Mercurous Ion

The kinetics of oxidation of the mercurous ion by peroxidase have been measured by following the disappearance of mercurous ion using cold-vapour atomic absorption spectroscopy. Pseudo-first-order kinetics are observed with respect to mercurous ion, and the pseudo-first-order rate constants are linearly related to peroxidase concentration, showing first-order dependence on peroxidase. This behaviour is identical to oxidation of elemental mercury, and the second-order rate constant, 1.44 × 104 M−1 s−1 at 23 °C, is also, within experimental error, the same as that for elemental mercury oxidation. The data are interpreted in terms of peroxidase-induced disproportionation of the mercurous dimer, followed by two-electron oxidation of zero-valent mercury.

Degradation Kinetics of Reactive Brilliant Red X-3B Dye by UV/Mn2+/H2O2/Micro-Aeration

2012 ◽  
Vol 441 ◽  
pp. 549-554
Author(s):  
Ying Jie Cai ◽  
Xiao Jun Yang ◽  
Dong Sheng Xia ◽  
Qing Fu Zeng
Keyword(s):  
Degradation Rate ◽  
Ph Value ◽  
Degradation Kinetics ◽  
H2o2 Concentration ◽  
Kinetics Equation ◽  
Linear Least Squares ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order ◽  
Kinetics Of

Abstract. Degradation of reactive brilliant red X-3B (X-3B) by a UV/Mn2+/H2O2/micro- aeration method was investigated. The influencing factors of degradation of X-3B including UV irradiation, aeration, pH value, H2O2 concentration and X-3B concentration were examined. The results show that X-3B was effectively degraded by the UV/Mn2+/H2O2/micro-aeration method. The degradation rate of X-3B was obtained from weighted linear least squares analysis of the experimental data, and accorded with the pseudo-first order kinetics equation.

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