Kinetics and Mechanism of the Polymerization of Styrene by Triphenylmethyl Chloride and Mercuric Chloride in 1,2-Dichloroethane, and the Initiation Rate Constant

1970 ◽  
Vol 3 (3) ◽  
pp. 351-355 ◽  
Author(s):  
Manjit S. Sambhi
Keyword(s):  
Rate Constant ◽  
Mercuric Chloride ◽  
Kinetics And Mechanism ◽  
Initiation Rate

scholarly journals Synthesis, kinetics and mechanism of nucleophilic substitution in octahedral (cat)2Sn(py)2

2005 ◽  
Vol 70 (12) ◽  
pp. 1389-1393 ◽  
Author(s):  
K.S. Siddiqi ◽  
Shahab Nami
Keyword(s):  
Nucleophilic Substitution ◽  
Rate Constant ◽  
Substitution Reaction ◽  
Molar Conductance ◽  
Chloride Ions ◽  
Kinetics And Mechanism ◽  
Nucleophilic Substitution Reaction ◽  
Nucleophilic Reagents

Dicatecholatodipyridinetin(IV) in nitrobenzene showed an increase in molar conductance with time, suggesting solvation of the complex. In the presence of nucleophilic reagents, such as SOCl2, C6H5COCl and CH3COCl, the conductance increased sharply owing to the substitution of pyridine by chloride ions. The data for the rate constant of solvation (k s) and for nucleophilic substitution (k 1 and k 2) have been calculated and it was found that the solvation is a slower process compared to the substitution by chloride ions, i.e., k1, k 2 > k s. The nucleophilic substitution reaction follows the SN1 mechanism.

Photochemical reaction kinetics and mechanism of bisphenol A with K2S2O8 in aqueous solution: a laser flash photolysis study

2021 ◽  
Vol 99 (1) ◽  
pp. 43-50
Author(s):  
Yongchao Zhu ◽  
Mengyu Zhu ◽  
Jingjing Xie ◽  
Yadong Hu ◽  
Ying Liu ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Rate Constant ◽  
Photochemical Reaction ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Phenoxyl Radical ◽  
Laser Flash ◽  
Kinetics And Mechanism ◽  
Main Reaction ◽  
Specific Rate

The photochemical reaction kinetics and mechanism of bisphenol A (BPA) with potassium persulfate (K2S2O8) were investigated by using 266 nm laser flash photolysis and gas chromatography mass spectrum (GC-MS) technique. Sulfate radical (SO4•−), generated upon K2S2O8 photolysis, reacted with BPA with the overall rate constant of (1.61 ± 0.15) × 109 L mol−1 s−1, and two main reaction mechanisms were involved. One was addition channel to generate BPA–SO4•− adduct with a specific second-order rate constant of (1.09 ± 0.15) × 109 L mol−1 s−1. Molecular oxygen was involved in the decay of the BPA–SO4•− adduct with a rate constant of (1.28 ± 0.14) × 108 L mol−1 s−1. Another channel was the formation of BPA’s phenoxyl radical, likely derived from a deprotonation of the cation radical (BPA•+) generated from single electron transfer reactions. The specific rate constant of BPA’s phenoxyl radical formation was determined to be (6.16 ± 0.08) × 108 L mol−1 s−1. The overall rate constant was in line with the sum of aforementioned two specific rate constants for two main reaction channels. By comparing these rate constants, it was indicated that SO4•− addition channel accounted for ∼65% (1.09/1.61) to the overall reaction, and phenoxyl radical formation accounted for only ∼35% (0.62/1.61). The transformation products of BPA were identified by using GC-MS including 4-isopropylphenol, 4-isopropenylphenol, and 2,4-di-tert-butylphenol, and the reaction mechanism was proposed. These results may provide microscopic kinetics and mechanism information on BPA degradation using SO4•−-based advanced oxidation processes.

Solvent effects on kinetics and mechanism of acid-catalyzed decomposition of 1,3-bis(4-methylphenyl)-triazene II. Reactions in aprotic solvents

1990 ◽  
Vol 55 (1) ◽  
pp. 156-164 ◽  
Author(s):  
Oldřich Pytela ◽  
Taťjana Nevěčná ◽  
Miroslav Ludwig
Keyword(s):  
Rate Constant ◽  
Acid Catalyst ◽  
Kinetics And Mechanism ◽  
Aprotic Solvents ◽  
Catalytic Rate Constant ◽  
Negative Effect ◽  
Acid Catalyzed ◽  
Catalytic Rate ◽  
Positive Effect ◽  
Solvent Acidity

The effect of aprotic solvents (hexane, cyclohexane, dichloromethane, 1,2-dichloroethane, benzene, acetonitrile, acetone, 1,2-dimethoxyethane, ethyl acetate, dioxane) on kinetics and mechanism of acid-catalyzed decomposition of 1,3-bis(4-methylphenyl)triazene has been studied with trichloroacetic acid as the acid catalyst. It has been found that beside the non-dissociated monomer of the acid also its dimer acts as the catalytic species. With regard to the results obtained in protic solvents (the catalysis by proton and general acid) three cases can be encountered of the dependence of observed rate constant on analytical concentration of the acid. The effect of solvents (inclusive of the protic ones) on the catalytic rate constant of the reaction with the non-dissociated monomer of acid is best interpreted by the equation suggested by Koppel and Palm and by the solvent scale suggested by us earlier. The solvent acidity and polarity have positive effect, whereas its basicity has negative effect. The catalytic rate constant of the reaction with the acid dimer decreases with increasing solvent basicity and polarity, due predominantly to the decrease in the equilibrium constant of dimerization.

Kinetics and Mechanism of Acid-Catalyzed Decomposition of 1,3-Bis(4-methylphenyl)triazene in Hexane-Organic Acid Medium

1996 ◽  
Vol 61 (3) ◽  
pp. 355-363 ◽  
Author(s):  
Miroslav Ludwig ◽  
Miriam Kabíčková
Keyword(s):  
Kinetic Model ◽  
Organic Acid ◽  
Acid Medium ◽  
Rate Constant ◽  
Fourth Order ◽  
Kinetics And Mechanism ◽  
Acid Catalyzed ◽  
Kinetics Of

The kinetics of acid-catalyzed decomposition of 1,3-bis(4-methylphenyl)triazene have been studied in mixtures of hexane and organic acid of various ratios using acetic, isovaleric, and pivalic acids as the catalysts. In all the cases, a monotonously increasing dependence of the observed rate constant upon mol fraction of the acid has been found. The results obtained are discussed with the help of the classic third- and fourth-order functions by Margules and the respective kinetic model. The main catalyzing particle appears to be the dimer of the respective acid, the reaction probably going via a complex formed by two molecules of acid and one molecule of the triazene.

scholarly journals Rate constant of the reaction of the peroxyl radical of 1,4-dioxane with α-Tocopherol and trolox

2020 ◽  
Vol 64 (11) ◽  
pp. 55-60
Author(s):  
Olesya V. Semikasheva ◽  
◽  
Lucia R. Yakupova ◽  
Rustam L. Safiullin ◽  
◽  
...  
Keyword(s):  
Induction Period ◽  
Rate Constant ◽  
Peroxyl Radical ◽  
Practical Interest ◽  
Water Soluble ◽  
Oxygen Absorption ◽  
Initiation Rate ◽  
Radical Chain ◽  
Decay Rate Constant ◽  
Integral Methods

The study of the properties of water-soluble antioxidants is of practical interest. Research is hindered by the fact that such substances are poorly soluble in substrates, which are most widespread in determining the quantitative characteristics of antioxidants. Usually it is cumene, ethylbenzene, styrene. In this work, we used a method based on a model reaction of the radical chain 1,4-dioxane oxidation. This substrate is the most suitable solvent for evaluating the water-soluble substances antioxidant activity. The inhibitory activity of α-tocopherol (vitamin E) and trolox (a water-soluble analogue of α-tocopherol) was studied in a model system of radical chain 1,4-dioxane oxidation. Air oxygen served as the oxidizing agent. The experiments were carried out at 333 K. Initiation was carried out with 2,2'-azo-bis-isobutyronitrile. The reaction kinetics was monitored by the rate of oxygen uptake using a manometric setup. In this work to measure the initiation rate, the inhibitors method is used. The standard α-tocopherol inhibitor was used for this purpose. α-Tocopherol is an effective inhibitor with a known stoichiometric inhibition ratio of two. The method used in our study makes it possible to measure correct the length of the induction period using the kinetics of oxygen absorption. The induction period was determined by graphical and integral methods. The initiation rate was calculated based on the induction period values. The resulting value is in satisfactory agreement with the data based on the literary value of the decay rate constant 2,2'-azo-bis-isobutyronitrile. The rate constant of the reaction of the 1,4-dioxane peroxyl radical with α-tocopherol and trolox (fk7, L mol-1s-1, 333 K) was measured: (1.6 ± 0.1)∙106, (1.2 ± 0.1)∙106. The stoichiometric inhibition coefficient for trolox in the system of radical chain 1,4-dioxane oxidation was determined: f = 2.4 ± 0.2.

Kinetics and mechanism of the oxidation of oxalate ion by tris(acetylacetonato)-manganese(III) and its hydrolytic derivatives in aqueous perchlorate media

1993 ◽  
Vol 71 (12) ◽  
pp. 2155-2159 ◽  
Author(s):  
Subrata Mukhopadhyay ◽  
Swapan Chaudhuri ◽  
Rina Das ◽  
Rupendranath Banerjee
Keyword(s):  
Free Radicals ◽  
Rate Constant ◽  
Decomposition Rate ◽  
Rate Constants ◽  
Kinetics And Mechanism ◽  
Unimolecular Decomposition ◽  
Decomposition Rate Constant ◽  
Mixed Complexes ◽  
Ph Range ◽  
Oxalate Ion

In the pH range 6.6–8.6, [MnL2(H2O)2]+ and [MnL2(H2O)(OH)] (HL = acetylacetone) oxidize oxalate ion (ox2−) to CO2 through the inner-sphere intermediates [MnL2(ox)]− and [MnL2(OH)(ox′)]2−, where ox′ is a half-bonded (unidentate) oxalate ion. Their rate constants of decomposition are 1.0 × 10−4 s−1 and 11.2 × 10−2 M−1 s−1 at 30 °C and at I = 1.0 M (NaClO4). Decomposition of these mixed complexes produces free radicals, presumably CO2−, which is further oxidized to CO2 by another Mn(III) in a fast step. At pH 4.2, [Mn(ox)3]3− is produced quantitatively when [ox]0 ≥ 0.12 M, which has been characterized spectrally, and its unimolecular decomposition rate constant k (= 2.7 × 10−4s−1 at 30 °C and I = 1.0 M) compares well with that reported earlier (2.44 × 10−4 s−1 at 25 °C and I = 1.0 M).

Rate constant for the reaction Br + O3 ? BrO + O2 from 248 to 418 K: Kinetics and mechanism

1988 ◽  
Vol 20 (2) ◽  
pp. 131-144 ◽  
Author(s):  
Darin W. Toohey ◽  
Wm. H. Brune ◽  
J. G. Anderson
Keyword(s):  
Rate Constant ◽  
Kinetics And Mechanism
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