- A method for esterification reaction rate prediction of aliphatic monocarboxylic acids with primary alcohols in 1,4-dioxane based on two parametrical taft equation
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Esterification reaction rates of aliphatic monocarboxylic acids with primary alcohols in 1,4-dioxane as inert solvent were investigated. Acids were esterified with 1-propanol and alcohols with acetic acid as model reactants at a constant temperature of 60°C, at a fixed ionic strength and pH in a batch reactor with a constant volume. For evaluation of reaction rates, an exact kinetic equation for the equilibrium reaction was applied. Under these conditions and for low reactants, concentrations reaction rate depends only on the structure of reactants and, therefore, can be predicted by a correlation equation with two Taft coefficients (inductive and steric effects). From these equations, it is possible to estimate the esterification reaction rate constant for other acid-alcohol pairs. This methodology may also be suitable for other kinetic systems measured under comparable experimental conditions.
- Vojtko, Jan,Tomcik, Peter
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p. 189 - 196
(2014/02/14)
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- Solid sodium stannate as a high-efficiency superbase catalyst for anti-Markovnikov hydroamination and hydroalkoxylation of electron-deficient olefins under mild conditions
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A solid superbase with H- above 26.5 has been obtained through thermal treatment of sodium stannate hydrate. It was found to be an efficient catalyst for anti-Markovnikov hydroamination and hydroalkoxylation of electron-deficient olefins under mild conditions.
- Zhang, Shuguo,Wei, Yudan,Yin, Shuangfeng,Au, Chak-Tong
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p. 712 - 716
(2013/01/09)
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- Cyclopropanation of olefins with diazo compounds catalyzed by a dicopper-substituted silicotungstate [γ-H2SiW 10O36Cu2(μ-1,1-N3) 2]4-
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The dicopper-substituted γ-Keggin silicotungstate (TBA) 4[γ-H2SiW10O36Cu 2II(μ-1,1-N3)2] (I, TBA = tetra-n-butylammonium) could act as an efficient precatalyst for the chemoselective cylopropanation of olefins with diazo compounds. Various kinds of olefins were efficiently converted to the corresponding cyclopropane derivatives in good yields.
- Kamata, Keigo,Kimura, Toshihiro,Mizuno, Noritaka
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supporting information; scheme or table
p. 702 - 703
(2011/01/08)
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- Indium triiodide catalysed one-step conversion of tetrahydropyranyl ethers to acetates with high selectivity
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Chemoselective one-step conversion of tetrahydropyranyl ethers of primary alcohols to corresponding acetates was carried out. The reaction occurred through an indium triiodide catalyzed transesterification process in ethyl acetate. The method provided advantages such as operational simplicity, acceptable reaction conditions to acid-sensitive functional groups and good yield.
- Ranu, Brindaban C.,Hajra, Alakananda
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p. 355 - 357
(2007/10/03)
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- Highly selective one-pot conversion of THP and MOM ethers to acetates by indium triiodide-catalysed deprotection and subsequent transesterification by ethyl acetate
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The chemoselective one-pot conversion of tetrahydropyranyl (THP) and methoxymethyl (MOM) ethers of primary alcohols to the corresponding acetates was presented. It was done using indium triiodide-catalysed deprotection and subsequent acetylation by ethyl acetate through a transesterification process. The advantages offered by the method included operational simplicity, 'green' methodology involving no toxic or hazardous chemicals and high yield.
- Ranu, Brindaban C.,Hajra, Alakananda
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p. 2262 - 2265
(2007/10/03)
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- The chemistry of organoborates. 9. A regiospecific and highly stereoselective construction of trisubstituted αβ-unsaturated ketones, tetrasubstituted αβ-unsaturated ketones and specifically protected 1,3-diketones from alkynyltrialkylborates
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Lithium alkynyltrialkylborates react with dioxolanium fluorosulphonates in a highly stereoselective fashion such that the dioxolanium group and the migrating group and the migrating group are on the same side of the new alkene intermediate. Hydrolysis of the intermediate yields Z-trisubstituted αβ-unsaturated ketones in which all three substituents have different origins and can be independently varied. Oxidation of the intermediates gives β-ketoacetals, which are regiospecifically protected 1,3-diketones. If the initial intermediates are allowed to stand, then another migration occurs and tetra-substituted αβ-unsaturated ketones result.
- Pelter,Colclough
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p. 811 - 828
(2007/10/02)
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- Effects of Polar β Substituents in the Gas-Phase Pyrolysis of Ethyl Acetate Esters
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The rates of the gas phase pyrolysis of six β-substituted ethyl acetates were studied in a static system over the temperature range 319-450 deg C and the pressure range 63-207 mmHg.In seasoned vessels the reactions are homogenous, follow a first-order rate law, and are unimolecular.The temperature dependence of the rate constants is given by the following Arrhenius equations for the compounds indicated: 2-(dimethylamino)ethyl acetate, log k(s-1) = (13.90 +/- 0.30) - (220.4 +/- 3.8) kJ*mol-1 (2.303RT)-1; 2-methoxyethyl acetate, log k(s-1) = (12.04 +/- 0.24) -(203.7 +/- 2.9) kJ*mol1- (2.303RT)-1; 2-(methylthio)ethyl acetae, log k(s-1 = (11.27 +/- 0.39) - (179.0 +/- 4.6) kJ*mol-1 (2.303RT)-1; 2-chloroethyl acetate, log k(s-1) = (12.14 +/- 0.66) - (202.0 +/- 8.4)kJ*mol-1 (2.303RT)-1; 2-fluoroethyl acetate, log k(s-1) = (12.68 +/- 0.60) - (211.2 +/- 7.1) kJ*mol-1 (2.303RT)-1; 2-cyanoethylacetate, Log k(s-1) = (11.51 +/- 0.13) - (171.9 +/- 1.7) kJ*mol-1 (2.303RT)-1.The effect of substituents in the gas-phase elimination of β-substituted ethyl acetates may be grouped in three types.The linear correlation of several -I electron-withdrawing groups along strong ? bonds is presented and discussed.A small amount of anchimeric assistance is proposed in the pyrolysis of the 2-(methyltio)ethyl acetate.The experimental data are consistent with the transition state where the Cα-O bond polarization is the rate-determining process.
- Chuchani, Gabriel,Martin, Ignacio,Hernandez, Jose A. A.,Rotinov, Alexandra,Fraile, German,Bigley, David B.
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p. 944 - 948
(2007/10/02)
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