Kinetics of the base-catalyzed halogenation of 2-carbetboxycyclobexanone

1952 ◽  
Vol 210 (1102) ◽  
pp. 322-326 ◽  
Keyword(s):  
Carboxylic Acids ◽  
Opposite Direction ◽  
Zero Order ◽  
Water Molecules ◽  
Ring Strain ◽  
Aqueous Buffer ◽  
First Order ◽  
Buffer Solutions ◽  
Carboxylate Anions ◽  
Kinetics Of

The kinetics of iodination of 2-carbethoxycyclohexanone have been studied colorimetrically in aqueous buffer solutions. The reaction is of the first order with respect to the ester, of zero order with respect to iodine, and is catalyzed by water molecules and by the anions of carboxylic acids. The catalytic constants of four carboxylate anions obey a relation of the Bronsted type, the exponent of which conforms to regularities previously established for a series of ketones and esters. Under comparable conditions 2-carbethoxycyclohexanone is halogenated 100 to 400 times more slowly than is 2-carbethoxycyclopentanone. This difference is in the opposite direction to that anticipated on the basis of ring strain, though it is paralleled by some other observations on 5- and 6-membered rings.

Kinetics of the base-catalyzed bromination of ethyl nitroacetate

1959 ◽  
Vol 251 (1264) ◽  
pp. 41-45 ◽  
Keyword(s):  
Zero Order ◽  
Aqueous Buffer ◽  
First Order ◽  
Keto Esters ◽  
Buffer Solutions ◽  
Pyridine Bases ◽  
Carboxylate Anions ◽  
Ethyl Nitroacetate ◽  
Kinetics Of ◽  
Catalytic Effects

The kinetics of the bromination of ethyl nitroacetate have been studied in aqueous buffer solutions. The reaction is of the first order with respect to the ester, and of zero order with respect to bromine; it exhibits general catalysis by bases. The catalytic effects of six carboxylate anions and two pyridine bases are closely related to their basic strengths, but in other respects the reaction does not conform to the regularities previously found for the rates of ionization of ketones and keto-esters.

Kinetics of the base-catalyzed bromination of nitroacetone

1962 ◽  
Vol 270 (1342) ◽  
pp. 411-416 ◽  
Keyword(s):  
Zero Order ◽  
Aqueous Buffer ◽  
Buffer Solutions ◽  
Carboxylate Anions ◽  
Kinetics Of ◽  
Catalytic Effects

The kinetics of the bromination of nitroacetone at 0 °C have been studied in aqueous buffer solutions, the disappearance of bromine being followed by measuring the redoxpotential. The reaction is of zero order with respect to bromine and exhibits general catalysis by bases, so that the observed rate is that of the ionization of the ketone. The catalytic effects of five carboxylate anions are closely related to the basic strengths of the catalysts. The results are discussed in relation to the behaviour of analogous substances.

Kinetics of the base-catalyzed bromination of s -dichloroacetone

1960 ◽  
Vol 255 (1281) ◽  
pp. 214-217 ◽  
Keyword(s):  
Aqueous Solution ◽  
Carbonyl Group ◽  
Zero Order ◽  
Degree Of Hydration ◽  
Aqueous Buffer ◽  
Buffer Solutions ◽  
Polar Groups ◽  
Carboxylate Anions ◽  
Kinetics Of ◽  
Catalytic Effects

The kinetics of the bromination of s -dichloroacetone have been studied in aqueous buffer solutions. The reaction is of zero order with respect to bromine and exhibits general catalysis by bases, so that the observed rate is that of the ionization of the ketone. The catalytic effects of four carboxylate anions and of water are closely related to the basic strengths of the catalysts. In relating rates of ionization to the structures of substituted ketones it is neces­sary to correct the observed rates for the degree of hydration of the carbonyl group in aqueous solution. The corrected rates for acetone and its chloro-derivates are discussed in terms of the polar groups which they contain.

Kinetics of catalytic reduction of nitrogen oxide by carbon monoxide on CuO/Al2O3 catalyst

1983 ◽  
Vol 48 (11) ◽  
pp. 3202-3208 ◽  
Author(s):  
Zdeněk Musil ◽  
Vladimír Pour
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Oxide ◽  
Rate Equation ◽  
Catalytic Reduction ◽  
Zero Order ◽  
Spectroscopic Measurements ◽  
First Order ◽  
Ir Spectroscopic ◽  
Kinetics Of ◽  
Al2o3 Catalyst

The kinetics of the reduction of nitrogen oxide by carbon monoxide on CuO/Al2O3 catalyst (8.36 mass % CuO) were determined at temperatures between 413 and 473 K. The reaction was found to be first order in NO and zero order in CO. The observed kinetics are consistent with a rate equation derived from a mechanism proposed on the basis of IR spectroscopic measurements.

Supercritical Fluid Deposition of Ruthenium Thin Films: A Kinetic Study

2007 ◽  
Vol 992 ◽  
Author(s):  
Christos F. Karanikas ◽  
James J. Watkins
Keyword(s):  
Thin Films ◽  
Growth Rate ◽  
Deposition Temperature ◽  
Zero Order ◽  
Measurable Effect ◽  
Deposition Rates ◽  
Reaction Pressure ◽  
Deposition Kinetics ◽  
First Order ◽  
Kinetics Of

AbstractThe kinetics of the deposition of ruthenium thin films from the hydrogen assisted reduction of bis(2,2,6,6-tetramethyl-3,5-heptanedionato)(1,5-cyclooctadiene)ruthenium(II), [Ru(tmhd)2cod], in supercritical carbon dioxide was studied in order to develop a rate expression for the growth rate as well as to determine a mechanism for the process. The deposition temperature was varied from 240°C to 280°C and the apparent activation energy was 45.3 kJ/mol. Deposition rates up to 30 nm/min were attained. The deposition rate dependence on precursor concentrations between 0 and 0.2 wt. % was studied at 260°C with excess hydrogen and revealed first order deposition kinetics with respect to precursor at concentrations lower then 0.06 wt. % and zero order dependence at concentrations above 0.06 wt. %. The effect of reaction pressure on the growth rate was studied at a constant reaction temperature of 260°C and pressures between 159 bar to 200 bar and found to have no measurable effect on the growth rate.

Protodemercuration of organomercuric chlorides. II. Heterocyclic mercuric chlorides

1965 ◽  
Vol 18 (10) ◽  
pp. 1513 ◽  
Author(s):  
RD Brown ◽  
AS Buchanan ◽  
AA Humffray
Keyword(s):  
Chloride Ion ◽  
Ion Pair ◽  
Zero Order ◽  
Hydrogen Ion ◽  
First Order ◽  
Entropy Effects ◽  
Kinetics Of ◽  
Complex Anions ◽  
Dominant Influence ◽  
Electron Effects

The kinetics of protodemercuration, or displacement of the HgCl group by hydrogen, have been measured for 2- and 3-furyl, 2-thienyl, and 2-selenophenylmercuric chlorides. The reactions of these compounds with aqueous alcoholic hydrochloric acid were first order in hydrogen ion, first order in RHgC1, and zero order in chloride ion, when the latter was present at concentrations less than 0.1M. At 70�, the relative rates were: 3-furyl, 1; 2-furyl, 27; 2-thienyl, 11; 2-seleno- phenyl, 25. At higher chloride concentrations, the rate increases; this is discussed in terms of formation of complex anions of the type RHgCl32- and in terms of H+Cl- ion pair attack. The dominant influence of entropy effects in the case of furan compounds emphasizes the danger of trying to account for observed relative rates in terms of π-electron effects alone.

Pseudo-Homogenous Kinetics Model for the Synthesis of Dimethyl Carbonate from Urea and Methanol with Heterogeneous Catalyst

2011 ◽  
Vol 233-235 ◽  
pp. 481-486
Author(s):  
Wen Bo Zhao ◽  
Ning Zhao ◽  
Fu Kui Xiao ◽  
Wei Wei
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Dimethyl Carbonate ◽  
Side Reaction ◽  
Order Reaction ◽  
Zero Order ◽  
Kinetics Model ◽  
First Order ◽  
Zero Order Reaction ◽  
Kinetics Of

The synthesis of dimethyl carbonate (DMC) from urea and methanol includes two main reactions: one amino of urea is substituted by methoxy to produce the intermediate methyl carbamate (MC) which further converts to DMC via reaction with methanol again. In a stainless steel autoclave, the kinetics of these reactions was separately investigated without catalyst and with Zn-containing catalyst. Without catalyst, for the first reaction, the reaction kinetics can be described as first order with respect to the concentrations of methanol and methyl carbamate (MC), respectively. For the second reaction, the results exhibit characteristics of zero-order reaction. Over Zn-containing catalyst, the first reaction is neglected in the kinetics model since its rate is much faster than second reaction. After the optimization of reaction condition, the macro-kinetic parameters of the second reaction are obtained by fitting the experimental data to a pseudo-homogenous model, in which a side reaction of DMC synthesis is incorporated since it decreases the yield of DMC drastically at high temperature. The activation energy of the reaction from MC to DMC is 104 KJ/mol while that of the side reaction of DMC is 135 KJ/mol.

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.

Sign in / Sign up

Export Citation Format

Share Document