Reactions of alicyclic ketones in carbon tetrachloride. I, The kinetics of the chlorination of cyclopentanone and cyclohexanone catalyzed by hydrogen chloride

1986 ◽  
Vol 64 (9) ◽  
pp. 1681-1689 ◽  
Author(s):  
Eize J. Stamhuis ◽  
Henk Maatman ◽  
Henk Stinissen ◽  
Geert E. H. Joosten
Keyword(s):  
Carbon Tetrachloride ◽  
Hydrogen Chloride ◽  
Isotope Effects ◽  
Reaction Rates ◽  
Zero Order ◽  
Rate Determining Step ◽  
Conjugate Acid ◽  
Deuterium Isotope Effects ◽  
Self Association ◽  
Kinetics Of

The kinetics of the direct chlorination of cyclopentanone (cp) and cyclohexanone (ch) in carbon tetrachloride, catalyzed by hydrogen chloride, was studied. The rate of chlorination, measured by flow and stopped-flow techniques, is zero order in chlorine; the order in cp and ch increases from 1 at [cp] and [ch] of 0.01 M concentration to 2 at concentrations of 1 M. This is explained by self-association of the ketones in carbon tetrachloride solutions. The order in hydrogen chloride is 1. Since this compound is one of the products, the reaction is autocatalytic. Deuterium isotope effects and the kinetic data strongly point to a mechanism in which the oxygen-protonated monomeric ketone is α-carbon deprotonated in a rate-determining step. This step, which is catalyzed by the bases cp or ch, respectively, leads to the corresponding enol as intermediate. The enol is then chlorinated very rapidly. In addition to the chloro ketone, very reactive chloride anions are formed. A small fraction of these anions deprotonate α- or α′-carbon atoms of the oxygen-conjugate acid of the monochloro ketone. The remainder are captured by HCl to form energetically more favored Cl--(HCl)n complexes with n = 1, 2, or 3. This explains why, even at low conversions of the ketones, substantial amounts of the various dichloro isomers are formed in addition to monochloro products. A rate expression is derived, which excellently describes the experimentally obtained rates of chlorination of cp and ch over a range of reaction rates of more than three decades.

Reactions of alicyclic ketones in carbon tetrachloride. II. Kinetics of the chlorination of 2-chlorocyclopentanone and 2-chlorocyclohexanone, catalyzed by hydrogen chloride

1986 ◽  
Vol 64 (9) ◽  
pp. 1690-1696 ◽  
Author(s):  
Eize J. Stamhuis ◽  
Henk Maatman ◽  
Geert E. H. Joosten
Keyword(s):  
Carbon Tetrachloride ◽  
Hydrogen Chloride ◽  
Kinetic Equations ◽  
Base Catalysis ◽  
Strong Increase ◽  
Reaction Products ◽  
Reaction Models ◽  
Basic Catalysts ◽  
Self Association ◽  
Kinetics Of

The kinetics of the direct chlorination of 2-chlorocyclopentanone (2-mccp) and 2-chlorocyclohexanone (2-mcch) in carbon tetrachloride, catalyzed by hydrogen chloride, were studied. Reaction products are all the possible 2,2-, 2,5-, and 2,6-dichloro compounds. The ratios depend on the concentrations of the monochloro compound and hydrogen chloride. Surprisingly, even at conversions of the monochloro compound as low as 2%, 2,2,5-trichlorocyclopentanone and 2,2,6-trichlorocyclohexanone, respectively, are also formed. The chlorination reaction of both monochloro ketones shows zero order in chlorine. The order in hydrogen chloride is 1.3. The order in 2-mccp and 2-mcch varies somewhat with the concentration of the ketone and was found to be roughly 1.7. The variation in reaction order is explained by a partial self-association of the ketones. The ketones act as substrates as well as basic catalysts in the rate-determining α- or α′-carbon deprotonation. General base catalysis is clearly demonstrated by a strong increase in the rate of chlorination of 2-mccp upon addition of cyclopentanone (cp) to the reaction mixture, which agrees with the mechanism as presented in a previous paper. Kinetic equations derived from the reaction models for the "separate" and "mixed" ketone chlorinations accurately describe the observed rates of the chlorination of 2-mccp and 2-mcch in the concentration range of 0.04–1.0 M.

scholarly journals The kinetics of the hydrogen chloride oxidation

2013 ◽  
Vol 78 (12) ◽  
pp. 2115-2130 ◽  
Author(s):  
Martinez Gonzalez ◽  
Tanja Vidakovic-Koch ◽  
Rafael Kuwertz ◽  
Ulrich Kunz ◽  
Thomas Turek ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Gas Phase ◽  
Hydrogen Chloride ◽  
Reaction Order ◽  
Membrane Electrode ◽  
Polarization Data ◽  
Rate Determining Step ◽  
Electrode Assemblies ◽  
Apparent Kinetic Parameters ◽  
Kinetics Of

Hydrogen chloride (HCl) oxidation has been investigated on technical membrane electrode assemblies in a cyclone flow cell. Influence of Nafion loading, temperature and hydrogen chloride mole fraction in the gas phase has been studied. The apparent kinetic parameters like reaction order with respect to HCl, Tafel slope and activation energy have been determined from polarization data. The apparent kinetic parameters suggest that the recombination of adsorbed Cl intermediate is the rate determining step.

Studies on Hydrogen–Oxygen Systems in the Electrical Discharge. VII. Deuterium Isotope Effects in the Chemistry of the Hydrogen Polyoxides

1975 ◽  
Vol 53 (16) ◽  
pp. 2490-2497 ◽  
Author(s):  
José L. Arnau ◽  
Paul A. Giguère
Keyword(s):  
Hydrogen Peroxide ◽  
Electrical Discharge ◽  
Microwave Discharge ◽  
Isotope Effects ◽  
Cold Trap ◽  
Manometric Method ◽  
Deuterium Isotope Effects ◽  
Kinetics Of ◽  
Hydrogen Polyoxides ◽  
Hydrogen Peroxide Vapor

The kinetics of oxygen evolution on warming the trapped products (at −196 °C) from water or hydrogen peroxide vapor dissociated in a glow discharge were studied by the manometric method. Under closely controlled conditions it was possible to distinguish clearly the decomposition of the two intermediates, H2O3 and H2O4. The latter begins to decompose measurably following crystallization of the glassy solid at about −115°; the trioxide decomposes readily between −50 and −35°. Typically, the yields of H2O3 from dissociated water vapor were of the order of 3 to 5 mol%; those of H2O4, only about one-tenth as much. Varying the distance between the microwave discharge and the cold trap was found to affect differently the yields of the various products. Those of water and peroxide showed a simple, direct correlation; the minor constituents H2O3 and H2O4 followed entirely different patterns. Only a small fraction of the peroxide is formed via the H2O4 intermediate in these systems. Less water, and more of the higher oxides, were obtained from dissociated hydrogen peroxide than from water vapor.The deuterated systems showed some unusual isotope effects. The yields of D2O3 were always higher (up to twice and even more) than those of H2O3 under similar conditions. The other products showed little or no such effect, except for occluded oxygen and ozone which decreased by about half. Finally, the deuterium polyoxides decompose at slightly higher temperatures (10 to 15°) than their hydrogen analogs. Mechanisms are proposed for the formation and decomposition of the polyoxides.

Kinetics of hydrosilylation of tert-butylphenylketone by diphenylsilane catalysed by [Rh(1,5-COD)(-)-DIOP]+ClO-4

1980 ◽  
Vol 45 (8) ◽  
pp. 2224-2239 ◽  
Author(s):  
Ivan Kolb ◽  
Jiří Hetflejš
Keyword(s):  
Activation Parameters ◽  
Reaction Rates ◽  
Reaction Model ◽  
Initial Reaction ◽  
Title Reaction ◽  
Rate Determining Step ◽  
Kinetic Isotope ◽  
Arene Complex ◽  
Kinetics Of

Kinetic analysis of the title reaction has been made by the method of initial reaction rates. On the basis of the rate data, kinetic isotope effect and spectroscopic study of the reaction of the organosilicon hydride with the catalyst, the reaction model was proposed involving the following steps: the displacement of the diene by reaction with the silicon hydride from a rhodium-arene complex in an induction period of the hydrosilylation, the oxidative addition of the organosilicon hydride to the rhodium-arene complex, followed by the interaction of the ketone with the silylhydridorhodium (III) species in the rate determining step. The process is characterized by the following activation parameters: ΔU = 54.5 ± 8.5 kJ mol-1 and ΔS = -88± 25 J mol-1.K-1. The significant role of the entropic factor was supported by the analysis of the temperature dependence of the asymmetric efficiency of the catalyst.

Enantioselective hydrosilylation of tert-butyl phenyl ketone by diphenylsilane catalysed by [Rh{(-)-DIOP}2]+ClO4-

1980 ◽  
Vol 45 (10) ◽  
pp. 2808-2816 ◽  
Author(s):  
Ivan Kolb ◽  
Jiří Hetflejš
Keyword(s):  
Reaction Rates ◽  
Reaction Model ◽  
Rhodium Complex ◽  
Initial Reaction ◽  
Chiral Ligand ◽  
Title Reaction ◽  
First Order ◽  
Rate Determining Step ◽  
Phenyl Ketone ◽  
Kinetics Of

Kinetics of the title reaction has been studied by the method of initial reaction rates. In the presence of free chiral ligand the hydrosilylation was found to be first order in the catalyst and in the ketone and fractional order in the organosilicon hydride. The rate data and the results of spectroscopic study of interaction of diphenylsilane with the rhodium complex have been interpreted in terms of a reaction model involving formation of the corresponding cationic silyl(hydrido)rhodium complex followed by interaction of the ketone with this complex in the rate determining step. The results are confronted with those obtained for the analogous reaction catalysed by [Rh(1,5-COD)(-)-DIOP]+ClO4-.

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