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.

REACTIONS IN DISSOCIATED PEROXIDE VAPOR

1953 ◽  
Vol 31 (3) ◽  
pp. 262-271 ◽  
Author(s):  
J. S. Batzold ◽  
C. Luner ◽  
C. A. Winkler
Keyword(s):  
Hydrogen Peroxide ◽  
Water Vapor ◽  
Electrical Discharge ◽  
Molecular Hydrogen ◽  
Volume Ratio ◽  
Cold Trap ◽  
Gas Phase Reactions ◽  
Hydrogen Atoms ◽  
A Chain ◽  
Hydrogen Peroxide Vapor

The products of the electrical discharge through hydrogen peroxide vapor were hydrogen peroxide, water, oxygen, and hydrogen, in amounts which depended upon the arrangement and temperature of the trap, reaction time, and surface to volume ratio of the reaction vessel. Water, hydrogen, and oxygen resulted from the gas phase reactions of the dissociated hydrogen peroxide, with hydrogen peroxide produced only in a trap cooled below −120 °C. Products trapped below −150 °C evolved oxygen on warming to room temperature. The decomposition products of the electrical discharge through hydrogen peroxide correspond closely with products obtainable both from a similar discharge through water vapor and from the interaction of hydrogen atoms with oxygen molecules in a cold trap. A mechanism which accounts for their correspondence is included. Water was the only product when molecular hydrogen peroxide was caused to react with hydrogen atoms, dissociated hydrogen peroxide vapor, or dissociated water vapor in the presence or absence of molecular hydrogen. A chain mechanism is postulated for these reactions.

THE THERMAL DECOMPOSITION OF HYDROGEN PEROXIDE VAPOUR

1945 ◽  
Vol 23b (5) ◽  
pp. 167-182 ◽  
Author(s):  
Bruce E. Baker ◽  
C. Ouellet
Keyword(s):  
Hydrogen Peroxide ◽  
Temperature Coefficient ◽  
Pure Hydrogen ◽  
First Order ◽  
Soda Glass ◽  
Manometric Method ◽  
Apparent Activation Energies ◽  
Reaction Vessels ◽  
First Time ◽  
Kinetics Of

The kinetics of the decomposition of hydrogen peroxide in the vapour state have been studied by a manometric method, with pure hydrogen peroxide at a concentration of about 99.5%. The temperature coefficient of the reaction has been measured for the first time. The pressures ranged from 1 to 2 cm. of mercury and the temperatures from 70° to 200 °C. Pyrex reaction vessels of various sizes and shapes, and also a fused Pyrex and a soda-glass vessel, were used. The reaction was purely heterogeneous, of the first order up to 140 °C. but more complicated at higher temperatures. Identical vessels yielded consistent results. The rates were not affected by air, carbon dioxide, or water vapour, but they varied greatly with the size and shape of the vessel. The reaction was very slow on fused Pyrex and very rapid on soda-glass. In one vessel, the temperature coefficient became negligible above 120 °C. No explosion was detected up to 335 °C. at a pressure of 18 cm. of mercury. The apparent activation energies in various vessels ranged from 13.5 to 18.5 kcal. per mole. A tentative reaction mechanism is suggested.

The oxidation of secondary alcohols by potassium tetraoxoferrate(VI)

1997 ◽  
Vol 75 (2) ◽  
pp. 129-139 ◽  
Author(s):  
Bruce E. Norcross ◽  
William C. Lewis ◽  
Huifa Gai ◽  
Nazih A. Noureldin ◽  
Donald G. Lee
Keyword(s):  
Acid Catalysis ◽  
Isotope Effects ◽  
Low Ph ◽  
Base Catalysis ◽  
Secondary Alcohols ◽  
Acid And Base ◽  
Deuterium Isotope Effects ◽  
Reactive Oxidant ◽  
Kinetics Of ◽  
Large Primary

The kinetics of the oxidation of 2-propanol, 1,1,1-trifluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 1-phenyl-2,2,2-trifluoroethanol, 1-(4-methylphenyl)-2,2,2-trifluoroethanol, 1-(3-bromophenyl)-2,2,2-trifluoroethanol, and 1-(3-nitrophenyl)-2,2,2-trifluoroethanol by potassium tetraoxoferrate(VI) have been studied under basic conditions. The products are ketones, formed in almost quantitative yields, iron(III) hydroxide, and dioxygen. The reactions are characterized by substantial enthalpies of activation (40–60 kJ/mol), very unfavorable entropies of activation, large primary deuterium isotope effects, and a positive Hammett ρ value. Both acid and base catalysis are observed. Acid catalysis is attributed to formation of a more reactive oxidant, HFeO4−, at low pH. Base catalysis is attributed partly to the conversion of the reductants to alkoxide ions at high pH, and partly to the reaction of hydroxide ion with tetraoxoferrate(VI) to give a five-coordinated species, HOFeO43−, that reacts rapidly with nucleophiles. A reaction mechanism involving formation of an intermediate ferrate ester is proposed. Keywords: oxidation, alcohols, potassium tetraoxoferrate(VI), ferrate esters, base catalysis, acid catalysis.

Quaternary Nitrogen Heterocycles. II. Kinetics of Reversible Pseudobase Formation from N-Methyl Heterocyclic Cations

1973 ◽  
Vol 51 (12) ◽  
pp. 1965-1972 ◽  
Author(s):  
John W. Bunting ◽  
William G. Meathrel
Keyword(s):  
Isotope Effects ◽  
Nitrogen Heterocycles ◽  
Activation Parameters ◽  
Hydroxide Ion ◽  
Quaternary Nitrogen ◽  
Equilibrium And Kinetics ◽  
Temperature Dependences ◽  
Deuterium Isotope Effects ◽  
Heterocyclic Cations ◽  
Kinetics Of

The kinetics of the formation and decomposition of the pseudobases from the 2-methyl-4-nitroisoquinolinium, 10-methylacridinium, and 10-methyl-9-phenylacridinium ions have been studied. The pH–rate profiles of these reactions indicate that for each of these ions, pseudobase formation may kinetically involve either attack of a water molecule or of hydroxide ion on the heterocyclic cation depending upon the pH of the reaction. Pseudobase decomposition to the cation may occur through either the neutral or protonated pseudobase species or their kinetic equivalents. The temperature dependences of the equilibrium and kinetics are reported for each ion, and deuterium isotope effects for the reactions of the 2-methyl-4-nitroisoquinolinium ion have been measured. Possible mechanisms for the reactions are discussed on the basis of the observed activation parameters and isotope effects and are compared with related reactions.

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