ChemInform Abstract: PULSE RADIOLYTIC DETERMINATION OF KINETIC ISOTOPE EFFECTS OF THE ADDITION REACTION OF HYDROGEN ATOMS TO ETHYLENE AND PROPENE

1976 ◽  
Vol 7 (12) ◽  
pp. no-no
Author(s):  
D. MIHELCIC ◽  
V. SCHUBERT ◽  
F. HOEFLER ◽  
P. POTZINGER
Keyword(s):  
Addition Reaction ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Hydrogen Atoms ◽  
Kinetic Isotope

Arrhenius-Parameter und kinetischer Isotopeneffekt für die Reaktion von Wasserstoffatomen mit Silan

1974 ◽  
Vol 29 (3) ◽  
pp. 493-496 ◽  
Author(s):  
Peter Potzinger ◽  
Louis C. Glasgow ◽  
Bruno Reimann
Keyword(s):  
Kinetic Isotope Effect ◽  
Relative Rate ◽  
Isotope Effects ◽  
Preexponential Factor ◽  
Kinetic Isotope Effects ◽  
Hydrogen Atoms ◽  
Kinetic Isotope ◽  
Abstraction Reaction ◽  
Upper Limits ◽  
Relative Rate Constants

The Reaction of Hydrogen Atoms with Silane; Arrhenius Parameters and Kinetic Isotope Effect Relative rate constants were measured for the systems H + C2H4/SiD4 and D + C2D4/SiH4 over a wide temperature range. From the known arrheniusparameter for the reaction H + C2H4 the activation energy EA and the preexponential factor A of the abstraction reactionH + SiD4 → HD + SiD3may be calculated. Values of EA = 3.2 kcal/Mol and A = 4.92 • 1013 cm3 Mol-1 sec-1 were obtained. Upper limits for the kinetic isotope effects are given in the paper

QM/MM Determination of Kinetic Isotope Effects for COMT-Catalyzed Methyl Transfer Does Not Support Compression Hypothesis

2004 ◽  
Vol 126 (28) ◽  
pp. 8634-8635 ◽  
Author(s):  
Giuseppe D. Ruggiero ◽  
Ian H. Williams ◽  
Maite Roca ◽  
Vicent Moliner ◽  
Iñaki Tuñón
Keyword(s):  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope ◽  
Methyl Transfer

Micelle-induced change of mechanism in the reaction of muonium with acetone

1996 ◽  
Vol 74 (11) ◽  
pp. 1945-1951 ◽  
Author(s):  
John M. Stadlbauer ◽  
Krishnan Venkateswaran ◽  
Hugh A. Gillis ◽  
Gerald B. Porter ◽  
David C. Walker
Keyword(s):  
Dielectric Constant ◽  
Free Radical ◽  
Key Words ◽  
Resonance Spectrum ◽  
Addition Reaction ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Level Crossing ◽  
Kinetic Isotope ◽  
Abstraction Reaction

Muonium atoms add to the O atom of the carbonyl group of acetone to give the muonated free radical (CH3)2Ċ-O-Mu when the reaction takes place in water or hydrocarbons, but not when the acetone is localized in micelles. Micelles have no effect on the formation of muonated cyclohexadienyl radicals when muonium reacts with benzene under similar conditions. The addition reaction with acetone appears to have been subsumed by a faster alternative reaction in the micellar environment. Evidence is presented for this interpretation rather than for an inhibition of the radical or for a shift in the muon level-crossing resonance spectrum with hydrogen (muonium) bonding, though major shifts are seen for the spectrum of this radical in pure solvents of widely different dielectric constant. It is suggested that muonium's "abstraction" reaction takes over in micelles because significant micelle-induced enhancement effects were previously observed in that type of reaction. The data are consistent with a rate constant for the abstraction reaction of muonium with acetone in micelles of >6 × 108 M−1 s−1. Key words: muonium, kinetic isotope effects, micelle enhancement, H/Mu-addition, H/Mu abstraction.

Kinetic isotope effects from reactions of muonium atoms in water with various ketones, and acetaldehyde: contrasts with hydrogen atoms

1997 ◽  
Vol 75 (1) ◽  
pp. 74-76 ◽  
Author(s):  
John M. Stadlbauer ◽  
Krishnan Venkateswaran ◽  
David C. Walker
Keyword(s):  
Hydrogen Atom ◽  
Muon Spin ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Muon Spin Rotation ◽  
Hydrogen Atoms ◽  
Tert Butyl ◽  
Kinetic Isotope ◽  
Dilute Aqueous Solutions ◽  
Butyl Ketone

This paper presents data showing that in dilute aqueous solutions of butanone, 3-pentanone, cyclohexanone, di-tert-butyl ketone, and acetaldehyde the addition reaction of muonium atoms occurs with a rate constant close to 1 × 108 M−1 s−1. The same value was obtained previously for acetone. Thus the reaction rate is virtually independent of the group attached to the C=O, be it a methyl, methylene, tert-butyl, or even a hydrogen atom. This is in sharp contrast to the reactivity of ordinary 1H atoms, whose rate constants are much slower and dependent on adjacent groups. In fact muonium and 1H react by different mechanisms, to form different products, so their rate ratio represents a complex kinetic isotope effect. Keywords: kinetic isotope effects, muonium atoms, muon spin rotation, ketones, hydrogen atom reactions.

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