Kinetic isotope effects of nitrogen and hydrogen in reaction of N-tert-butyl-P-phenylphosphonamidothioic acid with alcohols

2005 ◽  
Vol 690 (10) ◽  
pp. 2553-2558
Author(s):  
Stefan Jankowski ◽  
Adam Mazur ◽  
Tomasz Nonas ◽  
Barbara Vokal
Keyword(s):  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Tert Butyl ◽  
Kinetic Isotope

SOME DEUTERIUM KINETIC ISOTOPE EFFECTS: IV. β-DEUTERIUM EFFECTS IN WATER SOLVOLYSIS OF ETHYL, ISOPROPYL, AND tert-BUTYL COMPOUNDS

1960 ◽  
Vol 38 (11) ◽  
pp. 2171-2177 ◽  
Author(s):  
K. T. Leffek ◽  
J. A. Llewellyn ◽  
R. E. Robertson
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Alkyl Halides ◽  
Tert Butyl ◽  
Kinetic Isotope ◽  
Deuterium Isotope Effects ◽  
Intramolecular Forces

The secondary β-deuterium isotope effects have been measured in the water solvolytic reaction of alkyl halides and sulphonates for primary, secondary, and tertiary species. In every case the kinetic isotope effect was greater than unity (kH/kD > 1). This isotope effect may be associated with varying degrees of hyperconjugation or altered non-bonding intramolecular forces. The experiments make it difficult to decide which effect is most important.

Secondary α-deuterium kinetic isotope effects for the E2 reaction of the 2-phenylethyl halides with tert-butoxide ion in tert-butyl alcohol

1985 ◽  
Vol 63 (1) ◽  
pp. 100-102 ◽  
Author(s):  
Peter James Smith ◽  
Kanchugarakoppal S. Rangappa ◽  
Kenneth Charles Westaway
Keyword(s):  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Order Rate Constant ◽  
Butyl Alcohol ◽  
Tert Butyl ◽  
Kinetic Isotope ◽  
Tert Butyl Alcohol ◽  
Elimination Reactions ◽  
Leaving Groups ◽  
High Base

Secondary α-deuterium kinetic isotope effects have been determined for the elimination reactions of 2-phenylethyl halides with tert-butoxide in tert-butyl alcohol at 40 °C in the presence and absence of the crown ether 18C6. The second-order rate constant k2 and the normal (kH/kD)α effect remained constant when the tert-butoxide concentration was varied for reaction of the iodo and bromo compounds. However, both the magnitude of k2 and the secondary α-deuterium isotope effect were significantly dependent on [t-BuO−] when chlorine and fluorine are the leaving groups. It is noteworthy that (kH/kD)α is inverse for the reaction of both the chloro and fluoro compounds at "low" base concentrations and normal at "high" base concentrations. These results are discussed in terms of both syn- and anti-elimination pathways promoted by various associated and dissociated base species. It is suggested that the (kH/kD)α effect may be useful as a criterion for determining the stereochemistry of E2 elimination reactions.

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.

Using secondary alpha deuterium kinetic isotope effects to determine the stereochemistry of an E2 reaction; the stereochemistry of the E2 reaction of 1-chloro-2-phenylethane with potassium tert-butoxide in tert-butyl alcohol

2001 ◽  
Vol 79 (7) ◽  
pp. 1145-1152 ◽  
Author(s):  
Peter James Smith ◽  
David AJ Crowe ◽  
Kenneth Charles Westaway
Keyword(s):  
Transition State ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Butyl Alcohol ◽  
State Structure ◽  
Transition State Structure ◽  
Isotopic Labelling ◽  
Tert Butyl ◽  
Kinetic Isotope ◽  
Tert Butyl Alcohol

Isotopic labelling studies have shown that the E2 reaction of 1-chloro-2-phenylethane with potassium tert-butoxide in tert-butyl alcohol occurs via an anti-periplanar stereochemistry. This demonstrates that the different secondary alpha deuterium kinetic isotope effects found for the high and low base concentrations and in the presence of 18-crown-6 ether are because of changes in transition state structure that occur when the form of the reacting base changes rather than to a change in the stereochemistry of the reaction.Key words: E2 reaction, stereochemistry, secondary alpha deuterium kinetic isotope effects, transition state.

Sign in / Sign up

Export Citation Format

Share Document