Direct Observation of the Molecular Structural Changes during the Claisen Rearrangement Including the Transition State

2010 ◽  
Vol 39 (4) ◽  
pp. 374-375 ◽  
Author(s):  
Izumi Iwakura ◽  
Atushi Yabushita ◽  
Takayoshi Kobayashi
Keyword(s):  
Transition State ◽  
Direct Observation ◽  
Structural Changes ◽  
Claisen Rearrangement

Direct observation of charge-inducedπ-electronic structural changes in a conjugated polymer

1989 ◽  
Vol 63 (17) ◽  
pp. 1841-1844 ◽  
Author(s):  
M. Lögdlund ◽  
R. Lazzaroni ◽  
S. Stafström ◽  
W. R. Salaneck ◽  
J.-L. Brédas
Keyword(s):  
Direct Observation ◽  
Conjugated Polymer ◽  
Structural Changes

scholarly journals Direct observation of photolysis-induced tertiary structural changes in hemoglobin

2003 ◽  
Vol 100 (12) ◽  
pp. 7039-7044 ◽  
Author(s):  
S.-i. Adachi ◽  
S.-Y. Park ◽  
J. R. H. Tame ◽  
Y. Shiro ◽  
N. Shibayama
Keyword(s):  
Direct Observation ◽  
Structural Changes

Isotope Effect Studies on Elimination Reactions. XI. The Nature of the Transition State for the E2 Reaction of 2-Phenylethyldimethylanilinium Salts Containing Substituents in the Aniline Ring with Sodium Ethoxide in Ethanol

1975 ◽  
Vol 53 (23) ◽  
pp. 3513-3525 ◽  
Author(s):  
Peter Schmid ◽  
Arthur Newcombe Bourns
Keyword(s):  
Transition State ◽  
Isotope Effect ◽  
Structural Changes ◽  
Isotope Effects ◽  
Sodium Ethoxide ◽  
Nitrogen Isotope ◽  
Structural Variations ◽  
Hydrogen Deuterium ◽  
Elimination Reactions ◽  
Pass Through

Kinetic isotope effects have been determined for the E2 reactions of a series of 2-phenylethyldimethylanilinium salts containing substituents in the aniline ring with sodium ethoxide in ethanol at 40 °C. The nitrogen isotope effect, (k14/k15−1)100, is not very sensitive to substituent changes but appears to increase slightly with increasing electron-withdrawing ability of the substituents, i.e., 1.19 ± 0.07, 1.13 ± 0.06, 1.12 ± 0.08, 1.30 ± 0.07, and 1.32 ± 0.06 for p-OCH3, p-CH3, p-H, p-Cl, and, m-CF3, respectively. The hydrogen–deuterium isotope effects pass through a minimum in the region of the unsubstituted compound and increase both with increasing electron-donating as well as with electron-withdrawing power of the substituents, i.e. kH/kD = 4.70 ± 0.06, 4.61 ± 0.04, 4.51 ± 0.04, 4.53 ± 0.09, 5.00 ± 0.07, and 5.39 ± 0.07 for p-OCH3, p-CH3, p-H, p-Cl, m-CF3, and p-CF3, respectively. The results are discussed in terms of recent theoretical treatments of the effect of structural variations in the reactants on the nature of the transition state of E2 elimination reactions. The conclusion is reached that the transition states in the present reaction series can be characterized as 'central with slight carbanion character' and that the effect of a change in the ability of the leaving group on the structure of the transition state manifests itself mainly in the direction perpendicular to the reaction coordinate. A simple novel hypothesis is formulated which emphasizes the importance of the location of the transition state in a More O'Ferrall-type potential energy diagram in determining its sensitivity to structural changes in the reactants.

ChemInform Abstract: Asymmetric Thio-Claisen Rearrangement Induced by an Enantiopure Alkylsulfinyl Group. Unusual Preference for a Boat Transition State in the Acyclic Series.

ChemInform ◽  
2010 ◽  
Vol 33 (18) ◽  
pp. no-no
Author(s):  
Stephanie Nowaczyk ◽  
Carole Alayrac ◽  
Vincent Reboul ◽  
Patrick Metzner ◽  
Marie-Therese Averbuch-Pouchot
Keyword(s):  
Transition State ◽  
Claisen Rearrangement

Direct observation of oxygen-induced structural changes in stainless-steel surfaces

2000 ◽  
Vol 18 (2) ◽  
pp. 868 ◽  
Author(s):  
Boklae Cho ◽  
Sukmin Chung ◽  
Kijeong Kim ◽  
Taihee Kang ◽  
Chongdo Park ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Direct Observation ◽  
Structural Changes ◽  
Steel Surfaces

Synthesis and Claisen rearrangement of alkoxyallyl enol ethers. Evidence for a dipolar transition state

1987 ◽  
Vol 109 (4) ◽  
pp. 1160-1170 ◽  
Author(s):  
Robert M. Coates ◽  
Brian D. Rogers ◽  
Steven J. Hobbs ◽  
Dennis P. Curran ◽  
David R. Peck
Keyword(s):  
Transition State ◽  
Claisen Rearrangement ◽  
Enol Ethers

ChemInform Abstract: Synthesis and Claisen Rearrangement of Alkoxyallyl Enol Ethers. Evidence for a Dipolar Transition State.

ChemInform ◽  
1987 ◽  
Vol 18 (26) ◽  
Author(s):  
R. M. COATES ◽  
B. D. ROGERS ◽  
S. J. HOBBS ◽  
D. R. PECK ◽  
D. P. CURRAN
Keyword(s):  
Transition State ◽  
Claisen Rearrangement ◽  
Enol Ethers
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