Mechanism of the benzidine rearrangement. Kinetic isotope effects and transition states. Evidence for concerted rearrangement

The kinetic energy distribution in the reactive mode in transition states correlates the asynchronicity of CPET with relative kinetic isotope effects.

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Secondary Deuterium Kinetic Isotope Effects in Irreversible Additions of Hydride and Carbon Nucleophiles to Aldehydes: A Spectrum of Transition States from Complete Bond Formation to Single Electron Transfer

Journal of the American Chemical Society ◽

10.1021/ja982504r ◽

1999 ◽

Vol 121 (2) ◽

pp. 326-334 ◽

Cited By ~ 25

Author(s):

Joseph J. Gajewski ◽

Wojciech Bocian ◽

Nathan J. Harris ◽

Leif P. Olson ◽

John P. Gajewski

Keyword(s):

Electron Transfer ◽

Isotope Effects ◽

Bond Formation ◽

Transition States ◽

Kinetic Isotope Effects ◽

Single Electron ◽

Single Electron Transfer ◽

Carbon Nucleophiles ◽

Kinetic Isotope

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A Theoretical Study of the Relationship between Secondary .alpha.-Deuterium Kinetic Isotope Effects and the Structure of SN2 Transition States

Journal of the American Chemical Society ◽

10.1021/ja00085a037 ◽

1994 ◽

Vol 116 (6) ◽

pp. 2526-2533 ◽

Cited By ~ 86

Author(s):

Raymond A. Poirier ◽

Youliang Wang ◽

Kenneth C. Westaway

Keyword(s):

Theoretical Study ◽

Isotope Effects ◽

Transition States ◽

Kinetic Isotope Effects ◽

Kinetic Isotope ◽

The Relationship

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Heavy Atom Kinetic Isotope Effects in HCN Elimination from Some Tricyanides in Methanol [1]

Zeitschrift für Naturforschung B ◽

10.1515/znb-1978-1227 ◽

1978 ◽

Vol 33 (12) ◽

pp. 1496-1502

Author(s):

Fouad M. Fouad ◽

Patrick G. Farrell

Keyword(s):

Transition State ◽

Opposite Direction ◽

Isotope Effects ◽

Heavy Atom ◽

Transition States ◽

Kinetic Isotope Effects ◽

The Other ◽

Kinetic Isotope ◽

Solvent Isotope ◽

Solvent Isotope Effects

AbstractRates of HCN elimination from polycyanides N,N-dimethyl-4-(1,2,2-tricyanoethyl)-aniline (1), 9-cyano-9-dicyanomethyl fluorene (2), 1,1-diphenyl-1,2,2-tricyanoethane (3), and 2-phenyl-1,1,2-tricyanopropane (4) have been studied in methanol. Elimination from 1 occurs via (E 1 c B)R, mechanism. On the other hand olefin formation from 2-4 has been shown to occur via (E 1)anion pathway. Heavy atom kinetic isotope effects indicated that product stability is not the sole factor controlling the transition state geometries. Values of k12/k14 were found to be in the order 2 > 3 > 4 > 1 which implied transition states with more carbanion-like structure in the opposite direction. Solvent isotope effects and enthalpies of activation were also determined and discussed in terms of transition states geometries.

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Isotope effects in nucleophilic substitution reactions. VII. The effect of ion pairing on the substituent effects on SN2 transition state structure

Canadian Journal of Chemistry ◽

10.1139/v89-004 ◽

1989 ◽

Vol 67 (1) ◽

pp. 21-26 ◽

Cited By ~ 12

Author(s):

Zhu-Gen Lai ◽

Kenneth Charles Westaway

Keyword(s):

Nucleophilic Substitution ◽

Isotope Effects ◽

Transition States ◽

Substituent Effects ◽

Ion Pairing ◽

Kinetic Isotope Effects ◽

Ion Pair ◽

Substitution Reactions ◽

Kinetic Isotope ◽

Free Ion

The secondary α-deuterium kinetic isotope effects and substituent effect found in the SN2 reactions between a series of para-substituted sodium thiophenoxides and benzyldimethylphenylammonium ion are significantly larger when the reacting nucleophile is a free ion than when it is a solvent-separated ion pair complex. Tighter transition states are found when a poorer nucleophile is used in both the free ion and ion pair reactions. Also, the transition states for all but one substituent are tighter for the reactions with the solvent-separated ion pair complex than with the free ion. Hammett ρ values found by changing the substituent on the nucleophile do not appear to be useful for determining the length of the sulphur–α-carbon bond in the ion pair and free ion transition states. Keywords: Isotope effects, ion pairing, nucleophilic substitution, SN2 reactions, transition states.

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