On the Rotation of Ammonium Ions within Ammonium-Carbanide Ion Pairs.

Bergson, Göran; Ohlsson, Lennart; Larsen, Inga; Levstek, I.; Eržen, V.; Blinc, R.; Paušak, S.; Ehrenberg, L.; Dumanović, J.

doi:10.3891/acta.chem.scand.21-1393

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Cited by 4 publications

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“…The crucial point is that the 1,3-hydron transfer is allowed to compete with isotopic exchange of the 'mobile' hydron mediated by ammonium ion rotation within the ion pair. [4][5][6] Our system (Scheme 2) mimics the simple case given in Scheme 1. 1,3-Dimethylindene, in which a trideuteriomethyl group is substituted for one of the methyl groups, was used as a substrate.…”

mentioning

confidence: 99%

Experimental evidence of partially rate limiting ion-pair interconversion in a base catalyzed 1,3-proton transfer reaction

Hussénius¹,

Matsson²,

Bergson³

1998

Chem. Commun.

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mentioning

confidence: 99%

Experimental evidence of partially rate limiting ion-pair interconversion in a base catalyzed 1,3-proton transfer reaction

Hussénius¹,

Matsson²,

Bergson³

1998

Chem. Commun.

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1,3‐Hydron transfer in some 5‐ and 7‐substituted 1‐methylindenes. Enantioselectivities and enantiomer‐dependent kinetic isotope effects

Aune

Bergson

Matsson

1995

J of Physical Organic Chem

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Base‐catalysed substrate‐enantioselective 1,3‐hydron transfer (kinetic resolution) was studied in the indene system. A series of 1‐methylindenes substituted in the aromatic ring [5‐methoxy‐ (2), 5‐fluoro‐ (3), 5‐nitro‐ (4) and 7‐nitro (5)] and 1‐methylindene (1) were employed as substrates. The rate constants, the enantioselectivities and the kinetic isotope effects (KIEs) for the enantioselective reactions [(kH/kD)+ and (kH/kD)−] were determined at 20°C using (+)‐(8R, 9S)‐dihydroquinidine as chiral catalyst in the solvent o‐dichlorobenzene. The rate constants vary according to the elecronic effects of the substituents. The primary deuterium KIE, ranging from 4·73 [for (+)‐(S)‐2] to 11·3 [for (−)‐(R)‐5], is correlated with the rate constants as expected on the basis of the Melander–Westheimer postulate. The introduction of a substituent in the aromatic ring decreases the enantioselectivity. All compounds except 5 show the same sense of the enantioselectivity [k+/k− > 1; all substrates used are (+)‐(S)/(−)‐(R)]. The enantiomer dependence of the KIE is most pronounced for 1 [(kH/kD)+ = 5·71 and (kH/kD)− = 6·46] and vanishes for the most acidic substrates (4 and 5).

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Isomerization of Olefins

Pines

1977

Base-Catalyzed Reactions of Hydrocarbons and Related Compounds

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On the Rotation of Ammonium Ions within Ammonium-Carbanide Ion Pairs.

Cited by 4 publications

References 0 publications

Experimental evidence of partially rate limiting ion-pair interconversion in a base catalyzed 1,3-proton transfer reaction

Experimental evidence of partially rate limiting ion-pair interconversion in a base catalyzed 1,3-proton transfer reaction

1,3‐Hydron transfer in some 5‐ and 7‐substituted 1‐methylindenes. Enantioselectivities and enantiomer‐dependent kinetic isotope effects

Isomerization of Olefins

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