Precise determination of stabilities of primary, secondary, and tertiary silicenium ions from kinetics and equilibria of hydride-transfer reactions in the gas phase. A quantitative comparison of the stabilities of silicenium and carbonium ions in the gas phase

1989 ◽  
Vol 111 (3) ◽  
pp. 900-906 ◽  
Author(s):  
Seung Koo Shin ◽  
J. L. Beauchamp
Keyword(s):  
Gas Phase ◽  
Hydride Transfer ◽  
Precise Determination ◽  
Quantitative Comparison ◽  
Transfer Reactions ◽  
Carbonium Ions ◽  
Hydride Transfer Reactions

Hydride-Transfer Reactions in the Gas Phase. 2.1Anchimeric Assistance in the H-Transfer from 1,1-Dimethylcyclopentane to Alkyl Cations

1996 ◽  
Vol 100 (20) ◽  
pp. 8285-8294 ◽  
Author(s):  
Maria Elisa Crestoni ◽  
Simonetta Fornarini ◽  
Massimo Lentini ◽  
Maurizio Speranza
Keyword(s):  
Gas Phase ◽  
Hydride Transfer ◽  
Transfer Reactions ◽  
Alkyl Cations ◽  
Hydride Transfer Reactions

Hydride transfer reactions. Oxidation of N-methylacridan by π acceptors

1977 ◽  
Vol 55 (14) ◽  
pp. 2741-2751 ◽  
Author(s):  
Allan K. Colter ◽  
Gunzi Saito ◽  
Frances J. Sharom
Keyword(s):  
Charge Transfer ◽  
Isotope Effect ◽  
Isotopic Exchange ◽  
Hydride Transfer ◽  
Transfer Reactions ◽  
Kinetic Measurements ◽  
Rate Of Reaction ◽  
Hydride Transfer Reactions ◽  
Isotope Partitioning

The oxidation of N-methylacridan (1) to N-methylacridinium ion (2) by the π acceptors p-benzoquinone (BQ), 7,7,8,8-tetracyanoquinodimethane (TCNQ), p-chloranil (CA), tetracyanoethylene (TCNE), and 2,3-dicyano-1,4-benzoquinone (DCBQ) has been investigated. Second-order rate constants in acetonitrile (AN) vary by a factor of more than 107 for this series. The rate of reaction of 1 with BQ increases 45-fold as the solvent composition is varied from AN to 50% (v/v) AN–water, but is insensitive to changes in buffer ratio or concentration in 75% AN. Spectroscopic evidence for charge-transfer complexing between the reactants was obtained with BQ and CA, and kinetic evidence for complexing was obtained with BQ in 75% AN. The primary isotope effect, p, calculated from the rates of oxidation of 1, 1-9-d, and 1-9,9-d2 (1(HH), 1(HD), and 1(DD)) in AN varied from 4.5 (TCNE) to 13 (BQ), while the secondary isotope effect, s, was approximately constant (∼1.1). Values of the isotope partitioning ratio, ipr (the ratio of 2(D) to 2(H) formed in reaction of 1(HD)) were determined for BQ in three AN-water mixtures and for CA, TCNE, and DCBQ in AN. For all systems studied, except BQ in 90% AN, where determination of the ipr is complicated by isotopic exchange between unreacted 1 and product (2), the ipr agrees with p/s from the kinetic measurements. These results are discussed in terms of mechanism and compared with those of other hydride transfer reactions involving dihydronicotinamide donors.

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