Electrophilic aromatic substitution in substituted anilines; kinetics of the reaction with 4,6-dinitrobenzofuroxan

1999 ◽  
Vol 77 (5-6) ◽  
pp. 639-646 ◽  
Author(s):  
Michael R Crampton ◽  
Lynsey C Rabbitt ◽  
François Terrier
Keyword(s):  
Electrophilic Substitution ◽  
Kinetic Isotope Effect ◽  
Acidic Solution ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Substituted Anilines ◽  
Kinetic Isotope ◽  
A Value ◽  
Kinetics Of ◽  
Ring Carbon Atom

Kinetic results are reported for reaction of aniline and six of its N- and ring-substituted derivatives with 4,6-dinitrobenzofuroxan (DNBF) in water - dimethyl sulfoxide mixtures. In acidic solution σ-adducts, the result of electrophilic substitution in the anilines, are formed with bonding between a ring-carbon atom of the anilines and the 7-position of DNBF. Reaction normally occurs at the 4-position of the aniline unless this carries a substituent, when reaction occurs at the 2-position. A value of 2.0 for kH/kD, the kinetic isotope effect, indicates that in the reaction with aniline bond formation is largely rate determining in the substitution pathway. The results allow estimates to be made for the pKa values relating to carbon protonation of the anilines.Key words: electrophilic substitution, σ-adducts, 4,6-dinitrobenzofuroxan, ambident reactivity of anilines.

Substituent Effects in Electron Transfer Reactions: The Preparation and Chromium(II) Reduction of 3-Formylpentane-2,4-dionatobis(ethylenediamine)cobalt(III). Preparation of the Linkage Isomer 2-Acetylbutane-1,3-dionatobis(ethylenediamine)cobalt(III)

1975 ◽  
Vol 53 (8) ◽  
pp. 1154-1164 ◽  
Author(s):  
Robert J. Balahura ◽  
N. A. Lewis
Keyword(s):  
Electron Transfer ◽  
Acidic Solution ◽  
Substituent Effects ◽  
Activation Parameters ◽  
Transfer Reactions ◽  
Linkage Isomers ◽  
A Value ◽  
Parent Complex ◽  
Kinetics Of ◽  
Sphere Mechanism

The preparation of the linkage isomers, 3-formylpentane-2,4-dionatobis(ethylenediamine)cobalt(III), (1), and 2-acetylbutane-1,3-dionatobis(ethylenediamine)cobalt(III), (2), are described. The kinetics of the reaction of Cr(OH2)62+ with 1 and the parent complex, 2,4-pentanedionatobis(ethylenediamine)cobalt(III), (3), have been studied spectrophotometrically in acidic solution. For 1, the reduction is described by the rate law −d ln [Co(III)complex]/dt = k[Cr2+], and k = 0.0863 M−1 s−1 at 25 °C, μ = 1.0 M (LiClO4). The activation parameters for this reaction were found to be ΔH≠ = 9.9 ± 0.5 kcal mol−1 and ΔS≠ = −30 ± 3 e.u. The reaction proceeded by an inner-sphere mechanism and the product of this reaction was isolated and characterized as 2-acetylbutane-1,3-dionatotetraaquochromium(III). The linkage isomer of this complex was also prepared. The parent complex (3) was not reduced by Cr(OH2)62+ at an observable rate and an upper limit for the rate constant of this reaction was assigned a value of 10−4–10−6M−1s−1 at 25 °C. The ability of the formyl group to enhance the rate of electron transfer is discussed, and the chromium(II) reduction studies of related chelated systems are compared with the results obtained in this investigation.

Hydride transfer reactions. A kinetic study of oxidation of 10-methyl-9-phenylacridan by some π acceptors and a one-electron oxidant

1985 ◽  
Vol 63 (8) ◽  
pp. 2237-2240 ◽  
Author(s):  
Allan K. Colter ◽  
A. Gregg Parsons ◽  
Karen Foohey
Keyword(s):  
Kinetic Study ◽  
Kinetic Isotope Effect ◽  
Isotope Effects ◽  
Hydride Transfer ◽  
Transfer Reactions ◽  
Kinetics Of Oxidation ◽  
Kinetic Isotope ◽  
One Step ◽  
The One ◽  
Kinetics Of

The kinetics of oxidation of 10-methyl-9-phenylacridan (1(H)) and 9-deuterio-10-methyl-9-phenylacridan (1(D)) to 10-methyl-9-phenylacridinium ion (3) by eight oxidants have been investigated. The oxidants included the π-acceptors 1,4-benzoquinone (BQ), 7,7,8,8-tetracyanoquinodimethane (TCNQ), p-bromanil (BA), p-chloranil (CA), tetracyanoethylene (TCNE), 2,3-dicyano-1,4-benzoquinone (DCBQ) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in acetonitrile (AN), BQ in 50:50 (v/v) AN-water, and the one-electron oxidant tris(2,2′-bipyridyl)cobalt(III), [Formula: see text] in AN. The seven π acceptors cover a 109-fold range of reactivity from BQ to DDQ and the deuterium kinetic isotope effect varies from 11.9 (BQ in AN) to 5.8 (DDQ). For π acceptors (BQ, TCNQ, CA, TCNE, and DCBQ) previously investigated with 10-methylacridan (NMA), 1(H) is less reactive than NMA by factors ranging from 9.1 (BQ) to 1.7 × 102 (TCNE). The isotope effects and relative reactivities for the π acceptor oxidations are most simply explained by a one-step hydride transfer mechanism.

Atmospheric chemistry of ethers, esters, and alcohols on the lifetimes, temperature dependence, and kinetic isotope effect: an example of CF3CX2CX2CX2OX with OX reactions (X = H, D)

RSC Advances ◽  
2016 ◽  
Vol 6 (42) ◽  
pp. 36096-36108 ◽  
Author(s):  
Feng-Yang Bai ◽  
Xu Wang ◽  
Yan-Qiu Sun ◽  
Rong-Shun Wang ◽  
Xiu-Mei Pan
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Atmospheric Chemistry ◽  
Theoretical Basis ◽  
Kinetic Isotope Effect ◽  
Kinetic Isotope ◽  
Kinetics Of ◽  
Sound Theoretical Basis

Mechanisms and kinetics of the reaction of CF3CX2CX2CX2OX with OX (X= H, D) radical are investigated on a sound theoretical basis.

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