- Electronic and steric effects in the SNAr substitution reactions of substituted anilines with 2,4-dinitrophenyl 2,4,6-trinitrophenyl ether in acetonitrile
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Rate measurements are reported for the reactions of 12 ring-substituted anilines with 2,4-dinitrophenyl 2,4,6-trinitrophenyl ether (1) in acetonitrile. Formation of the products, the correspondingly substituted 2,4,6- trinitrodiphenylamines, occurs without the observation of intermediates in detectable amounts by both base-catalysed and uncatalysed pathways and Hammett ρ value were determined for these processes. The results show that although substituents at the 3- or 4-positions of the anilines have only small steric effects, alkyl substituents at the 2-position may result in considerable reductions in reactivity. These effects are more pronounced for the base-catalysed pathway and in 2,6-dimethylaniline the uncatalysed pathway takes all the reaction flux. In the case of the 2-fluoro substituent the electronic effect, strong inductive electron withdrawal, is dominant over steric effects. Copyright
- Crampton, Michael R.,Emokpae, Thomas A.,Isanbo, Chukwuemeka
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- Aromatic nucleophilic substitution reactions of 1-dialkylamino-substituted activated benzenes with various amines in dimethyl sulfoxide
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In the reactions of 1-dlalkylamino-2,4,6-trinitro- and 1-dialkylamlno-2, 4-dinitrobenzenes with various amines in dimethyl sulfoxide, 1-dialkylamino group is easily replaced with primary n-alkylamines at room temperature, and in a low yield with pyrrolidine only among secondary amines.
- Sekiguchi, Shizen,Ishikura, Hiromi,Hirosawa, Yukitoshi,Ono, Nobuyuki
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p. 5567 - 5578
(2007/10/02)
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- Mechanism of the Reactions of Substituted Anilines with Phenyl 2,4,6-Trinitrophenyl Ether in Benzene: Evidence for a Cyclic Transition State involving an Eight-membered Ring
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Rates and activation parameters have been determined for the reactions of phenyl 2,4,6-trinitrophenyl ether with substituted anilines in benzene.For some of the nucleophiles, the rates decrease with increasing temperature in the range 5-35 deg C resulting in negative activation enthalpies (ΔH(excit.) -3.1 to -27.3 kJ mol-1).This is strong evidence for a stepwise mechanism involving (at least) a pre-equilibrium.These base-catalysed nucleophilic substitution reactions are sensitive to the nature of the arylated amine as indicated by the Hammett's constant (ρ -7.7).
- Banjoko, Olayinka,Ezeani, Chike
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p. 1357 - 1360
(2007/10/02)
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