M.R. Crampton
Effects of ortho- and para-ring activation on the kinetics of S<sub>N</sub>Ar reactions of 1-chloro-2-nitro and 1-phenoxy-2-nitrobenzenes with aliphatic amines in acetonitrile
Crampton, M.R.; Emokpae, T.A.; Isanbor, C.; Batsanov, A.S.; Howard, J.A.K.; Mondal, R.
Authors
T.A. Emokpae
C. Isanbor
Dr Andrei Batsanov a.s.batsanov@durham.ac.uk
Academic Visitor
J.A.K. Howard
R. Mondal
Abstract
Rate constants are reported for reaction of 4-substituted 1-chloro-2,6-dinitrobenzenes 1, 6-substituted 1-chloro-2,4-dinitrobenzenes 2, and some of the corresponding 1-phenoxy derivatives, 3 and 4, with n-butylamine, pyrrolidine and piperidine in acetonitrile as solvent. Values of k1, the rate constant for nucleophilic attack at the 1-position, increase with increasing ring-activation but may be reduced by steric repulsion at the reaction centre which increases in the order Cl < OPh, and n-butylamine < pyrrolidine piperidine. ortho-Substituents may also have adverse steric effects, and those of the trifluoromethyl group are particularly serious. X-ray crystal structures of phenyl 2,4-dinitro-6-trifluoromethylphenyl ether and phenyl 2,6-dinitro-4-trifluoromethylphenyl ether are reported. Base catalysis in the 1-phenoxy derivatives is attributed to rate-limiting proton transfer from the zwitterionic intermediates 6 to base. Values of rate constants for this process decrease with increasing steric congestion at the reaction centre and in the order n-butylamine > pyrrolidine > piperidine.
Citation
Crampton, M., Emokpae, T., Isanbor, C., Batsanov, A., Howard, J., & Mondal, R. (2006). Effects of ortho- and para-ring activation on the kinetics of SNAr reactions of 1-chloro-2-nitro and 1-phenoxy-2-nitrobenzenes with aliphatic amines in acetonitrile. European Journal of Organic Chemistry, 2006(5), 1222-1230. https://doi.org/10.1002/ejoc.200500774
Journal Article Type | Article |
---|---|
Online Publication Date | Dec 22, 2005 |
Publication Date | Mar 1, 2006 |
Deposit Date | Apr 26, 2007 |
Journal | European Journal of Organic Chemistry |
Print ISSN | 1434-193X |
Electronic ISSN | 1099-0690 |
Publisher | Wiley |
Peer Reviewed | Peer Reviewed |
Volume | 2006 |
Issue | 5 |
Pages | 1222-1230 |
DOI | https://doi.org/10.1002/ejoc.200500774 |
Keywords | Kinetics, Nucleophilic aromatic substitution, Steric hindrance, Substituent effects. |
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