Base catalysis in nucleophilic aromatic substitution reactions: evidence for cyclic transition state mechanism over the dimer mechanism in a non-polar aprotic solvent
- 1 January 1986
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 4,p. 531-536
- https://doi.org/10.1039/p29860000531
Abstract
The reactions of X-phenyl 2,4,6-trinitrophenyl ethers [X = 2-NO2, 3-NO2, 4-NO2, 2,4-(NO2)2, 3,4-(NO2)2, 2,5-(NO2)2, and 2,6-(NO2)2] with aniline in benzene display three distinct mechanisms even though all except the 2,6-dinitrophenyl ether are base catalysed. The catalysis of the mononitro-substituted ethers involves two aniline molecules and proceeds at a temperature-independent rate in the temperature range 5–35 °C while that of the dinitro-substituted ones involves only one aniline molecule and proceeds at a temperature-dependent rate over the same temperature range. The results are interpreted in terms of a cyclic mechanism involving four-, six-, and eight-membered rings in the transition state.Keywords
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