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ABSTRACT:
SUBMITTER: Bowler JT
PROVIDER: S-EPMC4110164 | biostudies-literature | 2014 Aug
REPOSITORIES: biostudies-literature
Bowler Jeannette T JT Wong Freeman M FM Gronert Scott S Keeffe James R JR Wu Weiming W
Organic & biomolecular chemistry 20140801 32
The "element effect" in nucleophilic aromatic substitution reactions (SNAr) is characterized by the leaving group order, L = F > NO2 > Cl ≈ Br > I, in activated aryl substrates. A different leaving group order is observed in the substitution reactions of ring-substituted N-methylpyridinium compounds with piperidine in methanol: 2-CN ≥ 4-CN > 2-F ∼ 2-Cl ∼ 2-Br ∼ 2-I. The reactions are second-order in [piperidine], the mechanism involving rate determining hydrogen-bond formation between piperidine ...[more]