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Definition of Nucleophilic aromatic substitution

Nucleophilic aromatic substitution Definition from Encyclopedia Dictionaries & Glossaries
English Wikipedia - The Free Encyclopedia
A nucleophilic aromatic substitution is a substitution reaction in organic chemistry in which the nucleophile displaces a good leaving group, such as a halide, on an aromatic ring. There are 6 nucleophilic substitution mechanisms encountered with aromatic systems:
  • the SNAr (addition-elimination) mechanism
  • the aromatic SN1 mechanism encountered with diazonium salts
  • the benzyne mechanism
  • the free radical SRN1 mechanism
  • the ANRORC mechanism
  • Vicarious nucleophilic substitution.
The most important of these is the SNAr mechanism, where electron withdrawing groups activate the ring towards nucleophilic attack, for example if there are nitro functional groups positioned ortho or para to the halide leaving group.

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