Nucleophilic aromatic substitution

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) mechanismthe aromatic SN1 mechanism encountered with diazonium saltsthe benzyne mechanismthe free radical S_RN1 mechanism the ANRORC mechanismVicarious 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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