Wheel of Nucleophilic Aromatic Substitution by Addition-Elimination

In a nucleophilic aromatic substitution (NAS or SNAr) the nucleophile displaces a good leaving group, viz., a halide, on an aromatic ring.

Aromatic rings are usually nucleophilic, but some aromatic compounds do undergo nucleophilic substitution especially if o-,p-positions carry strong electron withdrawing groups (EWGs).

One such NAS takes place via addition-elimination mechanism that makes use of the Meisenheimer complex.



Wheel of NAS by addition-elimination: Click/tap to enlarge the image


Reagents -> Products (on the infographic):

  1. 1. Sodium hydroxide, Î” 2. Acid workup-> o-,p-substituted phenol
  2. Sodium methoxide, Î” -> o-,p-substituted anisole
  3. Potassium phenoxide, Î” -> o-,p-substituted diphenyl ether
  4. Sodium disulfide, Î” -> o-,p-substituted diphenyl disulfide
  5. Sodium thiophenoxide Î” -> o-,p-substituted diphenyl sulfide
  6. Secondary amine, Î” -> N-,o-,p-substituted aniline
  7. Aniline -> o-,p-substituted diphenylamine
  8. Hydrazine, Î” -> o-,p-substituted phenyl hydrazine
  9. Potassium iodide, Î” -> o-,p-substituted iodobenzene
  10. Stabilized carbon nucleophile -> 1,2,4-substituted benzene


The substrate is o-,p-substituted (strong EWGs) chlorobenzene.


What other wheel(s) 🛞 of organic reactions would you like to see❓ Questions❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com❗

References:

(1)    Roman A. Valiulin, ChemInfoGraphic. ChemInfoGraphic. https://cheminfographic.wordpress.com.

‌(2)    Nucleophilic aromatic substitution. Wikipedia. https://en.wikipedia.org/wiki/Nucleophilic_aromatic_substitution.

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