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Basic IUPAC Organic Nomenclature

Polysubstituted benzenes


  • Principle functional group is the methylbenzene therefore root = toluene
  • There is a bromine substituent therefore bromo
  • There is a chlorine substituent therefore chloro
  • Numbering from the -CH3 (priority group at C1) gives the substituents the locants = 2 and 4
2-bromo-4-chlorotoluene
polysubs aromatic
  • Principle functional group is the aromatic alcohol therefore = phenol
  • There are two C1 substituents therefore dimethyl
  • Numbering from the -OH (priority group at C1) gives the substituent the locant = 3,5
3,5-dimethylphenol
polysubs aromatic
  • Principle functional group is the aromatic amine therefore = aniline
  • There is a C1 substituent therefore methyl
  • There is a C2 substituent therefore ethyl
  • Numbering from the -NH2 (priority group at C1) gives the substituents the locants = 2 and 3
2-ethyl-3-methylaniline
polysusbs aromatic



organic chemistry ©Dr. Ian Hunt, Department of Chemistry University of Calgary