1.2 Nomenclature of Aromatic Compounds

1.2 Nomenclature of Aromatic Compounds

• The ring can be monosubstituted, disubstituted, or even polysubstituted, and it can accommodate up to six different groups.
• Many of the derivatives of benzene are odorless.

• An aromatic ring should be viewed as a single functional group.

• All groups connected to the ring must be listed as substituents.
• We don't refer to the compound as benzenol if it is connected to the ring.
• The term benzene is already a suffix, so we can't add another one.

• Many monosubstituted derivatives of benzene have the same names.

• The first compound can either be called methylbenzene or toluene.
• The second compound can be called hydroxybenzene or phenol.
• Common names are used as parents when more than one substituent is present.
• The following compound has a benzene ring with two substituents.

• The OH group's position is indicated by the number (2).
• The compound can be called 1-bromo-2hydroxybenzene.

• In the previous example, numbers must be assigned when more than one group is present.
• The #1 position is determined by the parent.

• The lower possible number is assigned to the next substituent.
• In this case, we assign the numbers in acounterclockwise fashion because we have a lower number.
• The same method is used for polysubstituted rings, first we choose the parent, and then we assign numbers in the direction that gives the lowest possible number to the second substituent.

• A disubstituted phenol can be called a trisubstituted benzene.
• The OH group is assigned the top position.

• We assign numbers in the direction that gives the lowest possible number to the second substituent.

• The compound can be named as a trisubstituted benzene, but it will be more efficient to call it a disubstituted derivative of aniline.

• The name is 5-bromo-2-chloroaniline.
• The substituents appear in alphabetical order in accordance with the general rules for IUPAC nomenclature.