Recognize aromatic compounds from structural formulas.
Name aromatic compounds given formulas.
Write formulas for aromatic compounds given their names.
istorically, benzene-like substances were called aromatic hydrocarbons because they had distinctive aromas. Today, an aromatic compound is any compound that contains a benzene ring or has certain benzene-like properties (but not necessarily a strong aroma). You can recognize the aromatic compounds in this text by the presence of one or more benzene rings in their structure. Some representative aromatic compounds and their uses are listed in Table 1.9 “Some Representative Aromatic Compounds”, where the benzene ring is represented as C₆H₅.

Example

Which compounds are aromatic?

Solution

The compound has a benzene ring (with a chlorine atom substituted for one of the hydrogen atoms); it is aromatic.
The compound is cyclic, but it does not have a benzene ring; it is not aromatic.
The compound has a benzene ring (with a propyl group substituted for one of the hydrogen atoms); it is aromatic.
The compound is cyclic, but it does not have a benzene ring; it is not aromatic

Replacement of one or more of the hydrogen atoms on benzene with other groups produces benzene derivatives. Naming of benzene derivatives with one substituent is considered first, then naming of those with two substituent and finally naming of those with three or more substituent. Mono, di and poly substituted benzene: Name the substituent and add the word benzene.

For example: Chlorobenzene:

1-bromo-2-chlorobenzene:

1, 2 diamino-5-bromo-3-chlorobenzene

Many mono substituted benzenes have their special names.

HOMEWORK EXERCISE

Exercises

Is each compound aromatic?a.

b.
Is each compound aromatic?a.

b.
Draw the structure for each compound.a. tolueneb.m-diethylbenzenec. 3,5-dinitrotoluene
Draw the structure for each compound.a.p-dichlorobenzeneb. naphthalenec. 1,2,4-trimethylbenzene
Name each compound with its IUPAC name.a.

b.

c.

d.
Name each compound with its IUPAC name.a.

b.

c.

d.