This document provides an introduction to aromatic chemistry and benzene compounds. It defines arenes as aromatic hydrocarbons containing one or more benzene rings. Benzene itself is represented by the formula C6H6, where a ring of 6 carbon atoms is bonded to a hydrogen atom on each carbon. When a hydrogen is replaced on the benzene ring, the compound takes the name of the replacing group followed by "benzene", such as chlorobenzene. Numbering positions on rings with multiple groups is also discussed.

1. Introduction: Aromatic
Chemistry

2. Arenes
• Arenes: aromatic hydrocarbons containing one
or more benzene ring.
• A benzene ring is a ring of 6 carbon molecules,
each bonded with one hydrogen molecule
with the formula C6H6.
• Represented like this:

3. Naming Benzene Compounds
• When a hydrogen on the benzene ring is
replaced by a molecule or group it takes the
form “(group)benzene”

4. Eg: C6H5Cl = “Chlorobenzene”
Common groups include:
-Cl (Chloro)
-Br (Bromo)
-I (Iodo)
-NO2 (Nitro)
-CH3 (Methyl)

5. Numbering Groups
• With 2 or more groups, the name must show
their positions on the ring.
• Smallest possible numbers are used.
• Groups are listed in alphabetical order. (Eg:
bromomethyl, not methylbromo).

6. Numbering based on methylbenzene at
position 1:

7. Benzene
• Used to synthesize many aromatic compounds
and materials.
• Derivatives used to make detergents,
explosives, dies.
• Component of crude oil, cigarette smoke and
petrol.

8. Properties of Benzene
• Colourless liquid, sweet smell, highly
flammable.
• Formed naturally (volcanoes + forest fires) and
artificially.