Download - Aromatic compounds
Aromatic compounds
Aromatic compounds
Aromatic compounds are compounds which contain a benzene ring in their molecules
Aromatic hydrocarbons
Benzene C6H6
Methylbenzene C7H8
Ethylbenzene C8H10
Benzene
Benzene molecule
The six carbon-carbon bonds in benzene are identical, intermediate in length between double and single bonds
Sigma bonding in benzene
Six carbon atoms joined to form a hexagonal planar ring.
Each carbon has four valence electrons One of these is used to form a bond with a
hydrogen atom. Two other electrons are used to form sigma
bonds with the carbon atoms on either side.
What the circle means
The 6 valence electrons not involved in sigma bonding are shared between the six carbon atoms in the molecule
not localised into 3 double bonds For convenience the C and H atoms are not
shown Ring in centre indicates a delocalised pi bond
Methylbenzene
Ethylbenzene
Physical properties
Physical state: Benzene. methylbenzene and ethylbenzene are liquids
Insoluble in water Soluble in non-polar solvents such as
cyclohexane
Uses
Methylbenzene is used as an industrial solvent
Range and scope of aromatic chemistry
Pharmaceutical compounds, e.g. Morphine
Herbicides, e.g. Diuron
Detergents, e.g. Sodium dodecylbenzenesulfonate
Dyes, e.g. Martius Yellow
Aromatic acid-base indicators
The acid-base indicators phenolphthalein and methyl orange are also aromatic compounds
Phenolphthalein Methyl orange
Aromatic compounds and cancer
Some aromatic compounds are carcinogenic, e.g. Benzene
However, not all aromatic compounds are carcinogenic; aspirin is an example