- Arenes have considerable energetic stability because of the delocalised pi bonding electrons. Arenes require much more vigorous reaction conditions than alkenes to undergo addition reactions because of this extra stability.
- Arene chemistry is dominated by electrpophilic substitution reactions that enable arenes to retain the delocalised pi electrons (ring). Hydrogen atoms on the benzene ring may be replaced by a variety of other atoms or groups including halogen atoms & nitro (-NO2) groups.
- The variety of substituition reactions on benzene provides access to many useful compounds including medicines, dyes, explosives and polymers.
- When the -OH group is joined directly to a benzene ring, the resulting alcohol is called a phenol.
- Phenols are weakly acidic and form salts, called phenoxides, plus water on reaction with sodium hydroxide.
- The reaction of sodium with phenol produces sodium phenoxide and hydrogen gas.
- The -OH group enhances the reactivity of the benzene ring towards electrophiles. Bromine water is decolourised by phenol, producing a white precipitate of 2,4,6-tribromophenol.
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