Phenol

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Phenol is a benzene ring with an OH group.

The oxygen must be directly bonded to the benzene ring.

If not it is just called an aromatic alcohol.

Uses of phenols:

Alkyl phenols are used in detergents.

Chlorophenols are used as antiseptics.

Salicylic acid is important in the synthesis of analgesics.

Properties of phenols:

Solid under standard conditions.

Slightly water soluble due to the presence of the hydrogen bond between the O and the H.

The large, non-polar benzene ring reduces water solubility slightly.

Reacts like other weak acids with metals it produces a salt.

Reacts like other weak acids with alkalis to produce a salt and water.

Reacts in a neutralisation reaction to produce a salt and water.

Reacts with halogens at room temperature without the need of a catalyst.

Phenol as a weak acid

Less soluble than alcohols because of the non-polar benzene ring.

Partially dissociates in water, however, so is a weak acid.

Phenol is more acidic than alcohols but less acidic than carboxylic acids.

How weak?

Ethanol doesn't react with NaOH or sodium carbonate.

However, phenols react with NaOH.

Carboxylic acids react with both.

Bromination

Reacts with bromine to produce a white precipitate. 2,4,6-tribromophenol is a white precipitate.

The bromine decolourises.

Phenols reactivity

The lone pairs on the -OH group are in p-orbitals.

This overlaps with benzene's delocalised pi system.

This increases the electron density of the benzene ring. (EDG).

This allows the ring to induce a dipole across the halogen.

The positive end of the halogen induced dipole acts as an electrophile.

Nitration of phenol

Unlike benzene which requires concentrated nitric acid, nitration of phenol can occur with dilute nitric acid. No catalyst is required and it can occur at room temperature. Two isomers are made from this.