6.1.5: Phenols

Question 1

What is a phenol?

Answer 1

The first member of a type of aromatic compounds where a hydroxyl group (-OH) is attached directly to an aromatic ring.

Question 2

When would an aromatic ring no longer be considered a phenol derivative but an aromatic alcohol?

Answer 2

When the hydroxyl group is attached to an alkyl chain on the aromatic ring. (see examples in book)

Question 3

Phenol is a weak acid, as it partially dissociates in water. How can the chemical equilibrium be shown in a balanced symbol equation?

Answer 3

C6H5OH —> H3O+ +C6H5O-

Question 4

As a weak acid, what does phenol form when it reacts with a strong base?
What is the balanced symbol equation for the reaction between phenol and sodium hydroxide.

Answer 4

salt and water
C6H5OH + NaOH —> C6H5O-Na+ + H2O
(sodium phenoxide)

Question 5

Phenol is an acid because it reacts with strong bases such as sodium hydroxide, however it is a weak acid because…

Answer 5

It does not react with carbonates. Phenol will not react with weak bases such as sodium carbonate.

Question 6

Why sis phenol more reactive than benzene?

Answer 6

• The p-orbital electrons from the oxygen of the hydroxyl group add to the delocalised electrons of the aromatic ring.
• This makes the aromatic ring more nucleophilic.
• This increase in electron density allows the aromatic ring in phenol to be more susceptible to electrophilic attack as it can induce a dipole in non-polar molecules.

Question 7

Why can phenol undergo direct halogenation, unlike benzene?

Answer 7

Because the aromatic ring in phenol is more electron dense and can induce a dipole in the non polar bromine molecule.