7.4 Hydroxy Compounds (A Level Only)

Phenyl 2-hydroxybenzoate is an antiseptic and is shown in Fig. 2.1.

Fig. 2.1

A molecule of phenyl 2-hydroxybenzoate has 13 carbon atoms

[3]

Phenyl 2-hydroxybenzoate can be made from 2-hydroxybenzoic acid and phenol by heating the two compounds strongly together.

Write an equation, using the displayed formula, for this reaction.

Complete and balance the equation in Fig. 2.2 for the alkaline hydrolysis of phenyl 2-hydroxybenzoate.

Fig. 2.2

This question is about a drug called mesalamine (also known as 5-aminosalicylic acid) that is used to treat bowel disease. It can be synthesised from salicylic acid, the chemical structure of which is shown in Fig. 3.1

Fig. 3.1

State the systematic IUPAC name for salicylic acid and deduce the two positional isomers are possible, giving their names and structures.

IUPAC name of salicylic acid ............................................

A possible two step synthesis of mesalamine is shown below in Fig. 3.2.

Fig. 3.2

Draw the structures of compound X and mesalamine.

State the reagents and conditions required for steps 1 and 2 in Fig. 3.2 in part (b).

• step 1

   reagent(s) ...................................................

   conditions(s) .................................................

• step 2

   reagent(s) ...................................................

   conditions(s) .................................................

This question is about phenol. 

Phenol is an aryl compound. 

[1]

[1]

Explain why phenol is a weak acid. 

You should include an equation in your answer. 

Describe and explain how the acidities of ethanol and phenol compare to that of water. 

Phenol reacts with bromine water. 

Explain how the reactions of phenol and benzene with bromine can show that phenol is more reactive than benzene.  

Phenol can be prepared from phenylamine

There are three stages that take place during this preparation:

• Stage 1: Prepare nitric(III) acid using sodium nitrate and hydrochloric acid
• Stage 2: React phenylamine with nitric(III) acid and hydrochloric acid to form a diazonium salt 
• Stage 3: Thermal decomposition of the diazonium salt to form phenol, hydrochloric acid, and nitrogen gas

Write balanced symbol equations for the reactions that occur at each stage:

Stage 1: ...................................................................................................
Stage 2: ...................................................................................................
Stage 3: ...................................................................................................

The diazonium salt formed during stage 2 can also react with phenol to form a useful substance, Z. 

The first step of substance Z involves creating the diazonium ion. 

The reaction is the same as that in stage 2 in part (a). 

Explain why the reaction to produce the diazonium ion is carried out at below 10 ^oC. 

Rodinol is used as a photographic developer.

It can be synthesised from phenol by the following route:

[1]

[1]

[1]

[2]

Rodinol can undergo many reactions. 

Suggest the structural formulae for the compounds E, F and G in the following chart of the reaction so of rodinol. 

Acyl chlorides are useful reagents in synthesis.

They react with aromatic compounds and also with alcohols. 

Phenyl benzoate is made from the reaction between benzoyl chloride and phenol. 

Its structure is shown below.

What is the molecular formula of phenyl benzoate? 

During the initial reaction to produce phenyl benzoate, the phenoxide ion is formed.