Paracetamol is a medicine commonly used to relieve mild pain - AQA - A-Level Chemistry - Question 8 - 2019 - Paper 2

The complete equation for the reaction in Step 2 can be represented as:

$\text{4-aminophenol} + \text{NO}_2\text{(conc.)} \rightarrow \text{4-nitrophenol} + \text{H}_2\text{O}$

The mechanism involves the nucleophilic attack of the ammonium component of 4-aminophenol on the carbon atom of the carbonyl group in ethanoyl chloride, leading to the formation of paracetamol.

One reason why ethanoyl chloride is not used in the industrial synthesis is because it is corrosive and poses a risk to health and safety during its handling.

One possible structure of an aromatic product is 4-nitrochlorobenzene:

    Cl
     | 
   C6H4
     | 
    NO2

Alternatively, another product might be 2-nitrophenol.

The complete equation for the second step is:

$\text{hydroquinone} + \text{NH}_4\text{OEt} \rightarrow \text{paracetamol} + \text{H}_2\text{O}$

To find the mass of hydroquinone needed:

1. Calculate moles of paracetamol: $\text{Moles of paracetamol} = \frac{250000 \text{g}}{151.0 \text{g/mol}} = 1655.6 \text{ mol}$

2. Use stoichiometry to find moles of hydroquinone, which is equal to moles of paracetamol: $\text{Moles of hydroquinone} = 1655.6 \text{ mol}$

3. Calculate mass of hydroquinone: $\text{Mass of hydroquinone} = 1655.6 \text{ mol} \times 110.0 \text{ g/mol} = 18211.9 \text{ g} = 18.2 \text{ kg}$