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

The equation for the reaction in Step 2 is:

The mechanism for the reaction of 4-aminophenol with ethanoyl chloride is as follows:

1. The lone pair on the nitrogen of 4-aminophenol attacks the carbonyl carbon of ethanoyl chloride, forming a tetrahedral intermediate.
2. The intermediate collapses, releasing HCl and forming paracetamol.

The overall equation can be illustrated as follows:

One reason why ethanoyl chloride is not used in industrial synthesis is that it is corrosive and can release harmful fumes during the reaction.

One other aromatic product that can be formed is 4-nitrophenol, represented structurally as:

    OH
     |  
  C6H4-NO2

The equation for the reaction of hydroquinone with ammonium ethanoate is:

To calculate the mass of hydroquinone needed:

1. Calculate the moles of paracetamol: $ext{Moles of paracetamol} = \frac{250 \text{ kg}}{0.15 \text{ kg/mol}} = 1666.67 \text{ moles}$

2. You'll need the same amount of hydroquinone (1:1 molar ratio in the reaction). So, moles of hydroquinone = 1666.67 moles.

3. Calculate the mass of hydroquinone: $ext{Mass of hydroquinone} = \text{moles} \times M_r = 1666.67 \text{ moles} \times 110.0 \text{ g/mol} = 183333.7 \text{ g} = 183.34 \text{ kg}$