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Paracetamol is a commonly used painkiller - VCE - SSCE Chemistry - Question 3 - 2008 - Paper 1
Question 3
Paracetamol is a commonly used painkiller. The equation below shows one method of preparing paracetamol. \[\text{4-aminophenol} + \text{reagent} \rightarrow \text{p... show full transcript
Worked Solution & Example Answer:Paracetamol is a commonly used painkiller - VCE - SSCE Chemistry - Question 3 - 2008 - Paper 1
Step 1
a. Give the formula of a possible reagent that can be used in this synthesis.
Answer
A possible reagent that can be used in the synthesis of paracetamol from 4-aminophenol is acetic anhydride. The reaction can be represented as:
[\text{4-aminophenol} + \text{acetic anhydride} \rightarrow \text{paracetamol} + \text{acetic acid}]
Step 2
i. On the diagram of a TLC plate below, use a horizontal line to mark the spot where paracetamol would appear in such an analysis.
Answer
On the TLC plate, mark a horizontal line at the height corresponding to the value of paracetamol, which is 0.4. This means the line should be placed at 40% of the distance from the origin to the solvent front.
Step 3
ii. Predict whether the $R_f$ value of 4-aminophenol in this analysis is greater or smaller than that of paracetamol, giving a reason for your choice.
Answer
The value of 4-aminophenol is expected to be greater than that of paracetamol. This is because 4-aminophenol adsorbs less strongly onto the stationary phase compared to paracetamol, allowing it to travel further up the TLC plate during the analysis.