2020 H2 Chem P1 Q26 — Nitrogen Compound Solution

The answer is D (3 only).

Cold NaOH(aq) reacts only with the groups in X that are acidic enough to be neutralised; it does not hydrolyse the amide group at room temperature.
• Group 1 does not react: an alcohol is a weaker acid than water, so the alcoholic OH group does not react with NaOH(aq).
• Group 2 does not react: an amide is neutral, and its hydrolysis by NaOH(aq) needs prolonged heating, not cold conditions.
• Group 3 reacts: phenol is weakly acidic because the negative charge of the phenoxide ion is delocalised into the benzene ring. It is neutralised by cold NaOH(aq): \(\text{ArOH} + \text{NaOH} \rightarrow \text{ArO}^-\text{Na}^+ + \text{H}_2\text{O}\).

• A is wrong: it includes group 1, the alcoholic OH, which does not react.
• B is wrong: it includes group 2, the amide, which is not hydrolysed without heating.
• C is wrong: the amide does not react, and the phenolic OH group, which does react, is left out.