A-Level Chemistry: Aromatic Chemistry and Amines

Aromatic chemistry is Year 2 organic at its most conceptual: a ring that refuses addition, an electrophile that must be manufactured, and a basicity order that runs on delocalisation. This quiz covers benzene, amines, amino acids and polymers as the specification groups them.

The benzene questions start with the evidence: why the enthalpy of hydrogenation falls short of three-double-bond expectations, the thermodynamic signature of delocalisation, tested both as evidence selection and as explanation. The mechanistic core follows: why substitution preserves what addition would destroy (the delocalised π-system), nitration with the nitronium electrophile generated by the nitric/sulfuric acid pair, and Friedel-Crafts acylation with aluminium chloride tested twice — as the required reagent set and, more deeply, through its Lewis-acid role in creating the acylium electrophile.

The amine questions centre on the basicity order every paper asks: alkyl groups pushing electron density onto nitrogen versus the aryl ring delocalising the lone pair away — primary aliphatic amines above ammonia above phenylamine, tested through the reasons. Preparation appears through nitrile reduction to primary amines.

Amino acids are covered as bifunctional molecules: amphoteric behaviour and the zwitterion. The polymer questions close the loop begun in Organic I: condensation polymerisation losing a small molecule per link, the amide linkage formed from diacid and diamine, and the contrast with addition polymerisation.

The blind-solver verification pass returned complete agreement across all ten questions. Explanations consistently argue from electron density and delocalisation — the register in which aromatic chemistry is actually marked.

• Use hydrogenation enthalpy as evidence for benzene's delocalised structure
• Explain why benzene substitutes rather than adds
• Describe nitration and Friedel-Crafts acylation including electrophile generation
• Rank amine basicity through electron-density reasoning
• Contrast condensation and addition polymerisation and identify amide links

Aligned to the Year 2 organic content of the DfE A level science subject content as delivered in current specifications: benzene's structure and electrophilic substitution, amines and their basicity, amino acids, and condensation polymers.