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Aldehydes, Ketones and Carboxylic Acids

Aldehydes and ketones contain the carbonyl group, but their position in the carbon chain changes their names, preparation methods, and chemical behaviour. Aldehydes are generally more easily oxidised than ketones, which is why many test reactions distinguish them. The most important reaction idea in this chapter is the polar nature of the C=O bond. The carbonyl carbon is electron-deficient, so nucleophiles attack it and form addition products. This explains reactions with HCN, sodium hydrogen sulphite, alcohols, and ammonia derivatives. Carboxylic acids contain the -COOH group and show acidity because the carboxylate ion is resonance-stabilised. Their acidity is strongly affected by substituents: electron-withdrawing groups increase acidity, while electron-donating groups decrease it. For exams, this chapter is often asked through conversions, named reactions, product prediction, distinguishing tests, and acidity comparison. Students should focus on reagent role, reaction conditions, observations, and the reason behind the product.