Carboxylic acids and esters
Carboxylic acids (RCOOH) are made by oxidising primary alcohols or aldehydes (reflux with acidified dichromate) or hydrolysing nitriles with acid. They are weak acids: react with metals (H₂), bases (salt + water) and carbonates (CO₂: the test that distinguishes them from phenols and alcohols). LiAlH₄ reduces them to primary alcohols. With alcohols and conc. H₂SO₄ they form esters, named alkyl-first (methyl ethanoate). Ester hydrolysis: acid (reversible, gives acid + alcohol) or alkaline (irreversible, gives carboxylate salt + alcohol: saponification). Esters are used as flavourings, solvents and plasticisers; fats are triesters of glycerol.
≈ 45 min