Build a route, one bond at a time.
A carboxylic acid and an alcohol can form an ester and water under acid catalysis and heating. The reaction is reversible; excess reactant or removal of a product can improve equilibrium yield. Hydrolysis reverses the bond formation.
Carboxylic acids donate protons; amines accept them through the nitrogen lone pair. Mixing an amine and a carboxylic acid first favours an ammonium carboxylate salt. Appropriate heating/dehydration or activated-acid conditions are required to form the amide; simply mixing them is not enough.
Plan pathways by comparing starting and target functional groups. Ethene can be hydrated to ethanol, oxidised to ethanoic acid, then esterified. Show each transformation and its conditions instead of drawing an unexplained arrow.
Spot the functional group
Condensed structural diagrams. Bonds show connectivity, not measured bond angles. Compare the molecular formula with the arrangement of atoms.
Explore: Trace the reacting groups into an ester or amide and identify the small molecule removed.
Why can using excess ethanol improve the yield of ethyl ethanoate in esterification?
- Ethanol is a reactant.
- The forward shift consumes some extra ethanol and forms more ester.
Answer: Adding ethanol shifts the equilibrium towards ester and water, consuming some of the added reactant.
Assumed knowledge
Conservation of the carbon skeleton unless a reaction explicitly changes it.
Learning checkpoints & source
YOUR SYLLABUS CHECKPOINT- Write esterification equations and explain reversibility.
- Connect reactants, products, reagents and conditions.
- Explain acid–base behaviour of amines and carboxylic acids.