Hydrolyse an amide with aqueous acid or alkali
Aqueous acid or aqueous alkali hydrolyses an amide; acid gives a carboxylic acid, while alkali gives a carboxylate salt.
A Level; Cambridge International Chemistry 9701, 2028–2030 syllabus, Topic 34. Use the stated reagents, conditions and product scope. Written practice is self-checked This online lesson cannot demonstrate supervised laboratory skills.
Before you begin
- Recall nucleophilic substitution, reduction, acyl-chloride addition–elimination, acid–base equilibria and covalent bonding.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which reagent classes hydrolyse amides in the syllabus?
What you will learn
- Recall acid and alkali as amide-hydrolysis reagents
- Compare the organic products
- Account for the nitrogen-containing product
Acidic hydrolysis
An amide can be hydrolysed with aqueous acid. A primary amide gives a carboxylic acid and an ammonium ion/salt; for example, CH₃CONH₂ + H₂O + HCl → CH₃COOH + NH₄Cl.
Hydrolysis breaks the C(O)–N bond and restores a carboxyl group. Heating is commonly used to drive the reaction; the syllabus outcome identifies aqueous acid as the reagent class.
Alkaline hydrolysis
With aqueous alkali, a primary amide gives a carboxylate salt and ammonia: CH₃CONH₂ + NaOH → CH₃COONa + NH₃ (overall, with water in the medium).
Acidic hydrolysis leaves the acid protonated; alkaline hydrolysis leaves the carboxylate deprotonated. Do not write the same carboxyl product for both conditions.
Pause and explain
What is the carboxyl product in alkaline amide hydrolysis?
Worked example
Compare the products of ethanamide hydrolysis in aqueous acid and aqueous NaOH.
Show the worked solution
- Acid hydrolysis forms ethanoic acid and an ammonium salt.
- Alkali hydrolysis forms sodium ethanoate and ammonia.
- Keep the carbon skeleton unchanged.
Answer Acid: CH₃COOH + NH₄⁺ (or NH₄Cl with HCl). Alkali: CH₃COONa + NH₃.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Predict the products when propanamide is hydrolysed with aqueous NaOH.
Give me a hint
Use the alkaline product form and account for nitrogen.
Compare my reasoning
- The acyl skeleton becomes propanoate.
- Na⁺ pairs with the carboxylate.
- The amide nitrogen forms NH₃.
CH₃CH₂COONa + NH₃ (sodium propanoate and ammonia).
Look for these in your work
- Carboxylate
- Counterion
- Nitrogen product
Write the organic product difference between acidic and alkaline hydrolysis of an amide.
Give me a hint
Compare protonation state after C–N bond cleavage.
Compare my reasoning
- Acidic conditions yield RCOOH.
- Alkaline conditions yield RCOO⁻/RCOONa.
- Both break the amide bond and release a nitrogen product.
Acid gives a carboxylic acid; alkali gives a carboxylate salt.
Look for these in your work
- Acid form
- Base form
- Hydrolysis recognised
A learner gives sodium ethanoate for amide hydrolysis in aqueous HCl. Correct the acid-base form.
Give me a hint
An acidic medium protonates the carboxylate.
Compare my reasoning
- Aqueous acid gives the carboxylic acid.
- The nitrogen appears as NH₄⁺/an ammonium salt.
- Sodium is not supplied by HCl.
The products include ethanoic acid and an ammonium salt, not sodium ethanoate.
Look for these in your work
- Acid product
- Nitrogen product
- Counterion corrected
Common mistakes
- Writing an amine as the direct hydrolysis product
- Using carboxylate for the acidic product
- Using carboxylic acid for the alkaline product
- Forgetting the nitrogen-containing product
What can you explain now?
Which reagent classes hydrolyse amides in the syllabus?
Compare with the explanation
Aqueous acid or aqueous alkali
Both acidic and alkaline hydrolysis are specified.
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Make it stick
How do aqueous acid and aqueous alkali change the carboxyl product in amide hydrolysis?
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