Last updated: 24 August 2026
An amide may look rather like an amine because both contain nitrogen, but placing that nitrogen directly beside a carbonyl group changes its chemistry dramatically. The C=O and nitrogen lone pair interact with one another, so an amide cannot simply be treated as an amine with an extra carbonyl group attached.
Ethanamide, CH₃CONH₂, is the main example used here. Once you understand how its structure controls its basicity, formation, hydrolysis and reduction, the reactions of primary amides become much easier to organise rather than memorise as separate equations.
Try these five questions before reading the chapter. Look carefully at the functional group and ask what happens to the carbonyl carbon and nitrogen during each reaction.
- 5 diagnostic questions
- Structures and reaction schemes where useful
- Instant explanation for every answer option
What are amides?
Amides are carboxylic acid derivatives in which the –OH part of the carboxyl group has been replaced by a nitrogen-containing group. For the primary amides considered here, the functional group is –CONH₂.
The simplest way to recognise an amide is therefore to look for a carbonyl group, C=O, whose carbon atom is bonded directly to nitrogen. In ethanamide, the complete condensed structural formula is CH₃CONH₂.
Recognition rule: an amide contains a nitrogen atom bonded directly to the carbonyl carbon. An –NH₂ group by itself does not necessarily mean that a compound is an amide.
Naming primary amides
Primary amides are named from the corresponding carboxylic acid. Replace the -oic acid ending of the acid name with -amide. For example, ethanoic acid gives ethanamide, while propanoic acid gives propanamide.
Ethanoic acid: CH₃COOH
Ethanamide: CH₃CONH₂
Amides are not the same as amines
This distinction matters because the nitrogen atom behaves very differently in the two functional groups. In an amine such as ethylamine, the nitrogen lone pair is relatively localised and can readily accept H⁺. In an amide, the nitrogen lone pair interacts with the neighbouring carbonyl group.
When deciding whether a nitrogen-containing compound is an amine or an amide, do not look only for nitrogen. Ask what the nitrogen is bonded to. If it is bonded directly to C=O, the compound contains an amide group.
Why are amides effectively neutral?
Amines are bases because the nitrogen atom has a lone pair that can accept H⁺. Since amides also contain nitrogen with a lone pair, it is tempting to expect them to behave in the same way. They do not.
The difference comes from delocalisation. The nitrogen lone pair in an amide occupies an orbital that can overlap with the adjacent carbonyl π system. Electron density can therefore be spread over the O–C–N region rather than remaining localised entirely on nitrogen.
These forms are not separate molecules rapidly changing from one to another. They are resonance contributors used to describe one delocalised electronic structure. The real amide has electron density distributed across the O–C–N system.
How delocalisation reduces basicity
For an amine to behave as a Brønsted–Lowry base, its nitrogen lone pair must be available to form a bond to H⁺. In an amide, using that lone pair to bond to H⁺ would disrupt the favourable delocalisation involving the carbonyl group.
As a result, the nitrogen lone pair is much less available for protonation. At A-Level, amides are therefore described as neutral, or more precisely as extremely weak bases compared with amines.
The key explanation: amides are effectively neutral because the lone pair on nitrogen is delocalised into the carbonyl π system and is therefore much less available to accept H⁺.
Why this explanation is better than saying oxygen “pulls” the lone pair away
Electronegativity certainly affects electron distribution, but the crucial A-Level idea is orbital overlap and delocalisation. The nitrogen lone pair interacts with the neighbouring carbonyl π system, producing resonance stabilisation across the amide group.
Therefore, an examination answer should use the word delocalised rather than simply saying that oxygen attracts the electrons.
Formation of amides from acyl chlorides
Primary amides can be prepared by reacting an acyl chloride with ammonia. Using ethanoyl chloride as the example gives ethanamide.
The reaction is a nucleophilic acyl substitution. Ammonia acts as the nucleophile and replaces the chlorine attached to the acyl carbon.
Why are two moles of ammonia required?
This is an important stoichiometric point. One ammonia molecule provides the nitrogen that becomes part of the amide. During the substitution, HCl is effectively produced. A second ammonia molecule reacts with this acid to form ammonium chloride.
First role of NH₃: acts as the nucleophile and supplies the nitrogen incorporated into CH₃CONH₂.
Second role of NH₃: neutralises the HCl formed, producing NH₄Cl.
Because ammonia is inexpensive and a second mole is required to remove the acid formed, excess concentrated ammonia is normally used. The reaction occurs readily at room temperature.
A common equation error is CH₃COCl + NH₃ → CH₃CONH₂ + HCl. That describes only part of the chemistry. In the actual reaction mixture, HCl reacts with ammonia, so the overall equation contains 2NH₃ and forms NH₄Cl.
Hydrolysis of amides
Hydrolysis reverses the idea behind forming an amide: the C–N bond of the amide group is broken and the carbonyl-containing portion becomes a carboxylic acid or carboxylate ion.
Amides are relatively stable because of delocalisation, so hydrolysis is not rapid under mild conditions. Heating is required, together with either aqueous acid or aqueous alkali.
Acidic hydrolysis
Ethanamide is heated with dilute aqueous acid, such as dilute HCl or dilute H₂SO₄. The organic product is ethanoic acid, while the nitrogen-containing product is present as an ammonium ion because the solution is acidic.
If hydrochloric acid is used, the ammonium ion is present as ammonium chloride. The important distinction is that NH₃ does not remain as free ammonia in strongly acidic solution; it is protonated to NH₄⁺.
Alkaline hydrolysis
When ethanamide is heated with aqueous sodium hydroxide, the organic product is not ethanoic acid. Any ethanoic acid formed in strongly alkaline solution is immediately deprotonated, so the final organic product is the ethanoate ion.
With sodium hydroxide, this can also be written as:
The nitrogen-containing product is ammonia because the reaction mixture is alkaline. This gives a useful way of recognising the outcome experimentally: the ammonia released can turn damp red litmus paper blue.
Use the reaction conditions to decide the products: acidic hydrolysis gives a carboxylic acid and NH₄⁺, whereas alkaline hydrolysis gives a carboxylate ion and NH₃.
Acidic versus alkaline hydrolysis
| Hydrolysis | Reagents and conditions | Products from ethanamide |
|---|---|---|
| Acidic | Dilute HCl or H₂SO₄, heat under reflux | CH₃COOH and NH₄⁺ |
| Alkaline | NaOH(aq), heat under reflux | CH₃COO⁻ and NH₃ |
Reduction of amides
Amides can also be reduced to amines. The reducing agent normally used is LiAlH₄ in dry ether.
During this reaction, the carbonyl C=O part of the amide is converted into a CH₂ group. Importantly, the carbon–nitrogen bond is retained.
Follow the carbonyl carbon
A useful way to predict the product is to track the carbonyl carbon. Reduction does not remove this carbon atom. Instead, the carbonyl carbon becomes a CH₂ carbon attached to nitrogen.
Before reduction: CH₃–CO–NH₂
After reduction: CH₃–CH₂–NH₂
This means that ethanamide, which contains two carbon atoms, produces ethylamine, which also contains two carbon atoms. Similarly, propanamide produces propylamine.
Do not shorten the carbon chain when reducing an amide. The carbonyl carbon remains part of the molecule; C=O is converted into CH₂.
Putting the reactions of ethanamide together
The reactions become easier to remember when you focus on what happens to the amide functional group rather than memorising isolated equations.
| Process | Reagents and conditions | Main organic product |
|---|---|---|
| Formation from ethanoyl chloride | Excess concentrated NH₃, room temperature | CH₃CONH₂ |
| Acidic hydrolysis | Dilute H⁺(aq), heat under reflux | CH₃COOH |
| Alkaline hydrolysis | NaOH(aq), heat under reflux | CH₃COO⁻ / CH₃COONa |
| Reduction | LiAlH₄, dry ether | CH₃CH₂NH₂ |
Think in patterns: hydrolysis breaks the C–N part of the amide and regenerates a carboxylic acid or carboxylate, whereas reduction keeps the C–N bond and converts C=O into CH₂.
Common Mistakes
| Common mistake | Why it is wrong | Better approach |
|---|---|---|
| Saying amides have no nitrogen lone pair | Nitrogen does have a lone pair. Its reduced basicity comes from delocalisation, not from the absence of the lone pair. | State that the nitrogen lone pair is delocalised into the carbonyl π system and is therefore less available to accept H⁺. |
| Using only one NH₃ in the overall acyl chloride equation | A second NH₃ molecule is needed to react with the HCl formed. | Write CH₃COCl + 2NH₃ → CH₃CONH₂ + NH₄Cl. |
| Writing ethanoic acid as the product of alkaline hydrolysis | In alkaline solution, the acid is deprotonated to form the ethanoate ion. | Write CH₃COO⁻, or CH₃COONa when NaOH is specified. |
| Removing the carbonyl carbon during reduction | LiAlH₄ reduces C=O to CH₂; it does not remove that carbon atom. | Keep the same number of carbon atoms when converting an amide into an amine. |
What you should be able to do
Recognise an amide
Identify the –CONH₂ functional group and distinguish it from an amine.
Explain amide neutrality
Use delocalisation of the nitrogen lone pair into the carbonyl system to explain why amides are much less basic than amines.
Prepare an amide
Write the reaction between an acyl chloride and excess ammonia, including the formation of NH₄Cl.
Predict acidic hydrolysis products
Recognise that acidic hydrolysis forms a carboxylic acid and NH₄⁺.
Predict alkaline hydrolysis products
Recognise that alkaline hydrolysis forms a carboxylate ion and NH₃.
Predict reduction products
Convert –CONH₂ into –CH₂NH₂ using LiAlH₄ while retaining the carbon skeleton.
These ten questions test whether you can apply the chapter to structures, reactions and unfamiliar examples.
- 10 mastery questions
- Structures and reaction schemes where useful
- Instant explanation for every answer option
Frequently asked questions
Questions students often ask about amides
The equations for amides are fairly compact, but several details repeatedly cause confusion — especially the neutrality of amides and the different products formed under acidic and alkaline conditions.
Why is ethanamide called an amide rather than an amine?
In ethanamide, the nitrogen atom is bonded directly to a carbonyl carbon, giving the functional group –CONH₂. That makes it an amide. In an amine such as ethylamine, CH₃CH₂NH₂, the nitrogen is not directly attached to a C=O group.
Does the nitrogen atom in an amide still have a lone pair?
Yes. The nitrogen has a lone pair, but the pair is delocalised into the adjacent carbonyl π system. It is therefore much less available to form a bond to H⁺ than the more localised lone pair in an amine. This is why amides are treated as effectively neutral at A-Level.
Why do we use two moles of NH₃ when an acyl chloride forms a primary amide?
One NH₃ molecule acts as the nucleophile and supplies the nitrogen that becomes part of the amide. A second NH₃ molecule reacts with the HCl produced, forming NH₄Cl. Hence the overall equation for ethanoyl chloride is CH₃COCl + 2NH₃ → CH₃CONH₂ + NH₄Cl.
Why does acidic hydrolysis give NH₄⁺ but alkaline hydrolysis gives NH₃?
The nitrogen-containing product depends on the reaction medium. In acidic solution, NH₃ accepts H⁺ and becomes NH₄⁺. In strongly alkaline solution, NH₃ remains predominantly unprotonated. The same reasoning explains why the organic product is a carboxylic acid under acidic conditions but a carboxylate ion under alkaline conditions.
Does LiAlH₄ reduction remove the carbonyl carbon of an amide?
No. The carbonyl carbon remains in the molecule. Reduction converts the C=O portion of the amide into CH₂ while retaining the C–N bond. Therefore ethanamide, CH₃CONH₂, forms ethylamine, CH₃CH₂NH₂, and both molecules contain two carbon atoms.
Amide chemistry becomes much easier once you connect every reaction back to the –CONH₂ group. Delocalisation explains why amides are exceptionally weak bases, hydrolysis breaks the C–N connection to regenerate a carboxylic acid or carboxylate, while reduction keeps that connection and converts C=O into CH₂. Those structural changes are the pattern worth remembering.