Form an ester from an acyl chloride and an alcohol
React an acyl chloride with an alcohol at room temperature to form an ester and HCl.
A Level; Cambridge International Chemistry 9701, 2028–2030 syllabus, Topic 33. Focus on the named compounds, reagents and conditions in each outcome; apply the specified reaction type rather than extending it to unlisted cases. Written practice is self-checked
Before you begin
- Recall carboxylic acids, esters, phenols, alcohols, halogenoalkanes and electrophilic/nucleophilic reaction ideas from earlier topics.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What product class forms when an alcohol reacts with an acyl chloride?
What you will learn
- Describe ester formation from an acyl chloride and alcohol
- Predict the ester from each reactant
- Identify HCl as the by-product
Combine acyl and alcohol fragments
An acyl chloride reacts with an alcohol at room temperature to form an ester and HCl: RCOCl + R′OH → RCOOR′ + HCl.
The acyl chloride supplies RCO–; the alcohol supplies the group attached to the ester oxygen. The C–Cl bond is replaced by a C–O bond.
Name the ester from its two parts
For example, ethanoyl chloride plus ethanol forms ethyl ethanoate. Track the alcohol-derived alkyl group and the acyl-derived carboxylate name separately.
This reaction is one of the listed acyl-chloride substitution reactions and proceeds by addition–elimination at the carbonyl carbon.
Pause and explain
Which part of an ester name comes from the alcohol?
Worked example
Predict the products from ethanoyl chloride and propan-1-ol.
Show the worked solution
- The acyl portion is ethanoate.
- The alcohol supplies propyl.
- Add HCl as the by-product.
Answer Propyl ethanoate and HCl form.
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Test this topic →From guided practice to a new situation
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.
Complete CH₃COCl + CH₃CH₂CH₂OH → …
Give me a hint
Join the ethanoyl group to the alcohol oxygen.
Compare my reasoning
- The acyl fragment is CH₃CO–.
- The alcohol contributes propyl through oxygen.
- Include HCl.
CH₃COOCH₂CH₂CH₃ + HCl (propyl ethanoate and hydrogen chloride).
Look for these in your work
- Ester linkage
- Propyl group
- HCl
Name the ester formed from butanoyl chloride and methanol.
Give me a hint
Name the alcohol-derived group first.
Compare my reasoning
- Methanol contributes methyl.
- Butanoyl chloride contributes butanoate.
- Combine alkyl then carboxylate.
Methyl butanoate.
Look for these in your work
- Methyl identified
- Butanoate identified
- Order correct
A student predicts propanoic acid from ethanoyl chloride and ethanol. Which reactant change would actually produce the ester they expect?
Give me a hint
Compare water hydrolysis with alcoholysis.
Compare my reasoning
- Water hydrolysis of ethanoyl chloride forms ethanoic acid.
- Ethanol reacts to form an ester.
- The ester is ethyl ethanoate, not propanoic acid.
Ethanoyl chloride with ethanol forms ethyl ethanoate and HCl; ethanoic acid would form by hydrolysis with water.
Look for these in your work
- Reagent distinction
- Ester product
- Acid route compared
Common mistakes
- Using the alcohol name for the acyl portion
- Forgetting HCl
- Reversing the alkyl and carboxylate parts
- Writing a carboxylic acid instead of an ester
What can you explain now?
What product class forms when an alcohol reacts with an acyl chloride?
Compare with the explanation
An ester
The alcohol oxygen becomes part of the ester linkage.
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Make it stick
How do the acyl chloride and alcohol determine the ester and by-product?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.