Form an ester from an acyl chloride and phenol
Use phenol and an acyl chloride at room temperature to form an aryl 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 does phenol contribute when it forms an ester with an acyl chloride?
What you will learn
- Describe the reaction of phenol with an acyl chloride
- Predict a phenyl ester
- Connect this reaction with phenyl benzoate
Phenol supplies the ester oxygen
Phenol reacts with an acyl chloride at room temperature to form an ester and HCl. For benzoyl chloride, the product is phenyl benzoate: C₆H₅COCl + C₆H₅OH → C₆H₅COOC₆H₅ + HCl.
The phenolic oxygen is bonded to the acyl carbon in the ester. The product retains one phenyl group from phenol and one benzoyl-derived ring from the acyl chloride.
Do not confuse phenyl and benzyl
The group from phenol is phenyl, C₆H₅–, attached through oxygen. Benzyl would include an extra –CH₂– group.
The reaction follows the acyl-chloride addition–elimination pattern; write the HCl by-product and keep the carbonyl in the ester.
Pause and explain
What is the ester from phenol and ethanoyl chloride?
Worked example
Name the ester from phenol and ethanoyl chloride.
Show the worked solution
- Phenol contributes phenyl through oxygen.
- Ethanoyl chloride contributes ethanoate.
- Name alkyl/aryl first and carboxylate second.
Answer Phenyl ethanoate and HCl form.
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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.
Complete C₆H₅OH + CH₃COCl → …
Give me a hint
Use phenol's oxygen to link phenyl to the acyl carbon.
Compare my reasoning
- The acyl part is CH₃CO–.
- Phenol contributes C₆H₅O–.
- Include HCl.
CH₃COOC₆H₅ + HCl (phenyl ethanoate and hydrogen chloride).
Look for these in your work
- Ester structure
- Phenyl group
- HCl
Compare the alcohol-derived group in ethyl ethanoate with the phenol-derived group in phenyl benzoate.
Give me a hint
Check whether a CH₂ group separates the ring from oxygen.
Compare my reasoning
- Ethyl ethanoate has CH₃CH₂– attached through oxygen.
- Phenyl benzoate has C₆H₅– attached directly through oxygen.
- Neither is a benzyl group in these examples.
Ethyl is an aliphatic group; phenyl is a ring attached directly to oxygen, with no intervening CH₂.
Look for these in your work
- Ethyl identified
- Phenyl identified
- Benzyl excluded
A response says phenol does not react because it is not an alcohol. Correct it using the syllabus outcome.
Give me a hint
The reaction is specifically listed for phenol and acyl chlorides.
Compare my reasoning
- Phenol has an O–H group attached to an aromatic ring.
- It reacts with an acyl chloride at room temperature.
- An ester and HCl form.
Phenol reacts with an acyl chloride to form a phenyl ester and HCl; the syllabus explicitly includes this reaction.
Look for these in your work
- Phenolic group recognised
- Reaction condition
- Products
Common mistakes
- Writing benzyl ethanoate
- Removing the carbonyl oxygen
- Calling the product phenyl ethanoic acid
- Omitting HCl
What can you explain now?
What does phenol contribute when it forms an ester with an acyl chloride?
Compare with the explanation
A phenyl group attached through oxygen
The phenolic oxygen forms the ester linkage.
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Make it stick
How does phenol form an ester with an acyl chloride, and what group name appears in the product?
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