A LevelChemistryCIETopic Questions33. Carboxylic Acids & Derivatives (AL)33.3 Acyl Chlorides

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First teaching 2023

First exams 2025

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Acyl Chlorides (CIE A Level Chemistry)

Topic Questions

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1a1 mark

This question is about derivatives of carboxylic acids.

Fig 1.1 shows the structure of a carboxylic acid derivative.

 

butanoyl-chloride

Fig 1.1

State the name of the carboxylic acid derivative in Fig 1.1.

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1b2 marks

Ethanoyl chloride reacts with ethanol to form ethyl ethanoate as shown in Fig 1.2.

formation-of-ethyl-ethanoate-from-ethanoyl-chloride
Fig 1.2

i)
Name the other product formed in this reaction.
[1]
ii)
This reaction can be described as an esterification reaction or an acylation reaction.

   Explain why this reaction can also be described as a condensation reaction.

 [1]

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1c1 mark

Ethanoyl chloride can also react with ammonia to form ethanamide. 

Write an equation for this reaction. 

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1d1 mark

During the preparation of propanoyl chloride, SO2 and HCl were also produced. 

Name the two reactants used to form propanoyl chloride. 

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2a1 mark

Propanoyl chloride is used for the synthesis of other organic compounds. 

Draw the skeletal formula for propanoyl chloride. 

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2b3 marks
i)
Name the two products formed when propanoyl chloride undergoes hydrolysis.
[2]
ii)
Name the mechanism by which hydrolysis occurs. 
[1]

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2c2 marks

Explain why propanoyl chloride will more readily undergo hydrolysis compared to 2-chloropropane.

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1a2 marks

Propyl propanoate can be prepared using propanal.

Suggest a reaction scheme, using fully displayed formulae, that could be used to prepare asample of propyl propanoate.

Conditions and reagents are not required.

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1b1 mark

Use your answer from part (a) to help answer this question. One of the intermediates in the reaction scheme, from part (a), has a molecular mass of 74.0 g mol-1.

State the reagents and conditions required to form this intermediate.

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1c2 marks

Propanal and the other intermediate (Mr = 60.0) in the reaction scheme, from part (a), are to be separated by distillation.

Explain which chemical will distil first.

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2a5 marks

Esters have important commercial uses, such as artificial flavourings in food. 

They can be prepared in several ways, including through the reactions of alcohols with carboxylic acids, as well as the carboxylic acid derivatives, acid anhydrides and acyl chlorides.

Ester Z, CH3CH2COOCH2CH(CH3)2 is used in rum flavouring. 

Outline how you could obtain a sample of ester Z, beginning with a named alcohol and carboxylic acid.

Include any essential reaction conditions and write an equation for the reaction.

You do not need to include details of the separation or purification methods involved.

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2b2 marks

Another ester, phenyl ethanoate, can be used as a starting material for the formation of a variety of other organic compounds. 

i)
Draw the skeletal formula for the symmetrical acid anhydride that could be used to form phenyl ethanoate. 
 
[1]
 
ii)
Write an equation for the preparation of phenyl ethanoate from this acid anhydride and an alcohol. 
 
[1]

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2c3 marks

Phenyl ethanoate can also be formed from ethanoyl chloride.

Describe the steps involved, using equations, to form phenyl ethanoate, starting with the synthesis of ethanoyl chloride. State one condition needed.

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3a5 marks

The carbon-13 (13C) NMR spectrum of compound A, C3H8O, contains three peaks.

Compound A reacts with acidified potassium dichromate to give a mixture of compounds B and C.

Compound C reacts with sulfur dichloride oxide, SOCl2, to form compound D.

Compound D reacts with phenol to form compound E, C9H10O2.

Draw the structures of compounds A, B, C, D and E in the boxes.

phenyl-propanoate-reaction-scheme-blank

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3b3 marks

A mixture of compound B and compound C is formed when compound A reacts with acidified potassium dichromate.

i)
Explain how the mixture can be separated into compounds B and C.
 
[2]
 
ii)
Suggest an improvement to the reaction with acidified potassium dichromate to ensure the production of compound C only.
 
[1]

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3c4 marks

When heated in the presence of sodium hydroxide, compounds C and D can both react with phenol to form compound E. 

i)
Draw a mechanism for the formation of compound E from compound D and an appropriate nucleophile. Include all necessary curly arrows and charges.
 
[3]
 
ii)
Under these conditions, the reaction of compound D with phenol is faster than compound C.
 
Suggest why the reaction with compound D is faster. Explain your answer.
 
[1]

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1a2 marks

Acyl chlorides are commonly used carboxylic acid derivatives. 

Ethanoyl chloride reacts with an excess of ammonia. 

A student proposes the following equation to represent the reaction:

CH3COCl + NH3  →  CH3CONH2 + HCl

Correct and explain the student's error.

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1b3 marks

N-methylethanamide can also be formed from ethanoyl chloride. 

i)
Draw the skeletal formula of N-methylethanamide.

[1]

ii)
Write an equation for the formation of N-methylethanamide from ethanoyl chloride. 

[2]

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1c1 mark

Ethanoyl chloride will react with 2-methylpropan-1-ol to form an ester. 

Draw the structure of the ester formed.

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2a3 marks

This question is about butanoyl chloride. 

Butanoyl chloride can be produced from butanoic acid. 

i)
Draw the displayed formula of butanoyl chloride. 
[1]
ii)
Give the name and formula of a reagent that produces butanoic acid from butanoyl chloride. 

[2]

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2b3 marks
i)
Explain why butanoic acid is a weaker acid than 2-chlorobutanoic acid.

[2]

ii)
Draw the skeletal formula for 2-chlorobutanoic acid.

[1]

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2c1 mark

Name a chloro-substituted butanoic acid that is a strong acid than 2-chlorobutanoic acid. 

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2d4 marks

Butanoyl chloride can undergo hydrolysis. 

Outline a mechanism for the hydrolysis of butanoyl chloride. 

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2e5 marks

Explain the relative ease of hydrolysis for butanoyl chloride, chlorobenzene and 1-chorobutane. 

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3a5 marks

A common method for esterification is to react an alcohol with an acyl chloride.

Name and outline the mechanism for the reaction of butan-2-ol with ethanoyl chloride.

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3b3 marks

Acyl chlorides undergo various reactions with water, alcohols, ammonia and primary amines.

Ethanamide is the product of a chemical reaction.

Identify the necessary reactants and name the other product.

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3c4 marks

Ethanoyl chloride can react with primary aliphatic and aromatic amines to produce different amides.

i)
Explain why ethanoyl chloride is quicker to react with ethylamine than phenylamine. 

ii)
Name the products of both reactions and classify the nitrogen in the product.

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