Acyl Chlorides (Cambridge (CIE) A Level Chemistry): Exam Questions

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.

N-methylethanamide can also be formed from ethanoyl chloride. 

i) Draw the skeletal formula of N-methylethanamide.

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

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

Draw the structure of the ester formed.

This question is about butanoyl chloride. 

Butanoyl chloride can be produced from butanoic acid. 

i) Draw the displayed formula of butanoyl chloride. 

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ii) Give the name and formula of a reagent that produces butanoic acid from butanoyl chloride. 

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

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

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

Butanoyl chloride can undergo hydrolysis. 

Outline a mechanism for the hydrolysis of butanoyl chloride. 

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

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.

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.

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.

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.

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.

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

Explain which chemical will distil first.

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.

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.  

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 ii) Write an equation for the preparation of phenyl ethanoate from this acid anhydride and an alcohol.  

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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.

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.

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. 

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 ii) Suggest an improvement to the reaction with acidified potassium dichromate to ensure the production of compound C only. 

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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. 

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 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. 

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