Give the general formula of an acyl chloride.

It is RCOCl, a carbonyl group bonded to a chlorine atom.

Why is an acyl chloride so much more reactive than the corresponding carboxylic acid?

Chlorine is strongly electron withdrawing and is a good leaving group, so the carbonyl carbon is highly positively charged and easily attacked.

Write an equation for the reaction of ethanoyl chloride with ethanol.

CH₃COCl + CH₃CH₂OH → CH₃COOCH₂CH₃ + HCl.

What would you observe when ethanoyl chloride is added to ethanol?

A vigorous reaction occurs at room temperature and misty fumes of hydrogen chloride are given off.

Why is making an ester from an acyl chloride preferred to making it from a carboxylic acid?

The reaction is fast at room temperature, needs no catalyst and goes to completion because it is not reversible.

OCR A-Level Chemistry B H433

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Polymers and Life

Reactions of acyl chlorides

3 things to know
Components 01, 02 and 03

Overview

Recall questions on why an acyl chloride is so reactive, and its reactions with water, alcohols and amines and what is observed.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Numbers

Why is an acyl chloride more reactive than the carboxylic acid, and what is the equation for, and what is seen when, ethanoyl chloride meets ethanol?

Numbers

What is the equation for ethanoyl chloride with methylamine, why is excess amine used, and which part attacks?

Key term

Name the ester and the other product formed when propanoyl chloride reacts with methanol.

Questions from this subtopic

Each one with the model answer underneath.

1
Give the general formula of an acyl chloride.
Model answer
It is RCOCl, a carbonyl group bonded to a chlorine atom.
2
Why is an acyl chloride so much more reactive than the corresponding carboxylic acid?
Model answer
Chlorine is strongly electron withdrawing and is a good leaving group, so the carbonyl carbon is highly positively charged and easily attacked.
3
Name the organic product when an acyl chloride reacts with an alcohol.
Model answer
An ester.
4
Write an equation for the reaction of ethanoyl chloride with ethanol.
Model answer
CH₃COCl + CH₃CH₂OH → CH₃COOCH₂CH₃ + HCl.
5
What would you observe when ethanoyl chloride is added to ethanol?
Model answer
A vigorous reaction occurs at room temperature and misty fumes of hydrogen chloride are given off.
6
Why is making an ester from an acyl chloride preferred to making it from a carboxylic acid?
Model answer
The reaction is fast at room temperature, needs no catalyst and goes to completion because it is not reversible.

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