Unit Overview

Carboxylic acid derivatives

CIE A-Level Chemistry· 5 min read 📊 n/a

1. Unit at a Glance

This unit builds on your prior knowledge of carboxylic acids to study related compounds that have critical industrial (polymer production, food preservatives) and biological (protein amide bonds) roles. The learning sequence progresses from general properties and reactivity of all derivative classes to a deep dive into acylation, a key reaction used frequently in CIE exam synthesis questions.

This unit is split into two connected sub-topics:

Properties and reactions of carboxylic acid derivatives

Learn nomenclature, physical properties, reactivity trends, and core reactions of all common carboxylic acid derivative classes.

★★★⏱ 15 min

Acylation reactions

Master nucleophilic acyl substitution mechanisms and key applications of acylation in organic synthesis.

★★★★⏱ 18 min

2. Common Pitfalls

Wrong move:

Reversing the reactivity order of carboxylic acid derivatives

Why:

Many students forget that electron-donating groups reduce the electrophilicity of the acyl carbon, slowing nucleophilic attack

Correct move:

Remember reactivity from highest to lowest: acyl chlorides > acid anhydrides > esters > amides

Wrong move:

Drawing nucleophilic addition instead of substitution for acyl reactions

Why:

Acyl derivatives have a good leaving group attached to the acyl carbon, unlike aldehydes/ketones

Correct move:

Always include the leaving group departure step to form a substituted acyl product

3. Quick Reference Cheatsheet

Concept	Key Summary
Reactivity order	$Acyl chloride > Acid anhydride > Ester > Amide$
General nucleophilic acyl substitution	$R C O Z + N u^{-} \to R C O N u + Z^{-}$
Acidic ester hydrolysis	Reversible, produces carboxylic acid + alcohol
Alkaline ester hydrolysis	Irreversible, produces carboxylate salt + alcohol
Acylation definition	Transfer of an acyl group ( $R C O -$ ) to a nucleophile via nucleophilic acyl substitution

What's Next

Begin this unit by learning the core properties and reactivity trends of carboxylic acid derivatives to build a foundation for more complex reaction mechanisms. Once you complete this sub-topic, you will move on to study acylation reactions in depth. After finishing the entire unit, you can proceed to the next topic on nitrogen compounds.