aldol condensation

chemistry

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 18, 2026

Quick Summary

The aldol reaction, also known as aldol condensation, is a chemical reaction where two molecules of an aldehyde that has at least one alpha-hydrogen combine. This reaction typically occurs in the presence of a base, such as sodium hydroxide. The product of this reaction is a beta-hydroxyaldehyde.1

A condensation reaction, in general, involves two molecules combining with the elimination of a small molecule, often water. Aldehydes, ketones, and esters are examples of organic compounds that can undergo self-condensation. The aldol itself is a beta-hydroxy aldehyde, used in organic synthesis.23

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

acid–base reaction
Aldol condensation, base-catalyzed
Self-condensation of aldehydes, the so-called aldol condensation, occurs readily, when catalyzed by bases, to give β-hydroxy aldehydes. The prototype of this reaction is the conversion of acetaldehyde to β-hydroxybutyraldehyde, or aldol. The first step of this reaction is the production of an…
Read More
Self-condensation of aldehydes, the so-called aldol condensation, occurs readily, when catalyzed by bases, to give β-hydroxy aldehydes. The prototype of this reaction is the conversion of acetaldehyde to β-hydroxybutyraldehyde, or aldol. The first step of this reaction is the production of an…
Read More

ketone
Reactions of ketones
…undergo aldol reactions (also called aldol condensation) by the use of certain techniques. The reaction is often used to close rings, in which case one carbon provides the carbonyl group and another provides the carbon with an α-hydrogen. An example is the synthesis of 2-cyclohexenone. In this example, the aldol…
Read More
…undergo aldol reactions (also called aldol condensation) by the use of certain techniques. The reaction is often used to close rings, in which case one carbon provides the carbonyl group and another provides the carbon with an α-hydrogen. An example is the synthesis of 2-cyclohexenone. In this example, the aldol…
Read More