The key difference between aldol addition and aldol condensation is that aldol addition refers to the addition of a ketone enolate or an aldehyde enolate to a carbonyl compound, whereas aldol condensation refers to the loss of a water molecule from an aldol product to form an α,β-unsaturated carbonyl compound.
Aldol reaction is a type of coupling reaction that has two steps: aldol addition and aldol condensation. This reaction is very important in organic synthesis for the formation of a carbon-carbon chemical bond. In this reaction, two carbonyl compounds combine with each other and form a new beta-hydroxyl carbonyl compound. This product is called an aldol; thus, the reaction is named an aldol reaction.
CONTENTS
1. Overview and Key Difference
2. What is Aldol Addition
3. What is Aldol Condensation
4. Aldol Addition vs Aldol Condensation in Tabular Form
5. Summary – Aldol Addition vs Aldol Condensation
What is Aldol Addition?
Aldol addition is an organic reaction that involves the addition of a ketone enolate to an aldehyde. The term aldol is a combination of aldehyde and alcohol. In this reaction, the alpha carbon of an enolate of an aldehyde or a ketone reacts with the carbonyl group of another organic compound to give a beta-hydroxy aldehyde or beta-hydroxy ketone.
The aldol reaction can occur in two ways: under acidic conditions or under basic conditions. The base or the acid acts as a catalyst for the reaction. In the base-catalyzed reaction, the hydroxide ion of the base attacks the alpha hydrogen of the carbonyl compound. In the acid-catalyzed mechanism, the H+ ion or the proton released from the acid attacks the oxygen atom of the carbonyl group.
What is Aldol Condensation?
Aldol condensation is an organic synthesis reaction in which the dehydration of an aldol product occurs. The end product is a conjugated enone. This reaction is very important in introducing a carbon-carbon bond to a particular molecule.
If the reactant is an aldehyde, then the intermediate product is beta-hydroxyaldehyde, but if the reactant is a ketone, then the intermediate product is beta-hydroxyketone. These products then undergo dehydration to produce an α,β-unsaturated carbonyl compound. This dehydration step is an elimination reaction.
What is the Difference Between Aldol Addition and Aldol Condensation?
Aldol reaction is a type of coupling reaction that has two steps: aldol addition and aldol condensation. Aldol addition is an organic reaction that involves the addition of a ketone enolate to an aldehyde, while aldol condensation is an organic synthesis reaction in which the dehydration of an aldol product occurs. Therefore, the key difference between aldol addition and aldol condensation is that aldol addition refers to the addition of a ketone enolate or an aldehyde enolate to a carbonyl compound, whereas aldol condensation refers to the loss of a water molecule from an aldol product to form an α,β-unsaturated carbonyl compound.
The below infographic lists the differences between aldol addition and aldol condensation in tabular form for side by side comparison.
Summary – Aldol Addition vs Aldol Condensation
Aldol reaction has two steps as aldol addition and aldol condensation. The key difference between aldol addition and aldol condensation is that aldol addition refers to the addition of a ketone enolate or an aldehyde enolate to a carbonyl compound, whereas aldol condensation refers to the loss of a water molecule from an aldol product to form an α,β-unsaturated carbonyl compound.
Reference:
1. “Introduction to Volume 2: Additions to CX π-Bonds, Part 2.” Comprehensive Organic Synthesis II, 2014, p. xiii., doi:10.1016/b978-0-08-097742-3.09032-7.
2. “Aldol Addition Aldol Reaction.” Organic Chemistry.
3. “Aldol Reaction.” Wikipedia, Wikimedia Foundation, 18 Dec. 2019.
Image Courtesy:
1. “Typical aldol-en” By derivative work (translated text): DMacks (talk)Typical aldol-id.svg: Hand15Typicalaldol.gif: E kwanTypicalaldol2.gif: Dr Zak – Typical aldol-id.svgTypicalaldol.gifTypicalaldol2.gif (Public Domain) via Commons Wikimedia
2. “Simple aldol reaction” By Krishnavedala – Own work (CC0) via Commons Wikimedia