Waiting
Login processing...

Trial ends in Request Full Access Tell Your Colleague About Jove

15.21: Crossed Aldol Reactions: Overview

TABLE OF
CONTENTS
JoVE Core
Organic Chemistry

A subscription to JoVE is required to view this content.

Education
Crossed Aldol Reactions: Overview
 
TRANSCRIPT

15.21: Crossed Aldol Reactions: Overview

Crossed aldol addition is the reaction between two different carbonyl compounds under acidic or basic conditions. Here, both the carbonyl compounds function as nucleophiles and electrophiles. As shown in Figure 1, such a reaction yields a mixture of products, two of which are formed via self-condensation, while the remaining two are formed via crossed-condensation. Without adjustment, the reaction's usefulness in organic chemistry is decreased.

Figure1

Figure 1. Crossed aldol addition reaction of two different aldehydes

Various strategies are employed to prevent self-condensation and improve the reaction's efficiency. For example, if one of the two reacting carbonyl compounds has no α hydrogen, such as the formaldehyde, it cannot form the enolate ion in the presence of a base. Hence, the reaction of formaldehyde with another carbonyl compound that does have an α hydrogen yields a single crossed aldol product. Here, the formaldehyde functions exclusively as an electrophile. Claisen–Schmidt condensation, directed aldol reaction, and the Reformatsky reaction also aim to yield a single crossed aldol product.

Tags

Crossed Aldol Reactions Carbonyl Compounds Nucleophiles Electrophiles Self-condensation Crossed-condensation Organic Chemistry Reaction Efficiency Enolate Ion Base Formaldehyde Crossed Aldol Product Claisen-Schmidt Condensation Directed Aldol Reaction Reformatsky Reaction

Get cutting-edge science videos from JoVE sent straight to your inbox every month.

Waiting X
Simple Hit Counter