What is the product of the aldol condensation between cyclopentanone and 4-methylbenzaldehyde?

The product is probably (##2E,5E##)-2,5-bis(4-methylbenzylidene)cyclopentanone.

The aldol condensation involves attack of an enolate ion on the base of a carbonyl compound to form a β-hydroxycarbonyl compound (an aldol).

(from www.chem.ucla.edu)
The aldol can then dehydrate to form an α,β-unsaturated carbonyl compound.
The process requires an active methylene adjacent to a carbonyl group.

If there are two active methylenes, the condensation can occur on each side of the carbonyl group.
For example, benzaldehyde with acetone gives dibenzalacetone.

By analogy, I predict that 4-methylbenzaldehyde with cyclopentanone will form

The ##E,E## isomer should be more stable because the steric interactions of the ortho hydrogens with the ##”H”## atoms on the cyclopentane ring are smaller than those with the carbonyl oxygen

Posted in Uncategorized

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes:

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>