What is the product of a mixed aldol condensation between p-tolualdehyde (C8H8O) and acetone?

1 Answer
Dec 27, 2015

The major product should be (#E,E#)-bis(4-methylbenzylidene)acetone.


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

Aldol condensation
(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 reacts with acetone to give dibenzalacetone.


By analogy, I predict that 4-methylbenzaldehyde will react with acetone to form (#E,E#)-bis(4-methylbenzylidene)acetone.


The major product should be the more stable #E,E# isomer.