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

1 Answer
Dec 27, 2015

Answer:

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

Explanation:

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.

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

(E,E)-bis(4-methylbenzylidene)acetone

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