Question

Why is the major product between p-anisaldehyde and acetophenone the crossed aldol product rather than the Cannizzaro reaction or the self-condensation ofacetophenone?

Please actually explain instead of showing a mechanism. I do know the mechanism but am having a hard time understanding why these two other reactions are not favored.

Answer 1

Only the acetophenone has an acidic hydrogen (on the methyl group), so it's going to be a nucleophile in the Aldol reaction. The aldehyde can't be thenucleophile because it can't form an enolate. On the other hand the aldehyde is a more reactive electrophile than the ketone, so the major product arisesfrom the crossed condensation reaction. The cannizzaro reaction typically needs more forcing conditions -- it's just a slower reaction typically than theAldol condensation.