Frequently Asked Question

The slow addition of acetaldehyde to a benzaldehyde solution containing base minimizes self-condensation because it allows for the rapid reaction of the acetaldehyde with the benzaldehyde, preventing the acetaldehyde from reacting with itself. This is due to the higher reactivity of benzaldehyde compared to acetaldehyde under basic conditions. The addition of a strong base, like NaOH, deprotonates the acetaldehyde to form an enolate ion, which is highly reactive and will preferentially react with the more electrophilic benzaldehyde.
One other method to combat this competitive reaction is to use a milder base, such as a weak base like triethylamine. This will decrease the rate of both reactions, but it will significantly reduce the rate of self-condensation of acetaldehyde compared to the aldol condensation with benzaldehyde.