Answer:
[tex]\mathbf{a \ strong \ base \ such \ as\ LiOH \ or \ NaOH.}[/tex]
Explanation:
In the condensation reactions of carbonyl compounds, it is essential to establish the order of events in advance to minimize or suppress the possibilities of self-condensation and the occurrence of cross-condensation, which unfortunately are an obvious threat in these reactions.
Self-condensation:
Any carbonyl compound that has one or more alpha hydrogens, on the carbons adjacent to the carbonyl group, runs the risk of undergoing a self-condensation reaction if the corresponding rigor is not carried out.
Cross-condensation:
Ideally, in the condensation reactions of carbonyl compounds, one of the reacting molecules should quickly enolise, while the other preferably should not have Hα, to ensure that no other by-products are formed.
[tex]\text{To achieve this process;}[/tex] [tex]\text{A self-aldol or crossed aldol requires a strong base such as LiOH or NaOH.}[/tex]