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Synthesis of Dibenzalacetone from Bezaldehyde and Acetone

Reacting Benzaldehyde with acetone to yield Dibenzalacetone.

Increased the amount of benzaldehyde used from 2 equivalents to 4 equivalents. NaOH catalyst solution and benzaldehyde is stirred, BEFORE adding the acetone. Added acetone to solution. This mixture is stirred for 30 min and a yellow precipitate is collected (dibenzalacetone product). Washed the product with water, and tested for a neutral solution. Recrystallization was performed to purify the product using warm 95% ethanol.

The NaOH catalyst is prepared dissolving .4g sodium hydroxide in 4.0ml water. To this solution 3.0ml of 95% ethanol was added.

1. Why would the procedure need to be adjusted to add 4 equivalents of benzaldehyde in the reaction instead of 2 equivalents?

2. Why was acetone added to the reaction mixture only after we briefly mixed the catalyst and the behzaldehyde?

3. Why doesn't the dibenzalacetone product react (via the aldol condensation pathway) with the excess benzaldehyde in the reaction mixture?

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