THE ALDOL CONDENSATION
SYNTHESIS OF DIBENZALACETONE
Organic Chemistry II Lab – Section 7515
March 24, 2004
The purpose of this experiment was to obtain dibenzalacetone through
condensation of acetone with 2 equivalents of benzaldehyde and to calculate
the percent yield and the melting point(s) of the final product.
5ml of benzaldehyde and 1.8ml of acetone were mixed. Half of this
mixture was added to the already made solution containing 5g of sodium
hydroxide and 50ml of water and 40ml of ethanol. After some period of time,
the other half of mixture was added to the solution and the flask was
rinsed with ethanol. The mixture was swirled occasionally for about half an
hour, after which the product was collected by suction filtration. 100ml of
water was then poured over the product. This process of suction and the
addition of water was repeated several times. At last, the final product
was pressed between two sheets of filter paper to remove water. Small
sample was saved for the determination of the melting point, and the rest
of the product was re crystallized from ethanol (10ml of ethanol for 4g of
– DATA –
RESULTS AND CALCULATION
– DISCUSSION –
OBSERVATION AND EXPLANATION
The final product obtained was dibenzalacetone. This molecule
actually consists of three isomers having different properties.
The amount of dibenzalacetone before re crystallization was 3.647g.
The amount of ethanol used for re crystallization was 9.1ml. The amount of
re crystallized dibenzalacetone was 3.893g. The percent yield was 67%.
As mentioned earlier, dibenzalacetone consists of three isomers: two
solids and a liquid. The melting points obtained were 107-110 degrees
Celsius and 58-60 degrees Celsius.