DIBENZALACETONE


BY


THE ALDOL CONDENSATION


-


SYNTHESIS OF DIBENZALACETONE


























Post-Lab


Organic Chemistry II Lab – Section 7515


March 24, 2004


INTRODUCTION


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.





EXPERIMENTAL PROCEDURE


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 dibenzalacetone).


- 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.