Preparation and Identification of Dibenzylidene Acetone

Experiment: Preparation and Identification of Dibenzylidene Acetone
Purpose:
Prepare dibenzylidene acetone by the famous Claisen-Schmidt condensation reaction.
Learn the experimental skills of organic synthesis, separation, purification, structural characterization by instrumental analysis.
Train the ability to solve the practical problems.
Principle:
Aromatic aldehydes can have aldol reaction with aldehydes or ketones which have α-hydrogen atoms, dehydrate to form high yield of α,β-unsaturated aldehydes or α,β-unsaturated ketones under catalytic of alkalis.
These kinds of reactions are called Claisen-Schmidt condensation reaction. It is an important approach to grow the carbon chain and can be used to synthesize aromatic compounds which have two different function groups on their side chains, or the aliphatic system intermediates which have several benzenes.
This experiment will synthesize dibenzylidene acetone by the reaction of benzaldehyde and acetone under the catalytic of alkalis.
Dibenzylidene acetone is an important organic synthesis intermediate, which can be used to synthesize spices, pharmaceutical intermediates, sunscreen products and other fine chemicals.
The reaction formula is stated as following:

And the mechanism of this reaction is stated as following:

Reagents and Apparatus:
The reagents will be used in this experiment include benzaldehyde, 95% ethanol, 0.5M NaOH solution and acetone. Here are some of their physical properties.
Name
Molecular Formula
Molecular Weight
Melting Point (℃)
Boiling Point (℃)
Density (g·cm-3)
Character
Benzaldehyde
C7H6O
106.12
－26
178
1.0415
(10/4℃)
Colorless fluid, bitter almond flavor.
Acetone
C3H6O
58.08
-94.7
56.05
0.7845
Colorless fluid, pleasant spicy and sweet flavor.
Ethanol
C2H5OH
46.07
-114.3
(158.8 K)
78.4
(351.6 K)
0.789
Colorless transparent fluid, pleasant and burning flavor. Easy to evaporate.
Sodium Hydroxide
NaOH
40.01
318
1390
2.13
Molten