Preparation of Dibenzalacetone

This experiment aims to prepare dibenzalacetone (dibenzylideneacetone).

Here, benzaldehyde undergoes condensation with acetone in the presence of aqueous sodium hydroxide (NaOH) to give dibenzalacetone. Let us take a look at the preparation of dibenzalacetone in a virtual lab.

Apparatus Required-

• Conical flask                  
• Beaker                   
• Buchner funnel       
• Ice bath                                   

Chemicals Required-

• Acetone: 2.3 mL
• Distilled water
• Ethanol: 25 mL
• NaOH: 3.15 g
• Benzaldehyde: 3.2 mL

Procedure-

To prepare dibenzalacetone, we have to follow the following procedure: 

• Firstly dissolve 3.15 g of sodium hydroxide into 25 mL of ethanol and 30 mL of distilled water in a beaker.
• Cool the beaker in an ice bath maintained at a temperature of about 20–25 °C.
• Prepare a mixture of 3.2 mL of benzaldehyde and 2.3 mL of acetone in a conical flask.
• Slowly add half of this mixture to the ice-cooled NaOH solution prepared in the first step with vigorous stirring.
• A fluffy precipitate will form within a few minutes.
• Stir the mixture gently for about fifteen minutes. Then, add the remaining mixture of benzaldehyde and acetone and stir it for 30 more minutes.
• Filter the pale yellow solid obtained and wash it with cold water.
• Dry it and recrystallise its small amount in ethanol.

Precautions-

• Maintain the temperature at around 20 °C while shaking the reaction mixture. 
• Always use freshly distilled benzaldehyde or the sample from a freshly opened bottle.

In this experiment, we conclude that:

Dibenzalacetone is a pale yellow crystalline solid that can be prepared by the Claisen-Schmidt reaction between benzaldehyde and acetone.

FAQs on Preparation of Dibenzalacetone