Preparation of Dibenzalacetone by the Aldol Condensation
Preparation of Dibenzalacetone by the Aldol condensation
David o Neill
Date of experiment: 14/12/2011
Apparatus
Steam bath, ice bath, Buchner funnel, beaker, conical flask, filter paper, TLC apparatus, Melting point apparatus
Materials / chemicals
Benzaldehyde, acetone, ethanolic sodium hydroxide, ethanol
Introduction
The synthesis of dibenzalacetone is formed from an Aldol condensation reaction. An Aldol condensation reaction is a very effective way of forming a carbon – carbon bond reaction, in which the enolate anion adds to the carbonyl group of the aldehyde. Aldol condensations are very versatile, as the enolate anion of the carbonyl compound can be added to the carbonyl carbon of another. The synthesis of dibenzalacetone is an example of a mixed Aldol condensation reaction.
This experiment involves condensating acetone with two measures of Benz aldehyde (giving dibenzalacetone, an organic sun screen). The carbonyl group on the aldehyde is more reactive than that of the keytone. Therfore the enolate ion of Benz aldehyde adds to the carbonyl group of the acetone giving b-hydroxykeytone. This then undergoes base catalysed reaction with ease. Depending on the quantity of reactants used the reaction may produce mono or dibenzalacetone. Because we want dibenzalacetone, 2 moles of Benz aldehyde is reacted with one mole of acetone in the presence of sodium hydroxide.
The reaction scheme is given by:
Procedure
· Initially in the synthesis of Dibenzalacetone I mixed 5 mL (0.049 moles) of Benz aldehyde with 1.8 mL (0.0245 moles) of acetone in a small beaker.
· I then added half of this mixture to 90 mL of ethanoic sodium hydroxide in a 100 mL conical flask.
· I allowed this mixture to stand for 15 mins.
· I then placed the remainder of the previous aldehyde- keytone mixture into this conical flask and swirled the solution for 30 mins.
· The product was collected under suction using the Buchner funnel and the suction pump.
· The collected product was then
David o Neill
Date of experiment: 14/12/2011
Apparatus
Steam bath, ice bath, Buchner funnel, beaker, conical flask, filter paper, TLC apparatus, Melting point apparatus
Materials / chemicals
Benzaldehyde, acetone, ethanolic sodium hydroxide, ethanol
Introduction
The synthesis of dibenzalacetone is formed from an Aldol condensation reaction. An Aldol condensation reaction is a very effective way of forming a carbon – carbon bond reaction, in which the enolate anion adds to the carbonyl group of the aldehyde. Aldol condensations are very versatile, as the enolate anion of the carbonyl compound can be added to the carbonyl carbon of another. The synthesis of dibenzalacetone is an example of a mixed Aldol condensation reaction.
This experiment involves condensating acetone with two measures of Benz aldehyde (giving dibenzalacetone, an organic sun screen). The carbonyl group on the aldehyde is more reactive than that of the keytone. Therfore the enolate ion of Benz aldehyde adds to the carbonyl group of the acetone giving b-hydroxykeytone. This then undergoes base catalysed reaction with ease. Depending on the quantity of reactants used the reaction may produce mono or dibenzalacetone. Because we want dibenzalacetone, 2 moles of Benz aldehyde is reacted with one mole of acetone in the presence of sodium hydroxide.
The reaction scheme is given by:
Procedure
· Initially in the synthesis of Dibenzalacetone I mixed 5 mL (0.049 moles) of Benz aldehyde with 1.8 mL (0.0245 moles) of acetone in a small beaker.
· I then added half of this mixture to 90 mL of ethanoic sodium hydroxide in a 100 mL conical flask.
· I allowed this mixture to stand for 15 mins.
· I then placed the remainder of the previous aldehyde- keytone mixture into this conical flask and swirled the solution for 30 mins.
· The product was collected under suction using the Buchner funnel and the suction pump.
· The collected product was then
References: used School of Pharmacy and Pharmaceutical sciences laboratory manual (PH1001)