lala
Shabnaz Rob 4.29.14
Aldol Condensation
Introduction
The purpose of this lab was to prepare dibenzalacetone (1,5-diphenyl-1,4-pentadiene-3-one). The preparation of dibenzalacetone is base catalyzed. It is a compound reaction that involves an aldol reaction and then dehydration. This overall reaction is known as the Clasien-Schmidt condensation.
Aldol addition occurs when an aldehyde forms an aldol in equilibrium. Usually two molecules of aldehydes combine with a base two form the aldol, which is a compound with an aldehyde with a hydroxyl group attached. During this reaction, the enolate ion of the aldehyde, which is the nucleophile, adds to the carbonyl group of the aldeyde to from the alkoxide ion. The alkoxide ion abstracts a proton from water to yield an aldol. Aldol condensation is when two molecules of an aldehyde combine to eventually form an α,β–unsaturated aldehyde and a molecule of water.
Main Reaction
Procedure
1. Dissolve 5 grams of solid NaOH in 50mL of deionized water in a 250 mL beaker and place it in an ice bath.
2. Add 40mL of 95% of ethyl alcohol adding a stirring bar gently into the solution.
3. Transfer the beaker from the ice bath onto the hot plate and measure the temperature of this solution to make sure it was still at or under 25 °C.
4. After letting the mixture stir for some time, prepare 5mL of benzaldehyde with 1.85mL of acetone into a 50mL Erlenmeyer Flask.
5. Transfer about half of the mixture into the stirring solution of NaOH, water and ethanol. After 2 -3 minutes, yellow cloudiness formed. After 10 minutes add the remainder of the solution. Allow the solution to stir for 30 more minutes.
6. Filter the mixture using a Buchner funnel and transfer the product into a large beaker with 300mL of water.
7. Refilter the mixture with the same Buchner funnel and weigh the final product.
8. Measure the melting point of the final product using the Mel temp.
Results
Final Yield: 6.660g
Melting
Aldol Condensation
Introduction
The purpose of this lab was to prepare dibenzalacetone (1,5-diphenyl-1,4-pentadiene-3-one). The preparation of dibenzalacetone is base catalyzed. It is a compound reaction that involves an aldol reaction and then dehydration. This overall reaction is known as the Clasien-Schmidt condensation.
Aldol addition occurs when an aldehyde forms an aldol in equilibrium. Usually two molecules of aldehydes combine with a base two form the aldol, which is a compound with an aldehyde with a hydroxyl group attached. During this reaction, the enolate ion of the aldehyde, which is the nucleophile, adds to the carbonyl group of the aldeyde to from the alkoxide ion. The alkoxide ion abstracts a proton from water to yield an aldol. Aldol condensation is when two molecules of an aldehyde combine to eventually form an α,β–unsaturated aldehyde and a molecule of water.
Main Reaction
Procedure
1. Dissolve 5 grams of solid NaOH in 50mL of deionized water in a 250 mL beaker and place it in an ice bath.
2. Add 40mL of 95% of ethyl alcohol adding a stirring bar gently into the solution.
3. Transfer the beaker from the ice bath onto the hot plate and measure the temperature of this solution to make sure it was still at or under 25 °C.
4. After letting the mixture stir for some time, prepare 5mL of benzaldehyde with 1.85mL of acetone into a 50mL Erlenmeyer Flask.
5. Transfer about half of the mixture into the stirring solution of NaOH, water and ethanol. After 2 -3 minutes, yellow cloudiness formed. After 10 minutes add the remainder of the solution. Allow the solution to stir for 30 more minutes.
6. Filter the mixture using a Buchner funnel and transfer the product into a large beaker with 300mL of water.
7. Refilter the mixture with the same Buchner funnel and weigh the final product.
8. Measure the melting point of the final product using the Mel temp.
Results
Final Yield: 6.660g
Melting