Researcher

Matthew McBride

Objective

To determine the recrystallization yield of trans-dibenzalacetone from 1:1 ethanol/water (volume)

Procedure

Add approximately 0.5 g of trans-dibenzalacetone to a Erlenmeyer flask and add 3 mL of a ethanol/water(50:50)vol mixture to the flask. Place the flask on the hot plate to boil. Once the solution is boiling, add the boiling solvent to the boiling solution until all of the crystals have entered the solution. Then allow the solution to cool at 25°C. Filter the solution using suction filtration to recover the product.

Results

Characterization of Product 322A
Amount: 0.4397 g
Appearance: Mostly bright yellow crystals, but contains a very hard small clump of solid that is not crystals.
Calculation Sheet

Discussion

A small clump of the trans-dibenzalacetone would not dissolve into the mixture and so a large amount of the solvent was added. The recrystallization was carried out even with this clump of crystals still present. The solubility at boiling was calculated to be 0.04M, but due to the presence of this clump that did not dissolve, this value is not reliable. The temperature curve predicted a solubility of 0.4M at boiling point.

Conclusion

Trans-dibenzalacetone was recrystallized from ethanol/water(50:50)vol in a 76% yield and the solubility at the boiling point was measured to be 0.04M, but it is unsure whether this value is completely accurate due to the presence of a clump of crystals that would not dissolve.

Log

2012-07-19

13:32 The weight of an empty 10 mL Erlenmeyer flask with the cap was 13.5566 g.
13:35 The weight of the flask and cap with trans-dibenzalacetone (Product 284A from UCEXP284) was 13.9963 g. This is 0.4397 g of crystals.
13:42 Add 5.3988 g of ethanol (6.8399 mL) to a separate flask. Added 6.8557 g of distilled water (6.8557 mL) to the flask and mixed.
13:52 Added approximately 3 mL of the solution to the flask with the crystals and placed on hot plate.
13:56 Added 1 mL of solution.
13:57 Added 1 mL of solution.
13:58 Added 2 mL of solution.
13:59 Added 2 mL of solution.
14:04 The weight of a 25 mL Erlenmeyer flask with the cap was 33.8289 g. The solution was transferred to the 25 mL flask.
14:16 4.8665 g of distilled water and 3.8600 g of ethanol were mixed together in a separate flask.
14:17 Added 1 mL of solution. Crystals still visible in the boiling solution. Continued to add small amounts of the solvent to the solution.
14:26 Added 4.7957 g of distilled water and 3.8365 g of ethanol were mixed together in a separate flask. Crystals were still visible and small amounts of the solvent was continued to be added to the boiling solution.
14:34 The weight of a 50 mL Erlenmeyer flask with the cap was 49.7755 g. The recrystallization solution was transferred to this 50 mL flask.
14:43 9.8389 g of distilled water and 7.8741 g of ethanol were mixed together in a separate flask. Continued to add small amounts of the solvent to the boiling solution.
14:52 The 50 mL flask was removed from the hot plate and weighed 89.139 g (flask, cap, crystals and solvent). A small clump of crystals were still present at the bottom of the solution. These crystals would not dissolve into the solution.
14:54 The weight of the flask with parafilm was 89.548 g. The flask was placed in the 25°C water bath.

2012-07-24

14:28 Removed the flask from the water bath. The weight of the flask with the cap, parafilm and content was 89.452 g.
14:33 Filtered the solution on the Buchner funnel using suction filtration. The crystals were left on the filter paper to dry.
16:09 An empty 5-dram snap cap vial with a label weighed 11.9803 g.
16:10 The crystals on the filter paper seemed dry. There was a clump of crystals that were very hard and stuck together unlike the remaining flaky yellow crystals.
16:13 The crystals were transfered to the 5-dram vial and it weighed 12.3125 g. There were 0.3322 g of recovered product.