Aldol
Aldol Condensation
Wei-Hsuan Tsui
4/16/14
The reaction of an aldehyde with a ketone employing sodium hydroxide as the base is an example of a mixed aldol condensation reaction, the Claisen-Schmidt reaction. Dibenzalacetone is readily prepared by condensation of acetone with two equivalents of benzaldehyde
-26 -95 113.9
1. Weigh 0.212 g of pure benzaldehyde directly into a 10 x 100 mm reaction tube.
2. 2. Add 1.6 mL 95% ethanol and 2 mL of 3M sodium hydroxide solution. Then add 0.058 g of acetone to the reaction mixture.
3. Cap the tube immediately with a septum, and shake the mixture vigorously. Continue to shake the tube, from time to time, for the next 30 minutes. If the product fails to crystallize, open the tube and scratch the inside of the tube with a glass rod.
4. Remove the liquid from the tube using a Pasteur pipette by squeezing the bulb of the pipette, pressing the tip against the bottom of the tube, and bringing the liquid into the pipette, leaving the crystals in the tube(pipet filtration technique). Add 3 mL of water, cap, and shake the tube vigorously. Remove the wash liquid as before and wash the crystals twice more with 3-mL portions of water.
5. After the final washing, add 3 mL of water to the tube and collect the crystals on a Hirsch funnel using vacuum filtration. Use a few mLs of water to wash all the crystals into Hirsch funnel.
6. Squeeze the product between sheets of filter paper to dry it, and then recrystallize the crude dibenzalacetone from 70:30 ethanol water. Insert a wooden boiling stick to promote even boiling.
7. Remove the boiling solution from the hot sand bath, and place it in a beaker of glass wool to insulate it so it cools slowly to room temperature.Should the product separate as an oil, try to obtain a seed crystal, heat the solution to dissolve the oil, and add the seed crystal as the solution cools. If it continues to
Wei-Hsuan Tsui
4/16/14
The reaction of an aldehyde with a ketone employing sodium hydroxide as the base is an example of a mixed aldol condensation reaction, the Claisen-Schmidt reaction. Dibenzalacetone is readily prepared by condensation of acetone with two equivalents of benzaldehyde
-26 -95 113.9
1. Weigh 0.212 g of pure benzaldehyde directly into a 10 x 100 mm reaction tube.
2. 2. Add 1.6 mL 95% ethanol and 2 mL of 3M sodium hydroxide solution. Then add 0.058 g of acetone to the reaction mixture.
3. Cap the tube immediately with a septum, and shake the mixture vigorously. Continue to shake the tube, from time to time, for the next 30 minutes. If the product fails to crystallize, open the tube and scratch the inside of the tube with a glass rod.
4. Remove the liquid from the tube using a Pasteur pipette by squeezing the bulb of the pipette, pressing the tip against the bottom of the tube, and bringing the liquid into the pipette, leaving the crystals in the tube(pipet filtration technique). Add 3 mL of water, cap, and shake the tube vigorously. Remove the wash liquid as before and wash the crystals twice more with 3-mL portions of water.
5. After the final washing, add 3 mL of water to the tube and collect the crystals on a Hirsch funnel using vacuum filtration. Use a few mLs of water to wash all the crystals into Hirsch funnel.
6. Squeeze the product between sheets of filter paper to dry it, and then recrystallize the crude dibenzalacetone from 70:30 ethanol water. Insert a wooden boiling stick to promote even boiling.
7. Remove the boiling solution from the hot sand bath, and place it in a beaker of glass wool to insulate it so it cools slowly to room temperature.Should the product separate as an oil, try to obtain a seed crystal, heat the solution to dissolve the oil, and add the seed crystal as the solution cools. If it continues to