Bromination of Acetanilide
Bromination of Acetanilide
Objective: The objective of this experiment was to use melting point and NMR to determine which of two isomers, ortho or para, would most likely form after brominating Acetanilide through electrophilic aromatic substitution. Procedure/Observations:
1. Weigh out ~280 mg of acetanilide in a 10 mL r.b. flask with a stir bar.
2. Then, add 2.0 mL of glacial acetic acid using a calibrated Pasteur pipet.
3. Stir the mixture until all of the acetanilide has dissolved. It may be necessary to add more acetic acid dropwise until full dissolution has occured.
4. In the fume hood, add 0.6 mL of 4.1 M bromine solution in acetic acid.
5. Cap the round bottom flask before returning to the bench.
6. For 15-20 minutes, stir the reaction mixture at room temperature so that the reddish-orange coloration will fade and a solid precipitate will form.
7. Return to the hood and add a few more drops of the bromine solution in the hood if all the coloration fades.
8. Once the reaction is complete, return to the hood.
9. Transfer the mixture to a 25 mL Erlenmeyer flask with 10 mL of water. 10. Rinse the reaction flask out using another 5.0 mL of water.
11. Using a Pasteur pipet, add 30% sodium thiosulfate dropwise while swirling until the bromine coloration is no longer visible.
12. Return to the bench to complete the final work-up.
13. Cool the reacting mixture in an ice bath.
14. Collect the solid precipitate using a Hirsch funnel through vacuum filtration.
15. Wash with ice cold water to complete the transfer. If the crude product is yellow, disconnect the vacuum, add a few drops of the sodium thiosulfate solution, then reconnect the vacuum.
16. Follow with 1 or 2 washings of ice cold water.
17. Dry the crude product 5-10 minutes using the vacuum.
18. Recrystallize the crude product using an ethanol/water mixed solvent combination. Be sure to dissolve the crude product in the minimal
Objective: The objective of this experiment was to use melting point and NMR to determine which of two isomers, ortho or para, would most likely form after brominating Acetanilide through electrophilic aromatic substitution. Procedure/Observations:
1. Weigh out ~280 mg of acetanilide in a 10 mL r.b. flask with a stir bar.
2. Then, add 2.0 mL of glacial acetic acid using a calibrated Pasteur pipet.
3. Stir the mixture until all of the acetanilide has dissolved. It may be necessary to add more acetic acid dropwise until full dissolution has occured.
4. In the fume hood, add 0.6 mL of 4.1 M bromine solution in acetic acid.
5. Cap the round bottom flask before returning to the bench.
6. For 15-20 minutes, stir the reaction mixture at room temperature so that the reddish-orange coloration will fade and a solid precipitate will form.
7. Return to the hood and add a few more drops of the bromine solution in the hood if all the coloration fades.
8. Once the reaction is complete, return to the hood.
9. Transfer the mixture to a 25 mL Erlenmeyer flask with 10 mL of water. 10. Rinse the reaction flask out using another 5.0 mL of water.
11. Using a Pasteur pipet, add 30% sodium thiosulfate dropwise while swirling until the bromine coloration is no longer visible.
12. Return to the bench to complete the final work-up.
13. Cool the reacting mixture in an ice bath.
14. Collect the solid precipitate using a Hirsch funnel through vacuum filtration.
15. Wash with ice cold water to complete the transfer. If the crude product is yellow, disconnect the vacuum, add a few drops of the sodium thiosulfate solution, then reconnect the vacuum.
16. Follow with 1 or 2 washings of ice cold water.
17. Dry the crude product 5-10 minutes using the vacuum.
18. Recrystallize the crude product using an ethanol/water mixed solvent combination. Be sure to dissolve the crude product in the minimal