Purification of Ferrocene by Sublimation

1. Setup of the Schlenk Line

For a more detailed procedure, please review the "Schlenk Lines Transfer of Solvent" and "Degassing Liquids" videos in the Essentials of Organic Chemistry series. Schlenk line safety should be reviewed prior to conducting this experiment. Glassware should be inspected for star cracks before use. Care should be taken to ensure that O₂ is not condensed in the Schlenk line trap if using liquid N₂. At liquid N₂ temperature, O₂ condenses and is explosive in the presence of organic solvents. If it is suspected that O₂ has been condensed, or a blue liquid is observed in the cold trap, leave the trap cold under dynamic vacuum. Do NOT remove the liquid N₂ trap or turn off the vacuum pump. Over time the liquid O₂ will sublime into the pump - it is only safe to remove the liquid N₂ trap once all of the O₂ has sublimed.

1. Close the pressure release valve.
2. Turn on the N₂ gas and the vacuum pump.
3. As the Schlenk line vacuum equilibrates, prepare the cold trap with either liquid N₂ or dry ice/acetone.
4. Assemble the cold trap.

2. Add 500 mg (2.7 mmol) of ferrocene to the base of the sublimation chamber.

3. Assembly of the Sublimation Chamber

1. Place the O-ring in the groove of the chamber base.
2. Gently place the cold finger into the chamber base and make sure that the O-ring fits into the groove of the glassware.
3. Secure the two pieces of the sublimation chamber using a clamp.

4. Connect the sublimation chamber to the Schlenk line and open the chamber to vacuum for 1 min. Close the vacuum valve on the sublimation chamber. The sublimation will be carried out under static vacuum.

5. Fill the cold finger with an ice bath.

6. Place the base of the sublimation chamber into a water bath heated to 80°C.

7. After the sublimation is complete, remove the sublimation chamber from the bath.

8. Close the stopcock on the Schlenk line.

9. Remove the Schlenk line tube from the sublimation chamber and repressurize the sublimation chamber by slowly opening the valve. Be careful! If the chamber is repressurized too quickly it will disturb the purified crystals on the cold finger.

10. Unclamp the sublimation chamber and remove the water from the cold finger with a pipette.

11. Carefully lift the cold finger out of the sublimation chamber.

12. Scrape the purified ferrocene from the cold finger and transfer to a vial. Record the weight of the purified product. If the compound being sublimed is air-sensitive, the entire apparatus should be brought into an inert-atmosphere glovebox prior to opening the sublimation chamber.