Separating Ferrocene and Acetylferrocene by Adsorption Chromatography Dry Pack Method Leah Monroe February 27, 2003
Organic Chemistry Lab II Experiment performed on February 18 and 20, 2003
Adsorption column chromatography is one way to separate compounds out of a mixture. In this technique, a solid stationary phase called the adsorbent is packed in a glass column and an eluent, which is the mobile phase, moves slowly through the packed column. In this experiment, an adsorption chromatography column was constructed using silica gel as the adsorbent. A 50:50 mixture of ferrocene and acetylferrocene was then separated using the eluents hexane and tert-butyl methyl ether (TBME). The less polar ferrocene was attracted to the less polar hexane, so as the hexane passed through the stationary phase, the ferrocene moved with it and the acetylferrocene was left behind. When TBME was passed through the stationary phase, the acetylferrocene moved with it because the more polar acetylferrocene was attracted to the more polar TBME. The percent recovery of ferrocene was 72.41% and the percent recovery of acetylferrocene was 82.76%.
Separating Ferrocene and Acetylferrocene by Adsorption Chromatography
Introduction: In this experiment, a 50:50 mixture of ferrocene and acetylferrocene will be separated using adsorption column chromatography. A microscale chromatography column will be constructed using the dry pack method. The eluents hexane and tert-butyl methyl ether will be used to separate ferrocene and acetylferrocene, and percent recoveries will be calculated.
2 beakers, 50-mL 3-mL conical vial cotton or Kim wipe 4 Erlenmeyer flasks, 50-mL fine sand labels marking pen microspatula 2 Pasteur pipets, with latex bulbs 9-mm Pasteur pipet water bath @ 60°C #1 stopper support stand utility clamp 20-cm wire
Reagents and Properties:
Melting Point °C
Boiling Point °C
N/A N/A 0.7405 N/A 0.659
acetylferrocene Silica gel Tert-butyl methyl ether ferrocene hexane
228 102 88 186 86
29 mg 3.3 g 20 mL 29 mg 20 mL
1.27 x 10-4 0.0324 0.1683 1.56 x 10-4 0.1533
81 – 83 2054 N/A 174 - 176 N/A
N/A N/A 55 - 56 N/A 69
Part 1 – Labeling and Weighing Collection Containers Label four 50-mL Erlenmeyer flasks “hexane”, “hexane eluent”, “TBME”, and “TBME eluent”, respectively. Label two 50-mL beakers “ferrocene” and “acetylferrocene”, respectively. Weigh each beaker and record the masses.
Separating Ferrocene and Acetylferrocene by Adsorption Chromatography Part 2 – Preparing Dry Pack Column Prepare a column in a short stem, wide-bore, 9-mm Pasteur pipet by placing a small plug of cotton or Kim wipe at its tip. Use a wire to push the cotton into place. Be careful not to make the plug too tight or eluent flow will be restricted. Using a utility clamp, attach the column to a support stand. Make sure the column is vertical. If the clamp is too large to firmly hold the column, use paper towels or a split stopper to hold the column in the clamp tightly. Then, pour approximately 50 mg of sand on top of the cotton or Kim wipe plug. Slowly pour 3 g silica gel on top of the sand. Tap the side of the pipet in order to pack the column as you add the silica gel. Part 3 – Preparing a Sample Weigh 55 – 60 mg of a 50:50 mixture of ferrocene and acetylferrocene. Place the mixture into a 3-mL vial and add 0.75 mL TBME to the vial. Swirl the vial to dissolve the mixture. Add 100 mg of silica gel to the solution and mix. Note that the silica gel does not dissolve. Then, evaporate the mixture to dryness by placing the vial briefly in a 60°C water bath in a fume hood and then using a gentle stream of air or nitrogen to speed the evaporation. Part 4 – Applying the Sample to...