Friedel-Crafts Acylation Procedure
1. Before the lab period go to the lab and put the following glassware into a 150 mL beaker with your name on it: 5 mL vial, Claisen head, and a drying tube packed with CaCl2. Put into the 110 degree oven on the back bench next to the whiteboard. It must stay in the oven ½ hr at least to get perfectly dry.
2. The glassware must then be placed in a dessicator to cool to room temperature.
3. Prepare 2 TLC plates for 6 spots. Spot four standards: ferrocene, acetyl ferrocene, diacetyl ferrocene and the solution that is a mixture of all three. Spot each solution several times, particularly the ferrocene and the mixture. Set aside.
4. You will need a large cap and septum for mixing the reactants and a large cap and O-ring and a small cap and septum to assemble the glassware for the experiment. Put the drying tube into the top of the Claisen head (no cap). Put the small cap and septum onto the other arm of the Claisen head. Put the large spin vane in the 5 mL vial.
5. Weigh out 150 mg of anhydrous AlCl3 on a piece of glassine weighing paper and put it immediately into the 5 mL vial and cap it.
6. Quickly add 2.0 mL of CH2Cl2 to the 5 mL vial and then add 80 µL of acetyl chloride to the vial.
Put the Claisen head on the vial with the large cap and O-ring.
7. Set the apparatus in an aluminum block on the stirring hot plate and begin stirring. Do not use any heat!
8. Weigh out 100 mg of ferrocene and put into a clean vial 3 mL vial. Add 1.5 mL of CH2Cl2, cap tightly and shake to dissolve.
9. Add the ferrocene solution (using your syringe) through the septum of the 3 mL vial and the septum of the Claisen head. The solution in the vial should immediately turn dark purple.
10. Quickly spot the TLC plate with the purple mixture several times to get a dark spot. Wrap the plates in plastic wrap and keep them in your drawer until next week.
11. Let the reaction mixture stir for 15 minutes, without heat.
12. Meanwhile put 5 mL of ice water in a centrifuge tube with a cap. Add the reaction mixture with a Pasteur pipet. Note all colors of the layers.
13. Cool the tube in an ice bath and neutralize the contents with about 0.5 mL of 25% NaOH,
using pink litmus. Check to see if the litmus turns blue by dipping a stirring rod into the tube and touching it to the litmus paper. Mix well!! Note colors of layers.
14. Extract 3 times with 3 mL CH2Cl2, shaking and venting the tube each time. The bottom CH2Cl2 layers should be combined in a 25 mL Erlenmeyer flask.
15. If there is no obvious water in the flask add enough anhydrous sodium sulfate to cover the bottom of the flask in order to dry the CH2Cl2 solution.
16. When the solution is deemed dry, transfer to a weighed, labeled beaker. Rinse the drying agent with a few mL of fresh CH2Cl2 and add this to the beaker.
17. Leave the beaker in the hood to evaporate.
1. Weigh your beaker with the dried residue from last week’s reaction. Subtract the weight of the empty beaker and report to the instructor your weight of dried residue. You will probably get less than 0.100 grams. If not, you have a weighing error!
2. Add a few drops of CH2Cl2 to the residue to make a concentrated solution and spot your TLC plate from last week.
3. Prepare a TLC chamber using a 400 mL beaker with a strip of paper towel for a wick and about 0.5 cm CH2Cl2. Put saran wrap snugly over the top of the beaker with a rubber band and let the chamber sit in the hood to saturate the atmosphere with the solvent vapors.
4. Develop the TLC plates from last week, place in an I2 chamber and circle all spots in pencil! Prepare another TLC plate for the 2 or 3 bands that you will collect from the column today.
5. Obtain 3 small beakers, and label them ferrocene, mono, and di. Weigh the beakers.
6. Make a product/alumina mixture: add 0.5 mL of CH2Cl2 to the product residue, dissolve product completely. Add 300 mg of alumina and mix well. Now evaporate off the CH2Cl2 to obtain the dry product mixture.
7. Clamp column to ring stand and pack in the following order: small, loosely packed cotton plug; 5 mm of sand; 5 grams of alumina (tap column while adding alumina and make sure the top of the alumina is level); add product/alumina mixture, level it on top; add 10 mm more of alumina, level.
8. Obtain solvents in 4 labeled Erlenmeyer flasks.
9. Add pure hexane to the column and collect any unreacted ferrocene that is present in the product.
10. Continue with the other 3 solvents to collect the individual mono and diacetylated products in their respective beakers.
11. Evaporate the solvents in a sand bath using a low temperature setting and when the solutions are concentrated spot each band on .
12. Add a few drops of hexane to each beaker to get a concentrated solution and spot a TLC plate.
13. Develop the plate in a chamber of CH2Cl2.
14. Place the plates in an I2 chamber. Circle all spots.
15. TLC plates will be taped into the lab report that you will submit.