Chemistry 351 Laboratory - Spring 2013

Expt #4. A Green Friedel-Crafts Acylation: Acetylation of Anisole using ZnO instead of Aluminum Chloride.

Relevant textbook readings - Klein, Chapter 19. Mohrig, Techniques 11 and 15.

Reference for Procedure - Sarvari, M. H.; Sharghi, H. J. Org. Chem., 2004, 69, 6953–6956

Overview - You will acetylate anisole using a procedure adapted from the above Journal of Organic Chemistry reference.

Procedure

  1. We will run the reaction at 2.5 times the scale of the literature procedure and use a two-fold excess of acetyl chloride. (2.5 mmol anisole + 5 mmol acetyl chloride).
  2. Use a 5-mL r.b. flask as the reaction vessel. Stir the reaction mixture for 10 minutes at room temperature.
  3. "Elute" with 25 mL dichloromethane. Do so by rinsing the solid out of the reaction flask repeatedly into a vacuum filtration apparatus. Only leave the vacuum on as necessary to pull the liquid through the Buchner funnel, we do not want to lose all of the solvent to evaporation prematurely.
  4. Transfer the filtrate into a separatory funnel.

For steps 5 and 6, use extreme caution to vent the separatory funnel quickly and often. (See Mohrig Technique 11.2 - 11.4 Extraction Procedures using a Separatory Funnel.)

  1. Wash with 10 mL water. Separate the layers and return the lower organic layer to the separatory funnel for step 6.
  2. Wash with 10 mL aqueous10% NaHCO3.
  3. Return the two aqueous washes to the separatory funnel and extract with 10 mL DCM.
  4. Combine the organic layers and dry over Na2SO4.
  5. Decant the liquid into a pre-weighed round bottom flask suitable for rotary evaporation. Rinse the drying agent with an additional 5 mL DCM so as to avoid loss of product in this step.
  6. Evaporate off the DCM solvent in vacuo using the rotary evaporator.
  7. Determine the yield of crude product and save a small sample for mp determination.
  8. Recrystallize the product using petroleum ether as solvent. (See Mohrig Technique 15.4-15.5 - Miniscale Procedure for Recrystallizing a Solid.)
  9. Obtain the mps of the crude and final products as well as the 1H and 13C NMR spectra of the final crystalline product.