Chemistry 351 Laboratory - Summer Session 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. We will attempt to "green up" the procedure by using ZnO pellets rather than the ZnO powder called for in the reference. The use of pellets should eliminate the need for a vacuum filtration and allow the use of a much smaller amount of extraction solvent.

Procedure

  1. Run the reaction at 2.5 times the scale of the literature procedure.
  2. Pay special attention to the specified order of addition of the reactants as specified in the literature reference.
  3. Use a reaction tube as the reaction vessel. Stir the reaction mixture by using a Pasteur pipet to withdraw the liquid from the tube and then shoot it back in. Continue this process for at least 10 min.
  4. Extract the reaction mixture with 5-10 mL dichloromethane (DCM). Do so by adding the DCM a few mL at a time and then using the Pasteur pipet to remove it. Use enough DCM so that most of the color is removed from the tube.
  5. Transfer the DCM extracts into a small separatory funnel.

For steps 6 and 7, 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 and the mp of the product.
  8. Obtain 1H NMR and IR spectra of the product.

Report:

  1. Use the proton NMR to determine the percent conversion of anisole to p-acetylanisole.
  2. Also use the proton NMR to determine whether any ortho product was formed. If a peak that can be clearly attributed to o-acetylanisole is present, then it should be integrated and the result used to estimate the p to o product ratio.
  3. Compare your results (yield, conversion, p:o ratio) to those reported in the literature reference.