Expt #2. Friedel Crafts Acylation of
Ethoxybenzene
Relevant textbook reading
- Mohrig - Chapter 7.1-7.2, 11.4, 22 Hart,
et.al., Chapter 4.9
Overview - You will react
propionyl chloride/AlCl3 with ethoxybenzene
and use NMR to determine the structure of the obtained
product. (The product structure is predictable from the
textbook reading assignment.)
Procedures
Running the reaction.
- Using the balance located
in the dispensing fume hood, weigh out 11 mmol AlCl3
into a dry 50-mL round bottom flask.
- Add a small stir bar and 10
mL dichloromethane (DCM).
- Cautiously add 1.0 mL
propionyl chloride.
- Attach a reflux condenser,
Claisen adapter, and addition funnel as shown in Fig
7.1a (p 88) in Mohrig.
- Prepare a solution of
ethoxybenzene (10 mmol) in 5 mL DCM and add this to
the addition funnel.
- Add the ethoxybenzene
solution dropwise over a period of 5 min to the
stirring solution.
- Stir for an additional 30
min.
Work-up procedures.
- Slowly add 7.5 mL cold water
via the addition funnel to stop the reaction and
quench any left over acyl chloride.
- Place the flask on an ice
bath and slowly add 7.0 mL concentrated HCl. At this
point all of the aluminum salts should have
dissolved. If this is not the case add another 0.5
mL of HCl.
- Transfer the reaction
mixture to a separatory funnel and drain the lower
layer into a small Erlenmeyer flask. Avoid getting
any of the aqueous layer when carrying out this
step.
- Extract the aqueous layer
with 5 mL additional DCM and combine the organic
layer with the previous organic layer.
- Wash the combined organic
layers with 5 mL 5% NaHCO3(aq). Caution,
CO2 gas is liberated here so the
separatory funnel will need to be vented early and
often.
- Dry the organic solution
over Na2SO4.
- Use the rotary evaporator to
remove the DCM solvent in vacuo. (The
instructor or TA will assist you with this.) (Mohrig
technique 11.4)
- Determine the yield.
Characterization
of Product
- Obtain the 1H
NMR spectrum of your product using CDCl3
as the solvent. One group will also be asked to
acquire a 13C NMR spectrum,
which will be shared with the rest of the class.
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