CHM
2201
Organic
Chemistry Lab I
Fall
2012
Department
of
Chemistry
Villanova University
Recrystallization
Preparation/Recrystallization of Acetanilide
Week 2 – September 7 - September 13, 2012
From Bell, Clark and Taber, pgs 30, 31
NHCOCH3
NH2
H2O
+
+
(CH3CO) 2 O
Acetic acid
Acetic a nhydride
Aniline
MW = 93.13
d = 1.02 g/mL
Amount: 0.125 mL
CH3CO 2H
Acetanilide
MW = 102.09
d = 1.08 g/mL
Amount: 0.240 mL
M W = 13 5.16
T heoretical yield: __ ____ _ g
Conduct this Experiment in your hood. Aniline is toxic and acetic anhydride is an irritant
to the eyes and nasal membranes.
1. For use in Step 5, prepare ahead of time a hot water bath by heating a 250 or 400
mL beaker filled about ½ to ¾ full with water on a hotplate.
2. Have a TA place 0.125 mL of aniline into a dry 13 x 100-mm test tube.
3. Add 2 mL of water to the test tube containing the aniline.
4. Add 0.240 mL of acetic anhydride to the test tube and gently stir the resulting
mixture with a spatula until a solid (the acetanilide product) forms.
5. Add 4 mL of water to the test tube containing the solid and heat the test tube in a
hot water bath with occasional stirring (spatula) until the solid dissolves.
6. Allow the test tube to cool for 5 minutes and then place it in an ice bath for 5 – 10
minutes to thoroughly cool the mixture and to complete the crystallization.
7. Use a spatula to break up any lumps of crystals that have formed during the
crystallization process and to ensure that the crystals are evenly suspended in the
water.
8. Set up a vacuum filtration apparatus using your small Hirsch funnel, a 50 mL
filter flask, and a rubber adapter (place the funnel in this adapter which is fitted on
top of the filter flask). To prevent the filter flask from tipping over, clamp it to a
bar in your hood.
9. Using a vacuum hose (use the black thick-walled hose), connect the filter flask
side arm to the house vacuum outlet in your hood.
10. Place a small filter paper on the Hirsch funnel (be sure all the funnel perforations
are covered by the filter paper) and moisten the filter paper with a few drops of
water.
11. Turn on the house vacuum and then pour the contents of the cold test tube onto
the funnel.
(continued)
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CHM
2201
Organic
Chemistry Lab I
Fall
2012
Department
of
Chemistry
Villanova University
12. Add a small quantity of ice cold water to the test tube and swirl or scrape loose
the solids remaining in the tube and pour the resulting suspension into the funnel
containing your previously collected material.
13. Leave the vacuum on and allow air to draw through the collected solids on the
funnel for ~10 - 15 minutes to remove as much water as possible from the solids.
14. While air is being drawn through the solid, use a spatula to carefully break up the
solid cake of crystals to facilitate air drying. Be careful not to tear the filter paper
during this scraping/breaking process.
15. When the solid appears to be dry and free flowing, use a spatula to remove the
solids and weigh the dried material. If the weight of your product is MORE than
the calculated theoretical yield, the acetanilide is still wet and requires additional
drying on the funnel.
16. Determine the melting point range of your material for comparison with the
literature value and calculate the actual yield of your product.
17. If your instructor requests you to hand in your product, place your product in a
labeled (with your name, weight of product, melting point range and structure of
product) screw cap vial and submit it to your TA for grading.
TMBare 8/2011
DLZubris modified – 8/2012
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