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Acetanilide_Prep_Recryst - CHM 2201 Fall 2009 Department of...

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Unformatted text preview: CHM 2201 Fall 2009 Department of Chemistry Organic Chemistry Lab 1 Villanova University Recrystallization Preparation/Recrystallization of Acetanilide Week 2 — August 31 - September 4 , 2009 From Bell, Clark and Taber, pgs 30, 31 NH2 NHCOC'H3 H20 E) + (CH3CO)20 + CHSCOZH . . Acetic acid Armin Acetic anhydrlde Acetanmde 9 MW: 102.09 MW: 135.16 MW = 93_13 d = 1.08 g/mL Theoretical yield: 9 d = 1.02 g/mL 7 drops = ~220 uL Conduct this Experiment in your hood. Aniline is toxic and acetic anhydride is an irritant to the eyes and nasal membranes. 1. U) 10. 11. For use in step 5, prepare ahead of time a hot water bath by heating a 250 or 400 mL beaker filled about 1/2 to 3% full with water on a hotplate. Have a TA place 125 [1L of aniline into a dry 13 x IOO-mm test tube. Add 2 mL of water to the test tube containing the aniline. Add 7 drops (~220 pL) of acetic anhydride to the test tube and gently stir the resulting mixture with a spatula until a solid (the acetanilide product) forms. NOTE: If you use more than 7 drops of acetic anhydride, you may not obtam solid and will have to start over. 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. 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. 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. 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. Using a vacuum hose (use the black thick-walled hose), connect the filter flask side arm to the house vacuum outlet in your hood. 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. Turn on the house vacuum and then pour the contents of the cold test tube onto the funnel. (continued) Page 1 of 2 CHM 2201 Fall 2009 Department of Chemistry Organic Chemistry Lab I Villanova University 12. Add a small quantity of i_ce go_ld water to the test tube and swirl or scrape loose the solids remaining in the tube and rinse the resulting suspension into the funnel. 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 to 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 l6. Determine the melting point range of your material for comparison with the literature value and calculate the actual yield of your product. TMBare 8/2009 Page 2 of 2 ...
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