Tuesday, August 16, 2011
Organic Chemistry Lab Question.?
The ethanol is slightly more basic than water and has a lipophilic ethyl group that dissolves the coating which is designed to dissolve in the basic environment of the intestine rather than the acidic environment of the stomach. The Excedrin can first be dissolved in water and all 3 drugs will remain soluble and the inactive non-solubles can be filtered. Then the water phase can be titrated with small amounts of base to convert the drugs from their acid salts into their free bases and extracted into organic solvents freeing each drug one at a time from the water phase. To recrystallize the caffeine, dissolve it into a warm organic solvent like ether or THF and add small amounts of ethanol until the mixture begins to get cloudy. Allow to cool and caffeine should precipitate. Sulfuric acid is used to neutralize the naproxen sodium salt because the hydronium ion on acetic acid is too weak to pull the naprosyn base away from the sodium atom. Good luck and I hope I have given you good answers.
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