Why is the Opadry coating removed using ethanol instead of water for an Aleve tablet?
Extra-strength Excedrin is a combination of 250mg acetaminophen, 250mg aspirin and 65mg caffeine plus inactive ingredients that are insoluble in waterand organic solvents. How can these three components could be separated using their solubility and acid base properties?
You have isolated caffeine from the over the counter pharmaceutical called NoDoz and wish to purify it by recrystallization. What solvent should you use?
Why sulfuric acid use to neutralize the sodium salt of Naproxen rather than acetic acid?
Organic Chemistry Lab Question.?
2009-07-26 8:24 am
回答 (2)
2009-07-27 11:10 pm
✔ 最佳答案
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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