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Author Question: You have isolated caffeine from the over-the-counter pharmaceutical called NoDoz and wish to purify ... (Read 43 times)

ashley

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on: Aug 23, 2018
You have isolated caffeine from the over-the-counter pharmaceutical called NoDoz and wish to purify it by recrystallization. Using the data in Table E9.1, explain which solvent you would use and why.

Question 2

Extra-strength Excedrin is a combination of 250 mg acetaminophen, 250 mg aspirin, and 65 mg caffeine plus inactive ingredients that are insoluble in water and organic solvents. Using the data in Table E9.1, draw a flowchart to show how these three components could be separated using their solubility and acid-base properties. Hint: Caffeine is a nitrogen base similar in reactivity to diisobutylamine.


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gasdhashg

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Reply #1 on: Aug 23, 2018
Answer to Question 1

The best solvent would be ethanol. The solubility of caffeine in water is extremely high at 100C, meaning that we would only need to start with 1.5 mL of water for every 1 gram of caffeine. The problem is that, when the solution is cooled to room temperature and then to ice-bath temperatures, almost all of the caffeine will crystallize out of a very small volume of solvent. This makes separating the solvent from the crystals difficult. This is not the case with ethanol, where a fair amount of solvent is required to get 1 gram of caffeine to dissolve at higher temperatures

Answer to Question 2



ashley

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Reply 2 on: Aug 23, 2018
Wow, this really help

miss_1456@hotmail.com

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Reply 3 on: Yesterday
Excellent

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