Villanova CHM 2201 - Isolation of Caffeine from Tea (4 pages)

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Isolation of Caffeine from Tea



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Isolation of Caffeine from Tea

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Pages:
4
School:
Villanova University
Course:
Chm 2201 - Organic Chemistry Lab I

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CHM 2201 Organic Chemistry Lab I Fall 2008 Department of Chemistry Villanova University Isolation of Caffeine from Tea Using Column Chromatography From Bell Clark Taber pages 70 71 O H3C O CH3 N N N N CH Carry out this experiment in your hood Work in pairs and plan your work efficiently since Caffeine this lab can take 3 or more hours to complete It is suggested that one person in the workgroup carry out part A the tea extraction and adsorption of the tea extract onto silica gel while the other person simultaneously starts with parts B column preparation and C preparing the test tubes obtaining the eluting solvents for the actual chromatography and preparing the TLC plates which will be used for analysis of the TLC fractions 3 A Extraction of Caffeine from Tea 1 Place 50 mL of the prepared tea solution in a 125 mL separatory funnel and add 20 mL of 5 aqueous HCl to help prevent emulsion formation 2 Extract this mixture 4 times with 10 mL portions of methylene chloride dichloromethane REMEMBER methylene chloride is heavier than water Do not shake the separatory funnel but vigorously SWIRL it you may invert the separatory funnel to get better mixing during the swirling process to help prevent the formation of an emulsion REMEMBER Vent the separatory funnel during the extractions to prevent pressure buildup 3 Drain each of the above four methylene chloride extracts into a single 125 mL Erlenmeyer flask make sure that there are not significant amounts of water drops in the methylene chloride extracts If you see significant amounts of water in the combined methylene chloride extracts place the combined extracts in a separatory funnel and drain off the methylene chloride being careful to keep the water in the separatory funnel layer into another dry 125 mL Erlenmeyer flask 4 Dry the combined methylene chloride extracts by adding 2 3 spatula scoops of anhydrous magnesium sulfate and swirling the flask After swirling the flask the drying agent should be a loose and granular



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