Department of Chemistry
Extraction and Sublimation
Caffeine is a stimulant found in tea, coffee, cocoa, OTC medication, and cola drinks.It stimulates the brain and the central nervous system, so that a person feels less tired and more alert. The purpose of this lab is to determine the amount of caffeine in tea. The major component of tea is cellulose which is a polymer of glucose. Materials
1 tea bag (1.615g)
50 mL beaker
500 mL Erlenmeyer flask
30 mL DI water
In this experiment the caffeine is extracted from tea leaves by hot water. From the aqueous extract the caffeine is isolated by multiple extractions with small portions of dichloromethane. In a 500 mL Erlenmeyer flask we placed one tea bag, which weighed 1.615g, along with 30 mL of DI water, and 2 grams of powdered calcium carbonate. After boiling the mixture gently for 20 minutes, occasionally swirling it, the hot solution is allowed to cool and the caffeine is then extracted from the water with dichloromethane, which is an organic solvent that is insoluble in water. The next step was to transfer the tea extract from the 500 ml Erlenmeyer flask to a 125 ml separate funnel that is supported by a ring on a ring stand. We added 15 mL’s of DCM to the funnel and shaken the solution gently three times to release any pressure that may have built up in the funnel. There were two different layers. We drained the lower (DCM) layer into a 50 mL beaker. We stored the beaker and resumed the experiment a week later. The next week we took out the beaker and boiled it on a hot plate. During this process we covered the beaker with a wash glass that was filled with ice. After it had boiled we recovered the caffeine on the wash glass.
After finishing up the experiment a week later, we were able to retrieve some caffeine on the...
Bibliography: Wilcox/Wilcox, Experimental Organic Chemistry, Chapter 8.3 and 9.7B, pages 97-98, pages 117-118
Rodriguez, Victor (2010, May 5). The Isolation of Caffeine from Tea. Retrieved from: http://www.oxford.net/~mavarod/portal/school/caffeine.html
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