Chemical Biology 3OA3, September 2009 Page 22 E XPERIMENT 1 I SOLATION OF C AFFEINE FROM T EA In this experiment, a common alkaloid natural product, caffeine, responsible for the mild stimulating action of tea and coffee, will be isolated from tea leaves, purified and characterized by preparation of a derivative. Caffeine is a derivative of one the bases found in nucleic acids, and provides a good illustration of the chemistry of these bases. The caffeine will be extracted by hot water from tea leaves, where it is present to the extent of about 5%. This treatment also extracts the tannins, another class of compounds present in tea. It is therefore necessary to separate the caffeine from the tannins by adding lead acetate to the extract. The tannins are acidic and form insoluble lead salts, whereas the caffeine remains in solution. The caffeine will be extracted from the aqueous solution with chloroform. It can be purified by recrystallization or sublimation.
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This note was uploaded on 01/08/2012 for the course CHM 30A3 taught by Professor Ricktroendle during the Fall '11 term at UNF.