II Isolation of natural products caffeine from Structure H

Last updated: 9/6/2023

II Isolation of natural products caffeine from Structure H Procedure H C N N CH N N CH3 Figure 3 Caffeine Introduction and Purpose Caffeine is a stimulant and psychoactive chemical which is found in a wide variety of plants worldwide including coffee beans and tea leaves The purpose of this lab is to isolate caffeine from black tea leaves by solid liquid extraction followed by a liquid liquid extraction to recover the caffeine from the aqueous extract The caffeine will be purified by sublimation Solid Liquid Extraction of Caffeine from Tea Leaves with Water Empty and pour 8 teabags of black tea powder into a 500 mL Erlenmeyer flask record the weight of the tea powder Add 150 mL of water 7 g of calcium carbonate to help eliminate tannic acids present and a stirring bar Bring the contents to a boil then simmer for 30 45 minutes on a hot plate with stirring Use small amounts of water from a squirt bottle to keep the tea powder off the walls of the flask Set up a 500 mL clean filter flask and a Buchner funnel with filter paper Seat the filter paper with water then place a thin layer of celite 10 gram across top of the filter paper Lightly wet the celite to form a cake of celite on the filter paper Filter the hot tea solution through the pre prepared vacuum Rinse the collected solid lightly with hot water then quickly press the tea leaves in the funnel with a stopper to help squeeze out excess liquid Discard the collected solid in the solid waste container Liquid Liquid Extraction of Caffeine from Tea Solution with Methylene Chloride Transfer the cool tea solution to a 250 mL separatory funnel Add 30 mL of dichloromethane then stopper the funnel and gently swirl the contents Occasionally vent any pressure that may have built up inside the funnel and place the funnel into a ring stand Allow the contents in the separatory funnel to settle There should be two separate layers If there is an emulsion cloudy layer between two clear layers it is sometimes possible to break the emulsion by stirring the contents using a glass rod or adding sodium chloride solution If the emulsion persists seek your TA or instructor to help Carefully drain the lower