Lab Report: Extraction of Caffeine from Tea Bags

Topics: Solvent, Chemistry, Tea Pages: 4 (1178 words) Published: December 11, 2013


Abstract

The purpose of this experiment was to perform a liquid-liquid extraction method to extract the caffeine from the tea bags that were provided, and then recrystallize the caffeine. The solvents used in the experiment were an aqueous sodium carbonate and dichloromethane (DCM). Anhydrous calcium chloride pellets were used to dry the solution and emulsion layer and the DCM was then decanted. After washing the anhydrous calcium chloride pellets with more DCM, the solvent was evaporated, leaving greenish-white crystalline caffeine residue weighing about .25 mg.

In order to recrystallize the caffeine, we used a mixed-solvent method, consisting of hot acetone and hexanes. The solution was cooled and a vacuum filtration was done to remove the caffeine crystals. The final product weighed about 3 mg. Introduction

Caffeine is an organic compound that is found in tea leaves and coffee beans. It is a basic substance (due to the nitrogen atoms in its structure) and it appears as a white crystalline solid at room temperature. In this experiment, we aimed to extract caffeine from the tea leaves in the tea bags provided beginning with a solid-liquid extraction method and then a liquid-liquid extraction. Extraction techniques are used to isolate and remove particular compounds form another substance. For both solid-liquid and liquid-liquid extraction techniques, solvents should be chosen by their miscibility in water (should be immiscible), they should have relatively low boiling points for faster and easier extraction, and they should be unreactive with the other substances being used in the experiment. In this experiment, a solid-liquid extraction method was used first to extract the caffeine from the tea leaves/tea bags to by dissolving sodium carbonate in hot water and creating an aqueous sodium carbonate solvent. Sodium carbonate and hot water were added to the tea bags and was let to stand for about 7 minutes in order to bring the caffeine molecules out...

References: Williamson, K., Masters, K. Macroscale and Microscale Organic Experiments, 6th ed.; Cengage Learning: Belmont, 2011.
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