Extraction of Caffeine from Tea
... Ÿ Stand Ÿ Watch glass Ÿ 100 ml conical flask Ÿ Hot plate Ÿ Steam bath Ÿ 15g tea leaves Ÿ 8g sodium carbonate Ÿ 200ml water Ÿ 4 x 15 ml dichloromethane Ÿ Anhydrous sodium sulphate Ÿ 5 ml hot acetone Ÿ Hexane Method: The tealeaves were boiled in the 200 ml of water on a hotplate together with the sodium carbonate to extract the caffeine out of the leaves. The solution was filtered and allowed to cool before half of it was poured into a separating funnel together with the dichloromethane. Each half was extracted twice with the dichloromethane. The denser dichloromethane was removed using the separator funnel and all of the dichloromethane extracts collected in a conical flask. The anhydrous sodium sulphate was then added to dry the sample. After filtering, the solution was poured into the round bottom flask, washed with a bit of dichloromethane and put into the steam bath in order to evaporate off the solvent. A white powder residue was left in the round bottom flask after evaporation. This caffeine was recrystallized by dissolving it in hot acetone. Crystals formed by cooling and were separated by vacuum separation with the aid of hexane. When they were dry we weighed them and transferred them into s sample bag. Results: Ÿ Weight of the product: 0.40g Ÿ Yield %: 2.7 % Ÿ Final appearance: white powder Questions: 1. Sodium carbonate has a role in the extraction of caffeine from the tea leaves in the first stage of the process. 2. 3. Because it has an appropriate vapor pressure below its melting temperature for purification through sublimation. 4. TLC is the easiest way to determine the identity and purity of the compound. By using standard caffeine spot ...