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Lab Experiment : Isolation Of Caffeine From Coffee

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Xingwang Cai October 2, 2017 Isolation of Caffeine from Coffee Introduction The purpose of this experiment was to isolate caffeine from coffee. The coffees contain caffeine, antioxidants and diterpenes. The experiment was to extract caffeine from those compounds. Purify the inorganic compound by the process of sublimation and determine its melting point1. Experiment Scheme Magnesium sulfate2 Calcium carbonate2 Methylene chloride2 Acetone2 Caffeine2 Figure 1. The Chemical structure of Magnesium sulfate, Calcium carbonate, Methylene chloride, Acetone, Caffeine. TA helps us use 50g of pre-ground coffee and 250ml water make the coffee1. Then collect it in a beaker containing 6.0 g of CaCO3. Heat the mixture about 70℃ for 10 minutes. This step is keep the mixture for 70℃, not the hot plate. The cool it and filter it use fritted funnel with Celite. After filter, transfer it into 2 separatory funnel and extract with 20 ml of CH2Cl2. Then roll the separatory slowly for 90 seconds. The stop should be open to release air every 30s. Collect the organic layer after the extraction. Then adding another 20 ml of CH2Cl2 for each and do the same step again and collect the organic layer. Use enough anhydrous MgSO4 to dry the combined organic layer. It will form some insoluble solids, filter and discard it. Transfer the liquid to a 250 ml round bottom flask, using rotary evaporator to evaporate the CH2Cl2. After all CH2Cl2 is gone, form crude caffeine. We used a small volume of
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