How to extract pure caffeine from coffee:
- Place 2 g instant coffee and 2 g Na2CO3 in 100 mL of water in a beaker.
- Heat the solution with occasional stirring for 5–10 mins.
- Cool the solution and decant it into a separatory funnel.
- Add 10 ml of methylene chloride and gently mix the two layers by inverting the funnel several times for about 5 minutes. Vigorous shaking of the funnel should be avoided as it will result in the formation of an emulsion between the two layers.
- Drain out the lower methylene chloride layer from the separatory funnel into an Erlenmeyer flask leaving behind any emulsion that forms.
- Repeat the extraction with another 5 mL of methylene chloride and add the two extracts together.
- Add a small amount of MgSO4 to the flask and shake it well. A clear solution indicates that it is dry.
- Transfer the dry solution to a weighed 25 mL RB flask and evaporate the solvent on the rotary evaporator.
- Determine the weight of the crude product and recrystallize it from ethanol or acetone. And there you have some pure caffeine!