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- Place 2g instant coffee and 2g Na2CO3 in 100mL 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 mins. 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!
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