作者：Ryan May 2 年以前
140
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With a pipet, add petroleum, one drop at a time, swirling in between drops. Continue until there is a cloudiness in the solution
Recover the recrystallized product through vacuum filtration using a Hirsch funnel
Transfer the product to filter paper and allow it to air dry for twenty minutes
Measure the mass and melting point of the recrystallized product Final mass: 0.416g Melting point: 231-234 degrees celcius
Heat the mixture on the hot plate. Allow it to boil for two minutes, then turn the hot plate off and allow the contents to settle.
Two samples: Aqueous layer containing caffeine
Two samples: tablet binder material and impurities that went undissolved
Carefully filter the alertness aid pill mixture into the separatory funnel. Rinse the residue remaining in the glass with a small amount of water
Allow the aqueous filtrate to cool down to room temperature as it is dangerous to add dichloromethane to a warm solution.
Add 7ml of dichloromethane to a cooled solution. The aqueous layer will be on the bottom, and the caffeine/dichloromethane will be on top, due to the density
Place the stopper in the neck of the separatory funnel and shake gently. Invert the funnel while holding the stopper securely in the neck, and vent the separatory funnel through the stopcock. The caffeine will be extracted from the aqueous phase to the organic phase
Drain the organic layer into the labelled Erlenmeyer flask
Repeat this process twice to ensure that the organic layer has been completely collected (Total of three times)
Two samples: Organic layer
Two samples: Aqueous layer
Once the extracts have been collected, add a fair amount of drying agent and let it sit in the flask for several minutes Try to add the drying agent little by little
Decant the dichloromethane solution into a 50ml beaker, and gently evaporate the solvent away in the hood
Measure the mass of the crude product in the beaker My mass was 0.467g
