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Extraction of caffeine from tea

Hi i was wondering if anybody could help me with my chemistry work? I carried out an experiment to extract caffeine from tea and now i have a few questions i need to answer in my lab book however i am struggling with a couple. if anyone could help me understand i would be very grateful.
The first question is why do you not record a melting point to determine purity of caffeine? and also what is the easiest way in which the identity and purity of the compound could be determined. Thank you :smile:

Reply 1

_NMcC_

I personally think that it's because caffeine starts sublimating at 178 degrees (boiling point) where as it's melting point of the anhydrous form (or the 'first') melting point is actually at 227 degrees. So you'll lose your sample as a gas before it even gets to the melting point of the 1st crystalline form.

. I think TLC might work.