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Topic: Caffeine why, sublimation and not recrystallization?  (Read 19628 times)

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UAphenix

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Caffeine why, sublimation and not recrystallization?
« on: October 03, 2005, 03:25:42 AM »
Can anyone explain to me why sublimation would be used to purify crude caffeine as opposed to recrystallization?  I reallize that caffeine doesn't boil, it does sublime though.  I may completely wrong here, if you can't tell i am to say the least completely lost.  Any ideas would be very helpful.  Thanks
« Last Edit: October 03, 2005, 03:38:06 AM by UAphenix »
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Offline Mitch

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Re:Caffeine why, sublimation and not recrystallization?
« Reply #1 on: October 03, 2005, 03:50:31 AM »
Its a better way to remove impurities.
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UAphenix

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Re:Caffeine why, sublimation and not recrystallization?
« Reply #2 on: October 03, 2005, 11:26:09 AM »
Thanks, what makes sublimation a better purifier than recrystallization?  I have been looking all over the web to find a comparison of the two, but have not had any luck.
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Offline xiankai

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Re:Caffeine why, sublimation and not recrystallization?
« Reply #3 on: October 09, 2005, 05:58:02 AM »
crystalisation relies on the partial precipitation of a salt based on the difference in solubility at different temperatures.

with sublimation however, u can be assured that all the substance will sublime, just like how water boils completely beyond 100oC
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