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Topic: Cooling vs Evaporation in Crystalisation  (Read 1411 times)

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Offline foxthreefour

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Cooling vs Evaporation in Crystalisation
« on: June 08, 2018, 04:03:01 PM »
So I'm no expert in crystallisation, not even a little bit but I was curious, when crystallising from a saturated solution would there be significant difference in the size and quality of the crystals obtained cooling from the solvent's boiling point slowly or evaporating over the same period of time? I ask because it seems that when hot the molecules are moving faster, that stacking in order and minimising new nucleation sites may be hard. Whereas when the saturated solution is at a stable temperature (say 20°C) and the compound is slowly coming out it may have the time and order to stack efficiently while minimising these new nucleation sites.

Thanks.
« Last Edit: June 08, 2018, 04:16:09 PM by foxthreefour »

Offline Arkcon

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Re: Cooling vs Evaporation in Crystalisation
« Reply #1 on: June 08, 2018, 04:15:21 PM »
You are correct that there are different results depending on how slowly the crystallization proceeds.  And yes this is very important, particularly for things like later instrument analytical tests, and pharmaceutical production.

Here's a scholarly article: https://www.sciencedirect.com/science/article/pii/S0032591004004929
(If you really care, you can try to get access)
But for just curiosity: http://orgchemboulder.com/Technique/Procedures/Crystallization/Crystallization.shtml
« Last Edit: June 08, 2018, 04:30:09 PM by Arkcon »
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline foxthreefour

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Re: Cooling vs Evaporation in Crystalisation
« Reply #2 on: June 08, 2018, 04:29:44 PM »
No there are different results depending on how slowly the crystallization proceeds.  And yes this is very important, particularly for things like later instrument analytical tests, and pharmaceutical production.

Here's a scholarly article: https://www.sciencedirect.com/science/article/pii/S0032591004004929
(If you really care, you can try to get access)
But for just curiosity: http://orgchemboulder.com/Technique/Procedures/Crystallization/Crystallization.shtml

Thank you, I'll check out the ScienceDirect article today.

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