Recrystallization Solvents

[ipodtouch]

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I am reading in the BR that
Impurities should be highly soluble in the solvents used in recrystallization.

I was wondering if it was also true that
Impurities should be highly insoluble in solvents used in recrystallization.
(hot filtering through sieves)


I couldn't find it reiterated anywhere, but just wanted to make sure it was true.

 

[chiddler]

would make sense for impurities to be highly soluble so they stay in solution while desired compound crystalizes.

 

[ipodtouch]

would make sense for impurities to be highly soluble so they stay in solution while desired compound crystalizes.

Yes that is a given


I'm asking if it would also make sense for impurities to be highly insoluble so that it can be filtered out physically during hot filtration.

 

[chiddler]

Yes that is a given


I'm asking if it would also make sense for impurities to be highly insoluble so that it can be filtered out physically during hot filtration.

probably not because there will be small particles that make it through the filter that may act as nucleation sites for crystallization.

probably. i've not read or done problems on this so just speculation.

 

[chaser0]

Yes but it must be near completely Insoluble.
Ex/ boiling chips and charcoal.
Oxyacids in hydrocarbon solutions etc.

You are correct