What properties are desirable in a recrystallization solvent?

Recrystallization Solvent

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RE:
What properties are desirable in a recrystallization solvent?

No it is not. Selecting a proper solvent for recrystallization can be somewhat of an art, and improves with practice. You want a good solvent to have good solubilities of all components at higher temperature, unless they are insoluble impurities, then they are simply filtered off when hot. Then as you slowly cool the solution you want the product to start to crystallize out, while the impurities remain in solution. The slower the product crystallizes out the higher the purity will be. So you want the product to start to crystallize when the solution is still warm. That way, product will come out pure, and impurities will still be in solution. Then you cool the mixture down and filter off the product. And good chemists will do many small scale recrystallization attempts at a very small scale, perhaps in a test tube, to see which solvent works best.

A good solvent for recrystallization must:

1. not react with the desired solid

2. be easily removed from the desired solid

3. dissolve a relatively large amount of desired solid at high temperatures (usually the bp) or not at all)

4. dissolve impurities at all temperatures or not at all

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