Removal of soluble an insoluble impurities.

[blazinfury]

If after one performs an organic rxn and wants to purify their sample of both soluble and insoluble impurities, is there a correlation to temp where insoluble impurities are removed when the sample is hot and then soluble are removed after the compound has crystallized? Or is it more case by case basis? Also why are some impurities removed when the sample has not crystallized and others removed after the sample has crystallized?

[crimsonpetal]

It's all related to solubility, and remember the impurities are little compared to the main product. The insoluble impurity can removed by filtration. The When you recrystallize, you heat the solvent to increase solubility and use the minimum hot solvent to dissolve your product, after cooling you get your product, the soluble impurity is so little that it can solube in the minimum solvent after cooling.

[Bromo_DragonFly]

the question doesn't have a certain constant answer. i mean it's very case-to-case.

sometimes a 2-solvent system recrystallization is all you need. (like ethanol & H2O or so)