what are some reasons why water isn't generally a good solvent for recrystallization?

Answer 1

Recrystallization in water can have a good yield of product if the compound you are using is soluble in water. Water would not be a suitable solvent in all reactions because of its high boiling point I think. It is important to choose a solvent which will not dissolve the substance at room temperature so that the pure crystals may be recovered. So it affects the yield of the crystals also.

This question did inspire me to research it because I couldn't recall the exact answer...though I'm sure we discussed it in class......

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

From what I read water is usually not good as a solvent by itself because it does not meet all of the above requirements....BUT as most compounds tend to violate one or more of these as well, water is often used in conjunction with other chemical compounds to form a solvent pair. Water IS a good solvent in the recrystallization of acetanilide due to the solubility of it in water. You would have to use the Merck guide to see the solubility of a compound in water to determine its suitability as a solvent.

Answer 2

because water, is simply water and it doesn't have the chemicals needed