Organic Chemistry Recrystallization

[CMATT]

Homework Statement

Why is ethanol a bad choice for recrystallization of phthalic acid?

2. The attempt at a solution
I know phthalic acid is very soluble in water, so water is a great candidate to recrystallize phthalic acid. I also know water and ethanol are not miscible. But I don't know how to properly answer this question. Please help.

 

[Bystander]

I also know water and ethanol are not miscible.

Say what?

 

[alchemistf9]

Water and ethanol are miscible!

Phthalic acid must be highly soluble in ethanol but not in water at room temp and therefore is a bad solvent for recrystallization. In order to have properly recrystallization the compound must be insoluble or only partially soluble in the solvent at room temperature but highly soluble in the solvent at or near its boiling point.

 

[CMATT]

Say what?

Sorry my chemistry book is confusing! I misread

 

[CMATT]

Water and ethanol are miscible!

Phthalic acid must be highly soluble in ethanol but not in water at room temp and therefore is a bad solvent for recrystallization. In order to have properly recrystallization the compound must be insoluble or only partially soluble in the solvent at room temperature but highly soluble in the solvent at or near its boiling point.

Thank you so much! This makes more sense. My book had some description about solubility and pure compounds when recrystallizing, but I just couldn't grasp the concept. Thanks again!

 

[Dr Uma Sharma]

Homework Statement

Why is ethanol a bad choice for recrystallization of phthalic acid?

2. The attempt at a solution
I know phthalic acid is very soluble in water, so water is a great candidate to recrystallize phthalic acid. I also know water and ethanol are not miscible. But I don't know how to properly answer this question. Please help.

A solvent should also not react with the compounds ...
Alcohols react with acids to form esters ...that can also be one of the reason.