Organic Chemistry Recrystallization

AI Thread Summary
Ethanol is a poor choice for recrystallizing phthalic acid because phthalic acid is highly soluble in ethanol at room temperature, which contradicts the requirements for effective recrystallization. A suitable solvent should allow the compound to be insoluble or only partially soluble at room temperature while being highly soluble at its boiling point. Additionally, ethanol can react with acids to form esters, complicating the recrystallization process. Water is a better solvent for this purpose due to its ability to dissolve phthalic acid effectively. Understanding these solubility principles is crucial for successful recrystallization.
CMATT
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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.
 
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CMATT said:
I also know water and ethanol are not miscible.
Say what?
 
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.
 
Bystander said:
Say what?
Sorry my chemistry book is confusing! I misread
 
alchemistf9 said:
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!
 
CMATT said:

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.
 
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