Question

I have impure (( aromatic Amine product)) , the lecturer used recrystallization by Water + ethanol. I used the same mixture solvents, but still the impurities presented. Any suggestions for better solvents system? Or maybe the amount of the solvent mixture I used was not correct ? ( I mixed 1 ml of each solvents )

Answer 1

Aromatic amines are prone to aerial oxidation and not very easy to purify it by simple re-crystalliation.

The better way to do it by converting the free amine to its HCl salt and then recrystalliation can work better without fearing the aerial oxidation.

Once, you have the pure crystals, then you can regenerate the amine by neutralliing it.

For aromatic amines this one of the best methods because you can wash out all other imurities in the slat stage. Handling of salt is also safer.