Question

I have a mixture of three compounds and I want to separate them. The compounds are ethyl aminobenzoate (50%), benzoin (40%), and 1,4-dibromobenzene(10%). I started the experiment by dissolving the mixture in the methylene chloride, then I added HCl, so I got two layers, first one is aqueous layer that contain ethyl aminobenzoate, and the second one is organic layer that contain benzoin and 1,4-dibromobenzene. After that I add NaOH to aqueous layer and I got a solid, then I filtered it ,so my question is what is the best solvent of those ( diethyl ether, 95% ethanol, methanol, isopropyl alcohol, acetone, hexane, toluene, methlene chloride)to make recrystallization for this solid. Also, what is the best solvent of those (diethyl ether, 95% ethanol, methanol, isopropyl alcohol, acetone, hexane, toluene, methlene chloride) to make crystallization for the organic layer?

Answer 1

for better recrystallization we want to choose partially soluble solvent.

in aqueous layer we will have sodium salt of benzoin. it is the ionic compound, therefore, we want to choose protic solvent like ethanol as a solvent for better recrystallization. since it will have partial solubility in room temperature and completely soluble in heating on further cooling we will get recrystallized product

in the organic layer we have 1,4-brom,obenzene in the non-polar compound therefore choose polar solvent like ethanol since it will have partial solubility in room temperature. and it will produce better-recrystallized product