Hi! I'm trying to reproduce the known recrystallization of an organic compound.
( doi.org/10.1016/S0040-4039(96)02334-9 , doi.org/10.1021/op060204l )
As you can see in these papers, ketalization product of Wieland-Mischer ketone should be recrystallized by iPr2O or the solvent mixture of Et2O/Hx=1/20.
After a work-up with EA, I've tried both of them(adding them slowly along the wall of RBF) at room temperature or below 0'C(fridge), but none of them actually worked out.
When (volume-wise 3X) ether/hexane was added, I can see white emulsion(fog?) being formed and then the existing crude mixture stays as a syrup under the transparent solvent. Even after putting it in the fridge, they still stay as separate layers. (As this reference is OPRD, I believe it'll work in a certain way, but I have no clue.)
Is there anyone who's recrystallized similar compounds before?
Thanks in advance for any help you are able to provide.
" When (volume-wise 3X) ether/hexane was added " What do you mean by this? 3x volume of what?
"Even after putting it in the fridge, they still stay as separate layers. " The hexane and ether form 2 layers? If this is true then something is wrong, hexane and ether should form a miscible layer.
Without knowing exactly what you do, it is difficult to say what is the problem. But as a start I recommend dissolving the crude compound in minimal amount of ether and add 20x volume of hexane to precipitate out the product.
Maybe the ethylene glycol is not completely removed.
Ethylene gylcol is immiscible with hexane and iPr2O
@Eugene Yang My bad, I meant 3~5 times the volume of the syrup. And of course not, ether AND hexane mixture remained as supernatant without being mixed with the syrup for some reason. Plus, this syrup isn't soluble to ether at all but it's soluble to large amount of DCM. Maybe I should try again after a filtration through a short silica pad to remove possibly remaining ethylene glycol. (But I doubt it as I've washed the organic layer with Na2S2O3 solution during a work-up)
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