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Author: Subject: DMF extraction?
nightflight
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[*] posted on 14-3-2007 at 07:24
DMF extraction?


What would be a suitable solvent for extracting a dmf reaction mixture and/or procedure?

thanks, nightflight
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Furch
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[*] posted on 14-3-2007 at 10:16


Take a look at the attachment in my post here. It suggests that DMF is immiscible with the following solvents: xylene, diisopropyl ether, pentane, hexane, heptane and cyclohexane.

This is a common problem when using DMF as solvent... If these don't work, you should consider distillation if the b.p.'s have a decent gap between them.

[Edited on 14-3-2007 by Furch]

Attachment: solvent.miscibility.pdf (231kB)
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vulture
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[*] posted on 14-3-2007 at 12:12


Diethylether should work too. If the stuff doesn't separate, add plenty of water, if that doesn't work, add KCl solution, if that fails, filter over MgSO4 and if it still isn't gone you're going to have to resort to vacuum distillation to get it off.



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nightflight
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[*] posted on 15-3-2007 at 00:31


Thanks a lot! -I tried Et2O, but I didn´t see layers forming, neither worked xylene.
I might try DMSO, or destillation is feasible, if I hadn´t to clean a flask -ups, did I type that? :D
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Tacho
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[*] posted on 15-3-2007 at 03:35


DMSO will probably not work, since both (DMF and DMSO) are very similar solvents. Considering the table posted by Furch, why dont you try petroleum ether (lighter fluid). It is usually a mix of hexane, heptane etc.

Or, as Vulture suggested, just add water. If your product is not soluble in it, it will separate or, at least, make the extration with PE easier. If your product is soluble in water, those hydrocarbon solvents won't help anyway. In fact, if your product is soluble in water, I don't think you will be able to extract it from DMF. Go for distillation or careful evaporation.

[Edited on 15-3-2007 by Tacho]

[Edited on 15-3-2007 by Tacho]




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vulture
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[*] posted on 15-3-2007 at 14:59


Quote:

Thanks a lot! -I tried Et2O, but I didn´t see layers forming, neither worked xylene.


Add about 30mL of water for every 10mL of DMF and then filter over MgSO4. Or just put it in a flask with some MgSO4 and swirl. That usually separates the layers for me.

DO NOT add DMSO. It'll only make your problems far worse.




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