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Topic: Drying of DMF  (Read 16959 times)

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Offline poorstudent83

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Drying of DMF
« on: May 16, 2011, 12:23:54 AM »
I need a large amount (approx.500 ml) of anhydrous DMF. Is it sufficient to reflux the solvent over 4A molecular sieves overnight then distill under reduced pressure?? I'm wary of the DMF decomposing if refluxed for that long...
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Offline ATMyller

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Re: Drying of DMF
« Reply #1 on: May 16, 2011, 04:37:41 AM »
Allowing the liquid to stand over the sieves for overnight is usually enough, no refluxing needed. You might need to add some metallic sodium shavings before distillation to make sure all of the water is removed from liquid phase.
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Chemists do it periodically on table.

Offline enahs

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Re: Drying of DMF
« Reply #2 on: May 16, 2011, 10:58:53 AM »
It decomposes slightly at its boiling point at atmospheric pressure to give a small amount of carbon monoxide and diethyl amine. If that is going to be a problem for your reactions, the distill at reduced pressure.
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Offline Biginelli

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Re: Drying of DMF
« Reply #3 on: July 24, 2011, 05:42:16 AM »
I was drying DMF over calcium hydride for a few hours, then performed a distillation over it. Further reactions comprised sodium cyanide and proceeded well enough; thus, the drying was successful.
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