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Topic: DMF removal (can't do aqueous extraction)  (Read 22923 times)

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Offline Polly Murs

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DMF removal (can't do aqueous extraction)
« on: February 28, 2012, 07:52:47 AM »
I've carried out Sonagashira coupling (iodine displaced by alkyne) and using DMF as solvent.

right now I'm using rotovap with CO2 trap to try and drive it off. slow but seems to work

just wondering if there are any other tips fro getting rid of dMF, DMSO, etc

as mentioned in title I can't use water as my stuff is water-soluble

t.i.a.

Offline Doc Oc

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Re: DMF removal (can't do aqueous extraction)
« Reply #1 on: February 28, 2012, 08:49:19 AM »
2 things:

1) My previous lab had nice rotovaps with good seals, so we could use those to drive off DMF, but we had to heat the bath to 60 or so to get it to pull off at a reasonable rate.  If your rotovap isn't as nice, you may not be able to do this.

2) Do a vacuum distillation of the solvent.  Set up a short path column, cool the collection flask to -78, then hit the vacuum.  You can periodically warm up the solvent by holding the flask in your hand.  Depending on the amount of DMF you have, you should be able to get this distilled out relatively quickly.

Offline Polly Murs

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Re: DMF removal (can't do aqueous extraction)
« Reply #2 on: February 28, 2012, 11:19:25 AM »
I read somewhere that toluene forms an azeotrope with DMF, so tried this and it worked! I used 3 or 4 lots of toluene to completely remove it

Offline Mobius1988

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Re: DMF removal (can't do aqueous extraction)
« Reply #3 on: March 02, 2012, 08:46:01 PM »
You can use a rotatory evaporator to remove DMF if the water bath is heated to 60 degrees C and you have a good vacuum. I do it all the time after sonogashira's, just be careful that you dont get any byproducts at high temperatures.

Alternately if your reaction is small scale and you only have a small amount of DMF you can use 10 x volume of organic solvent/water for your work up and the DMF should mix in with the organic layer.

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