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Topic: Removal of NaBr from an Ionic Liquid  (Read 2814 times)

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Offline Mcant

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Removal of NaBr from an Ionic Liquid
« on: July 25, 2013, 09:48:27 AM »
Hi all

I've lately been synthing a few Ionic liquids Pmim BF4 and iBmim BF4 (1-propyl-3-methylimidazolium tetrafluoroborate and 1-isobutyl-3-methylimidazolium tetrafluoroborate)

The steps i use are:

1) akylation of 1-methylimidazole + haloalkane (1-bromopropane and 1-bromo-2-methylpropane respectively)

2) metathesis of the 1-akyl-3-methylimidazolium bromide via acetone + NaBF4 (stirring at rt)

This is all well and good however after the metathesis is done and i remove the solvent I'm unsurprisingly left with a load of NaBr in the reaction vessle along with my Ionic liquid

Any thoughts on how to remove the salt (without just simply decanting the IL off) ?

Thanks in advance!!!

Offline Mcant

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Re: Removal of NaBr from an Ionic Liquid
« Reply #1 on: July 25, 2013, 09:49:29 AM »
I should add both of the ILs are water soluable

Offline opsomath

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Re: Removal of NaBr from an Ionic Liquid
« Reply #2 on: July 25, 2013, 10:06:51 AM »
Is there some reason you can't just filter it out?

Offline Mcant

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Re: Removal of NaBr from an Ionic Liquid
« Reply #3 on: July 25, 2013, 10:30:33 AM »
I have thought about that but the thing about the ionic liquids is that they are incredibly viscous / sticky so filtering is going to be difficult due to the fact that they are going to just get trapped on the filter and not pass through.

Bare in mind the scale of reaction i'm using is around 5ml of each starting material, I can't really afford to lose that much product.

Offline DrCMS

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Re: Removal of NaBr from an Ionic Liquid
« Reply #4 on: July 25, 2013, 10:49:00 AM »
Can you not filter the NaBr out from the acetone solution and then strip out the solvent?

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