Anyone know about ionic liquid separation/removal?

Hey guys!

After talking to some colleagues of mine and scouring the literature, I'm stumped.

I'm working on a little project that involves a transition metal catalyst in ionic liquid and I can't find a good reference on how to isolate intermediates in ionic liquid; which means I've got to be creative.

Can anyone think of a good method to isolate a transition metal catalyst complexed with a monosaccharide from an ionic liquid?

I can't use water because it will hydrolyze my catalyst; I want a snap shot of what's going on at various stages of the catalytic reaction and for some reason not many people have done this, I'd think it'd be an absolutely necessary step to determine a reaction mechanism but maybe I'm just thinking about it the wrong way.

I was thinking of two main options:
1. Replicate the reaction conditions with a different solvent: i.e. use something somewhat polar with a low affinity for water that can dissolve NaCl or some other ionizeable salt and then just strip off the solvent once I form the intermediate.

2. Use lyophillization or extreme vacuum to remove the ionic liquid, which would require borrowing some equipment and I'm not 100% sure would work due to the low vapor pressure of most ionic liquids.

So, questions:
Does anyone know a good solvent that may dissolve a moderately polar catalyst (~3 polarity index), some salt, and a monosaccharide? I've already tried DMSO, impossible to get rid of enough water and hard to evaporate, DMF is no-go, and ditto for MeCN.

or

Does anyone know of an ionic liquid with a high enough vapor pressure that I could pull it off at room temp?

Thanks guys, I see more intelligence and free-thought on this board than I've seen just about anywhere else so I know one of you might have a good idea or at least be able to help me have one


[Edited on 23-9-2013 by FreeMirage]

Quote: Originally posted by FreeMirage

So, questions: Does anyone know a good solvent that may dissolve a moderately polar catalyst (~3 polarity index), some salt, and a monosaccharide? I've already tried DMSO, impossible to get rid of enough water and hard to evaporate, DMF is no-go, and ditto for MeCN.

Quote: Originally posted by Cheddite Cheese

What about propylene carbonate? https://en.wikipedia.org/wiki/Propylene_carbonate

Quote: Originally posted by sonogashira

It's rather difficult to suggest anything if you won't divulge any useful information about what you are working with: the stability of your reaction intermediates, interation with the solvent etc. Perhaps this review will lead you to some helpful information: [Edited on 23-9-2013 by sonogashira]

Sorry, I could have been more specific, you're right. The (homogenous) catalysts I'm working with are Al(III) and Fe(III) compounds that very readily hydrolyze in the presence of water. The ionic liquids are [BMIM]Cl and [EMIM]Cl. That paper you provided looks excellent, I'm thumbing through it now as we speak. There are a few things I was unaware of in that paper and I'm surprised I didn't find it. Thanks!

The interaction with the solvent is completely unknown although I don't expect there to be any reaction with a ketone moiety as in Propylene Carbonate. The ether linkages alpha the ketone on both sides I think would be able to withstand a strong lewis acid like Al(III), the lone pairs might coordinate but after evaporation I should end up with something characterizable.

Thanks for the help guys! I'll keep you all updated on how it works out.