[johnpinecone]

Hi everyone, new to the forum so forgive me if i make any mistakes!

I'm currently in my 5th and final year of my undergraduate degree and am working on my final project. Im synthesising a new N-Heterocyclic carbene ligand for an enantioselective isomerisation reaction. Though I have reached a bit of a snag at the purification stage. The scheme should be shown below (assuming its worked). The proton NMR of my imidazolium salt products is showing  impurities which i just cant seem to get rid of. I suspect this is due to a small imidazole impurity due to the characteristic peak around 10.5. Any attempts to column have been unsuccessful as the compounds are just too polar - no solvent system seems to work. The literature claims they cleaned it up by column at the salt stage though did not publish any solvent system. I was just wondering if there are any old hands who are familiar with either removing imidazole or working with a similar sort of thing.

Any help would be greatly appreciated.

[cundi]

Have you try a reverse phase purification?
It is just a suggestion.

Good luck, with your final project.
It seems to be interesting.

[alphahydroxy]

yeah, if you can't get anywhere with say 10-15% methanol in ethyl acetate, I'd go down to the chromatography folks and see what they can do with reverse phase HPLC...