The product I'm trying to isolate is moderately acid sensitive and the only work ups I have seen have used ion exchange resins that are not compatible.
I can probably add silica then subject it directly to flash chromatography but I would rather avoid this.
Dissolve your mixture in diethylether. TBAF is also soluble in Et2O. Now you can use the fact that TBA-chloride is not soluble in Et2O and wash your mixture several times with NH4Cl. This will remove tetrabutylammonium salts completely for sure.
For a literature example see synthesis of fulicinerine (2), p. 7433
http://onlinelibrary.wiley.com/doi/10.1002/chem.201204545/pdf
Do you want to remove the residuals after TxMS removal?
If you need the TxMS removal, and before the reaction,, I would recommend NH4F (or NH4F*HF) in methanol instead of TBAF. The reaction is cleaner, practically neutral and the excess of NH4F is easy to remove.
If you are after the reaction, add ~equimolar NaI and extract your solution with e.g. toluene (TBAI is soluble toluene) see, http://dx.doi.org/10.1246/bcsj.73.2263.
The NaF is easier to remove because its solubility in organic solvents are considerably less than TBAF.
good luck
Try to use TBA+-BF4- which is soluble in methanol.
The exchange of counter ion can be accomplished by dissolving TBAF in acetonitrile, followed by addition of an equimolar amount of silver tetrafluoroborate. After stirring at room temperature for 15 minutes, the precipitate of silver halide is filtered off over high flow. Then the filtrate is concentrated in vacuo.
Thank you everyone,
I'm removing a TMSE ester and doing a protodesilylation in one step. The protodesilylation loses the desired E/Z selectivity at low pH. KF in wet THF and maybe 18-crown-6 could be an alternative.
Direct addition of silica worked alright but I think there were material losses on the column, potentially due to basicity.
I'll give the Et2O / aq NH4Cl a try the next time I bring material through.
I had trouble removing TBAF from my water-soluble product and found that use of calcium carbonate and sulfuric acid amberlyst resin worked best. Use of the sulfuric acid resin alone removed about 70-80% of TBAF, but addition of CaCO3 removed 99%. Calcium forms an insoluble precipitate (CaF2) with HF liberated from treatment with the acid resin, which drives the equilibrium to the right. This was a procedure developed and reported by Kaburagi and Joshi (please see their paper for more detailed explanation)
Ref: Y. Kaburagi and Y. Kishi, Org. Lett., 2007, 9, 723 - 726
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