[CPfeif13]

Hello,

I recently did a trichloroisocyanuric acid/TEMPO oxidation that I found in the literature but another member of my research group tried it in the past and found that the reaction work up did not remove all of the cyanuric acid byproduct, which then caused problems in the next reaction, even after normal-phase purification.

Does anyone have any suggestions on how to get rid of all of the cyanuric acid? The product is soluble in organic solvents.


Thank you in advance!

[phth]

What do you mean by normal-phase, a column?  What is your product?

[CPfeif13]

Yes, a silica column with a solvent system of hexane/ethyl acetate. I am oxidizing Cbz-protected hydroxyproline to the ketone.

[phth]

First, Recrystallize if you can.  Im guessing that the acid is making the spots very streaky.  Try to find a solvent mixture where the product is ~33% Rf, then carefully run a column with a gradient up to that.  Sand can be used to reduce the perturbation of the silica layer by the pipette.  Recrystallize.

If that fails, another way is ion exchange chromatography.  This will work: run a reverse phase column/HPLC, make it a anion with Na₂HPO₄. 1:19 0.005M Na₂HPO₄:MeOH; this can be very expensive depending on the scale of your reaction, however.