TLC Tips

TLC Tips: for when conventional thin layer chromatography on the crude reaction mixture is problematic:

1. Do a mini aqueous workup on a small amount of the reaction mixture, in a vial. Then TLC the organic layer.
2. For very polar compounds, use:
   1. 10% NH ₄OH in MeOH solution as your polar solvent: try 1-10% of this mixture in dichloromethane.
   2. EBAW: EtOAc/butanol/HOAc/H ₂O in a 80/10/5/5 ratio (note: this solvent system CANNOT be used for flash chromatography).
3. If your solvent is the problem, you can put the TLC plate on the high vac before running it.
4. To test stability of your compound on slice, run a 2D TLC:
   1. Using a square silica plate, spot the sample in one corner.
   2. Run the plate in one direction (all components of the sample will appear in a vertical line of spots).
   3. Turn the plate 90 degrees (your "line of spots" should be at the bottom) and run the plate again.
   4. If the sample is stable to silica, all spots will appear on the diagonal. If a compound is decomposing, it will appear below the diagonal.
5. Use Gas Chromatography (GC).
6. If all else fails, remove a sample of your reaction mixture and take an NMR.