Question

How do you remove residual Lawesson's reagent after thionation?

Answer 1

My recollection is that Lawseson's residues are fairly non-polar and elute early so I would go with several column volumes of neat DCM before starting at 1% MeOH for a couple of column volumes then 2% etc. This means a much shallower gradient and more fractions than you've previously uxed