[DoctorDomo]

Going on what someone here suggested, I started doing microscale reaction workups to help find the best procedure for isolating my products from the reaction mixture. This seems like a good idea when you're researching new compounds that haven't been characterised yet. I'm just wondering what kind of procedure people here use for these microscale workups. I've basically been lining up a series of plastic vials, adding a small amount of brine (or 5% LiCl when DMF is the solvent), then adding an aliquot of the reaction mixture to see what crashes out. If I can't get anything better than a cloudy suspension (which can't be filtered), I then add an immiscible solvent for a liquid-liquid extraction, I'll test out a few different solvents, starting with less dense ones such as ethyl acetate or diethyl ether so that they can be pipetted out of the vial without contaminating the pipette by submerging it in the wrong layer.

Like this I can see I'm left with when I rotavap off the organic solvent. Problems arise when there is a residual high boiling solvent like DMF or ethylene glycol, so I'm thinking a better approach would be to do a series of "crash" tests first, to see what I can get to precipitate out before going onto liquid-liquid extractions.

If anyone can tell me how they do things, it'll be a big help, I'd greatly appreciate it.