[Atom]

Hi:

I wonder if anyone knows what is the best eluent system for chromatographic purification of 1,2-amino alcohol. I assume this compound is very polar, and having free nitrogen around will make things that much harder. On the TLC, it looks very smeary. I have this material as a (suspected) mixture of diastereomers.

Thanks!

[movies]

Distillation is often better for these compounds.  It's the only method I have ever used to purify amino alcohols.

You might also be able to recrystallize.

[Atom]

I only have a small amount of this material as my crude oily product, so distillation or recyrstallization is not a viable option.

[smk67]

How much do you have? What are the impurities? Can you just do some simple extraction to remove the "oily material"? After that, if you have over a gram, distillations are still feasible. You can do a kugelrohr distillation if you have the equipment. I have not done many extractions in the lab, but my guess is that you could get that to work on a very small scale (look into any small scale organic lab text book and I bet you will find a general procedure).

As far as chromatography, just do some TLCs. In general, the best solvent system for a column is one that when ran as your TLC solvent system gives an Rf of ~.25-.35 for the desired component.

[alphahydroxy]

You could try dichloromethane : methanol : ammonia

I think a good starting point is something like 90:4:1   DCM : MeOH : methanolic ammonia

[Atom]

Thank you all for answers. I have less than 50 mg of the impure material so I think the best approach is probably by column. I will try CH2Cl2/MeOH/NH3 system first. What I am afraid of is complication from N-oxide.