[taurean]

Hmmm...usually base (aq KOH) is the way that I have broken up B-heteroatom junk.  Maybe methanol would be nucleophilic enough to get rid of the boron.

Please let me know if you think of anything else.  Methanol as reported in the literature would take ~170 hrs to cleave B-N bond.  So, trying to find a fast and efficient method.

Does Borane:Amine complex appears near the solvent front or somewhere near the base line of the TLC (10% MeOH/CH2Cl2) plate?

[kiwi]

if you want speed, maybe something more nucleophilic like ethanethiol? smells terrible though, but easy to get rid of (bp <40 deg C). or even another volatile amine, like NH3, NMe3 or EtNMe2

[movies]

Does Borane:Amine complex appears near the solvent front or somewhere near the base line of the TLC (10% MeOH/CH2Cl2) plate?

It's been a long time, so I don't really remember.  My guess is that you wouldn't see the complex because it would react with silica gel or air.  You would probably just see the amine.

[taurean]

Does Borane:Amine complex appears near the solvent front or somewhere near the base line of the TLC (10% MeOH/CH2Cl2) plate?

It's been a long time, so I don't really remember.  My guess is that you wouldn't see the complex because it would react with silica gel or air.  You would probably just see the amine.

Forgive my ignorance.  If it reacts with silica gel or air, after the borane reduction followed by workup with mild acid we can just put on the silica gel column and purify.....right?

[movies]

I think we got confused here.  My last post was referring to borane-amine complexes like BH₃-Pyridine complex.  These are convenient forms of BH₃, and the nature of the complexed amine can affect the reactivity and reducing power.

The complexes you are dealing with are not boranes, but borates (a higher oxidation state of boron).  These are usually harder to get rid of because the B-heteroatom bonds are so strong.  I doubt silica has enough acidity to break up a borate complex; they probably just stick to the top of the column.

[taurean]

I think we got confused here.  My last post was referring to borane-amine complexes like BH₃-Pyridine complex.  These are convenient forms of BH₃, and the nature of the complexed amine can affect the reactivity and reducing power.

The complexes you are dealing with are not boranes, but borates (a higher oxidation state of boron).  These are usually harder to get rid of because the B-heteroatom bonds are so strong.  I doubt silica has enough acidity to break up a borate complex; they probably just stick to the top of the column.

Okay, thanks.  I was thinking that you were talking about borates.  Movies, so you think 1N HCl is mild to break up the B-N bond of the borates?  As I mentioned before, I do not have the flexibility of using any strong acid or base for the workup because of the other functionality in the molecule.

[movies]

I don't know for sure, I have always used base to break them up.  I would think that acid would work too though.