imidazole and grignard rxn

[miznaz]

what would happen if imidazole acted as an acid to react with Ch3MgBr (a base).

im not too sure how this acid base rxn would go further?

[Theophrastus]

Of this, I'm not quite sure. I'll give it a shot, but don't take my word for it. Anyhow, I know imadazole is weakly acidic, however, despite being amphoteric, it does come up far more prominently as a base. As an acid, it is simply rather weak. The second compound, methylmagnesium bromine, seems to be only weakly basic, (if the information you've given is true) due to the possibilities of the methyl group, being protonated under acidic conditions.

 

Anyhow, I really see two angles from which the imadazole can attack the MMB (not a common acronym, but I'll use it to cut down on length)- from the bromine side, however the result will be that the imadazole ring ion, will have taken bromine's place, and formed hydrobromic acid. Not only due to the magnesium's affinity for the bromine ion, in contrast to the imadazole ion, and the low strength of imadazole as an acid is this reaction unlikely, but as the end product shall produce hydrobromic acid. A much stronger acid to be sure, the reaction will quickly reverse itself, thus it shall be of little consequence.

 

Far more likely, will be the fact that it will instead protonate the methyl group, (perhaps resulting in intramolecular forces between the two molecules, as in contrast, imadazole's conjugate basic ion, is quite strong) however, while this may occur, it shall do so too infrequently to be of much consequence.

 

No offense, but I don't believe I see the possibility of a serious reaction here. Sorry to have burst that bubble.

Edited July 13, 2009 by Theophrastus
paragraph revision

[John Cuthber]

MeMgBr is very strongly basic and will deprotonate the imidazole giving

methane and imidazolyl magnesium bromide.

Probably messy if you do this in a test tube.

[Theophrastus]

Oh damn- MeMgBr is a strong base? Looking back, I've realised I forgot to factor in electronegativity. That taken into account, the methyl carbon, would by nature have a partial negative charge, and thus would make an excellent proton acceptor. Is there anything else, I missed in my analysis?