[Puchini 101]

Does anyone know why Grignard reagent of CH3I can only be prepared using diethyl ether as a solvent and yields no reaction when developed in THF?

[orthoformate]

Does anyone know why Grignard reagent of CH3I can only be prepared using diethyl ether as a solvent and yields no reaction when developed in THF?

I think that magnesium degrades the THF. I looked all over for a reference, but I couldn't find one.

[clarkstill]

Does anyone know why Grignard reagent of CH3I can only be prepared using diethyl ether as a solvent and yields no reaction when developed in THF?

I don't think this is true. A reaxys gives quite a few hits for formation of MeMgI in THF although Et2O seems to be more common, for example:

http://pubs.acs.org/doi/suppl/10.1021/jo052418r

In general I think it's easier to get a hold of dry Et2O and less risk of contamination with peroxides etc., so quenching of the grignard by water or unwanted side reactions will be easier to avoid.