Sciencemadness Discussion Board

ethers for Grignards reaction

CrossxD - 29-4-2017 at 11:03

Hello,
can I use dioxane or dimethyl ether for Grignards reactions?

PirateDocBrown - 29-4-2017 at 11:28

At what temperature do you propose to work with dimethyl ether?

DraconicAcid - 29-4-2017 at 12:25

Dioxane will actually react with Grignard reagents to precipitate a magnesium halide solvate, leaving a dialkylmagnesium species in solution. This will generally react the same as a Grignard, though.

clearly_not_atara - 29-4-2017 at 13:32

It reacts similar to a Grignard but somewhat faster and the solution is pyrophoric. Not usually what you want.

Diethoxymethane is the only solvent for Grignards that isn't a simple aliphatic monoether afaik. It can be distilled as the azeotrope with ethanol from a rxn mixture of ethanol and formaldehyde with acid catalyst. It can then be purified by removing the lower-boiling ethanol as its azeotrope with ethyl acetate.

[Edited on 29-4-2017 by clearly_not_atara]

AvBaeyer - 29-4-2017 at 19:53

Tetrahydrofuran is a common solvent though sometimes reactions are sluggish. Dimethoxymethane and dibutylether have also been suggested as solvents in some of the older literature. I have never tried either one of these latter two.

AvB