# Why is ether used as the solvent during Grignard reactions?

Jan 13, 2016

Ether is used as a solvent because it is aprotic and can solvate the magnesium ion.

#### Explanation:

A Grignard reaction involves the reaction of an alkyl (or aryl halide) with magnesium metal to form an alkylmagnesium halide.

$\text{R-X" + "Mg" stackrelcolor(blue)("dry ether"color(white)(X))(→) "R-MgX}$

Diethyl ether is an especially good solvent for the formation of Grignard reagents for two reasons.

(a) Ether is an aprotic solvent

The $\text{R-Mg}$ bond is highly polar: stackrelcolor(blue)(δ^(-))("R"color(white)(l))-stackrelcolor (blue)(δ^+)("Mg")"X"

The Grignard carbon is highly basic and reacts with the acidic protons of polar solvents like water to form an alkane.

stackrelcolor (blue)(δ^(-))("R"color(white)(l))"-"stackrelcolor (blue)(δ^+)("Mg")"X" + "H-OH" → "R-H" + "HO-MgX"

Ether has no acidic protons, so Grignard reagents are stable in ether.

(b) Ether is a great solvating agent

The $\text{MgX}$ bond in a Grignard reagent is ionic: ${\text{R-Mg"^+ color(white)(l)"X}}^{-}$.

Hence, it is difficult to form a Grignard reagent in a nonpolar solvent.

The $\text{C-O}$ bond in an ether is quite polar, and the oxygen of the dipole can solvate and stabilize the ${\text{R-Mg}}^{+}$ ion.

Thus, Grignard reagents are soluble in ether.

Mar 29, 2017

the very simple reason is that in ether, there is no acidic Hydrogen present on which the Grignard reagent $R M g X$ can attack and get itself converted to $R - H$.

#### Explanation:

thus to prevent Grignard from decomposing simply to an alkane/ene/yne, we use ether.