Question

Why are Grignard reagents strong bases?

Answer 1

A Grignard reagent features a carbon that is more or less directly bound to a metal centre......

Explanation:

...and, therefore, the ipso carbon has strong carbanionic character. This makes it (i) a powerful nucleophile, and (ii) a powerful base.

`RCH_2-X + Mg rarr RCH_2^(delta-)""^(delta+)MgX`

Generally, Grignards reagents are deployed in aprotic media. Addition of water or alcohols usually quench the Grignard, i.e.

`RCH_2^(delta-)""^(delta+)MgX + H_2O rarr RCH_3 + Mg(OH)X`

Sometimes this can be useful synthetically to introduce, say, a deuterium label, `D=""^2H` on a hydrocarbyl chain:

`RCH_2^(delta-)""^(delta+)MgX + D_2O rarr RCH_2D + Mg(OD)X`

This would be a much cheaper way of labelling the alkyl chain than buying pre-deuterated material from a supplier. As deuterated solvents go, heavy water is cheap.