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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......

...and as a result, the ipso carbon exhibits strong carbanionic character, which confers upon it the ability to function as both a potent base and nucleophile.

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

Grignards reagents are typically used in aprotic media; the Grignard is typically quenched by the addition of water or alcohols, 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#

Heavy water is a cheap deuterated solvent, so this would be a much more affordable method of labeling the alkyl chain than purchasing pre-deuterated material from a supplier.

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Answer 2

Carter Allen

Grignard reagents are strong bases because they contain a polarized carbon-magnesium bond, which is highly polarized due to the large electronegativity difference between carbon and magnesium. This polarization facilitates the donation of electrons from the carbon atom to protonate acidic compounds, making Grignard reagents strong bases.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.