What is the Difference Between Gilman and Grignard Reagent?

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The main differences between Gilman and Grignard reagents are:

  1. Central Metal: Gilman reagents are organocopper compounds, while Grignard reagents are organomagnesium compounds.
  2. Solvent: Grignard reagents are typically prepared and used in anhydrous ether, while Gilman reagents are typically prepared and used in anhydrous THF (tetrahydrofuran).
  3. Reactivity: Gilman reagents are useful nucleophiles for conjugate addition reactions (“1,4-addition”) on α,β-unsaturated compounds, as well as SN2 reactions, forming C-C bonds with primary alkyl halides and sulfonates (e.g., tosylates, mesylates). In contrast, Grignard reagents tend to only add to the carbonyl carbon.
  4. Conjugate Addition: Gilman reagents perform conjugate addition reactions, while Grignard reagents generally only add to acid chlorides.
  5. Physical State: Gilman reagents occur in the liquid state, while pure Grignard reagents occur in the solid state.

Comparative Table: Gilman vs Grignard Reagent

The main difference between Gilman and Grignard reagents is the central metal atom in their composition. Gilman reagents are organocopper compounds, while Grignard reagents are organomagnesium compounds. Here is a comparison table highlighting the differences between Gilman and Grignard reagents:

Property Gilman Reagent Grignard Reagent
Central Metal Copper Magnesium
Reactivity Less reactive More reactive
Conjugate Addition Performs 1,4-addition on α,β-unsaturated ketones Adds to the carbonyl carbon
SN2 Reactions Useful nucleophile for forming C-C bonds with primary alkyl halides and sulfonates Not applicable
Acyl Chlorides Converts acid halides to ketones through nucleophilic acyl substitution Adds twice to acid halides to give tertiary alcohols

Gilman reagents are useful for conjugate addition reactions and SN2 reactions, while Grignard reagents are more reactive and typically add to the carbonyl carbon in reactions with acyl chlorides.