Reactions with Metals
Formation and reactions of Grignard reagents and the Wurtz reaction for coupling alkyl halides.
What is Reactions with Metals?
An organomagnesium compound of the general formula R-MgX, prepared by the reaction of an alkyl or aryl halide with magnesium metal in anhydrous ether. It acts as a strong nucleophile and base.
Key formula / rule: Grignard Reagent Formation
Key points
- To understand the formation of Grignard reagents.
- To learn the synthetic utility of Grignard reagents in forming C-C bonds.
- To comprehend the mechanism and scope of the Wurtz reaction.
- To differentiate between the applications of Grignard reagents and the Wurtz reaction.
Common exam trap
Using wet ether or water during Grignard reagent preparation, which destroys the reagent.
Definitions
- Term
Grignard Reagent
- Meaning
An organomagnesium compound of the general formula R-MgX, prepared by the reaction of an alkyl or aryl halide with magnesium metal in anhydrous ether. It acts as a strong nucleophile and base.
- Term
Wurtz Reaction
- Meaning
A coupling reaction in which two alkyl halide molecules react with sodium metal in anhydrous ether to form an alkane containing twice the number of carbon atoms as the original alkyl halide.
- Term
Organometallic Compound
- Meaning
A compound containing a bond between a carbon atom and a metal atom.
Learning objectives
To understand the formation of Grignard reagents.
To learn the synthetic utility of Grignard reagents in forming C-C bonds.
To comprehend the mechanism and scope of the Wurtz reaction.
To differentiate between the applications of Grignard reagents and the Wurtz reaction.
Formulae
- Name
Grignard Reagent Formation
- Note
X = Cl, Br, I. Reaction is carried out in anhydrous ether.
- Expression
R-X + Mg → R-MgX
- Name
Wurtz Reaction
- Note
Reaction is carried out in anhydrous ether. Primarily forms symmetrical alkanes.
- Expression
2 R-X + 2 Na → R-R + 2 NaX
Prerequisites
Structure and reactivity of haloalkanes
Understanding of nucleophiles and electrophiles
Basic concepts of organic reactions and reagents
Common mistakes
Using wet ether or water during Grignard reagent preparation, which destroys the reagent.
Expecting only the desired product in the Wurtz reaction when using different alkyl halides (leads to a mixture).
Forgetting the need for anhydrous conditions.
Keywords
Grignard reagent
Wurtz reaction
Organomagnesium halide
Alkyl halide
Magnesium
Sodium
Anhydrous ether
Carbon-carbon bond formation
Nucleophile
Coupling reaction
Practice preview
Grignard reagents are prepared by the reaction of alkyl or aryl halides with:…
easy
Grignard reagents are prepared by the reaction of:…
easy
The product formed when ethyl bromide reacts with sodium in the presence of dry ether is:…
easy