C

Carbanion

R⁻ (carbanion; carbon bears negative charge)
Quick Reference
Formula / NotationR⁻ (carbanion; carbon bears negative charge)
Also Known AsCarbanion intermediate, carbon anion, organometallic carbanion equivalent

What is Carbanion?

A carbanion is a carbon-containing anion in which the carbon bears a negative charge, meaning it has three bonds and an unshared pair of electrons. Carbanions are important reactive intermediates in organic chemistry, particularly in reactions with alkyl lithium and Grignard reagents. They are strong bases and nucleophiles.

Formula & Notation

R⁻ (carbanion; carbon bears negative charge)

Other Names / Synonyms: Carbanion intermediate, carbon anion, organometallic carbanion equivalent

Properties & Characteristics

A carbanion is an organic species in which a carbon atom bears a formal negative charge, having three bonds and a lone pair. Carbanions are sp³-hybridised and are the conjugate bases of C-H acids. They are highly nucleophilic and strongly basic. Stability increases with electron-withdrawing substituents (cyano, carbonyl) that delocalise the negative charge. Organolithium and Grignard reagents behave as carbanion equivalents.

Uses & Applications

Carbanions are key intermediates in organic synthesis: aldol condensations, Claisen condensations, Michael additions, and Grignard reactions all proceed via carbanion (or carbanion-equivalent) intermediates. They are exploited in polymer chemistry (anionic polymerisation) and in asymmetric synthesis.

Safety Information

Carbanion-generating reagents (organolithiums, Grignard reagents) are pyrophoric or highly moisture-sensitive. Use strict anhydrous, inert atmosphere (N₂ or Ar) techniques. Organolithiums react violently with water; keep dry solvent and appropriate fire extinguishers nearby.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Carbanion
Formula R⁻ (carbanion; carbon bears negative charge)
Synonyms Carbanion intermediate, carbon anion, organometallic carbanion equivalent

Frequently Asked Questions

A carbanion is a carbon-containing anion in which the carbon bears a negative charge, meaning it has three bonds and an unshared pair of electrons. Carbanions are important reactive intermediates in organic chemistry, particularly in reactions with alkyl lithium and Grignard reagents. They are strong bases and nucleophiles.

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