Karbonaadi

Karbonaadi is a term used in chemistry to describe carbanides, carbon-centered anions that carry a negative charge primarily on a carbon atom. In common English nomenclature, these species are called carbanions. The name derives from carbon (karbon) and a suffix used to form chemical classes.

Structure and properties are characterized by a negatively charged carbon center, which makes karbonaadid strong nucleophiles and bases. Stability depends on the ability to delocalize or stabilize the negative charge through resonance or inductive effects from adjacent groups, such as carbonyls, aromatic rings, or alkyl substituents. The more stabilized a carbanion, the less reactive it is toward proton sources and moisture. Carbanions are typically generated under strictly anhydrous conditions using strong, non-nucleophilic bases or metal–halogen exchange methods.

Formation methods commonly involve deprotonation of relatively acidic hydrocarbon substrates, such as alkylnes adjacent to electron-withdrawing groups, by bases like butyllithium, sodium hydride, or lithium diisopropylamide (LDA). Enolates and acyl anions are related classes of carbanions formed by deprotonation next to carbonyl groups, and they play central roles in many organic transformations.

Reactivity includes nucleophilic carbon attack on alkyl halides, carbonyl compounds, and other electrophiles, enabling carbon–carbon bond formation. Due to their high reactivity and sensitivity to moisture and air, karbonaadid are generally handled under inert atmospheres and stored at low temperature.

See also: carbanion, enolate, acyl anion equivalent.