source : slide

Carbanion –

When a covalent bond , in which Carbon is attached to a lesser electro negative atom , breaks up by heterolytic fission. Thus carbon-atom acquires a negative charge due to an extra electron.


“Organic ions containing a negatively charged carbon-atom are called carbanions”

These are named after the parent alkyl group & adding the word carbanion .These are also termed as Primary,  Secondary & Tertiary, depending upon the nature of carbon-atom bearing negative charge


Characteristics –

1) Its Carbon-atom contains negative charge .

2) The valence shell of negatively charged Carbon-atom   contains 8-electrons. Thus its octet is complete & it contains a lone pair of electron .

3) The negatively charged carbon is in a state of sp3  hybridization .The hybrid orbitals are directed towards the corners of a tetrahedron. Three of the hybrid orbitals are involved in the formation of single covalent bonds with other atoms while the IVth hybrid orbital contains a lone pair of electron. Thus it  has a pyramidal structure similar to NH3 molecule.

4) Its carbon contains eight electrons even they are highly reactive intermediate.

5) They are readily attacked by electrophillic reagents.

6) Carbanion is itself a nucliophile

7) The order of stability  is-


8) The stability of carbanion is influenced by resonance . Acetonyl & benzyl carbanions possess resonance  & thus extra stable.