Question

Which one of the following carbanions is the least stable?

• A. $ C{{H}_{3}}CH_{2}^{-} $
• B. $ HC\equiv {{C}^{-}} $
• C. $ {{({{C}_{6}}{{H}_{5}})}_{3}}{{C}^{-}} $
• D. $ CH_{3}^{-} $
• E. $ {{(C{{H}_{3}})}_{3}}{{C}^{-}} $

Answer 1

Answer: (E)

An organic ion with a pair of available electrons and a negative charge on the central carbon atom is called a carbanion.
Electron attracting group $ (-CN,>C=O) $ increases stability and electron releasing group ( $ -C{{H}_{3}} $ etc) decreases the stability of carbanion. In $ {{(C{{H}_{3}})}_{3}}{{C}^{-}}, $ three $ -C{{H}_{3}} $ groups (electron releasing group) are present, so it is least stable.