Question

Acetylacetone (pentane -2, 4-dione)reacts with sodium hydroxide to give water and the sodium salt of a carbanion. Write a complete structural formula for the carbanion, and use resonance forms to show the stabilization of the carbanion.

Short answer

Carbanion may be defined as an organic anion having a negative charge on carbon. Removal of an atom or group of atoms from a molecule without the bonding electrons generate the carbanions.

Step-by-step solution

Carbanions

Carbanion may be defined as an organic anion having a negative charge on carbon. Removal of an atom or group of atoms from a molecule without the bonding electrons generate the carbanions.

Stability of carbanions

The stability of carbanions is just the opposite of the stability o carbocations. Methyl carbanion is the most stable while the tertiary carbanion is the least stable. Carbanions are also stabilized by resonance.

Resonance structures

A single structural formula sometimes cannot explain all the properties of a compound that is given. In such cases, the compound may be represented by two or more structural formulae which differ from each other only in the arrangement of electrons. None of this structural formula alone can explain all the observed properties of the compound. The compound is then said to show resonance. The various structures are known as resonating structures. The true structure of the molecule is not represented by any of the resonating structures but is considered to be a resonance hybrid of the various resonating structures

Structural formula and resonance forms