Fundamentals of Organic ChemistryChemistryGeneral Organic Chemistry
Aldehydes and ketones having an -hydrogen are converted into a carbanion in the presence of a base as follows: This carbanion is stable because of:
Options
- AResonance delocalisation of the negative charge only
- BThe -I effect of the carbonyl group only
- CThe +I effect of the R group attached to the carbonyl carbon
- DBoth the -I effect of the carbonyl group and resonance delocalisation of the negative charge
Correct answer
D. Both the -I effect of the carbonyl group and resonance delocalisation of the negative charge
Step-by-step solution
The -hydrogen of aldehydes and ketones is acidic in nature due to the presence of the electron-withdrawing carbonyl group. When a base removes this proton, a carbanion (enolate ion) is formed. The stability of this carbanion is attributed to two main factors: 1. Inductive Effect ( -I effect): The carbonyl group ( > C = O ) is strongly electron-withdrawing. It exerts a -I effect, withdrawing electron density from the adjacent -carbon and thereby stabilizing the negative charge. 2. Resonance Delocalisation: The negat