Which of the following terms explain why aldehydes are more reactive than ketone.
Hybridization and resonance
Electronegativity and resonance
Electronegativity and hybridization
Sterics and electronics
The correct answer and explanation is :
The correct answer is Sterics and electronics.
Explanation:
Aldehydes are more reactive than ketones due to a combination of steric and electronic factors.
- Sterics: Steric factors refer to the physical hindrance around a molecule due to the size of its substituents. In aldehydes, the carbonyl group (C=O) is attached to one hydrogen atom and one alkyl group (or a simpler group, in some cases). This means that the carbonyl carbon is less sterically hindered because only one group (the alkyl or hydrogen) is attached to it. In contrast, ketones have two alkyl groups (or other substituents) attached to the carbonyl carbon, which creates more steric hindrance. This makes it more difficult for nucleophiles to approach and attack the carbonyl carbon in ketones.
- Electronics: The electronic factors involve the distribution of electrons in the molecule. In aldehydes, the carbonyl carbon is less shielded because it is bonded to a hydrogen atom (which is less electron-donating compared to alkyl groups). The presence of the hydrogen allows the carbonyl carbon to have a higher partial positive charge (δ+), making it more electrophilic and therefore more susceptible to nucleophilic attack.
On the other hand, ketones have two electron-donating alkyl groups attached to the carbonyl carbon. These groups donate electron density through both inductive effects and hyperconjugation, which helps to partially stabilize the carbonyl carbon by reducing its partial positive charge. This stabilization makes the carbonyl carbon in ketones less electrophilic, and hence, ketones are less reactive than aldehydes.
Thus, sterics (less steric hindrance in aldehydes) and electronics (less electron donation to the carbonyl carbon in aldehydes) both contribute to aldehydes being more reactive than ketones. These factors make aldehydes more prone to nucleophilic attack compared to ketones, which are more stabilized electronically and sterically.
