Why are $\mathrm{aldehydes}$ generally more reactive than $\mathrm{ketones}$ toward nucleophilic addition reactions?

• A. $\mathrm{aldehydes}$ are more basic than $\mathrm{ketones}$, making them more reactive toward nucleophiles.
• B. $\mathrm{aldehydes}$ always form more stable products than $\mathrm{ketones}$ in nucleophilic addition reactions.
• C. $\mathrm{aldehydes}$ have less steric hindrance and their carbonyl carbon is more electrophilic due to only one electron-donating alkyl group compared to two in $\mathrm{ketones}$.
• D. $\mathrm{ketones}$ have a more polarized carbonyl group, making them more reactive than $\mathrm{aldehydes}$.

Answer: (C)

Verified step by step guidance

1. Identify the key structural difference between aldehydes and ketones: aldehydes have one alkyl group attached to the carbonyl carbon, while ketones have two alkyl groups attached.
2. Understand how alkyl groups affect the electrophilicity of the carbonyl carbon: alkyl groups are electron-donating via inductive effects, which reduce the partial positive charge on the carbonyl carbon, making it less electrophilic.
3. Recognize that aldehydes, having only one alkyl group, have a more electrophilic carbonyl carbon compared to ketones, which have two electron-donating alkyl groups that decrease electrophilicity.
4. Consider steric hindrance: ketones have more bulky groups around the carbonyl carbon, which physically hinders the approach of nucleophiles, whereas aldehydes have less steric hindrance, facilitating nucleophilic attack.
5. Combine these factors to conclude that aldehydes are generally more reactive toward nucleophilic addition because their carbonyl carbon is more electrophilic and more accessible due to less steric hindrance.