Aldehydes and ketones are amphoteric. Thus they can act both as acids and bases. Under acidic conditions, the carbon of the protonated canbonyl group is much more electrophilic, reacting even with weak nucleopphilie. Carbonyl compound gives nucleophilic addition reaction. In this reaction the nucleophilic attack proceeds the elecrophilic attack.
Which one of the carbonyl compounds is more reactive towards `NaCN//H^(+)`?

Options

A.
B.
C.
D.

Answer

To determine which carbonyl compound is more reactive towards `NaCN/H^(+)`, we need to analyze the effect of substituents on the carbonyl group in different compounds. The reactivity of carbonyl compounds (aldehydes and ketones) towards nucleophilic addition reactions is influenced by the electrophilicity of the carbonyl carbon, which can be affected by the presence of electron-donating or electron-withdrawing groups.

### Step-by-Step Solution:

1. **Understanding Carbonyl Reactivity:**
Carbonyl compounds can be aldehydes or ketones. The reactivity towards nucleophiles is determined by the electrophilicity of the carbonyl carbon. An increase in positive charge on the carbonyl carbon makes it more reactive.

2. **Identifying the Compounds:**
We are given four options with different substituents attached to the carbonyl group. We will analyze each substituent's effect on the carbonyl carbon's electrophilicity:
- **Option A:** Benzaldehyde (C6H5CHO)
- **Option B:** Anisaldehyde (C6H5OCH3)
- **Option C:** Acetophenone (C6H5C(O)CH3)
- **Option D:** Benzonitrile (C6H5C≡N)

3. **Analyzing Each Compound:**
- **Option A (Benzaldehyde):** The benzene ring is an electron-donating group, which slightly reduces the positive charge on the carbonyl carbon, making it less reactive.
- **Option B (Anisaldehyde):** The methoxy group (OCH3) is an electron-donating group through resonance, further reducing the positive charge on the carbonyl carbon, decreasing reactivity.
- **Option C (Acetophenone):** The methyl group (CH3) is a weak electron-donating group, which also reduces the positive charge on the carbonyl carbon, leading to lower reactivity.
- **Option D (Benzonitrile):** The nitrile group (C≡N) is an electron-withdrawing group due to the electronegativity of nitrogen. This increases the positive charge on the carbonyl carbon, making it more reactive towards nucleophiles.

4. **Conclusion:**
Among the compounds analyzed, **Option D (Benzonitrile)** is the most reactive towards `NaCN/H^(+)` because the electron-withdrawing effect of the nitrile group increases the electrophilicity of the carbonyl carbon, making it more susceptible to nucleophilic attack.

### Final Answer:
The carbonyl compound that is more reactive towards `NaCN/H^(+)` is **Option D (Benzonitrile)**.