Arrange the following carbonyl compounds in increasing order of their reactivity in nucleophilic addition reaction.

Options

A. Butanone `lt` propanane `lt` propanal `lt` ethanal
B. Butanone `lt` propanal `lt` propanone `lt` ethanal
C. Butanone `lt` ethanal `lt` propanone `lt` propanal
D. Butanone `lt` ethanal `lt` propanal `lt` propanone

Answer

To arrange the given carbonyl compounds in increasing order of their reactivity in nucleophilic addition reactions, we need to consider the structure of each compound and how steric hindrance affects their reactivity.

### Step-by-Step Solution:

1. **Identify the Carbonyl Compounds**:
Let's assume the carbonyl compounds we are considering are:
- Ethanal (acetaldehyde)
- Propan-2-one (isopropyl ketone)
- Butan-2-one (ketone)
- Benzaldehyde (aromatic aldehyde)

2. **Understand Nucleophilic Addition**:
Nucleophilic addition reactions involve a nucleophile attacking the electrophilic carbon of the carbonyl group (C=O). The reactivity of carbonyl compounds in these reactions generally decreases in the following order:
- Aldehydes > Ketones > Aromatic Compounds
This is due to steric hindrance and the electronic effects of substituents.

3. **Consider Steric Hindrance**:
- **Aldehydes**: Generally more reactive because they have one alkyl group (or hydrogen) and one carbonyl group, allowing easier access for nucleophiles.
- **Ketones**: Less reactive than aldehydes because they have two alkyl groups, which create more steric hindrance.
- **Aromatic Compounds**: Both aromatic aldehydes and ketones are less reactive due to resonance stabilization of the carbonyl group and steric hindrance from the aromatic ring.

4. **Rank the Compounds**:
- **Most Reactive**: Ethanal (aldehyde)
- **Next**: Benzaldehyde (aromatic aldehyde)
- **Then**: Propan-2-one (ketone)
- **Least Reactive**: Butan-2-one (larger ketone)

5. **Final Order**:
Therefore, the increasing order of reactivity in nucleophilic addition reactions is:
**Butan-2-one < Propan-2-one < Benzaldehyde < Ethanal**