The most reactive amine towards dilute hydrochloric acid is…

Options

A. `CH_(3)-NH_(2)`
B.
C.
D.

Explanation

To determine which amine is the most reactive towards dilute hydrochloric acid (HCl), we need to analyze the basicity of the given amines. The reactivity of amines towards acids is directly related to their basic strength; stronger bases are more reactive.

### Step-by-Step Solution:

1. **Identify the Types of Amines**:
- We have four options:
- A: CH3NH2 (Primary amine)
- B: NH(CH3)2 (Secondary amine)
- C: N(CH3)3 (Tertiary amine)
- D: C6H5NH2 (Aniline, which is a primary amine)

2. **Understand Basicity and Reactivity**:
- The basicity of amines increases with the number of alkyl groups attached to the nitrogen atom. This is due to the +I (inductive) effect of alkyl groups, which increases electron density on the nitrogen, making it more capable of donating a pair of electrons.

3. **Evaluate Each Amine**:
- **Amine A (CH3NH2)**: This is a primary amine. It has a lower basic strength compared to secondary and tertiary amines.
- **Amine B (NH(CH3)2)**: This is a secondary amine. It has a higher basic strength than primary amines due to the presence of two alkyl groups, which provide more electron density to the nitrogen.
- **Amine C (N(CH3)3)**: This is a tertiary amine. While it has the highest number of alkyl groups, steric hindrance makes it less reactive towards acids compared to secondary amines.
- **Amine D (C6H5NH2)**: Aniline has a benzene ring attached to the amine group, which delocalizes the lone pair of electrons on nitrogen, reducing its basicity and reactivity.

4. **Conclusion**:
- Based on the analysis, the secondary amine (Amine B: NH(CH3)2) has the highest basic strength and thus is the most reactive towards dilute hydrochloric acid.

### Final Answer:
The most reactive amine towards dilute hydrochloric acid is **NH(CH3)2 (Secondary amine)**.