Among the following the strongest base is

Options

A. `C_6 H_5 NH_2 `
B. `p-NO_2 -C_6 H_4 NH_2`
C. `m-NO_2 -C_6 H_4 NH_2`
D. `C_6 H_5 CH_2 NH_2 `

Answer

To determine which among the given options is the strongest base, we need to analyze the basicity of each compound based on the availability of the lone pair of electrons on the nitrogen atom in the amine group. Basicity is defined by the ability of a compound to donate a lone pair of electrons to an electrophile (like a proton, H⁺).

### Step-by-Step Solution:

1. **Identify the Compounds**:
Let's denote the compounds as follows:
- Option 1: Aniline (C₆H₅NH₂)
- Option 2: Para-nitroaniline (C₆H₄(NH₂)(NO₂))
- Option 3: Meta-nitroaniline (C₆H₄(NH₂)(NO₂) at meta position)
- Option 4: Benzylamine (C₆H₅CH₂NH₂)

2. **Analyze Aniline (C₆H₅NH₂)**:
- Aniline has a benzene ring attached to the amine group. The lone pair on the nitrogen is partially delocalized into the aromatic ring, making it less available for donation. Therefore, aniline is a weak base.

3. **Analyze Para-nitroaniline (C₆H₄(NH₂)(NO₂))**:
- The para-nitro group (NO₂) is an electron-withdrawing group. It pulls electron density away from the nitrogen's lone pair, making it even less available for donation. Thus, para-nitroaniline is also a weak base.

4. **Analyze Meta-nitroaniline (C₆H₄(NH₂)(NO₂) at meta position)**:
- Similar to para-nitroaniline, the meta-nitro group also withdraws electron density from the nitrogen's lone pair, though to a slightly lesser extent than the para position. Thus, meta-nitroaniline is also a weak base.

5. **Analyze Benzylamine (C₆H₅CH₂NH₂)**:
- Benzylamine has a CH₂ group attached to the nitrogen, which is an electron-donating group. This increases the electron density on the nitrogen's lone pair, making it more available for donation. Therefore, benzylamine is the strongest base among the options.

6. **Conclusion**:
- Based on the analysis, the strongest base among the given options is **Benzylamine (C₆H₅CH₂NH₂)**.

### Final Answer:
The strongest base among the following is **Benzylamine (C₆H₅CH₂NH₂)**.