Consider the following compounds (1) `C_6H_5-NH-CH_3` (2) `C_6H_5-NH-C_6H_5` (3) `(C_6H_5)_3N (4)CH_3-CH_2-NH_2` write the basicity order

Options

A. `1 gt 2 gt 3 gt 4`
B. `4 gt 1 gt 2 gt 3`
C. `3 gt 2 gt 1 gt 4`
D. `4 gt 3 gt 2 gt 1`

Answer

To determine the basicity order of the given compounds, we need to analyze the ability of each compound to donate a lone pair of electrons from the nitrogen atom. Basicity is influenced by the availability of the lone pair on nitrogen, which can be affected by resonance and inductive effects from substituents.

Let's analyze each compound:

1. **Compound 1: C₆H₅-NH-CH₃ (Aniline derivative)**
- The nitrogen atom has a lone pair that can participate in resonance with the phenyl ring (C₆H₅). However, the presence of the methyl group (CH₃) does not significantly stabilize the lone pair through resonance. The lone pair is somewhat available for donation but is partially delocalized due to resonance with the phenyl ring.

2. **Compound 2: C₆H₅-NH-C₆H₅ (Diphenylamine)**
- In this compound, the nitrogen atom is bonded to two phenyl groups. The lone pair on nitrogen can participate in resonance with both phenyl rings, which means it is more delocalized and less available for donation compared to compound 1. This makes it a weaker base than compound 1.

3. **Compound 3: (C₆H₅)₃N (Triphenylamine)**
- Here, the nitrogen is bonded to three phenyl groups. The lone pair on nitrogen is highly delocalized due to resonance with all three phenyl rings, making it the least available for donation. Therefore, this compound is the weakest base among the four.

4. **Compound 4: CH₃-CH₂-NH₂ (Ethylamine)**
- In this case, the nitrogen atom is bonded to two alkyl groups (ethyl groups). Alkyl groups are electron-donating through the inductive effect, which increases the availability of the lone pair on nitrogen. Therefore, ethylamine is expected to be the strongest base among the four compounds.

Now, let's summarize the basicity order based on our analysis:

- **Basicity Order:** CH₃-CH₂-NH₂ (4) > C₆H₅-NH-CH₃ (1) > C₆H₅-NH-C₆H₅ (2) > (C₆H₅)₃N (3)

### Final Order:
1. CH₃-CH₂-NH₂ (4)
2. C₆H₅-NH-CH₃ (1)
3. C₆H₅-NH-C₆H₅ (2)
4. (C₆H₅)₃N (3)