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 how easily each compound can donate its lone pair of electrons from the nitrogen atom. The presence of phenyl (C6H5) groups can affect the availability of the lone pair due to resonance and conjugation.

### Step-by-step Solution:

1. **Identify the Compounds:**
- (1) C6H5-NH-CH3 (Aniline derivative with one phenyl group and one methyl group)
- (2) C6H5-NH-C6H5 (Diphenylamine with two phenyl groups)
- (3) (C6H5)3N (Triphenylamine with three phenyl groups)
- (4) CH3-CH2-NH2 (Ethylamine with no phenyl groups)

2. **Analyze Basicity:**
- Basicity is determined by the ability of the nitrogen atom to donate its lone pair of electrons. The more available the lone pair is, the stronger the base.
- **Compound (1):** C6H5-NH-CH3
- The lone pair on nitrogen is somewhat available for donation, but it is involved in resonance with one phenyl ring.
- **Compound (2):** C6H5-NH-C6H5
- The lone pair on nitrogen is involved in resonance with two phenyl rings, making it less available for donation compared to compound (1).
- **Compound (3):** (C6H5)3N
- The lone pair on nitrogen is involved in resonance with three phenyl rings, which significantly reduces its availability for donation.
- **Compound (4):** CH3-CH2-NH2
- The lone pair on nitrogen is fully available for donation as there are no phenyl groups to cause resonance or conjugation.

3. **Rank the Basicity:**
- **Most Basic:** Compound (4) CH3-CH2-NH2 (no resonance, lone pair is fully available)
- **Next Basic:** Compound (1) C6H5-NH-CH3 (one phenyl group, some resonance)
- **Less Basic:** Compound (2) C6H5-NH-C6H5 (two phenyl groups, more resonance)
- **Least Basic:** Compound (3) (C6H5)3N (three phenyl groups, least availability of lone pair)

### Final Order of Basicity:
4 > 1 > 2 > 3