Which one of the following isomeric amines has the highest boiling point

Options

A. `CH_(3)-CH_(2)-CH_(2)NH-CH_(3)`
B. `CH_(3)-CH_(2)-NH-CH_(2)-CH_(3)`
C. `(CH_(3))_(2)N-CH_(2)-CH_(3)`
D. `(CH_(3))_(2)CH-CH_2-NH_2`

Explanation

To determine which isomeric amine has the highest boiling point, we need to analyze the different types of amines and their ability to form hydrogen bonds. Here’s a step-by-step solution:

### Step 1: Identify the Isomeric Amines
We have four isomeric amines with the same molecular formula (C4H11N). The isomers can be classified as:
1. **Primary Amine (1°)**: R-NH2 (e.g., CH3-CH2-CH2-NH2)
2. **Secondary Amine (2°)**: R2-NH (e.g., CH3-CH2-NH-CH3)
3. **Tertiary Amine (3°)**: R3-N (e.g., (CH3)3N)
4. **Another Primary Amine (1°)**: R-NH2 (e.g., CH3-CH2-CH2-NH2)

### Step 2: Understand the Role of Hydrogen Bonding
Boiling points of amines are significantly influenced by hydrogen bonding. Hydrogen bonds form between the nitrogen atom of one amine molecule and the hydrogen atom of another. The strength and number of these hydrogen bonds will affect the boiling point:
- **Primary Amines** can form two hydrogen bonds (one from each hydrogen attached to nitrogen).
- **Secondary Amines** can form one hydrogen bond.
- **Tertiary Amines** cannot form hydrogen bonds because there are no hydrogen atoms attached to nitrogen.

### Step 3: Compare the Hydrogen Bonding Capabilities
- **Primary Amines (1°)**: Can form the most hydrogen bonds (2 per molecule).
- **Secondary Amines (2°)**: Can form fewer hydrogen bonds (1 per molecule).
- **Tertiary Amines (3°)**: Cannot form hydrogen bonds.

### Step 4: Determine the Boiling Point
Since primary amines can form more hydrogen bonds compared to secondary and tertiary amines, they will have higher boiling points due to stronger intermolecular forces. Therefore, the primary amine will have the highest boiling point among the isomers.

### Conclusion
The primary amine has the highest boiling point due to its ability to form more hydrogen bonds compared to secondary and tertiary amines.

**Final Answer**: The primary amine (1°) has the highest boiling point.

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