Among the following isomeric amines which one is expected to have the lowest boiling point ? .

Options

A. `CH_(3)CH_(2)N(CH_(3))_(2)`
B. `(CH_(2))_(2)CHNHCH_(3)`
C. `(CH_(3)CH_(2))_(2)NH`
D. `CH_(3)(CH_(2))_(3)NH_(2)`

Explanation

To determine which isomeric amine has the lowest boiling point, we need to analyze the structure and classification of each amine based on the number of hydrogen atoms attached to the nitrogen atom. The boiling point of amines is influenced by hydrogen bonding, which is affected by the number of acidic hydrogens present.

### Step-by-Step Solution:

1. **Identify the Isomeric Amines**:
- We have four options of isomeric amines. Let's denote them as:
- Option A: Tertiary amine (3 alkyl groups, 0 hydrogen)
- Option B: Secondary amine (2 alkyl groups, 1 hydrogen)
- Option C: Secondary amine (2 alkyl groups, 1 hydrogen)
- Option D: Primary amine (1 alkyl group, 2 hydrogens)

2. **Classify the Amines**:
- Tertiary amine (Option A): No acidic hydrogen, cannot form hydrogen bonds.
- Secondary amines (Options B and C): One acidic hydrogen each, can form some hydrogen bonds.
- Primary amine (Option D): Two acidic hydrogens, can form stronger hydrogen bonds.

3. **Understand the Role of Hydrogen Bonding**:
- Hydrogen bonding significantly affects boiling points. More hydrogen bonds lead to higher boiling points.
- Primary amines have the highest boiling point due to two acidic hydrogens.
- Secondary amines have a moderate boiling point due to one acidic hydrogen.
- Tertiary amines have the lowest boiling point since they lack acidic hydrogens and cannot participate in hydrogen bonding.

4. **Determine the Boiling Point Order**:
- Based on the classification:
- Primary amine (highest boiling point)
- Secondary amines (moderate boiling points)
- Tertiary amine (lowest boiling point)

5. **Conclusion**:
- Among the given options, the tertiary amine (Option A) is expected to have the lowest boiling point due to the absence of acidic hydrogens and thus no hydrogen bonding.

### Final Answer:
The isomeric amine expected to have the lowest boiling point is the **tertiary amine (Option A)**.