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

Options

A.
B.
C.
D.

Answer

To determine which isomeric amine has the lowest boiling point, we need to analyze the ability of each amine to form hydrogen bonds. The boiling point of a compound is influenced by the strength and number of hydrogen bonds it can form.

### Step-by-Step Solution:

1. **Identify the Types of Amines**:
- Amines can be classified as primary (1°), secondary (2°), or tertiary (3°) based on the number of carbon groups attached to the nitrogen atom.
- Primary amines have one carbon group and two hydrogen atoms attached to nitrogen.
- Secondary amines have two carbon groups and one hydrogen atom attached to nitrogen.
- Tertiary amines have three carbon groups and no hydrogen atoms attached to nitrogen.

2. **Assess Hydrogen Bonding**:
- **Primary Amines**: Can form two hydrogen bonds due to the presence of two hydrogen atoms on nitrogen. This leads to stronger intermolecular forces and higher boiling points.
- **Secondary Amines**: Can form one hydrogen bond due to the presence of one hydrogen atom on nitrogen. This results in lower boiling points compared to primary amines but higher than tertiary amines.
- **Tertiary Amines**: Cannot form hydrogen bonds because there are no hydrogen atoms attached to nitrogen. This results in the lowest boiling point among the three types of amines.

3. **Conclusion**:
- Since tertiary amines do not participate in hydrogen bonding, they will have the lowest boiling point compared to primary and secondary amines. Therefore, among the given isomeric amines, the tertiary amine is expected to have the lowest boiling point.

### Final Answer:
The isomeric amine expected to have the lowest boiling point is the tertiary amine.