Compare the boiling points of
1. n - butylamine
2. n - butyl alcohol
3. pentane

Options

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

Answer

To compare the boiling points of n-butylamine, n-butyl alcohol, and pentane, we need to analyze the molecular structures and the types of intermolecular forces present in each compound.

### Step 1: Identify the Structures
1. **n-butylamine (C4H11N)**: This molecule consists of a butyl group (four carbon atoms) attached to an amine group (NH2).
- Structure: CH3-CH2-CH2-CH2-NH2

2. **n-butyl alcohol (C4H10O)**: This molecule consists of a butyl group attached to a hydroxyl group (OH).
- Structure: CH3-CH2-CH2-CH2-OH

3. **Pentane (C5H12)**: This is a straight-chain alkane with five carbon atoms.
- Structure: CH3-CH2-CH2-CH2-CH3

### Step 2: Determine Intermolecular Forces
- **n-butylamine**: Can form hydrogen bonds due to the presence of the NH2 group. Hydrogen bonds are relatively strong intermolecular forces.

- **n-butyl alcohol**: Can also form hydrogen bonds due to the presence of the OH group. The oxygen atom is more electronegative than nitrogen, leading to stronger hydrogen bonding.

- **Pentane**: Being a non-polar molecule, it only exhibits weak van der Waals forces (London dispersion forces), which are significantly weaker than hydrogen bonds.

### Step 3: Compare Boiling Points
- **Boiling Point of n-butyl alcohol**: The strongest intermolecular forces are present due to hydrogen bonding with oxygen, leading to the highest boiling point among the three.

- **Boiling Point of n-butylamine**: The hydrogen bonding is present but is weaker than that of n-butyl alcohol because nitrogen is less electronegative than oxygen. Thus, n-butylamine has a lower boiling point than n-butyl alcohol but higher than pentane.

- **Boiling Point of pentane**: With only weak van der Waals forces, pentane has the lowest boiling point of the three compounds.

### Conclusion
The order of boiling points from highest to lowest is:
1. n-butyl alcohol (highest boiling point)
2. n-butylamine
3. Pentane (lowest boiling point)

Thus, the correct order is: **n-butyl alcohol > n-butylamine > pentane**.