Which of the following statement(s) is/are correct ?

Options

A. Anti conformation of `H_(2)N-CH_(2)-CH_(2)-NH_(2)` is more stable than its Gauche conformation.
B. Gauche conformation of `HO-CH_(2)-CH_(2)F` is more stable than its anti conformation temperature.
C. On increasing temperature, dipole moment of pure `F-CH_(2)-CH_(2)-F` increases.
D. In case of 1,4-Dihydroxycyclohaxane chair conformer is most stable.

Answer

To determine which statements are correct regarding the stability of conformations and dipole moments in certain compounds, we will analyze each statement step by step:

### Step 1: Analyze the First Statement
**Statement:** Anti-conformation of NH2-CH2-CH2-NH2 is more stable than its gauche conformation.

**Analysis:**
- In the anti-conformation, the two NH2 groups are positioned opposite each other, minimizing steric hindrance.
- In the gauche conformation, the NH2 groups are closer together, which can lead to increased steric strain.
- However, due to hydrogen bonding between the NH2 groups in the gauche conformation, it is actually more stable than the anti-conformation.

**Conclusion:** The first statement is **incorrect**.

### Step 2: Analyze the Second Statement
**Statement:** Gauche conformation of the compound is more stable than its anti-conformation.

**Analysis:**
- As previously discussed, the gauche conformation allows for hydrogen bonding between the NH2 groups, which stabilizes the structure.
- The anti-conformation lacks this stabilizing interaction, making it less stable.

**Conclusion:** The second statement is **correct**.

### Step 3: Analyze the Third Statement
**Statement:** On increasing the temperature, the dipole moment of the given compound increases.

**Analysis:**
- As temperature increases, the population of the more stable gauche conformation increases.
- The gauche conformation has a higher dipole moment due to the arrangement of the electronegative nitrogen atoms.
- Therefore, as the temperature increases, the overall dipole moment of the compound also increases.

**Conclusion:** The third statement is **correct**.

### Step 4: Analyze the Fourth Statement
**Statement:** In case of 1,4-dihydroxycyclohexane, chair conformation is more stable.

**Analysis:**
- In 1,4-dihydroxycyclohexane, both hydroxyl groups can adopt equatorial positions in the chair conformation, which minimizes steric hindrance.
- However, in the case of the boat conformation, there can be significant steric strain due to the proximity of the hydroxyl groups.
- The chair conformation is generally more stable than the boat conformation in cyclohexane derivatives.

**Conclusion:** The fourth statement is **incorrect**.

### Final Summary of Statements
- **Statement 1:** Incorrect
- **Statement 2:** Correct
- **Statement 3:** Correct
- **Statement 4:** Incorrect

Thus, the correct answer is that statements 1 and 4 are incorrect.