Write the most polar and most stable conformer of 1-nitropropane.

Answer

To solve the question of identifying the most polar and most stable conformer of 1-nitropropane, we can follow these steps:

### Step 1: Draw the Structure of 1-Nitropropane
1-nitropropane has the molecular formula CH3-CH2-CH2-NO2. The structure can be represented as follows:
- The first carbon (C1) is attached to three hydrogens (H) and one CH2 group.
- The second carbon (C2) is attached to one hydrogen, one CH3 group, and one NO2 group.
- The third carbon (C3) is attached to two hydrogens and one CH2 group.

### Step 2: Draw the Sawhorse Projection
In the Sawhorse projection, we can visualize the molecule in a staggered conformation:
- Place the first carbon (C1) in the front and the second carbon (C2) in the back.
- Arrange the substituents accordingly:
- C1 has two hydrogens and one CH2 group.
- C2 has one hydrogen, one CH3 group, and one NO2 group.

### Step 3: Convert to Newman Projection
Now, we will convert the Sawhorse projection into a Newman projection:
- Look down the C1-C2 bond.
- Position the CH3 group on C2 at the top and the NO2 group at the bottom to minimize steric hindrance.

### Step 4: Identify the Most Stable Conformer
The most stable conformer is the one where the bulky groups (CH3 and NO2) are positioned 180 degrees apart from each other. This is known as the anti-conformation:
- In this conformation, the CH3 group is on the top of C2, and the NO2 group is on the bottom of C2.

### Step 5: Determine the Most Polar Conformer
The polarity of the molecule is influenced by the electronegativity of the groups attached:
- The CH3 group is an electron-donating group (+I effect), while the NO2 group is an electron-withdrawing group (-I effect).
- The overall dipole moment will be directed towards the NO2 group, making this conformer the most polar.

### Conclusion
The most polar and most stable conformer of 1-nitropropane is the anti-conformation where the CH3 group is opposite the NO2 group.

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