Total number of conformational isomers obtained by C-C bond rotation of ethane are

Options

A. 2
B. 4
C. 5
D. Infinite

Answer

To determine the total number of conformational isomers obtained by C-C bond rotation of ethane (C2H6), we can follow these steps:

### Step 1: Understanding Ethane Structure
Ethane consists of two carbon atoms connected by a single bond (C-C bond) and each carbon atom is bonded to three hydrogen atoms. The molecular formula is C2H6.

**Hint:** Remember that the structure of ethane is a simple chain with a single bond between the carbon atoms.

### Step 2: Defining Conformational Isomers
Conformational isomers, or conformers, are different spatial arrangements of the same molecule that can be interconverted by rotation around single bonds. In the case of ethane, we are interested in the rotation around the C-C bond.

**Hint:** Conformers arise from the rotation around single bonds, leading to different spatial arrangements.

### Step 3: Identifying Types of Conformers
For ethane, there are two main types of conformers:
1. **Eclipsed Conformation**: In this arrangement, the hydrogen atoms on the front carbon overlap with the hydrogen atoms on the back carbon. This conformation is higher in energy due to steric hindrance.
2. **Staggered Conformation**: In this arrangement, the hydrogen atoms on the front carbon are positioned in between the hydrogen atoms on the back carbon. This conformation is lower in energy and more stable.

**Hint:** Visualize the molecule in 3D to understand how the hydrogen atoms can be arranged in eclipsed and staggered forms.

### Step 4: Considering Rotational Positions
As we rotate the C-C bond, we can achieve an infinite number of conformations. This is because the rotation can occur continuously, resulting in an endless number of staggered and eclipsed arrangements.

**Hint:** Think about how a circle (360 degrees) allows for continuous rotation, leading to many possible orientations.

### Step 5: Conclusion
Since the rotation around the C-C bond can produce an infinite number of conformational arrangements, we conclude that the total number of conformational isomers for ethane is infinite.

**Final Answer:** The total number of conformational isomers obtained by C-C bond rotation of ethane is infinite.

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