In 2 - Fluoroethanol which conformer will be most stable?

Options

A. Eclipsed
B. Fully Eclipsed
C. gauche
D. Staggered

Answer

To determine the most stable conformer of 2-fluoroethanol, we can analyze the different conformations that arise from the rotation around the carbon-carbon bond. Here’s a step-by-step solution:

### Step 1: Identify the Structure of 2-Fluoroethanol
2-fluoroethanol has the following structure:
- The molecule consists of a two-carbon chain (ethanol) with a hydroxyl (-OH) group on one carbon and a fluorine atom on the second carbon.
- The structural formula can be represented as CH2(OH)-CH(Fluorine)-H.

### Step 2: Understand the Conformations
Conformations arise from the rotation around the carbon-carbon single bond. The main conformations to consider are:
- **Staggered Conformation**: Atoms/groups are positioned as far apart as possible.
- **Eclipsed Conformation**: Atoms/groups are aligned with each other, leading to steric strain.

### Step 3: Analyze the Staggered and Eclipsed Conformations
1. **Staggered Conformation**:
- In this conformation, the bulky groups (OH and F) are positioned 180 degrees apart, minimizing steric hindrance.
- This conformation is generally more stable due to reduced torsional strain.

2. **Eclipsed Conformation**:
- In this conformation, the bulky groups are aligned, which increases steric repulsion.
- There are different degrees of eclipsed conformations, including fully eclipsed (where bulky groups are directly aligned) and partially eclipsed (where one bulky group is aligned with a hydrogen).

### Step 4: Identify the Most Stable Conformation
- The **Gauche Conformation** is a specific staggered conformation where the bulky groups (OH and F) are 60 degrees apart. This conformation allows for some interaction between the groups without significant steric hindrance.
- The **Fully Eclipsed Conformation** is the least stable due to maximum steric repulsion between the bulky groups.

### Conclusion
The most stable conformation of 2-fluoroethanol is the **Gauche Conformation** due to minimized steric hindrance and potential for hydrogen bonding.

### Final Answer
The most stable conformer of 2-fluoroethanol is the **Gauche Conformation**.

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