The most stable conformation of ethylene glycol is :

Options

A. Anti
B. Gauche
C. Partially eclipsed
D. fully eclipsed

Explanation

To determine the most stable conformation of ethylene glycol, we can follow these steps:

### Step 1: Understand the Structure of Ethylene Glycol
Ethylene glycol (C₂H₆O₂) has the following structure:
- It consists of two hydroxyl (-OH) groups attached to a two-carbon chain.
- The molecular formula can be represented as HO-CH₂-CH₂-OH.

### Step 2: Draw the Possible Conformations
Ethylene glycol can adopt various conformations due to rotation around the carbon-carbon single bond. The two main conformations to consider are:
- **Gauche Conformation**: where the hydroxyl groups are staggered and positioned to allow for hydrogen bonding.
- **Anti Conformation**: where the hydroxyl groups are positioned opposite each other.

### Step 3: Analyze Hydrogen Bonding
In the gauche conformation:
- The hydroxyl groups can form intramolecular hydrogen bonds with the hydrogen atoms on adjacent carbons.
- This stabilizes the structure significantly due to the strong intermolecular forces.

In the anti conformation:
- The hydroxyl groups are too far apart to effectively participate in hydrogen bonding, leading to a less stable structure.

### Step 4: Determine Stability
Given the ability of the gauche conformation to form hydrogen bonds:
- This conformation is favored due to the increased stability provided by these interactions.
- Therefore, the most stable conformation of ethylene glycol is the **gauche conformation**.

### Conclusion
The most stable conformation of ethylene glycol is the **gauche conformation** due to the presence of hydrogen bonding between the hydroxyl groups.