Benzenediazonium chloride is reduced to benzene by

Options

A. Water
B. Hypophosphorous acid
C. Hypophosphoric acid
D. Phosphine

Answer

To solve the question of how benzenediazonium chloride is reduced to benzene, we can follow these steps:

### Step 1: Understand the Structure of Benzenediazonium Chloride
Benzenediazonium chloride has the formula C6H5N2Cl. It consists of a benzene ring (C6H5) attached to a diazonium group (N2) and a chloride ion (Cl).

**Hint:** Remember that the diazonium group is a key functional group in this compound, and its reduction is what leads to the formation of benzene.

### Step 2: Identify the Possible Reducing Agents
The question provides four options:
1. Water
2. Hypophosphorous acid (H3PO2)
3. Hypophosphoric acid (H3PO3)
4. Phosphine (PH3)

**Hint:** Consider the properties of each reducing agent and their ability to donate electrons or hydrogen to facilitate the reduction process.

### Step 3: Analyze Each Option
- **Water:** When benzenediazonium chloride reacts with water, it forms phenol (C6H5OH) instead of benzene. Thus, this option is incorrect.

- **Hypophosphorous Acid (H3PO2):** This compound can act as a reducing agent. When it reacts with benzenediazonium chloride, it reduces it to benzene (C6H6), releasing nitrogen gas (N2) and hydrochloric acid (HCl). This is a valid reduction reaction.

- **Hypophosphoric Acid (H3PO3):** This compound has a higher oxidation state and cannot act as a reducing agent in this reaction. Therefore, it is not a suitable option.

- **Phosphine (PH3):** Phosphine is not a strong enough reducing agent to reduce benzenediazonium chloride to benzene. Hence, this option is also incorrect.

**Hint:** Focus on the ability of the reducing agent to lower the oxidation state of the diazonium compound to form benzene.

### Step 4: Conclusion
After analyzing all the options, we conclude that the correct reducing agent that can reduce benzenediazonium chloride to benzene is **Hypophosphorous Acid (H3PO2)**.

**Final Answer:** Benzenediazonium chloride is reduced to benzene by **Hypophosphorous Acid (H3PO2)**.