Select the reagent used and the intermediate formed in Stephen reaction.

Options

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Answer

**Step-by-Step Solution:**

1. **Understanding the Stephen Reaction:**
The Stephen reaction involves the reduction of alkyl cyanides to aldehydes. This reaction is significant in organic synthesis.

2. **Identifying the Reagents:**
The key reagent used in the Stephen reaction is **stannous chloride (SnCl2)**, which acts as a reducing agent in the presence of **aqueous hydrochloric acid (HCl)**. The aqueous HCl is necessary for the hydrolysis step that follows the reduction.

3. **Mechanism of the Reaction:**
- The reaction begins with the alkyl cyanide (R-C≡N) being reduced by stannous chloride in the presence of hydrochloric acid.
- The first step of the reaction results in the formation of an **intermediate**, which is an **imine salt**. The structure of this intermediate can be represented as R-C(=NH)-Cl.

4. **Hydrolysis Step:**
- After the formation of the imine salt, hydrolysis occurs, where water reacts with the imine salt to convert it into an aldehyde.
- The final product of the Stephen reaction is an **aldehyde** (R-CHO).

5. **Conclusion:**
- The reagent used in the Stephen reaction is **stannous chloride (SnCl2)**.
- The intermediate formed during the reaction is an **imine salt**.

**Final Answer:**
- Reagent used: Stannous chloride (SnCl2)
- Intermediate formed: Imine salt

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