Assertion : Reaction of alcohols with `SOCl_2` is catalysed by the presence of a tertiary amine `(R_3N)`.
Reason : Tertiary amine promote the reaction by reacting with the byproduct HCl.

Options

A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
B. Both Assertion and Reason are true and Reason is not the correct explanation of Assertion
C. Assertion is true but Reason is false
D. Both Assertion and Reason are false

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Analyze the Assertion
The assertion states that the reaction of alcohols with thionyl chloride (SOCl₂) is catalyzed by the presence of a tertiary amine (R₃N).

- **Understanding the Reaction**: When an alcohol (ROH) reacts with thionyl chloride, it typically forms an alkyl chloride (RCl), along with sulfur dioxide (SO₂) and hydrochloric acid (HCl) as byproducts.
- **Role of Tertiary Amine**: A tertiary amine, such as pyridine, is often used as a catalyst in this reaction. It helps facilitate the conversion of alcohols to alkyl chlorides by stabilizing the transition state and improving the reaction rate.

**Conclusion for Step 1**: The assertion is true.

### Step 2: Analyze the Reason
The reason states that tertiary amines promote the reaction by reacting with the byproduct HCl.

- **Understanding the Role of HCl**: In the reaction, HCl is produced as a byproduct. If HCl is present in the reaction mixture, it can potentially hinder the reaction by shifting the equilibrium or by protonating the reactants, making them less nucleophilic.
- **Reaction with Tertiary Amine**: Tertiary amines, such as pyridine, have a lone pair of electrons on the nitrogen atom. This lone pair can react with HCl, effectively neutralizing it and preventing it from interfering with the reaction. The amine forms a salt with HCl, which helps to drive the reaction forward.

**Conclusion for Step 2**: The reason is also true and correctly explains the assertion.

### Final Conclusion
Both the assertion and the reason are true, and the reason provides a correct explanation for the assertion. Therefore, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.