Question

Which reagent is used in the Lucas test to distinguish alcohols?

• A. \( \text{ZnCl}_2 + HCl \)
• B. \( KMnO_4 \)
• C. \( NaOH \)
• D. \( H_2SO_4 \)

Hint:

Lucas reagent = Anhydrous \(ZnCl_2\) + concentrated \(HCl\). It helps distinguish primary, secondary, and tertiary alcohols based on the rate of turbidity formation.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the composition of the Lucas reagent, which is used to identify the type of alcohol based on its reactivity.
Step 2: Detailed Explanation:
Lucas reagent consists of a solution of anhydrous zinc chloride (\(ZnCl_2\)) in concentrated hydrochloric acid (\(HCl\)).
The test works by converting alcohols to alkyl chlorides, which appear as turbidity in the solution.
- Tertiary alcohols: Immediate turbidity.
- Secondary alcohols: Turbidity after 5-10 minutes.
- Primary alcohols: No turbidity at room temperature.
Step 3: Final Answer:
The reagent used in the Lucas test is a mixture of \(ZnCl_2\) and \(HCl\).