Lucas reagent reacts fastest with :

Options

A. 1 - butanol
B. 2-butanol
C. 2-methy-1-propanol
D. 2-methyl- 2 -Propanol

Explanation

To determine which alcohol reacts fastest with Lucas reagent, we need to understand the nature of the alcohols involved and how they react with the reagent. Lucas reagent is anhydrous zinc chloride in concentrated hydrochloric acid, and it is primarily used to distinguish between primary, secondary, and tertiary alcohols based on their reactivity.

### Step-by-Step Solution:

1. **Identify the Nature of Lucas Reagent:**
- Lucas reagent is a mixture of anhydrous zinc chloride (ZnCl2) and concentrated hydrochloric acid (HCl). It is used to convert alcohols into alkyl chlorides.

2. **Understand the Classification of Alcohols:**
- Alcohols can be classified as primary, secondary, or tertiary based on the number of alkyl groups attached to the carbon atom that carries the hydroxyl (OH) group:
- **Primary Alcohol:** The carbon with the OH group is attached to one alkyl group.
- **Secondary Alcohol:** The carbon with the OH group is attached to two alkyl groups.
- **Tertiary Alcohol:** The carbon with the OH group is attached to three alkyl groups.

3. **Reactivity of Alcohols with Lucas Reagent:**
- **Primary Alcohols:** React slowly; turbidity appears after heating.
- **Secondary Alcohols:** React moderately; turbidity appears after about 5 minutes.
- **Tertiary Alcohols:** React very quickly; turbidity appears immediately.

4. **Analyze the Given Options:**
- Let's analyze the options provided:
- **Option A:** 1-butanol (Primary alcohol)
- **Option B:** 2-butanol (Secondary alcohol)
- **Option C:** 1-methyl-1-propanol (Primary alcohol)
- **Option D:** 2-methyl-2-propanol (Tertiary alcohol)

5. **Determine the Fastest Reacting Alcohol:**
- Among the options, 2-methyl-2-propanol (Option D) is a tertiary alcohol. According to the reactivity trend, tertiary alcohols react the fastest with Lucas reagent, producing turbidity immediately.

6. **Conclusion:**
- Therefore, the correct answer is **Option D: 2-methyl-2-propanol**, as it reacts fastest with Lucas reagent.