Which of the following is the most reactive with HCl in the presence of `ZnCl_(2)`?

Options

A. `(CH_(3))_(3)COH`
B. `(CH_(3))_(2)CH-CH_(2)-CH_(2)-OH`
C. `(CH_(3))_(2)CHOH`
D. `C_(6)H_(5)OH`

Explanation

To determine which of the given compounds is the most reactive with HCl in the presence of ZnCl2 (known as Lucas reagent), we need to analyze the reactivity of different types of alcohols (primary, secondary, and tertiary) with this reagent.

### Step-by-Step Solution:

1. **Understanding the Lucas Reagent**:
- The Lucas reagent is a mixture of HCl and ZnCl2. It is used to differentiate between primary, secondary, and tertiary alcohols based on their reactivity.

2. **Reactivity of Alcohols**:
- **Primary Alcohols**: React slowly with Lucas reagent, and turbidity (formation of an oily layer) appears after heating.
- **Secondary Alcohols**: React moderately with Lucas reagent, and turbidity appears within 3 to 5 minutes.
- **Tertiary Alcohols**: React immediately with Lucas reagent, resulting in the formation of turbidity or an oily layer almost instantly.

3. **Identifying the Alcohols**:
- We need to identify the degree (1°, 2°, or 3°) of each alcohol provided in the options.

4. **Analyzing the Options**:
- **Option 1**: This is a tertiary alcohol (3°) because the carbon with the OH group is connected to three other carbon atoms.
- **Option 2**: This is a primary alcohol (1°) because the carbon with the OH group is connected to only one carbon atom.
- **Option 3**: This is a secondary alcohol (2°) because the carbon with the OH group is connected to two other carbon atoms.
- **Option 4**: This is phenol, which does not react with Lucas reagent.

5. **Determining the Most Reactive Alcohol**:
- Since tertiary alcohols react the fastest with Lucas reagent, we conclude that the alcohol in **Option 1** (the tertiary alcohol) is the most reactive with HCl in the presence of ZnCl2.

### Conclusion:
The most reactive compound with HCl in the presence of ZnCl2 is **Option 1**, which is a tertiary alcohol.

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