What is the correct order of reactivity of alcohols in the following reaction ?
`R-OH+HCl overset(ZnCl_(2))to R-Cl+H_(2)O`

Options

A. `1^(@) gt 2^(@) gt 3^(@)`
B. `1^(@) lt 2^(@) gt 3^(@)`
C. `3^(@) gt 2^(@) gt 1^(@)`
D. `3^(@) gt 1^(@) gt 2^(@)`

Explanation

To determine the correct order of reactivity of alcohols in the reaction with HCl in the presence of ZnCl₂, we can follow these steps:

### Step 1: Identify the Reaction
The reaction in question is:
\[ R-OH + HCl \overset{ZnCl_2}{\rightarrow} R-Cl + H_2O \]
This indicates that an alcohol (R-OH) is being converted into an alkyl halide (R-Cl) through the action of hydrochloric acid (HCl) and zinc chloride (ZnCl₂).

### Step 2: Understand the Role of ZnCl₂
ZnCl₂ acts as a catalyst in this reaction and is part of the Lucas reagent, which is specifically used to differentiate between primary, secondary, and tertiary alcohols based on their reactivity.

### Step 3: Analyze the Reactivity of Alcohols
- **Tertiary Alcohols**: React the fastest with Lucas reagent. They form a stable carbocation intermediate immediately upon reaction, leading to the rapid formation of turbidity.
- **Secondary Alcohols**: React slower than tertiary alcohols. They form a carbocation intermediate, but it is less stable than that of tertiary alcohols, resulting in a slower reaction. Turbidity appears within about 5 minutes.
- **Primary Alcohols**: React the slowest. They require heating to form a stable carbocation intermediate and thus form turbidity only upon heating.

### Step 4: Establish the Order of Reactivity
Based on the stability of the intermediates and the speed of reaction:
1. Tertiary alcohols (fastest)
2. Secondary alcohols (moderate speed)
3. Primary alcohols (slowest)

Thus, the correct order of reactivity of alcohols in this reaction is:
\[ \text{Tertiary} > \text{Secondary} > \text{Primary} \]

### Conclusion
The correct answer is option C: **Tertiary > Secondary > Primary**.

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