Which of the following is correct order of reactivity

Options

A. Vinyl chloride `gt` Allyl chloride `gt` Propylchloride
B. Propylchloride `gt` Vinyl chloride `gt` Allyl chloride
C. Allyl chloride `gt` Propylchloride `gt` Vinyl chloride
D. Allyl chloride `gt` Vinyl chloride `gt` Propylchloride

Explanation

To determine the correct order of reactivity among vinyl chloride, allyl chloride, and propyl chloride, we need to analyze the stability of the carbocations formed during nucleophilic substitution reactions, specifically the SN1 mechanism.

### Step-by-Step Solution:

1. **Identify the Structures**:
- **Vinyl Chloride (C2H3Cl)**: It has the structure CH2=CH-Cl, where the chlorine is attached to a carbon involved in a double bond.
- **Allyl Chloride (C3H5Cl)**: It has the structure CH2=CH-CH2Cl, where the chlorine is attached to a carbon that is adjacent to a double bond.
- **Propyl Chloride (C3H7Cl)**: It has the structure CH3-CH2-CH2Cl, where the chlorine is attached to a primary carbon.

2. **Understand the SN1 Mechanism**:
- In the SN1 mechanism, the first step involves the formation of a carbocation after the departure of the leaving group (Cl-).
- The stability of the carbocation is crucial for the rate of the reaction; more stable carbocations lead to faster reactions.

3. **Draw the Carbocations**:
- **Vinyl Carbocation**: CH2=CH^+ (sp2 hybridized, less stable due to positive charge on an electronegative carbon).
- **Allyl Carbocation**: CH2=CH-CH2^+ (can stabilize through resonance, making it more stable).
- **Propyl Carbocation**: CH3-CH2-CH2^+ (stabilized by hyperconjugation from adjacent hydrogen atoms).

4. **Evaluate Carbocation Stability**:
- **Vinyl Carbocation**: Least stable due to the positive charge on sp2 carbon.
- **Allyl Carbocation**: Most stable due to resonance stabilization.
- **Propyl Carbocation**: Moderately stable due to hyperconjugation.

5. **Determine Reactivity Order**:
- Since allyl chloride forms the most stable carbocation, it will be the most reactive.
- Propyl chloride is next due to its moderate stability.
- Vinyl chloride is the least reactive due to the instability of its carbocation.

6. **Final Order of Reactivity**:
- The correct order of reactivity is: **Allyl Chloride > Propyl Chloride > Vinyl Chloride**.

### Conclusion:
The correct answer is **C: Allyl Chloride > Propyl Chloride > Vinyl Chloride**.