Which of the following is correct?

Options

A. Vinyl chloride is more reactive than ethyl chloride in `S_(N^(2))`
B. Vinyl chloride is more reactive than ethyl chloride in `S_(N^(1))`
C. allyl chloride is less reactive than n - propyl chloride in `S_(N^(1))`
D. allyl chloride is more reactive than n - propyl chloride in `S_(N^(2))`

Answer

To solve the question, we need to analyze each of the provided statements about the reactivity of vinyl chloride and allyl chloride in SN1 and SN2 reactions.

### Step-by-Step Solution:

1. **Evaluate the first statement**: "Vinyl chloride is more reactive than ethyl chloride in SN2."
- Vinyl chloride (C2H3Cl) has a double bond, which makes it less favorable for nucleophilic attack in an SN2 reaction due to steric hindrance and the electron-rich double bond. Ethyl chloride (C2H5Cl), on the other hand, is a primary alkyl halide and is more reactive in SN2 reactions. Therefore, this statement is **incorrect**.

2. **Evaluate the second statement**: "Vinyl chloride is more reactive than ethyl chloride in SN1."
- In an SN1 reaction, the first step is the formation of a carbocation. Vinyl chloride forms a vinyl carbocation, which is highly unstable due to the sp2 hybridization and the presence of the double bond. Ethyl chloride forms a more stable primary carbocation. Thus, vinyl chloride is not more reactive than ethyl chloride in SN1 reactions. This statement is also **incorrect**.

3. **Evaluate the third statement**: "Allyl chloride is less reactive than n-propyl chloride in SN1."
- Allyl chloride (C3H5Cl) forms a resonance-stabilized carbocation upon the loss of the leaving group (Cl). In contrast, n-propyl chloride (C3H7Cl) forms a primary carbocation, which is less stable. Therefore, allyl chloride is actually more reactive than n-propyl chloride in SN1 reactions. This statement is **incorrect**.

4. **Evaluate the fourth statement**: "Allyl chloride is more reactive than n-propyl chloride in SN2."
- In SN2 reactions, the nucleophile attacks the carbon atom. For allyl chloride, the nucleophile can attack a carbon that is involved in a double bond (the allylic position), which allows for better orbital overlap (sigma plus pi star). In n-propyl chloride, the nucleophile attacks a primary carbon with only sigma bonds. Thus, allyl chloride is indeed more reactive than n-propyl chloride in SN2 reactions. This statement is **correct**.

### Conclusion:
The correct answer is that **allyl chloride is more reactive than n-propyl chloride in SN2 reactions**.