JEE Chemistry 2024 Question with Solution

Given: We need to identify the example of a vinylic halide from the given options.

Find: Which structure has a halogen atom directly attached to an $sp^2$ hybridized carbon of a carbon-carbon double bond.

A vinylic halide is a compound in which a halogen atom is directly attached to an $sp^2$ hybridized aliphatic carbon atom that is part of a double bond.

• Option A: CH₂=CH–Cl contains a halogen attached directly to a double-bonded carbon, so it is a vinylic halide.
• Option B: CH₃–CH₂–CH₂Cl has the halogen on an $sp^3$ carbon, so it is not a vinylic halide.
• Option C: C₆H₅–CH₂Cl does not have the halogen attached to a double-bonded aliphatic carbon.
• Option D: CH₃–C≡CCl is not a vinylic halide because the halogen is associated with a carbon-carbon triple bond system, not a double bond.

Therefore, the correct option is A.

Given: The term to identify is vinylic halide.

Find: The option in which halogen is directly bonded to a carbon of a carbon-carbon double bond.

Step 1: Recall the definition. A vinylic halide is an organic compound where a halogen atom is directly bonded to a carbon-carbon double bond.

Step 2: Compare with related classes.

• In allylic halides, the halogen is attached to the carbon adjacent to the double bond.
• In aryl or benzylic halides, the halogen is associated with an aromatic system or a side-chain carbon, not a vinylic carbon.

Step 3: Examine the options one by one.

1. Option A: CH₂=CH–Cl The halogen is directly attached to a carbon involved in the double bond. Hence, this is a vinylic halide.
2. Option B: CH₃–CH₂–CH₂Cl The halogen is attached to a saturated carbon. Hence, it is not a vinylic halide.
3. Option C: C₆H₅–CH₂Cl The halogen is not attached to a double-bonded aliphatic carbon. Hence, it is not a vinylic halide.
4. Option D: CH₃–C≡CCl The halogen is not attached to a carbon of a double bond. Hence, it is not a vinylic halide.

Therefore, the correct example of a vinylic halide is Option A.