Allylic halide is

Options

A. compound in which halogen atom is bonded to `sp^3` hybridised carbon atom next to aromatic ring
B. compound in which halogen atom is bonded to `sp^3` hybridised carbon atom next to carbon-carbon double band
C. compound in which halogen atom is bonded to an alkyl group
D. None of the above

Answer

To understand what an allylic halide is, let's break down the definition and characteristics step by step.

### Step-by-Step Solution:

1. **Definition of Allylic Halide**:
- An allylic halide is defined as a compound in which a halogen atom (X) is bonded to a carbon atom that is adjacent to a carbon-carbon double bond (C=C).

2. **Structure of Allylic Halide**:
- The carbon atom to which the halogen is attached is typically sp³ hybridized. This means it is connected to four other atoms (or groups) with single bonds.
- The adjacent carbon atom involved in the double bond is sp² hybridized.

3. **Examples**:
- Consider a simple structure: CH2=CH-CH2X. Here, the halogen (X) is attached to the CH2 group, which is adjacent to the double bond (C=C). This is an allylic halide.
- Another example could be a cyclic compound with a double bond, such as a cyclohexene derivative where a halogen is attached to a carbon adjacent to the double bond.

4. **Identifying Allylic Halides**:
- When looking at a molecular structure, identify the double bond first. Then, check the carbon atoms adjacent to this double bond. If any of these sp³ hybridized carbons have a halogen attached, it qualifies as an allylic halide.

5. **Options Analysis**:
- **Option 1**: Incorrect, as it describes a halogen bonded to a carbon next to an aromatic ring, which does not define allylic halides.
- **Option 2**: Correct, as it accurately describes a halogen bonded to an sp³ hybridized carbon adjacent to a carbon double bond.
- **Option 3**: Incorrect, as it does not specify the requirement of adjacency to a double bond.
- **Option 4**: Incorrect, since option 2 is the correct definition.

### Conclusion:
The correct definition of an allylic halide is given in **Option 2**: "A compound in which a halogen atom is bonded to an sp³ hybridized carbon atom next to a carbon double bond."