In dehalogenation reaction of dihalides to get alkenes, the dihalide to be taken is

Options

A. Gem dihalide
B. Vicinal dihalide
C. Isolated dihalide
D. Any dihalide

Answer

To solve the question regarding the dehalogenation reaction of dihalides to obtain alkenes, we will analyze the types of dihalides and their behavior in this reaction.

### Step-by-Step Solution:

1. **Understanding Dihalides**:
- Dihalides are compounds that contain two halogen atoms attached to carbon atoms. They can be classified into different categories based on the position of the halogen atoms.

2. **Types of Dihalides**:
- **Geminal Dihalides**: Both halogen atoms are attached to the same carbon atom. For example, in a compound like CH3CBr2H, the two bromine atoms are on the same carbon.
- **Vicinal Dihalides**: The halogen atoms are attached to adjacent carbon atoms. For example, in 1,2-dibromoethane (CH2Br-CH2Br), the bromine atoms are on adjacent carbons.
- **Isolated Dihalides**: The halogen atoms are separated by more than one carbon atom. For example, in 1,3-dibromopropane (CH2Br-CH2-CH2Br), the bromine atoms are not adjacent.
- **Any Dihalide**: This term refers to any dihalide without specifying the arrangement of halogens.

3. **Dehalogenation Reaction**:
- The dehalogenation reaction typically involves the removal of halogen atoms from a dihalide to form an alkene.

4. **Analyzing the Types of Dihalides**:
- **Geminal Dihalides**: These do not readily undergo dehalogenation to form alkenes because both halogens are on the same carbon, making it difficult to eliminate them.
- **Vicinal Dihalides**: These are the most suitable for dehalogenation because the halogens are on adjacent carbons, allowing for the formation of a double bond between those carbons upon elimination of the halogens.
- **Isolated Dihalides**: These are less likely to form alkenes through dehalogenation since the halogens are not adjacent.
- **Any Dihalide**: This option is too broad and does not specify the necessary conditions for the reaction.

5. **Conclusion**:
- The correct choice for the dihalide to be used in the dehalogenation reaction to obtain alkenes is the **vicinal dihalide**.

### Final Answer:
In dehalogenation reactions of dihalides to get alkenes, the dihalide to be taken is **vicinal dihalide**.