Reaction involvin anti addition is

Options

A. `CH_(2)=CH_(2) overset(H^(+)//H_(2)O)(to)`
B. `CH_(3) CH= CH_(2) overset(HX)(to)`
C. `CH_(3)CH=CH_(2)overset(Hg(OA_(c))_(2)H_(2)O)underset(NaBH_(4))(to)`
D. `CH_(2)=CH_(2)overset(B_(2)H_(6)//THF)underset(H_(2)O_(2)//OH)(to)`

Explanation

To solve the question regarding the reaction involving anti addition, we will analyze the process step by step.

### Step-by-Step Solution:

1. **Identify the Reaction Type**:
The question asks for a reaction that involves anti addition. Anti addition refers to the addition of two substituents to opposite sides of a double bond.

2. **Consider Common Reactions**:
One of the well-known reactions that involves anti addition is the oxymercuration-demercuration reaction. This reaction typically involves the addition of water across a double bond in an anti manner.

3. **Mechanism of Oxymercuration-Demercuration**:
- Start with an alkene (e.g., CH2=CH2).
- The alkene reacts with mercuric acetate (Hg(OAc)2) in the presence of water. This forms a mercurinium ion intermediate.
- The mercurinium ion is a cyclic structure where the mercury atom is positively charged and is attached to one of the carbons of the double bond.

4. **Nucleophilic Attack**:
- Water (acting as a nucleophile) attacks the more substituted carbon of the mercurinium ion from the opposite side of the mercury atom. This is crucial because it leads to the anti addition of the hydroxyl group (OH) and the hydrogen (H) that will be added later.

5. **Formation of the Product**:
- After the nucleophilic attack, a proton (H+) is removed from the intermediate, resulting in the formation of the alcohol (OH) on one carbon and a hydrogen atom (H) on the other carbon of the original double bond.
- The final product is an alcohol where the OH and H are added to opposite sides of the double bond, confirming the anti addition.

6. **Conclusion**:
- The oxymercuration-demercuration reaction exemplifies a reaction involving anti addition, where the hydroxyl group and hydrogen are added to opposite sides of the double bond.

### Final Answer:
The reaction involving anti addition is the **Oxymercuration-Demercuration reaction**.

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