`CH-=CHoverset(Ni(CN)_2)rarrX` . Identify X in the given reaction

Options

A. Ethane
B. Benzene
C. Cycloctatetraene
D. Cyclohexane

Answer

To identify the product \( X \) formed in the reaction \( CH \equiv CH \overset{Ni(CN)_2}{\rightarrow} X \), we will analyze the reaction step by step.

### Step 1: Understand the Reactant
The reactant is 1-butyne (or ethyne), which has the structure:
\[ CH \equiv CH \]
This molecule contains a triple bond between two carbon atoms.

### Step 2: Identify the Role of \( Ni(CN)_2 \)
Nickel cyanide (\( Ni(CN)_2 \)) acts as a catalyst in this reaction. It facilitates the addition of cyanide ions (\( CN^- \)) to the ethyne molecule.

### Step 3: Mechanism of the Reaction
1. The \( CN^- \) ions generated from \( Ni(CN)_2 \) will abstract hydrogen ions (\( H^+ \)) from the ethyne.
2. As hydrogen ions are removed, the carbon atoms become negatively charged, leading to the formation of carbanions.

### Step 4: Formation of Carbanions
When \( H^+ \) is removed, we get:
\[ CH \equiv C^- \]
This carbanion can now react with another ethyne molecule.

### Step 5: Coupling of Carbanions
The carbanion formed from one ethyne molecule can attack another ethyne molecule, leading to the formation of a longer carbon chain. This process can repeat multiple times, resulting in the formation of a cyclic compound.

### Step 6: Formation of Cyclooctatetraene
Through the coupling of multiple ethyne molecules, we can form a cyclic structure known as cyclooctatetraene. This compound has the formula \( C_8H_8 \) and contains alternating double bonds.

### Conclusion
Thus, the product \( X \) formed in the reaction is **Cyclooctatetraene**.

### Final Answer
**X = Cyclooctatetraene**

---