Which of the following reaction involves homogeneous reduction ?

Options

A. `CH_(2)=CH_(2) overset(H_(2)//Ni)rarr CH_(3)-CH_(3)`
B. `CH_(3)-C-=C-CH_(3) overset("Wilkison's catalyst")rarr CH_(3)-CH=CH-CH_(3)`
C. `CH_(3)COCl overset(H_(2)//Pd//CaCO_(3)//"quinonline")rarr CH_(3)CHO`
D. `CH_(3)C-=CH overset(H_(2)//Pd//CaCO_(3)//"quinonline")rarr CH_(3)CH=CH_(2)`

Explanation

To determine which of the following reactions involves homogeneous reduction, we need to understand the difference between homogeneous and heterogeneous catalysis. Here’s a step-by-step solution:

### Step 1: Understand the Definitions
- **Homogeneous Catalysis**: This occurs when the catalyst and the reactants are in the same phase (i.e., both are in the gas phase or both are in the liquid phase).
- **Heterogeneous Catalysis**: This occurs when the catalyst is in a different phase than the reactants (e.g., a solid catalyst with gaseous or liquid reactants).

### Step 2: Analyze the Given Reactions
We have four reactions with different catalysts:
1. Hydrogen and Nickel (Heterogeneous)
2. Wilkinson Catalyst (Homogeneous)
3. Hydrogen and Palladium with Calcium Carbonate and Quinoline (Heterogeneous)
4. Hydrogen and Palladium with Calcium Carbonate and Quinoline (Heterogeneous)

### Step 3: Identify the Type of Catalysis
- **Reaction 1**: Nickel is a solid catalyst, so this is a heterogeneous reaction.
- **Reaction 2**: Wilkinson catalyst is a homogeneous catalyst, as it is typically used in a solution where it is in the same phase as the reactants.
- **Reaction 3**: Palladium with Calcium Carbonate and Quinoline is a solid catalyst, making this a heterogeneous reaction.
- **Reaction 4**: Similar to Reaction 3, this is also a heterogeneous reaction.

### Step 4: Conclusion
From the analysis, only the second reaction involving the Wilkinson catalyst is a homogeneous reduction. Therefore, the correct answer is:

**Option B: Wilkinson Catalyst**