But-2-yne is reduced to trans-but-2-ene using

Options

A. Zn in dil.HCI
B. `H_(2), Ni`
C. `H_(2)| Pd-BaSO_(4)`
D. Na in liq. `NH_(3)`

Answer

To reduce but-2-yne to trans-but-2-ene, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Compound**:
- But-2-yne is an alkyne with the structure CH₃C≡CCH₃. It has a triple bond between the second and third carbon atoms.

2. **Understand the Reduction Process**:
- We need to convert the alkyne (triple bond) into an alkene (double bond). Specifically, we want to form trans-but-2-ene, which has the structure CH₃CH=CHCH₃, with the two methyl groups (CH₃) on opposite sides of the double bond.

3. **Select the Appropriate Reducing Agent**:
- To achieve the trans configuration in the alkene, we can use sodium (Na) or potassium (K) in liquid ammonia (NH₃). This method is known as Birch reduction.

4. **Perform the Reaction**:
- When but-2-yne is treated with sodium in liquid ammonia, the triple bond is reduced to a double bond, resulting in the formation of trans-but-2-ene. The reaction can be summarized as follows:
\[ \text{CH}_3C≡CCH_3 + \text{Na (in NH}_3) \rightarrow \text{trans-CH}_3CH=CHCH_3 \]

5. **Draw the Product**:
- The product, trans-but-2-ene, will have the two methyl groups on opposite sides of the double bond, confirming that the reduction has produced the desired trans isomer.

### Final Answer:
The correct reducing agent to convert but-2-yne to trans-but-2-ene is **Sodium (Na) in Liquid Ammonia (NH₃)**.