2 - Butyne which treated with lithium in presence of liquid ammonia gives

Options

A. cis -2- butene
B. trans -2- butene
C. n - butane
D. 1 -butyne

Answer

To solve the question of what 2-butyne gives when treated with lithium in the presence of liquid ammonia, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Compound**:
- We start with 2-butyne, which is a terminal alkyne with the structure:
\[ CH_3-C \equiv C-CH_3 \]
- This compound has a triple bond between the second and third carbon atoms.

2. **Understand the Reaction Conditions**:
- The reaction involves lithium in liquid ammonia. This combination is known for performing Birch Reduction, which is a method to reduce alkynes to alkenes.

3. **Apply Birch Reduction**:
- In Birch Reduction, the alkyne is partially reduced to form a conjugated diene. The reduction typically leads to the formation of a mixture of cis and trans isomers of the alkene.
- For 2-butyne, the reduction will yield 2-butene.

4. **Determine the Products**:
- The product of the Birch Reduction of 2-butyne will be a mixture of cis-2-butene and trans-2-butene.
- Thus, the final products are:
- **cis-2-butene**
- **trans-2-butene**

### Final Answer:
When 2-butyne is treated with lithium in the presence of liquid ammonia, it gives a mixture of cis-2-butene and trans-2-butene.

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