The structural formula of the compound which yields ethylene upon reaction with zinc

Options

A. `CH_(2)Br – CH_(2)Br`
B. `CHBr_(2)–CHBr_(2)`
C. `CHBr = CHBr`
D. none

Answer

To determine the structural formula of the compound that yields ethylene (C2H4) upon reaction with zinc, we need to identify a suitable precursor that can undergo dehalogenation.

### Step-by-Step Solution:

1. **Understanding Ethylene**:
- Ethylene has the structural formula CH2=CH2. This means we need a compound that, when halogens are removed, will form this double bond.

2. **Identifying the Reaction Type**:
- Zinc is commonly used to facilitate the removal of halogens from vicinal dihalides (compounds with two halogen atoms on adjacent carbon atoms).

3. **Defining Vicinal Dihalides**:
- A vicinal dihalide has the general structure R-CH(X)-CH(Y)-R, where X and Y are halogens (e.g., Cl, Br, I) and R can be hydrogen or another carbon chain.

4. **Constructing the Compound**:
- To yield ethylene, we can consider a vicinal dihalide such as 1,2-dibromoethane (BrCH2-CH2Br).
- In this case, both bromine atoms are attached to adjacent carbon atoms.

5. **Reaction with Zinc**:
- When 1,2-dibromoethane reacts with zinc, the zinc facilitates the removal of the two bromine atoms, leading to the formation of a double bond between the two carbon atoms, resulting in ethylene.

6. **Final Structural Formula**:
- The structural formula of the compound that yields ethylene upon reaction with zinc is:
```
BrCH2-CH2Br
```

### Summary:
The compound that yields ethylene upon reaction with zinc is 1,2-dibromoethane (BrCH2-CH2Br).