Which among the following on dehalogenation will give trans alkene:

Options

A. `{:(" Br"),(" |"),(H_(3)C-C-H),(" |"),(H_(3)C-C-H),(" |"),(" Br"):}`
B. `{:(" Br"),(" |"),(H_(3)C-C-H),(" |"),(H-" C"-CH_(3)),(" |"),(" Br"):}`
C. `{:(" Br"),(" |"),(H_(3)C-C-CH_(3)),(" |"),(H_(3)C-C-CH_(3)),(" |"),(" Br"):}`
D. `{:(" Cl"),(" |"),(H_(3)C-C-CH_(3)),(" |"),(H_(3)C-C-CH_(3)),(" |"),(" l"):}`

Answer

To solve the question "Which among the following on dehalogenation will give trans alkene?", we will analyze the given compounds step by step.

### Step 1: Identify the Compounds
We are given four compounds. We need to examine each compound to determine if it can yield a trans alkene upon dehalogenation.

### Step 2: Eliminate Options
We can start by eliminating options based on their structure. The last two compounds have four methyl (CH₃) groups on the adjacent carbons. When dehalogenation occurs in these compounds, they will produce a tetra-substituted alkene, which cannot exhibit cis-trans isomerism. Therefore, these two options can be eliminated.

### Step 3: Analyze the Remaining Compounds
Now we focus on the first two compounds. We need to determine their configurations and whether they can yield a trans alkene.

### Step 4: Draw the Structures
For each of the first two compounds, we will draw their structures and identify the stereochemistry:

- **Compound 1**:
- Draw the structure with Br and H on one carbon and CH₃ groups on the adjacent carbon.
- Assign R/S configuration to the stereocenters.

- **Compound 2**:
- Similarly, draw the structure and assign R/S configuration.

### Step 5: Determine the Configuration
For Compound 1, if we find that the two bromine atoms are in an anti-periplanar arrangement, then dehalogenation can occur, leading to the formation of a trans alkene.

For Compound 2, if the bromine atoms are not in an anti-periplanar arrangement, the elimination will lead to a cis alkene instead.

### Step 6: Conclusion
After analyzing both compounds:
- Compound 1 yields a trans alkene upon dehalogenation.
- Compound 2 yields a cis alkene upon dehalogenation.

Thus, the answer to the question is **Compound 1**.