Which of the following compounds after complete hydrogenation will form three monochloro structural isomeric products ?

Options

A.
B. `CH_(3)-underset(CH_(3))underset(|)(CH)-underset(CH_(2))underset(||)(C )-CH_(3)`
C.
D. `HC-=C-overset(C -= CH )overset(|)(CH)-C-=CH`

Explanation

To determine which compound will form three monochloro structural isomeric products after complete hydrogenation, we can follow these steps:

### Step 1: Identify the Compound
We need to identify the compound from the options provided that, upon complete hydrogenation, will yield a saturated hydrocarbon (alkane) with the potential for three distinct monochloro derivatives.

### Step 2: Perform Complete Hydrogenation
Complete hydrogenation of an unsaturated compound (like an alkene or alkyne) converts it into a saturated compound (alkane). For example, if we have a compound like an alkene, it will convert to hexane (C6H14) after hydrogenation.

### Step 3: Structure of the Resulting Alkane
After hydrogenation, we will have a straight-chain alkane. For instance, if the compound is 1-hexene, the resulting product after hydrogenation will be hexane (C6H14).

### Step 4: Identify Possible Monochloro Derivatives
Now we need to identify the positions where chlorine can be substituted on the hexane molecule. The positions are as follows:
- Chlorine can be substituted at the 1st carbon (C1).
- Chlorine can be substituted at the 2nd carbon (C2).
- Chlorine can be substituted at the 3rd carbon (C3).

### Step 5: Check for Structural Isomerism
When chlorine is substituted at C1, C2, and C3, we need to check if these substitutions yield unique structural isomers:
1. **1-chlorohexane** (Cl at C1)
2. **2-chlorohexane** (Cl at C2)
3. **3-chlorohexane** (Cl at C3)

Substituting chlorine at C4 would yield a compound that is structurally identical to 2-chlorohexane due to symmetry, and substituting at C5 would yield a compound that is identical to 1-chlorohexane. Thus, we only have three distinct structural isomers.

### Conclusion
The compound that, after complete hydrogenation, forms three monochloro structural isomeric products is option C.

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