How many isomeric alkyne of hydrogenation gives 3,3 - Dimethylhexane.

Answer

To determine how many isomeric alkynes can yield 3,3-Dimethylhexane upon hydrogenation, we can follow these steps:

### Step 1: Understand the Structure of 3,3-Dimethylhexane
3,3-Dimethylhexane has the following structure:
- It is a hexane (6 carbon atoms) with two methyl (CH3) groups attached to the third carbon atom.
- The molecular formula for 3,3-Dimethylhexane is C8H18.

### Step 2: Identify Possible Alkynes
To find the isomeric alkynes that can be hydrogenated to form 3,3-Dimethylhexane, we need to consider the structure of alkynes:
- Alkynes have a triple bond (C≡C) between two carbon atoms.
- We need to place the triple bond in positions that allow for the formation of 3,3-Dimethylhexane after hydrogenation.

### Step 3: Draw Possible Alkynes
1. **1-Octyne**: The triple bond is at the first carbon.
- Structure: CH≡C-CH2-CH(CH3)-CH(CH3)-CH3
- Upon hydrogenation, this will yield 3,3-Dimethylhexane.

2. **2-Octyne**: The triple bond is at the second carbon.
- Structure: CH3-C≡C-CH(CH3)-CH(CH3)-CH3
- Upon hydrogenation, this will also yield 3,3-Dimethylhexane.

3. **3-Octyne**: The triple bond is at the third carbon.
- Structure: CH3-CH2-C≡C-CH(CH3)-CH(CH3)
- Upon hydrogenation, this will yield 3,3-Dimethylhexane as well.

### Step 4: Count the Isomers
From the structures drawn, we can see that there are three distinct alkynes that can be hydrogenated to yield 3,3-Dimethylhexane:
1. 1-Octyne
2. 2-Octyne
3. 3-Octyne

### Conclusion
Thus, the total number of isomeric alkynes that can be hydrogenated to give 3,3-Dimethylhexane is **3**.

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