Which is the correct structure of `5,6,6-` trimethyl `3-` heptyne ?

Options

A.
B.
C.
D.

Explanation

To determine the correct structure of `5,6,6-trimethyl-3-heptyne`, we will follow these steps:

### Step 1: Understand the Name
The name `5,6,6-trimethyl-3-heptyne` gives us important information about the structure:
- "heptyne" indicates a 7-carbon chain (heptane) with a triple bond.
- The "3" indicates that the triple bond is located at the third carbon.
- "5,6,6-trimethyl" indicates that there are three methyl (−CH₃) groups attached to the 5th and 6th carbons.

### Step 2: Draw the Carbon Chain
Start by drawing a straight chain of 7 carbon atoms (C1 to C7):
```
C1 - C2 - C3 - C4 - C5 - C6 - C7
```

### Step 3: Add the Triple Bond
Since the triple bond is located at the 3rd carbon, we will modify the structure:
```
C1 - C2 - C3≡C4 - C5 - C6 - C7
```

### Step 4: Add the Methyl Groups
Now, we need to add the methyl groups at the specified positions:
- 1 methyl group on C5
- 2 methyl groups on C6

The structure will look like this:
```
CH₃
|
C1 - C2 - C3≡C4 - C5 - C6
| |
CH₃ CH₃
```

### Step 5: Verify the Structure
- Count the total number of carbon atoms: 7 from the heptyne chain and 3 from the methyl groups, totaling 10 carbon atoms.
- Confirm the positions of the triple bond and the methyl groups:
- Triple bond is at C3.
- Methyl groups are at C5 (1) and C6 (2).

### Conclusion
The correct structure of `5,6,6-trimethyl-3-heptyne` is as drawn above.

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