Which of the following is true about the cycloheptatrienyl free radical ?

Options

A. It is an isolatable stable free radical
B. It is an aromatic free radical
C. It has `4n+2pi` electrons
D. None of these

Answer

To determine which statement is true about the cycloheptatrienyl free radical, we can follow these steps:

### Step 1: Understand the Structure of Cycloheptatriene
Cycloheptatriene is a seven-membered ring (cycloheptane) with three double bonds. The structure can be represented as follows:

```
C1
/ \
C7 C2
| |
C6 C3
\ /
C5
|
C4
```

### Step 2: Identify the Free Radical
In the cycloheptatrienyl free radical, one of the carbon atoms will have an unpaired electron, indicating that it is a free radical. This can be represented as:

```
C1
/ \
C7 C2
| |
C6 C3
\ /
C5
|
C4• (free radical)
```

### Step 3: Analyze Stability and Aromaticity
1. **Isolatable Stability**: Free radicals with more than six members are generally unstable due to thermodynamic factors. Therefore, cycloheptatrienyl free radical is **non-isolatable**.

2. **Aromaticity**: For a compound to be aromatic, it must follow Huckel's rule, which states that it should have \(4n + 2\) π electrons. In this case, cycloheptatrienyl has 7 π electrons (3 double bonds contribute 6 π electrons and the free radical contributes 1), which does not satisfy Huckel's rule. Therefore, it is **non-aromatic**.

3. **Electron Count**: The free radical has a total of 7 π electrons, which again does not satisfy the \(4n + 2\) rule.

### Step 4: Evaluate the Options
- **Option 1**: It is an isolatable stable free radical. **(Incorrect)**
- **Option 2**: It is an aromatic free radical. **(Incorrect)**
- **Option 3**: It has \(4n + 2\) π electrons. **(Incorrect)**
- **Option 4**: None of these. **(Correct)**

### Conclusion
The correct answer is that **none of the options provided are true about the cycloheptatrienyl free radical**.

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