Most stable radical among the following is

Options

A.
B.
C.
D.

Answer

To determine the most stable radical among the given compounds, we can analyze the stability of each radical based on the principles of radical stability, which is similar to the stability of carbocations. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand Radical Stability
Radical stability is influenced by the degree of substitution and the presence of electron-donating or electron-withdrawing groups. The stability order for radicals is similar to that of carbocations:
- Tertiary (3°) > Secondary (2°) > Primary (1°) > Methyl (CH3)

### Step 2: Analyze Each Compound
1. **Compound 1: CH3-CH2• (Ethyl Radical)**
- This is a primary radical. However, it has an ethyl group that can donate electrons, which stabilizes the radical.

2. **Compound 2: CH2F-CH2• (Fluoroethyl Radical)**
- The presence of fluorine, an electronegative atom, withdraws electron density from the radical center, making it less stable. This is an example of a primary radical affected by a -I (inductive) effect.

3. **Compound 3: CH2=CH-CH2• (Allyl Radical)**
- This is also a primary radical, but it has resonance stabilization due to the double bond. However, it is still affected by the presence of electronegative atoms if they are nearby.

4. **Compound 4: CF3-CH2• (Trifluoroethyl Radical)**
- This radical is destabilized significantly due to the presence of three fluorine atoms, which exert a strong -I effect, withdrawing electron density from the radical center.

### Step 3: Compare Stability
- **CH3-CH2• (Ethyl Radical)** is stabilized by the electron-donating effect of the ethyl group.
- **CH2F-CH2• (Fluoroethyl Radical)** is destabilized by one fluorine.
- **CH2=CH-CH2• (Allyl Radical)** has some resonance but is still a primary radical.
- **CF3-CH2• (Trifluoroethyl Radical)** is the least stable due to the strong electron-withdrawing effect of three fluorine atoms.

### Conclusion
The most stable radical among the given options is **CH3-CH2• (Ethyl Radical)** due to the electron-donating effect of the ethyl group.

### Final Answer
**The most stable radical is CH3-CH2• (Option A).**