Correct stability order of the given free radicals is

Options

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Answer

To determine the correct stability order of the given free radicals, we need to analyze the stability of each radical based on the effects of resonance, inductive effects, and hyperconjugation. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Free Radicals
The free radicals in question are:
1. Benzyl radical (C6H5-CH2•)
2. Tertiary radical (R3C•, where R = CH3)
3. Secondary radical (R2CH•, where R = CH3)
4. Methyl radical (CH3•)

### Step 2: Analyze the Stability Factors
1. **Benzyl Radical**:
- The benzyl radical can stabilize through resonance. The unpaired electron can be delocalized over the aromatic ring, which significantly increases its stability.
- Stability: High due to resonance.

2. **Tertiary Radical**:
- The tertiary radical is stabilized by both hyperconjugation and the inductive effect from the three surrounding alkyl groups (methyl groups).
- Stability: Moderate to high due to hyperconjugation and inductive effects.

3. **Secondary Radical**:
- The secondary radical is also stabilized by hyperconjugation and inductive effects, but to a lesser extent than the tertiary radical since it has only two alkyl groups.
- Stability: Moderate.

4. **Methyl Radical**:
- The methyl radical has no alkyl groups to stabilize it through hyperconjugation or inductive effects. It is the least stable of the radicals.
- Stability: Low.

### Step 3: Establish the Stability Order
Based on the analysis:
- The benzyl radical is the most stable due to resonance.
- The tertiary radical is next due to hyperconjugation and inductive effects.
- The secondary radical follows.
- The methyl radical is the least stable.

### Final Stability Order
The correct stability order of the given free radicals is:
**Benzyl radical > Tertiary radical > Secondary radical > Methyl radical**