The minimum heat of reaction is required in the formation of `:`

Options

A. Methyl radical
B. Ethyl radical
C. n-propyl radical
D. tert-butyl radical

Explanation

To determine the minimum heat of reaction required in the formation of various radicals, we need to analyze the stability of each radical formed from their respective parent hydrocarbons. Here’s a step-by-step breakdown:

### Step 1: Understand the Formation of Radicals
Radicals are formed through the homolytic cleavage of bonds in hydrocarbons. The stability of these radicals influences the heat of formation (ΔH). More stable radicals require less energy to form.

### Step 2: Analyze Methyl Radical
- **Formation**: Methyl radical (•CH₃) is formed from methane (CH₄).
- **Stability**: Methyl radical is highly unstable due to having no alkyl groups to stabilize it.
- **ΔH**: High ΔH of formation due to instability.

### Step 3: Analyze Ethyl Radical
- **Formation**: Ethyl radical (•C₂H₅) is formed from ethane (C₂H₆).
- **Stability**: Ethyl radical is more stable than methyl radical due to hyperconjugation from the adjacent CH₃ group.
- **ΔH**: Lower ΔH than methyl radical but still relatively high.

### Step 4: Analyze n-Propyl Radical
- **Formation**: n-Propyl radical (•C₃H₇) is formed from propane (C₃H₈).
- **Stability**: n-Propyl radical is more stable than ethyl radical because it is a secondary radical, which has more hyperconjugative stabilization.
- **ΔH**: Lower ΔH than ethyl radical due to increased stability.

### Step 5: Analyze Tertiary Butyl Radical
- **Formation**: Tertiary butyl radical (•C₄H₉) is formed from butane (C₄H₁₀).
- **Stability**: Tertiary butyl radical is the most stable among the radicals discussed, as it is a tertiary radical with maximum hyperconjugation (9 alpha hydrogens).
- **ΔH**: Lowest ΔH of formation due to its high stability.

### Conclusion
Among the radicals discussed, the tertiary butyl radical requires the minimum heat of reaction for its formation because it is the most stable radical.

### Final Answer
The minimum heat of reaction is required in the formation of **tertiary butyl radical**.

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