The strained tetracyclic alkane is isomerize thermally to the cyclic alkene. The reaction involves

Options

A. free radical
B. carbocation
C. carbanion
D. carbene.

Explanation

To solve the problem, we need to understand the thermal isomerization of a strained tetracyclic alkane to a cyclic alkene. Here’s a step-by-step breakdown of the process:

### Step 1: Identify the Structure of the Tetracyclic Alkane
- Draw the structure of the strained tetracyclic alkane. This compound consists of four interconnected rings, which introduces strain due to angle and torsional strain.

**Hint:** Visualize the tetracyclic structure and note the bonds that may be under strain.

### Step 2: Understand Thermal Isomerization
- Thermal isomerization refers to the process where heat is applied to facilitate the conversion of one molecular structure to another. In this case, the tetracyclic alkane is being converted to a cyclic alkene.

**Hint:** Remember that heat can provide the energy needed to break bonds in a molecule.

### Step 3: Bond Breaking and Electron Movement
- Upon heating, certain bonds in the tetracyclic alkane will break. For example, the bonds between carbon atoms will break, allowing the electrons to redistribute. This can lead to the formation of free radicals.

**Hint:** Focus on how the electrons are redistributed when the bonds break.

### Step 4: Formation of Free Radicals
- As the bonds break, free radicals are formed. A free radical is a species with an unpaired electron, which makes it highly reactive. The unpaired electrons from the broken bonds will seek to pair up with other unpaired electrons.

**Hint:** Identify the unpaired electrons and how they can interact with each other.

### Step 5: Reformation of Bonds
- The free radicals will then recombine to form new bonds, leading to the formation of the cyclic alkene. The new structure will have a lower energy state compared to the strained tetracyclic alkane.

**Hint:** Visualize how the free radicals combine to create a more stable structure.

### Step 6: Conclusion
- The process involves the formation of free radicals as intermediates during the thermal isomerization of the tetracyclic alkane to the cyclic alkene. Therefore, the correct answer to the question is that the reaction involves free radicals.

**Hint:** Recall that free radicals are often intermediates in reactions involving bond breaking and formation.

### Final Answer
The reaction involves free radicals.