Which of the following reaction liberates maximum amount of heat energy?

Options

A.
B.
C.
D.

Explanation

To determine which reaction liberates the maximum amount of heat energy, we need to analyze the stability of the alkenes involved in the hydrogenation reactions. Here’s a step-by-step solution:

### Step 1: Understand Hydrogenation
Hydrogenation is the process of adding hydrogen (H₂) to an alkene, which involves breaking the double bond (π bond) and forming new C-H bonds. This process is exothermic, meaning it releases heat energy.

**Hint:** Remember that the more unstable the alkene, the more heat is released upon hydrogenation.

### Step 2: Identify the Types of Alkenes
We have different types of alkenes in the options provided:
- Disubstituted alkenes (more stable)
- Monosubstituted alkenes (less stable)

**Hint:** Stability of alkenes affects their reactivity. Less stable alkenes are more reactive and will release more heat upon hydrogenation.

### Step 3: Compare Stability
- Disubstituted alkenes (found in options A, C, and D) are more stable due to the presence of substituents that stabilize the double bond.
- Monosubstituted alkenes (found in option B) are less stable and therefore more reactive.

**Hint:** Focus on the stability of each alkene type to predict which reaction will release more heat.

### Step 4: Analyze Reactivity
Since the reaction that liberates the maximum amount of heat energy is the one involving the least stable alkene, we can conclude:
- Option B (monosubstituted alkene) will react more readily and liberate more heat energy compared to the disubstituted alkenes.

**Hint:** The less stable the compound, the more energy is released during its conversion to a more stable form.

### Step 5: Conclusion
Based on the analysis, the reaction that liberates the maximum amount of heat energy is the hydrogenation of the monosubstituted alkene in option B.

**Final Answer:** Option B liberates the maximum amount of heat energy.