1,3-pentadiene and 1,4-pentadiene are compared with respect to their intrinsic stability and reaction with HI. The correct statement is :

Options

A. 1,3-pentadiene is more stable and more reactive than 1,4-pentadiene
B. 1,3-pentadiene is less stable and less reactive than 1,4-pentadiene
C. 1,3-pentadiene is more stable but less reactive than 1,4-pentadiene
D. 1,3-pentadiene is less stable but more reactive than 1,4-pentadiene

Answer

To compare the intrinsic stability and reactivity of 1,3-pentadiene and 1,4-pentadiene with respect to their reaction with HI, we can follow these steps:

### Step 1: Identify the Structures
1,3-pentadiene has its double bonds at the 1st and 3rd carbon positions, while 1,4-pentadiene has its double bonds at the 1st and 4th carbon positions.

**Hint:** Draw the structures of both compounds to visualize the positioning of the double bonds.

### Step 2: Determine the Type of Diene
1,3-pentadiene is a conjugated diene because the double bonds are separated by a single bond. In contrast, 1,4-pentadiene is an isolated diene because the double bonds are separated by two single bonds.

**Hint:** Recall that conjugated systems often have overlapping p orbitals, which can lead to increased stability.

### Step 3: Analyze Stability
Conjugated dienes (like 1,3-pentadiene) are generally more stable than isolated dienes (like 1,4-pentadiene) due to resonance stabilization. This means that the electrons in the double bonds can delocalize over the entire molecule, lowering the overall energy.

**Hint:** Consider how resonance structures can stabilize a molecule.

### Step 4: Analyze Reactivity with HI
Conjugated dienes are not only more stable but also more reactive towards electrophiles like HI. The presence of the double bonds makes them more likely to react, and the stability of the conjugated system allows for a more favorable reaction pathway.

**Hint:** Think about how the stability of a compound affects its reactivity; more stable compounds can often react more readily in certain conditions.

### Step 5: Conclusion
Based on the analysis, we conclude that 1,3-pentadiene is more stable and more reactive than 1,4-pentadiene when reacting with HI.

**Final Statement:** The correct statement is: "1,3-pentadiene is more stable and more reactive than 1,4-pentadiene."