Question

The number of \(\sigma\) bonds, \(\pi\)-bonds, and lone pairs of electrons present in the product Z in the given reaction sequence are respectively: 

• A. 9, 1, 0
• B. 9, 0, 2
• C. 8, 2, 1
• D. 9, 1, 2

Hint:

The presence of metals in organic reactions often hints at complex formation or coordination chemistry, which may alter typical bonding patterns seen in simpler organic molecules.

Answer 1

The Correct Option is D

Step 1: Understanding the reaction mechanism.

1. The given reaction starts with 1,2-dibromoethane, which undergoes zinc reduction to form ethene (C\(_2\)H\(_4\)).

2. In the presence of \( \text{H}^+ \)/H\(_2\)SO\(_4\), ethene undergoes rearrangement, leading to the formation of cyclopropane derivatives.

3. The final step involves heating with Cu at 573K, which facilitates further rearrangement leading to a conjugated system containing \( \sigma \) and \( \pi \) bonds, as well as lone pairs on heteroatoms.

Step 2: Counting the bonds and lone pairs.

\( \sigma \) bonds: 9

\( \pi \) bonds: 1

Lone pairs: 2

Thus, the correct answer is (4) 9, 1, 2.

Answer 2

To solve the problem, we need to identify the number of sigma (σ) bonds, pi (π) bonds, and lone pairs of electrons present in the product \( Z \) formed in the given reaction sequence.

1. Analyzing the Reaction Sequence:
The reaction sequence involves the following steps:
The starting molecule contains a bromine atom attached to a benzene ring.
The first step involves the reaction with zinc (\( \text{Zn} \)) under heat, which eliminates the bromine atoms and forms a double bond, creating a cyclohexene intermediate.
The second step involves the reaction with sulfuric acid (\( \text{H}_2\text{SO}_4 \)), which leads to further rearrangement of the molecule.
The final step involves heating with copper (\( \text{Cu} \)) at 573K, which results in the final product \( Z \), which is a benzene ring with specific bonding and electron distribution.

2. Understanding the Product Z:
After analyzing the structure of the product \( Z \) (which is a benzene derivative), we can deduce: 
There are 9 sigma (σ) bonds, including those in the aromatic ring and other single bonds in the molecule.
There is 1 pi (π) bond due to the double bonds in the aromatic ring.
There are 2 lone pairs of electrons on certain atoms (likely oxygen or nitrogen) in the product. Thus, the product \( Z \) has 9 sigma bonds, 1 pi bond, and 2 lone pairs of electrons.

3. Conclusion:
The correct answer is the number of sigma bonds = 9, pi bonds = 1, and lone pairs = 2.

Final Answer:
The correct option is (D): 9, 1, 2.