Question

Find the compounds P and Q in the following reactions:

• A.
• B.
• C.
• D.
• E.

Answer 1

The Correct Option is A

P to Q (Dehydration): The reaction shows compound P treated with H2SO4 and heat (Δ). This is a dehydration reaction, which typically converts an alcohol to an alkene by removing a molecule of water (H2O). Therefore, P is cyclohexanol.

Q to Dialdehyde (Ozonolysis): Compound Q is then treated with ozone (O3) followed by zinc and water (Zn/H2O). This is ozonolysis, a reaction that cleaves alkenes (double bonds) to form carbonyl compounds (aldehydes or ketones). The Zn/H2O is a reducing workup, which prevents the formation of carboxylic acids.
If Q is a cyclohexene, then ozone will add to the double bond, creating two CHO groups at either end of the break point.

Therefore, Q is cyclohexene.

The answer is (A), where P is cyclohexanol and Q is cyclohexene.

Answer 2

Step 1: Identify compound Q

The final product is cyclohexanedione (\( \text{C}_6\text{H}_8\text{O}_2 \)), which is formed by treating compound Q with ozone followed by reduction with zinc and water. This suggests that Q must be a cyclic compound with two double bonds that can be oxidized to ketones.

Step 2: Identify compound P

Compound P is converted to Q using sulfuric acid (\( \text{H}_2\text{SO}_4 \)) under heating conditions. This suggests that P is likely a cyclic alcohol or ether that undergoes dehydration to form a cyclic alkene (Q).

Step 3: Match with the options

Option (A): Cyclohexanol and cyclohexene. Cyclohexanol dehydrates to form cyclohexene, which upon ozonolysis and reduction forms cyclohexanedione. This matches the given sequence.

Other Options: Cyclohexane, cyclohexyl methyl ether, or benzene do not fit the dehydration pathway to form cyclohexene.

Conclusion: The correct compounds are cyclohexanol (P) and cyclohexene (Q).