Question

Benzene reacts with CO/HCl/AlCl₃ and give 'P'.
Benzene reacts with CH₃-C-Cl / AlCl₃ to give 'Q'.
P and Q react with each other in presence of NaOH / H₂O give product Z. Find number of π e⁻ in product Z.

• A. 12
• B. 14
• C. 16
• D. 18

Answer 1

The Correct Option is C

Step 1: Reaction of Benzene with CO/HCl/AlCl₃.
Benzene reacts with CO and HCl in the presence of AlCl₃ catalyst to form an aryl ketone. This is a Friedel-Crafts acylation reaction. The product formed here is P, which is an aryl ketone, where a -CO group is attached to the benzene ring.

Step 2: Reaction of Benzene with CH₃-C-Cl / AlCl₃.
Benzene reacts with CH₃-C-Cl in the presence of AlCl₃ catalyst to form a methyl group (-CH₃) attached to the benzene ring. This is also a Friedel-Crafts alkylation reaction. The product formed here is Q, which is toluene (C₆H₅-CH₃).

Step 3: Reaction of P and Q with NaOH / H₂O.
P (an aryl ketone) and Q (toluene) react with NaOH and H₂O in a condensation reaction known as a coupling reaction. This leads to the formation of a new compound, Z, which will have conjugated π-bond systems. The number of π electrons in the product Z can be calculated based on the conjugation of the double bonds in the aromatic rings. Since Z is formed from the coupling of an aryl ketone and toluene, it will have a conjugated π-system from both rings.

Step 4: Conclusion.
The final product Z will have 16 π electrons, considering the conjugation in both aromatic rings. Final Answer: 16