Question

The compound

is treated sequentially with: (A) Excess HI/Red P
(B) \( \text{V}_2\text{O}_5 \), 773 K
(C) Benzyl chloride/AlCl\(_3\)
Find the number of π-bonds in the final product.

Answer 1

Correct Answer: 2

Step 1: Reaction with Excess HI/Red P.
The compound undergoes reduction by HI/Red P, which cleaves the C–C bond in the chain and reduces the aldehyde and alcohol groups. This gives a hydrocarbon. Step 2: Reaction with \( \text{V}_2\text{O}_5 \), 773 K.
The hydrocarbon undergoes oxidative dehydrogenation by \( \text{V}_2\text{O}_5 \) at 773 K, leading to the formation of a conjugated system with a double bond. Step 3: Reaction with Benzyl chloride/AlCl\(_3\).
The reaction with benzyl chloride/AlCl\(_3\) leads to a Friedel-Crafts alkylation, introducing a benzyl group into the structure, forming another C–C bond. Step 4: Final product.
The final product will have two π-bonds from the double bond and the benzyl group, giving a total of 2 π-bonds.
Final Answer: 2 π-bonds.