JEE Main 2015 · 10 Apr · Shift 1 · Chemistry Q53

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ChemistrySingle correct+4 / -1Question 53 of 90

Dipotassium 1,4-dihydronaphthalene-1,4-dicarboxylate (structure shown) $\xrightarrow{\text{Electrolysis}}$ A

A is :

Dipotassium 1,4-dihydronaphthalene-1,4-dicarboxylate (COOK on C1 and C4, a C2=C3 double bond) → electrolysis → A.

A benzene ring fused to a bicyclic four-membered system (a Dewar-type isomer of naphthalene)

Naphthalene

Anthracene

A polymer of 1,4-dihydronaphthalene units

A polymer whose repeat unit is a dihydronaphthalene linked through C1 and C4.

Answer and worked solution

Official answer: B

Kolbe-type electrolysis of the dicarboxylate removes both $\ce{COO-}$ groups as $\ce{CO2}$ and forms a new double bond between C1 and C4. Combined with the existing C2=C3 bond this aromatises the ring: A is naphthalene.

Topics:Carboxylic acids Aromatic hydrocarbons and electrophilic substitution

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JEE Main 2015 · 10 Apr · Shift 1, Chemistry question 53