Assertion (A): Sulfonation of naphthalene at $80^{\circ} C$ gives mainly naphthalene-1-sulfonic acid. Reason (R): Naphthalene-1-sulfonic acid is thermodynamically more stable than the 2-isomer.

ABoth A and R are true and R is the correct explanation of A
BBoth A and R are true but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true

Answer: C

A is true, since the C-1 attack has the lower barrier (kinetic control). R is false, since the 1-isomer is strained by the peri interaction with H-8 and is the less stable isomer, which is why the 2-acid dominates at

160^{\circ} C

Practice General Organic Chemistry III: Reaction Intermediates More on Reaction energy profiles, kinetic vs thermodynamic control

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Assertion (A): Sulfonation of naphthalene at 80 ∘C gives mainly naphthalene-1-sulfonic acid. Reason (R): Naphthalene-1-sulfonic acid is thermodynamically more stable than the 2-isomer.

Answer: C

More questions on Reaction energy profiles, kinetic vs thermodynamic control

Assertion (A): Sulfonation of naphthalene at $80^{\circ} C$ gives mainly naphthalene-1-sulfonic acid. Reason (R): Naphthalene-1-sulfonic acid is thermodynamically more stable than the 2-isomer.