Question

Sulfonation of naphthalene, C10H8, results in two products. One product is kinetically favored and predominates in the beginning of the reaction. Because the reaction is reversible, eventually the kinetically slower but thermodynamically favored product predominates. Draw the structure of these two products. (The naphthalene ring is already drawn for you. Do not change the double bond configuration in the given structures.)

Answer 1

Explanation:

The sulfonation of the naphthalene yield 2 products under different conditions:

When the reaction is carried at 80 °C, 1-naphthalenesulfonic acid is the major product because it is kinetically favoured product as arenium ion formed in the transition state corresponding to 1-naphthalenesulfonic acid is more stable due to better resonance stabilization.

When the reaction is carried at 160 °C, 2-naphthalenesulfonic acid is the major product as it is more stable than 1-naphthalenesulfonic acid because of  steric interaction of the sulfonic acid group in 1-position and the hydrogen in 8-position.

The products are shown in image below.