Identify the product ' $A$ ' in the following reaction, Anisole $\xrightarrow[398 \mathrm{~K}]{\mathrm{HI}} \mathrm{A}+$ Iodomethane

The cleavage of anisole with hydroiodic acid at 398 K proceeds through nucleophilic substitution on the alkyl carbon of this aryl alkyl ether system.

The aryl-oxygen bond possesses partial double bond character due to resonance stabilization, rendering it resistant to cleavage. In contrast, the alkyl-oxygen bond is more labile. Protonation of the ether oxygen by HI yields an oxonium ion intermediate, which is then subject to $S_N2$ attack by the iodide nucleophile.

This nucleophilic attack occurs exclusively at the methyl carbon, as the phenyl group offers both steric hindrance and electronic stabilization that disfavors cleavage at that position. The reaction therefore produces phenol and iodomethane.

Thus, product A is benzenol.