See image — Reaction Mechanism Chemistry Question

💡 Solution & Explanation

Concept: Grignard reagents (RMgX) react with elemental sulfur (S8) in a nucleophilic addition, and subsequent acidification (hydrolysis) gives a thiol (mercaptan). Step 1: The Grignard reagent (RMgX) acts as a nucleophile. Elemental sulfur (S8) is an electrophilic sulfur source. Step 2: The carbon of the Grignard reagent attacks elemental sulfur to form an organomagnesium sulfide intermediate: R-S-MgX. Step 3: Upon acidification (H3O+), the R-S-MgX intermediate is hydrolyzed to give R-SH, which is a thiol (mercaptan). Overall: RMgX + S (elemental) → RSMgX → (H3O+) → RSH (mercaptan) Why other options fail: - Sulphoxide (R2S=O): requires oxidation of a thioether, not formed here. - Thioether (R-S-R): would require reaction of RSMgX with an alkyl halide, not simple acidification. - Sulphonic acid (RSO3H): requires extensive oxidation conditions, not formed by simple acidification. Therefore, the correct answer is A.