When propyne gas is passed through a red-hot iron tube at 873 K, it undergoes cyclic polymerization. — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Terminal alkynes undergo cyclic trimerization in a red-hot iron tube at 873 K. Three molecules of propyne ($CH_3-C\equiv CH$) orient themselves and polymerize to form an aromatic ring with three methyl groups symmetrically distributed. The product is 1,3,5-trimethylbenzene, commonly known as mesitylene.