When propyne is treated with aqueous H2SO4 in presence of HgSO4, the major product is

2 4 4 . / dil H SO HgSO is the reagent used for oxymercuration and demercuration. It works on the principle of Markownikoff’s addition. As per this rule, hydronium ion goes to the carbon bearing more number of hydrogens. The first step leads to the Markownikoff product due to the formation of stable carbocation as a reactive intermediate,while in the second step, keto- enol tautomerism takes place. Therefore, acetone will be a favorable product.