Application： 1-Methylimidazolium hydrogen sulfate is a Brønsted acidic ionic liquid that can be used: As a component of a catalytic system along with chlorotrimethylsilane used in the preparation of 3,4-dihydropyrimidin-2(1H)-ones and hydroquinazoline-2,5-diones. As a catalyst in the preparation of biologically important 2,5-dimethyl-N-substituted pyrroles. As a reusable catalyst in the preparation of spiro[indoline-3′,2-quinazoline]2′,4(3H)-dione. In the leaching of copper and zinc in brass dross using H2O2 as an oxidant.