1-Vinylimidazole dimethyl sulfate quaternary salt 1H-Imidazolium, 1-ethenyl-3-methyl-, methyl sulfate 220412-79-3 26591-72-0 3-Methyl-1-vinyl-1H-imidazolium methyl sulphate 52655-45-5 EINECS 247-832-2