Simple pyrimidines. Part XIII. The formation and hydrolysis of simple potassium pyrimidinesulphonates

Abstract

Potassium 4-methyl-, 5-methyl-, 4,5-dimethyl-, and 4,6-dimethyl-pyrimidine-2-sulphonate, as well as potassium 2-methyl-, 4-methyl-, 2,4-dimethyl-, 4,5-dimethyl-, and 2,4,5-trimethyl-pyrimidine-6-sulphonate are prepared from appropriate chloropyrimidines with aqueous potassium sulphite. The sulphonates undergo ready hydrolysis to the corresponding pyrimidinones in alkali or acid: at pH 14 (40°) the t_½ values vary from 12 to 830 min and at H₀–1 (25°) from 2 to 28 min, according to the position of the sulphonate group and the number and positions of the methyl groups (which retard hydrolysis). The pK_a values, characteristic i.r. bands, and u.v. spectra of the sulphonates are recorded and discussed; ¹H n.m.r. data are tabulated for the sulphonates, their chloro-intermediates, and their hydrolytic products.