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 t½ 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 pKa 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.