Sulfamic acid and its N- and O-substituted derivatives

The 21 year period of the development of sulfumic acid and its N- and O-substituted derivatives, from 1991 to the end of 2011, is studied. Several ab initio SCF(self-consistent field)-MO studies of sulfamic acid, sulfamate anion, NH₂SO₃, and N-methylsulfamate anion, MeNHSO₃, have been reported. For sulfamic acid and sulfamide the calculated acidities correlate well with the experimentally determined pK_a values. The dative bond between nitrogen and sulfur is believed to be only partially formed. ¹⁴N, ¹⁵N, and ¹⁷O NMR were used to study reactions of sulfamic acid with nitrite complexes of palladium, ruthenium, and rhodium giving cis-nitroaqua complexes. Several papers deal with the solubility of sulfamates in water. The kinetics of the dissolution and crystallization of sulfamic acid in water have been extensively probed. Interest in the structure-taste relationships of various mono- and disubstituted phenylsulfamates increased after the discovery in 1989 of the sweetness of some meta-substituted phenylsulfamates.