The Sulfonation of Acetone: Characterization of Acetonedisulfonic Acid and Its Salts.

We report the synthesis of acetonedisulfonic acid ([(HOSO2CH2)2CO], ADSA) by slow reaction of acetone and oleum (65% SO3) and subsequent removal of H2O. The new acid was used to prepare potassium acetonedisulfonate, K2[ADS] (ADS = [(OSO2CH2)2CO]2-), as well as the rubidium and the pyridinium salts, Rb2[ADS] and [PyH]3[ADS][HSO4], respectively. Furthermore, we present an alternative one-pot reaction yielding the ammonium salt [NH4]2[ADS], which we characterized spectroscopically. The latter was used for a subsequent salt metathesis reaction for the preparation of the strontium and calcium salts. For the first time, all these compounds were structurally elucidated by single-crystal X-ray diffraction methods (SCXRD), revealing different conformers that the [ADS]2- anion may adopt. Deeper insights into the structural versatility of the new compounds were gained by quantum chemical calculations. These investigations led to the molecular electrostatic potential (MEP) surfaces of the acid, as well as of the [NH4]+ and the [C5H6N]+ salt, mapping the energetic landscape of the different species as a tool to predict the different reactivities. Subsequently, energetic and Bader's quantum theory of atoms in molecules (QTAIM) analyses were used to show the stabilization potential of the strong hydrogen bonds present in all of the three species and their influence on the intramolecular assemblies found in the solid state.