A Convenient Multigram Synthesis of DABSO Using Sodium Sulfite as SO2 Source

A convenient synthesis of DABCO·(SO2)2 (abbreviated as DABSO) is reported. Using a two-chamber setup, sulfur dioxide is generated in one chamber and consumed in the other. This closed system overcomes safety issues related to working with toxic SO2 gas. Pressure build-up is avoided by gradually generating the gas using sodium sulfite as precursor. Moreover, only near-stoichiometric amounts of SO2 are required for this protocol. The use of anhydrous solvents is not necessary, and every step is performed at room temperature. A scale-up was carried out on a 10 g scale which, after overnight drying, resulted in a quantitative yield.