Green and Efficient Synthesis of 1,3,2-Dioxathiolane 2,2-Dioxide by a Microreaction System

1,3,2-Dioxathiolane 2,2-dioxide (DTD) as an electrolyte additive for lithium-ion batteries plays an important role in improving battery performance and extending cycle life. The more environmentally friendly and cleaner hydrogen peroxide/TS-1 oxidation method for preparing DTD has been hampered by issues such as long reaction times, low selectivity, and catalyst deactivation and cannot replace the existing sodium hypochlorite/ruthenium trichloride oxidation method. In this work, a continuous flow synthesis of DTD using a microreaction system was designed and developed. A micropacked bed reactor loaded with TS-1 particles was employed to enhance the heat- and mass-transfer efficiency in the heterogeneous reaction. The experiments systematically investigated the effects of solvents, superficial velocity, reaction temperature, and reagent equivalents on reaction conversion and selectivity. In addition, an intrinsic kinetic model involving ethyl sulfite, hydrogen peroxide, and water was established. Acetone was proven to be a superior solvent, compared to water, for stabilizing the critical peroxide intermediate. To achieve the rapid separation of the product from water, a toluene extraction-based phase separation scheme was proposed. Under optimal conditions, a continuous-flow reaction, extraction, and separation process resulted in an 89.3% isolated yield of DTD with relatively low oxidant consumption and a short reaction time. This work shows the significant potential of microreactors for the green and efficient preparation of DTD in industry.