Potential Explosion Hazards Associated with the Autocatalytic Thermal Decomposition of Dimethyl Sulfoxide and Its Mixtures

Dimethyl sulfoxide (DMSO) is widely used as a solvent for chemical reactions, as a cosolvent for crop protection formulations, and in medicines for topical administration of drugs. The potential explosion hazards associated with thermal decomposition of DMSO have been well-documented, with early reports dating back to the late 1950s. However, these explosion hazards are still underappreciated and inadequately communicated, as indicated by the fact that numerous severe accidents have occurred on both laboratory and industrial scales over the years. Differential scanning calorimetry studies show that decomposition of pure DMSO is detected at ca. 278 °C, while accelerating rate calorimetry analysis indicates that thermal decomposition of DMSO occurs at temperatures around its boiling point of 189 °C. Studies also show that the presence of certain substances can significantly lower the onset temperature of DMSO decomposition and also potentially increase the severity of the decomposition reaction through autocatalytic behavior. Further analysis of literature information indicates that there is a wide range of substances that exacerbate the thermal decomposition of DMSO, including acids, bases, halides, metals, electrophiles, oxidants, and reductants. This comprehensive review of explosion hazards associated with the thermal decomposition of DMSO and its mixtures will serve as an educational resource to alert researchers about the need to mitigate these hazards and to incentivize research toward its replacement with safer and greener solvents in the broader chemistry community.