Hazard analysis of tetrahydrofuran and dimethylsulfoxide mixture solvents for efficient use in reaction processes

Organic solvents are often used in mixture solvent systems to optimize synthetic reactions. However, they may also produce unexpected effects, some of which may be hazardous and cause a runaway reaction and/or lead to an accident. Thus, the proper accident scenarios and thermal risk assessment models are needed to use mixture solvents more safely and efficiently. For chemical process safety, Stoessel suggests the systematic assessment of accident scenarios. However, if scenarios are changed by the properties of mixture solvents, Stoessel’s concept does not cover them. Our previous study evaluated characteristic scenarios of mixture solvents based on Stoessel’s model. In this study, as a characteristic scenario pattern, we focused on the energy release of the solvent and the material derived from degraded solvent and investigated them experimentally using tetrahydrofuran (THF) and dimethylsulfoxide (DMSO) as a representative mixture solvent. From hazard and scenario identification of THF and DMSO, we assumed that THF peroxide and DMSO play roles in energy release. THF containing peroxide and DMSO were mixed, and thermal analysis and chemical composition analysis were performed. Our results indicated that DMSO promotes the decomposition of THF peroxide, and the decomposition temperature of DMSO decreases upon mixing with degraded THF. Therefore, we verified the scenario pattern of energy release of solvent and the material derived from degraded solvent.