Excellent Thermal Stability and Environmental Sustainability of Trifluorodimethyl Sulfide as a Potential Alternative...

Trifluorodimethyl sulfide (CH₃SCF₃) has been proposed to be a potential alternative refrigerant based on various rigorous quantum chemistry calculations. It is revealed that the half F-substitution is capable of tuning the stability and reactivity of dimethyl sulfide (CH₃SCH₃) significantly. The strength of both S-C bonds is enhanced. The bond dissociation energies increase by 5-6 kcal/mol with respect to CH₃SCH₃, and decomposition temperature of CH₃SCF₃ is predicted to be 875 K. Meanwhile, the existence of CH₃ group keeps the good reactivity of CH₃SCF₃ toward OH radicals in the troposphere. Complex-forming H-abstraction to produce H₂O and CF₃SCH₂ radicals is the predominant mechanism accompanied by minor S-O association/elimination pathways. The atmospheric lifetime and radiative efficiency of CH₃SCF₃ is 0.2-1 years and 0.25 Wm^2-ppb^-1, respectively, leading to a global warming potential of 9-90 for a 100-year time horizon. The possible degradation products of CH₃SCF₃ in the atmosphere include both radicals, e.g., CF₃SCH₂OO, CF₃SCH₂OONO, CF₃SCH₂OONO₂, CF₃SCH₂O, CF₃S, and molecules, e.g., (CF₃SCH₂OO)₂, CF₃SCH₂OOH, CH₂O, and CH₃S(O)CF₃. The present computational work not only provides interesting insights into the dramatic impact of the partial fluorination on stability and reactivity of sulfides but also demonstrates that CH₃SCF₃ should be a viable refrigerant replacement for hydrofluorocarbons and even hydrofluoroolefins with excellent thermal stability and environmental sustainability.