Specific Solvent Issues / Safety Issues with Thioether Formation

The use of NaH/KH with dipolar aprotic solvents is not recommended on safety grounds
Org. Process Res. Dev. 2019, 23, 10, 2210–2217

For, specific solvent issues with thioether synthesis -SN2, SNAr and metal-catalyzed approaches, see:

• Specific solvent issues with the SNAr reaction guide
• Specific solvent issues with Buchwald-Hartwig Amination guide
• Several examples exist of thioether formation in ionic liquids and deep eutectic solvents:

  Pant, P. L.; Shankarling, G. S. Deep Eutectic Solvent: An Efficient and Recyclable Catalyst for Synthesis of Thioethers. Chemistry Select. 2017, 2, 7645–7650.
  
  Ranu, B. C.; Jana, R. Ionic Liquid as Catalyst and Reaction Medium: A Simple, Convenient and Green Procedure for the Synthesis of Thioethers, Thioesters and Dithianes using an Inexpensive Ionic Liquid, [pmIm]Br. Advanced Synthesis & Catalysis 2005, 347, 1811–1818. 

  Zhang, X.; Lu, G.-P.; Cai, C. Facile aromatic nucleophilic substitution (SNAr) reactions in ionic liquids: an electrophile–nucleophile dual activation by [Omim]Br for the reaction. Green Chem. 2016, 18, 5580–5585.