Synthesis
3.0 g of 2,2'-thiodiacetic acid was accurately weighed in a 50 mL round bottom flask. To the flask was added 15 mL of acetic anhydride as reaction solvent. The reaction mixture was heated to 65 °C and kept at reflux for 4 hours. Upon completion of the reaction, the excess acetic anhydride and the by-product acetic acid were removed by distillation under reduced pressure. Subsequently, an appropriate amount of ether was added to the residue and the evaporation operation was repeated 2-3 times to purify the product. The final product was obtained as 2,2'-thiodiacetic anhydride in the form of a white solid powder and the product was dried at 40 °C overnight in 98.7% yield.
References
[1] Patent: CN108245683, 2018, A. Location in patent: Paragraph 0051; 0053
[2] Organic Letters, 2015, vol. 17, # 15, p. 3930 - 3933
[3] Tetrahedron Letters, 2017, vol. 58, # 32, p. 3160 - 3163
[4] Tetrahedron Letters, 2002, vol. 43, # 8, p. 1519 - 1522
[5] Tetrahedron Letters, 2017, vol. 58, # 37, p. 3672 - 3677
