Green Sulfonation

Sulfonic acid compounds have attracted considerable interest due to their extensive applications in drug discovery. Classically sulfonation involves the reaction of aromatic compounds with sulfuric acid or fuming sulfuric acid. This chapter summarized recent advances in the green sulfonation of aromatic rings, leading to the production of sulfonic acids and sulfonate compounds. This also focuses on the methodologies that were reported recently for the green synthesis of aryl sulfonic acid derivatives. Here, the presentation is organized according to the sulfonation reagents, sulfonation strategies, and sulfonation processes, with NaHSO₃, thiourea dioxide, sulfur-containing fuel, and 1,3-disulfonic acid imidazolium as the sulfonation reagents, gas-phase sulfonation as the sulfonation process, and microreaction device as the sulfonation strategy. Finally, this chapter ends with the discussion on the summary and outlook of the green sulfonation of aromatic rings.