Tully, Paul S. (Stepan Co.). Organic sulfonic acids having the formula RSO
3
H are described herein. Typical R‐groups are derived from organic radicals based on alkanes, alkenes, alkynes, and arenes. These groups may contain a wide variety of secondary functionalities. A wide variety of sulfonic acids and their derivatives are used industrially on a large scale in the manufacture of surfactants, dyes, inks, dispersing agents, and polymers. Those sulfonic acids that find broad application as catalysts in both alkylation processes and general organic reactions are also disclosed. More esoteric applications in the areas of custom organic syntheses and biological research involving sulfonic acid is described, as is the environmental fate of linear alkylbenzenesulfonic acid and its sulfonates.