Sulfonater

Sulfonater, or sulfonates, are chemical species that feature the sulfonate group, typically written as −SO3−, attached to an organic moiety or existing as salts of sulfonic acids. In organic chemistry, sulfonates are usually encountered as sulfonate esters (R–O–SO2–R') or as ionic salts formed from sulfonic acids (for example, sodium benzenesulfonate).

Sulfonates can be formed in several ways. Direct sulfonation of arenes with sulfur trioxide or fuming sulfuric acid yields aryl sulfonic acids that can be neutralized to sulfonate salts. Sulfonate esters are prepared by reacting alcohols with sulfonyl chlorides such as tosyl chloride (p-toluenesulfonyl chloride) or methanesulfonyl chloride, producing tosylates or mesylates that serve as good leaving groups in further reactions. Triflate esters (trifluoromethanesulfonates) are obtained from triflic anhydride or related reagents and are among the most effective leaving groups used in organic synthesis.

Applications of sulfonates are broad. They are key components of detergents, including alkylbenzene sulfonates, and are integral to ion-exchange resins due to their strongly acidic −SO3− groups. In synthesis, tosyl and mesyl esters are widely used to activate alcohols or to protect amines, while triflates enable a wide range of cross-coupling and substitution reactions. In biochemistry and medicine, sulfonate groups influence solubility and metabolic stability in some compounds and formulations.

Naming conventions vary by region, with sulfonate sometimes spelled sulphonate. Safety depends on the specific compound and method of synthesis, but many sulfonating reagents are corrosive and require proper handling.