Sulfonic acid

Sulfonic acid usually refers to a member of the class of organic acids with the general formula R-S(=O)2-OH, where R is usually a hydrocarbon side chain. The term sulfonic acid may also refer to a particular member of this class, namely the case where R=hydrogen. Sulfonic acids are related to sulfuric acid, with one hydroxyl group removed

 

Sulfonic acids are a class of organic acids with the general formula R-S(=O)2-OH, where R is usually a hydrocarbon side chain. Sulfonic acids are typically much stronger acids than their carboxylic equivalents, and have the unique tendency to bind to proteins and carbohydrates tightly; most "washable" dyes are sulfonic acids (or have the functional sulfonyl group in them) for this reason. They are also used as catalysts and intermediates for a number of different products. Sulfonic acids and their salts (sulfonates) are used extensively in such diverse products like detergents, antibacterial drugs sulfa drugs, anion exchange resins (water purification) and dyes. The simplest example is methanesulfonic acid, CH3SO2OH, which is a reagent regularly used in organic chemistry. P-Toluenesulfonic acid is also an important reagent.