Alkylbenzolsulfonate

Alkylbenzenesulfonates are a family of anionic surfactants derived from alkylbenzenes. They consist of a benzene ring bearing a sulfonate group (SO3−) and an attached alkyl chain. The most commercially important member is the linear alkylbenzene sulfonate (LAS), typically supplied as sodium or potassium salts with alkyl chains in the C10–C13 range. LAS is the dominant surfactant in many detergents due to its balance of detergency, cost, and compatibility with formulations.

Production and chemistry: LAS are produced by sulfonation of linear alkylbenzenes, which are themselves generated by the alkylation of benzene with long-chain olefins. The sulfonation yields mixtures of ortho- and para-substituted isomers, and the crude sulfonic acids are neutralized with alkali metals to form the soluble alkylbenzenesulfonate salts used in detergents. Commercial LAS typically reflects a distribution of chain lengths and isomeric forms, with linear chains preferred for better biodegradability.

Applications: As anionic surfactants, alkylbenzenesulfonates exhibit high surface activity and good detergency, emulsification, and tolerance to water hardness. They are widely used in laundry detergents, dishwashing products, household cleaners, and some personal care formulations. LAS are usually compatible with other surfactants and performance-enhancing additives.

Safety and environment: LAS are generally readily biodegradable under aerobic conditions and are largely removed by wastewater treatment. They can cause skin and eye irritation in concentrated forms and may exhibit aquatic toxicity at high concentrations. Due to foaming and environmental considerations, regulatory and industry efforts have focused on improving biodegradability and reducing ecological impact, while continuing to use LAS where appropriate.

Variants: Commercial LAS are typically sodium, potassium, or ammonium salts. The term often emphasizes linear alkyl chains, which are more biodegradable than older branched alternatives.