Sodium Secondary Alkyl Sulfonate (SAS) CAS 97489-15-1

Introduction to Sodium Secondary Alkyl Sulfonate

Sodium Secondary Alkyl Sulfonate is an anionic surfactant synthesized via the sulfoxidation or sulfochlorination of linear paraffins. The molecular structure consists of a hydrophobic alkyl chain where the sulfonate head group is attached to a secondary carbon atom rather than the terminal position. This specific architecture yields a material that remains highly soluble in water across a broad temperature range and resists phase separation in concentrated salt solutions.

The compound presents as a pale yellow viscous liquid or a free-flowing powder, depending on the active concentration. It exhibits excellent wetting, emulsifying, and dispersing properties. Chemical facilities utilize this surfactant to lower the surface tension of aqueous systems, allowing liquids to penetrate porous substrates and stabilize oil-in-water emulsions without requiring excessive mechanical shear.

Key Features of SAS

• Secondary sulfonate linkage: The attachment to a secondary carbon provides exceptional resistance to hydrolysis in extreme acidic or alkaline environments.
• Hard water tolerance: The sulfonate head group prevents the formation of insoluble calcium and magnesium salts, maintaining surface activity in untreated water.
• Electrolyte stability: Remains completely soluble and functional in high-salt formulations, preventing gelation or precipitation in concentrated liquid detergents.

SAS Chemical & Physical Properties

Applications of SAS

Industrial alkaline cleaners and degreasers: Dosed at 2-10% in heavy-duty metal cleaning formulations. The surfactant maintains stability in the presence of high concentrations of caustic soda and builders. Formulators frequently blend it with nonionic surfactants like Octylphenol Ethoxylate to synergistically lower the interfacial tension and accelerate the removal of stubborn machining oils.

Emulsion polymerization: Acts as a primary emulsifier in the synthesis of acrylic, vinyl acetate, and styrene-butadiene latexes. The steric bulk of the secondary alkyl chain provides robust colloidal stability to the polymer particles. In specific dispersion systems, it is paired with Dispersing Agent NNO to prevent agglomeration during the high-heat reaction phase.

Agrochemical and textile auxiliaries: Utilized as a wetting agent in pesticide tank mixes to ensure uniform coverage on waxy crop leaves. In textile processing, it assists in the rapid penetration of scouring baths into raw cotton fibers.

Storage & Safety Precautions for SAS

• Temperature management: Store liquid drums in a warehouse between 10 °C and 35 °C (50 °F – 95 °F). The 60% liquid grade may become highly viscous or stratify if exposed to freezing temperatures. Warm the drums gently using band heaters before pumping.
• Moisture control for powder grades: The powdered form is hygroscopic. Facilities run Calcium Chloride Anhydrous in warehouse dehumidifiers to maintain low ambient humidity and prevent the powder from caking into solid blocks.
• Handling and PPE: The concentrated liquid is a severe eye irritant. Wear chemical splash goggles and nitrile gloves during decanting. Clean spills immediately, as the surfactant creates an extreme slip hazard on concrete floors.

SAS FAQ

Q: How does Sodium Secondary Alkyl Sulfonate (SAS) perform in hard water?

A: SAS exhibits exceptional tolerance to hard water and multivalent metal ions. The sulfonate head group resists precipitation with calcium and magnesium, unlike traditional carboxylates. This ensures consistent wetting and emulsification in untreated industrial water supplies.

Q: Why is Sodium Secondary Alkyl Sulfonate used in alkaline cleaners?

A: The secondary alkyl chain and sulfonate bond grant SAS outstanding chemical stability in highly alkaline environments. It does not hydrolyze or degrade when exposed to caustic soda, making it a reliable primary surfactant for heavy-duty industrial metal degreasers.

Q: Does Sodium Secondary Alkyl Sulfonate (SAS) generate excessive foam?

A: SAS produces moderate to low foam compared to primary alkyl sulfates. This controlled foaming profile is highly desirable in industrial cleaning and emulsion polymerization, where excessive suds can cause overflow, reduce pump efficiency, and complicate wastewater treatment.