Sodium Alkylbenzene Sulfonate(CAS#68411-30-3)–Anionic Surfactant for Detergents

1. Properties:

• Appearance and Physical Form: Sodium salts of alkylbenzenesulfonic acid (C10–C13) are available in multiple physical forms depending on active content: white to light yellow powder or granules (high‑active grades: 80–98%); yellowish flowable paste (medium‑active grades: 30–60%); and viscous liquid/slurry (low‑active grades). The solid forms are free‑flowing powders or flakes with a mild characteristic odor. The product is APEO‑free and contains no alkylphenol ethoxylates.
• Solubility: The product is highly soluble in water (approximately 25 g/100ml at 20°C), forming clear to slightly hazy solutions depending on concentration and water hardness. It is soluble in lower alcohols and glycols but only slightly soluble in non‑polar organic solvents. The sodium salt exhibits excellent solubility across a wide temperature range, from cold water to elevated temperatures, without losing surface activity.
• Chemical Properties: As an anionic surfactant of the sulfonate class, sodium alkylbenzene sulfonate does not hydrolyze in aqueous solution and remains stable across a broad pH range (2–12), including acidic, neutral, and alkaline conditions. The molecule consists of a hydrophobic C10–C13 linear alkyl chain (primarily C12, with a typical mole ratio of C10:C11:C12:C13 = 13:30:33:24) attached to a benzene ring bearing a hydrophilic sodium sulfonate group (–SO₃Na). This amphiphilic structure imparts outstanding surface‑active properties including high detergency, foam generation, wetting, emulsification, lime soap dispersion, and antistatic behavior. The linear alkyl chain structure (>95% linear) ensures rapid and complete biodegradability (>60% ultimate biodegradation in OECD tests), unlike non‑biodegradable branched alkylbenzene sulfonates (ABS). The product also functions as a corrosion inhibitor on metal surfaces by forming a protective adsorbed film and as an antistatic agent by reducing surface charge accumulation. The HLB (hydrophilic‑lipophilic balance) value of its sodium salt is approximately 11–14, indicating strong hydrophilicity suitable for oil‑in‑water (O/W) emulsion systems.

2. Applications:

Household & Industrial Detergents and Cleaners (Primary):

• Laundry Detergents: As the most widely used anionic surfactant globally, sodium alkylbenzene sulfonate (LAS) serves as the primary active ingredient in laundry powders, liquid detergents, and detergent tablets. It provides excellent soil removal, grease cutting, foam generation, and soil suspension even in hard water conditions. High‑active powder grades (80–98%) are ideal for spray‑dried detergent powders and compressed tablets.
• Dishwashing Detergents (Hand and Automatic): Used in hand dishwashing liquids to generate stable, creamy foam while effectively cutting grease. Also applied in automatic dishwasher detergents (powders and tablets) where it contributes to spotting prevention and residue removal.
• Hard Surface Cleaners: Incorporated into bathroom, kitchen, floor, and all‑purpose cleaners for effective degreasing and soil removal on tiles, glass, stainless steel, and plastics.
• Institutional & Industrial (I&I) Cleaners: Applied in heavy‑duty industrial degreasers, janitorial cleaning formulations, car wash products (automatic and hand), dairy cleaners, and food processing sanitation chemicals.
• Hygienic Blocks and Tablets: Dried sodium alkylbenzene sulfonate (80–90% active) is directly incorporated into toilet blocks, urinal screens, and compressed tablets for sustained release cleaning and deodorizing.

Textile Industry:

• Wetting and Scouring Agent: Functions as an efficient wetting agent and scouring assistant in textile pretreatment processes (desizing, scouring, bleaching), improving fiber wettability and removing natural impurities (waxes, pectins, oils).
• Detergent in Dyeing: Used in dye baths to level dye uptake and prevent uneven coloration; also acts as a dispersant for pigments and as a post‑dyeing scouring agent to remove unfixed dyes.
• Antistatic Agent and Softener: Reduces static charge accumulation on synthetic fibers during processing (spinning, weaving, finishing), and contributes to fabric softness without affecting whiteness or shade.

Leather Processing:

• Degreasing Agent: Removes natural fats and oils from hides and skins during beamhouse operations (soaking, liming, deliming). Enhances penetration of subsequent tanning and finishing chemicals.
• Emulsifier and Wetting Agent: Facilitates emulsification of fatliquoring oils and improves wetting of leather during finishing operations.

Agrochemicals (Crop Protection):

• Emulsifier and Wetting Agent for Pesticides: Serves as an emulsifier in emulsifiable concentrate (EC) formulations for organophosphorus and pyrethroid pesticides. Also functions as a tank‑mix adjuvant to improve spray coverage, droplet adhesion, and leaf penetration of herbicide, fungicide, and insecticide formulations.
• Flowable and Suspension Concentrate Additive: Improves dispersion and stability of active ingredient particles in aqueous suspension concentrates (SC) and flowable formulations.

Metalworking & Metal Treatment:

• Metalworking Fluids (MWF): Used as an emulsifier, rust inhibitor, and wetting agent in semi‑synthetic and synthetic metalworking fluids (cutting oils, grinding fluids, drawing compounds). Provides emulsion stability, corrosion protection on ferrous metals, and improved cooling/lubrication.
• Metal Degreasing and Cleaning: Applied in alkaline and neutral metal cleaners for removal of oils, greases, and shop soils prior to electroplating, phosphating, painting, or assembly.
• Temporary Corrosion Protection: Forms a thin adsorbed protective film on metal surfaces to prevent flash rusting during storage or between processing steps.

Paper Industry:

• De‑inking Agent: Used in paper recycling processes (flotation de‑inking) to remove printing inks, toners, and coatings from waste paper pulp. LAS helps detach ink particles from fibers and disperse them in the flotation froth.
• Dispersant for Fillers and Pigments: Improves dispersion of calcium carbonate, clay, titanium dioxide, and other fillers/pigments in paper coating formulations, reducing agglomeration and improving coating uniformity.

Emulsion Polymerization:

• Emulsifier and Stabilizer: Sodium alkylbenzene sulfonate serves as an anionic emulsifier in emulsion polymerization of styrene‑butadiene rubber (SBR), acrylic polymers, vinyl acetate, polyvinyl chloride (PVC), and other latices. It provides excellent particle nucleation, stabilization against coagulation, and control of polymer particle size.

Oil & Gas Field Chemicals:

• Wetting Agent and Emulsifier: Applied in oil‑based drilling fluids to improve wetting of solids (barite, drill cuttings) and to stabilize water‑in‑oil emulsions. Also used in workover and completion fluids.
• Corrosion Inhibitor Component: Contributes to corrosion inhibition packages for downhole tubulars and surface equipment when formulated with appropriate co‑additives.

Construction Chemicals:

• Concrete Admixtures: Used as an air‑entraining agent in concrete to improve freeze‑thaw resistance and workability. Also functions as a dispersant for pigments in colored concrete and cementitious coatings.
• Gypsum and Plaster Additives: Improves wetting, dispersion, and flow properties of gypsum slurries in wallboard and plaster formulations.

Other Industrial Applications:

• Leather and Fur Cleaning: Applied as a wetting and cleaning agent in leather and fur cleaning formulations.
• Carpet and Upholstery Cleaners: Used in foam and liquid carpet cleaners to emulsify soils and provide quick drying.
• Pet Shampoos and Animal Care Products: Incorporated into veterinary shampoos as a mild cleansing and foaming agent for animals.
• Food Contact Applications: Certain purified grades of sodium alkylbenzene sulfonate are approved for use as a washing and peeling aid for fruits and vegetables (wash water additive) and as an emulsifier in food packaging adhesives, subject to local regulatory approvals.

3. Preparation Method:

• Laboratory Method: Sodium alkylbenzene sulfonate can be prepared by neutralizing alkylbenzenesulfonic acid (C10–C13) with sodium hydroxide or sodium carbonate in aqueous or alcoholic medium. The reaction is highly exothermic and requires controlled addition of the base to the acid with continuous stirring and cooling. The resulting neutralized product is then concentrated, filtered, and dried to obtain the desired active content and physical form.
• Industrial Process: Industrial production of high‑quality sodium alkylbenzene sulfonate follows a continuous two‑step process: (1) Sulfonation: Linear alkylbenzene (LAB, with C10–C13 alkyl chains, >95% linearity) is sulfonated with gaseous sulfur trioxide (SO₃) in a multi‑tube falling‑film reactor at controlled temperature (typically 40–60°C). The highly exothermic reaction produces alkylbenzenesulfonic acid (LABSA). (2) Neutralization: The crude LABSA is immediately neutralized with aqueous sodium hydroxide (NaOH) or sodium carbonate (Na₂CO₃) in a continuous neutralization system (e.g., loop reactor or stirred tank), yielding sodium alkylbenzene sulfonate at the desired concentration (typically 30–60% active for paste/liquid grades). For high‑active powder grades (80–98%), the neutralized product is further dried using spray drying, drum drying, or fluidized bed drying. Key quality parameters controlled include active matter content (30–98% depending on grade), unsulfonated matter (max. 0.5–3.0%), sodium sulfate content (max. 0.2–1.0%), sodium chloride content (max. 0.08%), pH (7.0–9.5), color (APHA/Hazen), alkyl chain distribution (C10–C13), and residual SO₃ or free alkali.

4. Safety Information:

• Hazard Classification: According to GHS and CLP Regulation (EC) No 1272/2008, sodium alkylbenzene sulfonate is classified with the following hazard statements:
  • H302 (Harmful if swallowed) – Acute toxicity, oral, Category 4
  • H315 (Causes skin irritation) – Skin corrosion/irritation, Category 2
  • H318 (Causes serious eye damage) – Serious eye damage, Category 1
  • H335 (May cause respiratory irritation) – Specific target organ toxicity, single exposure, Category 3
  • H412 (Harmful to aquatic life with long‑lasting effects) – Hazardous to the aquatic environment, long‑term hazard, Category 3
  • Additional: H330 (Fatal if inhaled, for certain high‑dust powder grades), Acute Toxicity Category 2
• Health Hazards: The substance is harmful if swallowed and causes skin irritation. Contact with eyes causes serious eye damage (corrosive). Inhalation of dust (powder forms) may cause respiratory tract irritation, coughing, and sore throat. The substance can be absorbed into the body by ingestion. For the 50% concentrate (typical commercial form), there is no hazard classification for acute toxicity, but the solid powder forms may carry additional inhalation hazards.
• Personal Protection: When handling concentrated or powder forms, wear appropriate protective equipment:
  • Respiratory protection: Use a particulate filter respirator (e.g., N95 or P2) if airborne dust concentrations exceed occupational exposure limits.
  • Eye protection: Chemical splash goggles or face shield (mandatory, due to risk of serious eye damage).
  • Skin protection: Chemical‑resistant gloves (nitrile or neoprene), protective clothing, and covered footwear.
  • General hygiene: Wash exposed skin thoroughly after handling. Do not eat, drink, or smoke in work areas.
• First Aid Measures:
  • Eye Contact: Rinse immediately with plenty of water for at least 15 minutes while keeping eyelids open. Remove contact lenses if easily possible. Seek immediate medical attention.
  • Skin Contact: Wash immediately with plenty of soap and water. Remove contaminated clothing. Seek medical attention if skin irritation persists.
  • Inhalation: Move victim to fresh air. Keep at rest in a position comfortable for breathing. If symptoms (coughing, throat irritation) persist, seek medical advice.
  • Ingestion: Rinse mouth immediately. Do NOT induce vomiting (risk of aspiration). Seek immediate medical attention. If vomiting occurs spontaneously, keep head low to prevent aspiration into lungs.
• Fire & Reactivity Hazards: The product is not combustible but may decompose on heating, producing toxic and corrosive fumes including sulfur oxides (SOₓ). Reacts with acids, generating toxic and corrosive fumes (including SOₓ). In case of fire in the surroundings, use appropriate extinguishing media (water spray, foam, dry powder, CO₂) suitable for the surrounding fire. Do not use water jets directly on burning material to avoid spreading.
• Environmental Precautions: Sodium alkylbenzene sulfonate is harmful to aquatic life with long‑lasting effects (H412). It is toxic to fish, daphnia, and algae (EC50/LC50 in the range of 1–100 mg/L). However, the product is readily biodegradable (rapid primary biodegradation; ultimate biodegradation >60% in OECD 301 tests), so environmental persistence is low. Avoid direct release into natural water bodies, drains, or the environment. Large spills should be contained and prevented from entering waterways, sewers, or soil. Follow local regulations for disposal.
• Storage & Stability: Store in sealed, corrosion‑resistant containers (plastic or lined drums) in a cool, dry, well‑ventilated area. Protect from direct sunlight, moisture, strong acids (risk of decomposition releasing SOₓ), and strong oxidizers. For paste and liquid grades, protect from freezing; if the material becomes hazy or separated after cold exposure, gently warm to 30–40°C and mix thoroughly before use. For powder/granule grades, protect from moisture and humidity to prevent caking and lump formation. Shelf life is typically 12–24 months in tightly closed original containers stored under recommended conditions.
• Regulatory Compliance: Sodium alkylbenzene sulfonate (CAS#68411-30-3, EC#270-115-0) is listed on EINECS, TSCA, DSL, AICS, NZIoC, KECI, ENCS, PICCS, and other regional chemical inventories. It is registered under REACH (Registration Number: 01-2119489428-22-0003) and is manufactured in and/or imported to the European Economic Area at ≥100,000 to <1,000,000 tonnes per annum. The product meets OECD SIDS criteria for high production volume (HPV) chemicals and is widely approved for use in consumer, industrial, and commercial detergents and cleaners worldwide. For formulations intended for food contact or agrochemical applications, additional regulatory approvals may be required depending on the jurisdiction. Always consult the Safety Data Sheet (SDS) and local regulations for complete safety, environmental, and regulatory information specific to each product grade and application.