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Sodium alkylbenzene sulphonates are alkylbenzenesulfonate salts in which an alkyl chain (R) is attached to a benzene ring and the ring carries a sulfonic acid group (–SO₃H) that is neutralized to the sodium salt (–SO₃Na).
In commercial LAS, the alkyl group is linear C10–C13 (hence the common name linear alkylbenzene sulphonate).
The chemical behavior is dominated by the amphiphilic molecular architecture: a hydrophobic long alkyl tail and a hydrophilic sulfonate head group. Representative molecular formula for a C12 chain: C₁₈H₂₉O₃S·Na (approx. molar mass ~348–350 g·mol⁻¹ depending on chain distribution).
CAS: 68411-30-3
SYNONYMS
LAS, LASNa, LABSNa,Sodium linear alkylbenzene sulfonate (Sodium LAB sulphonate),Sodium dodecylbenzenesulfonate (SDBS) — for the C12 predominating fraction (a common individual homolog),Sodium C10–C13 alkylbenzenesulfonate
Chemical nature and structure
Sodium alkylbenzene sulphonates are alkylbenzenesulfonate salts in which an alkyl chain (R) is attached to a benzene ring and the ring carries a sulfonic acid group (–SO₃H) that is neutralized to the sodium salt (–SO₃Na).
In commercial LAS, the alkyl group is linear C10–C13 (hence the common name linear alkylbenzene sulphonate).
The chemical behavior is dominated by the amphiphilic molecular architecture: a hydrophobic long alkyl tail and a hydrophilic sulfonate head group.
Representative molecular formula for a C12 chain: C₁₈H₂₉O₃S·Na (approx. molar mass ~348–350 g·mol⁻¹ depending on chain distribution).
Isomerism and structure notes: Historically, branched alkylbenzene sulphonates (from older propylene tetramer-based LABs) were widely used but show much poorer biodegradability.
Modern LAS uses linear LAB feedstocks so regio-isomer distributions are limited to positional isomers along the ring (para/o-meta substitution patterns) and minor branching arising from manufacturing. The linear character is critical for rapid aerobic biodegradation.
Typical commercial composition (why “80%” matters)
Commercial LAS is sold as technical powders, granules or pastes with a given active matter content.
An 80% grade generally indicates approximately 80 wt% sodium alkylbenzene sulphonate (active surfactant), with the remainder being water, processing aids, salts (from neutralization), and small amounts of neutral organics or inorganic residues.
The exact composition depends on supplier specification (particle size, counter-ion balance, presence of organic builders or stabilizers for detergency and handling).
Technical sheets from manufacturers list product grades at 70–90% active matter; 80% is a widely produced and traded concentration for many downstream formulations.
Synthesis and industrial production
Overview of the two main upstream stages
Synthesis of Linear Alkylbenzene (LAB): Alkylation of benzene with linear mono-olefins (n-olefins) derived from n-paraffins (C10–C13 feed) yields LAB.
Industrial processes include HF (hydrofluoric acid) catalysis, zeolite or solid-acid (Detal) processes and other liquid acid catalysts; modern plants increasingly favor zeolite/solid catalysts for safety and selectivity.
The important outcome for detergent performance is a relatively narrow chain-length distribution and a high degree of linearity.
Sulfonation of LAB and neutralization: LAB is sulfonated (most commonly by sulfur trioxide, SO₃, or chlorosulfonic acid in older processes) to produce the corresponding alkylbenzene sulfonic acid (HLAS).
This acid is then neutralized with sodium hydroxide (NaOH) to yield the sodium salt (LASNa). Variations include direct sulfonation vs. oleum processes and subsequent post-treatments to produce water-soluble or powder grades (e.g., by neutralization in alcohol or spray drying). Controlled sulfonation and neutralization are essential to achieve desired solubility, residual acidity and shelf stability.
Process considerations and by-products
Selectivity: Avoiding over-sulfonation and minimizing olefin oligomerization during LAB formation are important.
Neutralization control: Partial neutralization can yield HLAS/HLAS-Na mixtures with differing solubilities (useful for some product forms).
Post-processing: Powder grades (spray-dried) and paste/liquid grades (neutralized in water/alcohol) require different downstream drying and stabilizing steps.
Waste streams and off-spec product: Sulfonation generates acidic waste streams and requires careful SO₃ handling and neutralization policies.
Physicochemical properties and behavior
Basic physical data (representative)
Appearance (80% technical product): beige to light brown paste/powder (depending on grade).
Representative molecular weight: ~348–350 g·mol⁻¹ (for C12 representative).
Solubility: sodium salt is readily soluble in water (forms clear to slightly opalescent solutions above critical micelle concentration); insoluble in nonpolar organic solvents.
Commercial 80% grades form aqueous solutions readily on dilution.
Surface activity and aggregation
Critical micelle concentration (CMC): for a single homolog such as sodium dodecylbenzene sulfonate (SDBS) typical CMC values at 25 °C are on the order of 10⁻⁴ to 10⁻³ M (literature reports ~3.7×10⁻⁴ M for SDBS under certain conditions), but the exact CMC for a technical LAS mixture depends on homolog distribution, ionic strength, temperature and added co-solutes (e.g., electrolytes, alcohols). CMC affects detergency, foaming and wetting performance.
Compatibility and formulation behavior
Good compatibility with many nonionic surfactants and builders (e.g., phosphate substitutes), but may show sensitivity to hard water (calcium/magnesium) — salts of divalent cations cause precipitation (countered by builders or chelants).
LAS displays high foaming tendency and excellent grease emulsification. Temperature and pH affect micelle size and cloud points in mixed systems.
SAFETY INFORMATION ABOUT SODIUM ALKYL BENZENE SULPHATE 80%
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
