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Octadecylbenzenesulphonic Acid is a long-chain alkyl aromatic sulfonic acid containing a hydrophobic C18 alkyl group and a strongly acidic sulfonic acid group.
Octadecylbenzenesulphonic Acid combines oil affinity, surface activity, interfacial adsorption, and strong neutralisation capacity within the same molecular structure.
Octadecylbenzenesulphonic Acid is used principally as a specialty surfactant intermediate, acid catalyst, emulsification component, and starting material for alkali-metal, alkaline-earth-metal, amine, and phosphonium sulfonates.
CHEMICAL IDENTITY AND COMMON NAMES
Octadecylbenzenesulphonic Acid consists of an octadecyl-substituted benzene ring carrying one sulfonic acid group.
The term may describe a defined positional isomer or an industrial material containing an established distribution of ring and alkyl-chain isomers.
The octadecyl group is also known as a stearyl group.
Stearylbenzenesulphonic Acid is consequently used as a common industrial name for the same C18 alkylbenzene sulfonic acid class.
The spelling “sulphonic acid” is common in British and European usage, while “sulfonic acid” is standard in American chemical nomenclature.
Both spellings describe the same functional group and chemical class.
CAS Number 28855-17-6 and EC Number 249-268-2 identify a widely established general Octadecylbenzenesulphonic Acid entry.
CAS Number 93820-24-7 and EC Number 298-607-0 are also associated with Octadecylbenzenesulphonic Acid in chemical inventories.
The names 2-Octadecylbenzenesulfonic Acid and 4-Octadecylbenzenesulfonic Acid describe specific ortho and para positional isomers.
Ring-substitution pattern, alkyl-chain structure, active-acid content, and commercial composition are therefore important parts of the procurement identity.
Synonyms and Common Names: Octadecylbenzenesulfonic acid, Octadecylbenzenesulphonic acid, Octadecylbenzene sulfonic acid, Octadecylbenzene sulphonic acid, Benzenesulfonic acid, octadecyl-, Benzenesulphonic acid, octadecyl-, n-Octadecylbenzenesulfonic acid, n-Octadecylbenzenesulphonic acid, Stearylbenzenesulfonic acid, Stearylbenzenesulphonic acid, Stearylbenzene sulfonic acid, Stearylbenzene sulphonic acid, C18 alkylbenzenesulfonic acid, C18 alkylbenzenesulphonic acid, C18 alkylbenzene sulfonic acid, C18 alkylbenzene sulphonic acid, Long-chain alkylbenzenesulfonic acid, Long-chain alkylbenzenesulphonic acid
TECHNICAL IDENTIFICATION
CAS Number: 28855-17-6
Alternative CAS Number: 93820-24-7
EC / EINECS Number: 249-268-2
Alternative EC / EINECS Number: 298-607-0
Molecular Formula: C24H42O3S
Molar Mass: 410.65 g/mol
Theoretical Sulfur Content: Approximately 7.81% by weight
Acid Functionality: One sulfonic acid group per molecule
Theoretical Acid Equivalent: 410.65 g/eq
Theoretical Acid Value: Approximately 136.6 mg KOH/g for pure monoacid
Chemical Class: Long-chain alkyl aromatic sulfonic acid
Ionic Character: Strongly anionic after dissociation or neutralisation
Hydrophobic Group: C18 alkyl chain
Hydrophilic Group: Sulfonic acid or sulfonate group
PHYSICAL AND CHEMICAL PROPERTIES
Appearance: Waxy solid, soft paste, or viscous acid material according to isomer composition and product form
Colour: Commonly off-white to pale yellow or amber
Odour: Characteristic
Water Solubility: Limited for the unneutralised long-chain free acid
Oil Compatibility: High compatibility with many hydrocarbon, lubricant, resin, and nonaqueous phases
Organic Solubility: Soluble or dispersible in suitable polar organic solvents and hydrocarbon-containing systems
Acidity: Strong organic sulfonic acid
Acid Value: Approximately 136.6 mg KOH/g for pure C24H42O3S
Surface Activity: Anionic in ionising media and after neutralisation
Hydrophobicity: High because of the linear C18 hydrocarbon chain
Volatility: Low at ambient temperature
Vapour Pressure: Low at ambient temperature
Thermal Behaviour: Long-chain isomers can exhibit crystalline, waxy, or liquid-crystalline transitions
Chemical Stability: Stable under controlled storage conditions
Neutralisation Behaviour: Reacts readily with alkalis, alkaline-earth bases, amines, and other basic compounds
Neutralisation Heat: Exothermic
Incompatible Materials: Strong oxidising agents, strong bases under uncontrolled conditions, and reactive metals
Thermal Decomposition Products: Sulfur oxides, carbon monoxide, carbon dioxide, and irritating organic fumes
FUNCTIONAL CHARACTERISTICS
The C18 alkyl chain gives Octadecylbenzenesulphonic Acid strong affinity for oils, hydrocarbons, waxes, resins, pigments, and hydrophobic surfaces.
The sulfonic acid group provides strong acidity and becomes an anionic sulfonate group after neutralisation.
This amphiphilic structure allows Octadecylbenzenesulphonic Acid to concentrate at oil-water, solid-liquid, and polymer-additive interfaces.
The material can therefore assist wetting, emulsification, dispersion, surface modification, and compatibility between polar and nonpolar phases.
The long octadecyl chain provides greater oil affinity and lower water solubility than shorter-chain alkylbenzene sulfonic acids.
Octadecylbenzenesulphonic Acid is consequently more suitable for specialised oil-soluble, polymer-compatible, wax-compatible, or interfacial applications than for conventional high-water household detergent systems.
The strong sulfonic acid group provides proton-donating catalytic activity.
The hydrophobic alkylbenzene structure can retain that acidity within organic reaction media where inorganic mineral acids have limited compatibility.
Neutralisation changes the material’s solubility, ionic behaviour, thermal properties, and application profile.
Sodium and potassium salts are more suitable for aqueous or polar systems, while calcium, magnesium, barium, amine, and phosphonium salts provide greater compatibility with oils, polymers, lubricants, or specialised functional media.
PRODUCTION AND COMMERCIAL FORM
Octadecylbenzenesulphonic Acid is produced by sulfonating an octadecyl-substituted benzene intermediate.
The octadecylbenzene precursor can be manufactured through the alkylation of benzene with a C18 olefin or another suitable octadecylating feedstock.
Sulfonation may be performed with sulfur trioxide, oleum, sulfuric acid, or chlorosulfonic acid under controlled reaction conditions.
Temperature, reagent ratio, reaction time, mixing, and feedstock structure affect conversion, colour, ring-substitution distribution, residual unsulfonated material, and free inorganic acid content.
The sulfonation stage is followed by ageing, separation, purification, concentration, or neutralisation according to the intended product.
Precise process control limits excessive sulfone formation, oxidation, dark colour, residual sulfuric acid, and unreacted octadecylbenzene.
Octadecylbenzenesulphonic Acid may be supplied as an active acid, a concentrated paste, a softened material, or a solution in a compatible carrier.
Commercial derivatives include sodium, potassium, calcium, magnesium, barium, amine, and phosphonium octadecylbenzenesulfonates.
APPLICATIONS AND INDUSTRIES
Specialty surfactants and emulsifiers
Octadecylbenzenesulphonic Acid is used as a precursor for C18 alkylbenzene sulfonate surfactants.
Neutralisation converts the strongly acidic group into a sulfonate salt with an anionic hydrophilic head and an oil-compatible C18 tail.
The resulting salts can provide wetting, emulsification, detergency, dispersion, and interfacial stabilisation.
Counterion selection determines whether the derivative is better suited to aqueous, hydrocarbon, lubricant, polymer, or mixed-phase systems.
Sodium and potassium derivatives provide greater compatibility with water and polar formulations.
Calcium, magnesium, barium, amine, and organic-cation derivatives provide stronger compatibility with oils, resins, fuels, and hydrophobic matrices.
Lubricants and petroleum additives
Octadecylbenzenesulphonic Acid is used as a starting material for oil-soluble sulfonate additives.
Alkaline-earth-metal derivatives are relevant to lubricant detergents, dispersants, corrosion-control additives, and deposit-management systems.
The sulfonate group interacts with polar contaminants, acids, metal surfaces, and dispersed particles.
The long C18 chain maintains compatibility with mineral oils, synthetic fluids, greases, and hydrocarbon-based formulations.
Calcium and magnesium sulfonates can be prepared as neutral or overbased materials.
Overbased sulfonates combine an oil-soluble organic shell with dispersed alkaline reserve and are used where acid neutralisation, detergency, rust control, or deposit management is required.
Base number, metal content, sulfonate content, alkalinity, carbonate structure, water, sediment, and oil compatibility are important parameters for metal-sulfonate derivatives.
The free acid’s active content, molecular distribution, and residual inorganic acid influence neutralisation and the quality of the final additive.
Metalworking and process fluids
Octadecylbenzenesulphonic Acid derivatives can function as emulsifiers, wetting agents, corrosion-control components, and dispersants in oil-containing process fluids.
The long alkyl chain supports lubricant-phase compatibility, while the sulfonate group interacts with water, metal surfaces, and polar additives.
Neutralised derivatives are used where stable distribution of oil and water phases is required.
Emulsion stability depends on the counterion, degree of neutralisation, water hardness, electrolyte content, oil type, temperature, and the accompanying surfactant system.
Pigment, filler, and particle dispersion
Octadecylbenzenesulphonic Acid and its salts can adsorb at the surfaces of pigments, fillers, carbonaceous particles, and inorganic solids.
The polar sulfonic or sulfonate group anchors at the particle interface, while the octadecyl chain extends into the organic carrier.
This interfacial arrangement can improve wetting, reduce particle agglomeration, and support dispersion in oils, resins, waxes, and hydrophobic polymer media.
The selected acid or salt form must match the polarity of the pigment surface and continuous phase.
Polymerisation and polycondensation catalysts
Octadecylbenzenesulphonic Acid is used as an oil-compatible acid catalyst in specialised polymerisation and polycondensation processes.
The strong sulfonic acid functionality promotes acid-catalysed reactions, while the long alkyl group improves compatibility with hydrophobic monomers and resin phases.
Specialised applications include polyester polycondensation and the preparation of binder resins, resin dispersions, and toner-related polymer systems.
Low treatment levels can provide catalytic activity while also introducing a sulfonate-derived ionic group into the reaction environment.
The material has also been applied in acid-catalysed organosilicon and siloxane processes.
Its combined catalytic and surfactant character can support reaction control and dispersion formation in appropriately designed aqueous-organic systems.
Resin dispersions and toner materials
Octadecylbenzenesulphonic Acid is used in specialised processes for producing polyester binder resins and fine resin-particle dispersions.
Its hydrophobic chain provides compatibility with the polymer phase, while its acidic head group contributes catalytic and interfacial functions.
After neutralisation, sulfonate groups can assist the transfer of resin into aqueous dispersion.
This approach is relevant to controlled particle formation for electrostatic image-development toner and related functional resin systems.
Antistatic agents for polymers and fibres
Octadecylbenzenesulphonic Acid is a precursor for alkali-metal and organic-cation sulfonates used in antistatic formulations.
These ionic derivatives increase surface or bulk conductivity and help dissipate accumulated electrostatic charge.
Octadecylbenzenesulfonate salts have been evaluated in synthetic-fibre processing oils, thermoplastic resin modifiers, and antistatic polymer compositions.
The C18 chain improves compatibility with hydrophobic polymers and processing oils compared with shorter, more water-soluble sulfonates.
Counterion, ionic concentration, polymer compatibility, thermal stability, migration, transparency, and mechanical-property retention determine antistatic performance.
Phosphonium salts are especially relevant where greater compatibility with engineering thermoplastics is required.
Textile and fibre-processing auxiliaries
Neutralised Octadecylbenzenesulphonic Acid derivatives can be used as wetting, emulsifying, lubricating, and antistatic components in synthetic-fibre processing systems.
The long alkyl chain promotes fibre and oil affinity, while the sulfonate group provides ionic surface activity.
These derivatives can assist the distribution of processing oils and reduce static accumulation during spinning, drawing, winding, and downstream handling.
Salt form, electrolyte tolerance, thermal behaviour, and compatibility with other finishing agents determine formulation suitability.
Waxes, coatings, and surface treatments
Octadecylbenzenesulphonic Acid derivatives can help disperse or emulsify waxes, hydrophobic resins, and surface-treatment ingredients.
The long hydrocarbon chain associates with the wax or resin phase, while the ionic head group provides interfacial stabilisation.
Specialised salts may contribute to water repellency, antistatic behaviour, pigment wetting, and surface modification.
Coating performance depends on counterion selection, dosage, resin compatibility, moisture resistance, and the effect of the ionic component on film properties.
SPECIALISED AND DEVELOPMENTAL USES
Defined octadecylbenzenesulfonic acid isomers are used in research involving organised molecular layers, reverse micelles, interfacial assemblies, and liquid-crystalline behaviour.
The long straight alkyl chain promotes ordered packing, while sulfonic acid groups form strongly polar interfacial regions.
Octadecylbenzenesulphonic Acid has also been investigated in specialised photoresist-stripping, soldering, resin, and chemical-processing compositions.
These applications rely on its strong acidity, organic-phase compatibility, or ability to generate functional sulfonate salts.
GRADE SELECTION AND PRODUCT SUITABILITY
Identity control begins with the required CAS and EC numbers, ring-substitution pattern, alkyl-chain structure, and active-acid content.
A defined 2- or 4-isomer and a commercial isomer distribution can exhibit different phase behaviour, solubility, crystallinity, and formulation performance.
High-active acid grades are suitable for neutralisation, catalyst, and derivative-manufacturing processes.
Solution grades support easier pumping, metering, and blending when the selected carrier is compatible with the reaction or formulation.
Surfactant-intermediate grades require controlled active matter, free sulfuric acid, unsulfonated material, colour, water, and molecular distribution.
Low unsulfonated matter supports efficient neutralisation and reduces hydrophobic residue in the final salt.
Polymerisation grades emphasise acid activity, colour, thermal stability, water content, and compatibility with the monomer system.
Water and inorganic-acid content can influence reaction rate, molecular-weight development, side reactions, and resin appearance.
Lubricant-additive grades require suitable alkyl-chain structure, oil solubility, metal-salt conversion, colour, residual acidity, and low sediment formation.
The molecular structure of the acid affects the solubility, detergency, alkalinity response, and low-temperature behaviour of the resulting metal sulfonate.
FORMULATION AND PROCESS CONSIDERATIONS
Octadecylbenzenesulphonic Acid should be incorporated into organic phases or compatible solvent systems with controlled mixing.
Waxy or highly viscous material can be gently warmed to obtain uniform flow and accurate dosing.
Dilution and neutralisation generate heat.
Octadecylbenzenesulphonic Acid should be added gradually to the receiving medium under effective agitation and temperature control.
When dilution with water is required, the acid should be introduced slowly into water.
Adding water rapidly to concentrated acid can produce local overheating, splashing, and an uneven highly acidic phase.
Neutralisation with sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium oxide, amines, or other bases requires stoichiometric control.
Theoretical acid equivalent, active-acid content, water, and free sulfuric acid must be included in the neutralisation calculation.
The final pH should be controlled after the mixture has reached equilibrium.
Incomplete mixing can leave local acid or base excess and produce unstable emulsions, inconsistent salt composition, or colour development.
For polymer reactions, the acid must be distributed uniformly before or during the catalytic stage.
Temperature, catalyst concentration, residence time, moisture removal, and corrosion-resistant equipment are central process parameters.
QUALITY, SPECIFICATIONS AND DOCUMENTATION
Active-acid content measures the amount of functional Octadecylbenzenesulphonic Acid available for neutralisation, catalysis, or salt formation.
Active content is a central specification for reaction stoichiometry and commercial value.
Acid value provides a practical measure of neutralisable acidity.
Pure C24H42O3S has a theoretical acid value of approximately 136.6 mg KOH/g.
Free sulfuric acid indicates residual sulfonating agent or inorganic acidity.
Control of free sulfuric acid supports colour stability, predictable neutralisation, reduced corrosion, and consistent derivative quality.
Unsulfonated matter measures residual octadecylbenzene and other oil-soluble nonionic components.
Low unsulfonated matter supports higher active content and cleaner conversion to sulfonate salts.
Water content affects active concentration, viscosity, storage form, neutralisation heat, and catalyst performance.
Colour is particularly important for polymers, coatings, pale lubricants, and speciality chemical derivatives.
Useful procurement documentation includes a Technical Data Sheet, Safety Data Sheet, Certificate of Analysis, compositional statement, active-matter result, acid-value result, and applicable regulatory information.
Batch documentation should report the parameters controlling the intended neutralisation, catalytic, surfactant, polymer, or lubricant application.
SAFETY AND REGULATORY CONSIDERATIONS
Octadecylbenzenesulphonic Acid is a strongly acidic organic material that can cause severe skin burns and serious eye damage.
Direct contact with the concentrated acid requires strict prevention.
Mist, heated vapour, and decomposition fumes can irritate or damage the respiratory tract.
Closed transfer, local exhaust ventilation, and controlled heating reduce inhalation exposure.
Octadecylbenzenesulphonic Acid and concentrated sulfonate residues can be harmful to aquatic organisms and may produce long-lasting environmental effects.
The material, washings, and spill residues must be contained and kept out of drains, soil, and surface water.
Octadecylbenzenesulphonic Acid is an organic combustible material, although low volatility reduces vapour formation at ambient temperature.
Heating or burning can release sulfur oxides, carbon monoxide, carbon dioxide, and irritating fumes.
Acid-resistant gloves, protective clothing, chemical splash goggles, and a face shield are appropriate for transfer, dilution, sampling, and neutralisation.
Emergency eyewash and safety-shower facilities should be immediately accessible in processing and storage areas.
FIRST AID
Inhalation: Move the affected person to fresh air and keep the person at rest in a position comfortable for breathing.
Inhalation: Obtain immediate medical attention after significant exposure or if coughing, pain, or breathing difficulty occurs.
Skin Contact: Remove contaminated clothing and rinse the skin immediately with large quantities of water for at least 15 minutes.
Skin Contact: Obtain immediate medical attention because chemical burns can develop after contact.
Eye Contact: Rinse cautiously with clean water for at least 15 minutes while holding the eyelids open.
Eye Contact: Remove contact lenses when present and easy to do, then continue rinsing.
Eye Contact: Obtain urgent medical attention.
Ingestion: Rinse the mouth carefully and do not induce vomiting.
Ingestion: Never give anything by mouth to an unconscious person.
Ingestion: Obtain immediate medical attention.
Note to Physicians: Treat as exposure to a corrosive sulfonic acid and provide symptomatic and supportive care.
HANDLING AND STORAGE
Handle Octadecylbenzenesulphonic Acid in closed or well-ventilated systems using acid-resistant equipment.
Avoid contact with the skin, eyes, clothing, reactive metals, and incompatible chemicals.
Keep containers tightly closed in a cool, dry, well-ventilated storage area.
Protect the material from strong bases, strong oxidising agents, excessive heat, ignition sources, and moisture contamination.
Use compatible containers and transfer equipment such as suitable polymeric, glass-lined, or corrosion-resistant systems.
Ordinary reactive-metal containers can corrode and contaminate the material.
Maintain segregation from alkalis and oxidising chemicals.
Neutralisation should be performed only in designated equipment with agitation, cooling, and controlled addition.
If the material becomes waxy or difficult to pump, apply gentle indirect heat and mix until homogeneous.
Avoid flames, hot spots, steam injection into the material, and uncontrolled heating.
Contain leaks with acid-resistant barriers and collect the material using a compatible inert absorbent.
Do not use reactive absorbents or allow concentrated acid to contact incompatible neutralising material without temperature control.
PACKAGING AND PROCUREMENT CONSIDERATIONS
Octadecylbenzenesulphonic Acid can be supplied in compatible drums, intermediate bulk containers, or application-specific bulk packaging.
Packaging is selected according to physical form, active concentration, carrier solvent, unloading method, storage temperature, and corrosion-control requirements.
Procurement specifications should identify the required CAS and EC numbers, active-acid content, positional-isomer profile, alkyl-chain structure, acid value, free sulfuric acid, unsulfonated matter, water, colour, and physical form.
Solution products should additionally identify the carrier, concentration, density, viscosity, and flash-related handling requirements.
For sulfonate manufacture, neutralisation equivalent, active matter, inorganic acidity, and unsulfonated content are primary controls.
For polymer catalysis, acid activity, water, colour, thermal behaviour, and monomer compatibility receive greater emphasis.
For lubricant additives, oil compatibility, molecular distribution, metal-salt conversion, sediment, and low-temperature behaviour are central selection parameters.
For surfactants and emulsifiers, counterion, active content, solubility, electrolyte tolerance, dispersion behaviour, and interfacial performance determine product suitability.
For Octadecylbenzenesulphonic Acid grade selection, specifications, documentation, packaging, derivative requirements, and supply enquiries, contact Ataman Kimya at +90 216 577 10 10 or info@atamankimya.com.
