Calcium Alkylbenzene Sulfonate(CAS#68953-96-8)–Anionic Emulsifier

1. Properties:

• Appearance and Physical Form: Calcium salts of alkylbenzenesulfonic acid are supplied as a yellow to brownish transparent viscous liquid (typically 50%–70% active). Solid grades appear as a white to light yellow granular solid. The liquid product has a faint characteristic odor and is supplied as a non-aqueous, solvent-containing solution for easy formulation handling.
• Solubility: The product exhibits excellent solubility in organic solvents including methanol, toluene, xylene, and various hydrocarbon solvents, but is only slightly soluble in water. This lipophilic character makes it particularly suitable for oil-based and non-aqueous applications. It demonstrates outstanding compatibility with nonionic surfactants, enabling the formulation of robust emulsifier blends.
• Chemical Properties: As an anionic surfactant of the alkylbenzene sulfonate class, calcium alkylbenzene sulfonate is synthesized via sulfonation of alkylbenzene followed by neutralization with a calcium base. The molecule consists of a hydrophilic sulfonate head group and a hydrophobic alkyl tail (C11–C13 branched), imparting strong surface activity. Unlike sodium or amine salts, calcium salts provide superior oil solubility and serve as lipophilic emulsifiers that do not require water for activation. In its overbased form, it acts as an effective detergent and acid neutralizer in lubricating oils, providing corrosion protection and maintaining engine cleanliness. The HLB of its blends with nonionic surfactants can be optimized for specific pesticide emulsion stability requirements.

2. Applications:

Agrochemicals & Crop Protection (Primary):

• Pesticide Emulsifiable Concentrates (EC): Calcium alkylbenzene sulfonate serves as the primary anionic emulsifier component in emulsifiable concentrate formulations for organophosphorus and organochlorine pesticides. It is typically used in combination with nonionic surfactants to form stable emulsifier systems that ensure uniform dispersion and long-term stability of the active ingredient upon dilution with water.
• Herbicide Adjuvants: Used as a wetting agent and emulsifier in herbicide formulations to improve spray coverage, droplet adhesion, and leaf penetration for enhanced biological efficacy.
• Fungicide and Insecticide Formulations: Functions as a key emulsifier for crop protection chemicals, providing stable emulsions that prevent phase separation and ensure consistent application performance.

Lubricants & Metalworking:

• Lubricant Additives: In its overbased form, calcium alkylbenzene sulfonate is widely used as a detergent, acid neutralizer, and corrosion inhibitor additive in automotive engine oils, marine lubricants, and industrial crankcase oils. These additives are adsorbed on polar metal surfaces to form a water-repellent protective film, effectively reducing corrosion and neutralizing acidic combustion byproducts.
• Rust and Corrosion Protection: Provides effective rust and corrosion inhibition in metalworking fluids, hydraulic oils, and protective coatings.

Industrial & Oilfield Applications:

• Oil-Based Drilling Fluids: Functions as a wetting agent to reduce corrosion and control viscosity in oil-based drilling fluid systems.
• Demulsifier: Used in demulsification processes for oil-water separation in produced water treatment and crude oil dehydration.
• Industrial Degreasers: Serves as an emulsifier for solvent-based degreasers and industrial cleaning formulations.

Textile & Leather Processing:

• Textile Dispersant: Applied as a dispersant for polyester yarn dyeing and textile processing, ensuring uniform dye penetration and preventing agglomeration.
• Leather Processing: Used as an emulsifier and softening agent in leather tanning and finishing operations.

Coatings & Inks:

• Pigment Dispersant: Functions as a dispersant for pigments and fillers in paints, coatings, and printing ink formulations, improving color development and stability.

Other Industrial Applications:

• Polymerization Emulsifier: Used as an emulsifier in polymerization processes for the production of synthetic resins and polymers.
• Food Packaging Emulsifier: Employed as an emulsifier in coatings for food packaging materials.
• Water Treatment: Utilized in water treatment formulations for its surfactant properties.

3. Preparation Method:

• Laboratory Method: Calcium dodecylbenzenesulfonate can be prepared by neutralizing dodecylbenzenesulfonic acid (DDBSA) with a calcium base. Two moles of DDBSA are reacted with one mole of calcium oxide or calcium hydroxide in an inert organic solvent such as toluene or xylene under controlled conditions. The reaction generates heat and produces the calcium salt along with water as a byproduct, which is removed by azeotropic distillation.
• Industrial Process: Industrial production follows the same neutralization route on a larger scale. Alkylbenzene (typically C10–C13 linear or branched) is first sulfonated with gaseous sulfur trioxide (SO₃) in a falling-film reactor to produce alkylbenzenesulfonic acid. The resulting sulfonic acid is then neutralized with a calcium base (calcium hydroxide or calcium oxide) in the presence of a solvent such as toluene, xylene, or isobutanol. The reaction mixture is processed to remove water and unreacted materials, yielding a clear viscous liquid with active content typically ranging from 50% to 70%. For overbased calcium sulfonate products used in lubricant applications, an additional carbonation step is employed where carbon dioxide is introduced to convert excess calcium base into colloidal calcium carbonate dispersed in the sulfonate matrix, providing enhanced detergency and acid-neutralizing capacity.

4. Safety Information:

• Hazard Classification: According to GHS/CLP Regulation, calcium alkylbenzene sulfonate is classified with the following hazard statements: H302 (Harmful if swallowed), H312 (Harmful in contact with skin), H318 (Causes serious eye damage), H412 (Harmful to aquatic life with long-lasting effects). Hazard ratings: Flammability 1, Toxicity 2, Body Contact 2, Reactivity 1, Chronic 2 (scale 0–4).
• Health Hazards: Ingestion causes irritation of the mouth and stomach. Contact with eyes causes irritation and may cause serious eye damage. Prolonged skin contact may have a drying effect and cause irritation.
• Personal Protection: When handling concentrated solutions, wear appropriate protective equipment including chemical-resistant gloves (nitrile), protective clothing, chemical splash goggles, and a face shield. Use in well-ventilated areas. Avoid breathing mists or vapors. Wash exposed skin thoroughly after handling.
• First Aid Measures:
  • Eye Contact: Rinse immediately with plenty of water for at least 15 minutes while keeping eyelids open. Seek immediate medical attention.
  • Skin Contact: Wash immediately with plenty of soap and water. Remove contaminated clothing. Seek medical attention if irritation persists.
  • Inhalation: Move victim to fresh air. Keep at rest in a position comfortable for breathing. If symptoms persist, seek medical advice.
  • Ingestion: Rinse mouth immediately. Do NOT induce vomiting. Seek immediate medical attention.
• Fire & Reactivity Hazards: The product reacts as a base to neutralize acids, generating heat. Thermal decomposition may produce irritating and toxic fumes including sulfur oxides (SOₓ). Use water spray, foam, dry powder, or CO₂ as extinguishing media appropriate for surrounding fire.
• Environmental Precautions: Harmful to aquatic life with long-lasting effects (H412). Avoid direct release into natural water bodies, drains, or the environment. Large spills should be contained and prevented from entering waterways. Immediate steps should be taken to limit spread to the environment.
• Storage & Stability: Store in sealed, corrosion-resistant containers (plastic or lined drums) below 30°C in a cool, dry, well-ventilated area. Protect from direct sunlight, moisture, strong oxidizing agents, and strong bases. The product is hygroscopic—avoid exposure to atmospheric moisture. For liquid grades, protect from freezing; if the material becomes hazy after cold exposure, gently warm to 30–35°C and mix before use. Shelf life is typically 12–24 months in tightly closed original containers.
• Regulatory Information: This substance is listed on EINECS (273-234-6), TSCA, DSL, and other regional chemical inventories. It is registered under the REACH Regulation and is manufactured in and/or imported to the European Economic Area at ≥100 to <1,000 tonnes per annum. For formulations intended for use in pesticidal products, appropriate regulatory approvals may be required depending on the jurisdiction. Always consult the Safety Data Sheet (SDS) for complete safety and regulatory information specific to each product grade.