LABSA Chemical Formula, Properties and Specifications: A Guide to Linear Alkylbenzene Sulfonic Acid

Linear Alkylbenzene Sulfonic Acid (LABSA) is the most widely used synthetic anionic surfactant in the global chemical and detergent industry. Renowned for its excellent surface activity, stable chemical performance, high biodegradability, and cost-effectiveness, LABSA serves as a foundational raw material for household detergents, industrial cleaning agents, textile auxiliaries, and petrochemical additives. This guide systematically elaborates on the core definitions, chemical parameters, physical and chemical properties, technical specifications, mainstream grades, industrial applications, and supplier selection criteria of LABSA. It acts as a definitive core pillar article for LABSA chemical knowledge, supporting subsequent in-depth content expansion and internal link building for derivative LABSA-related topics.

1. What is LABSA Chemical?

LABSA chemical, fully named Linear Alkylbenzene Sulfonic Acid, is a synthetic organic sulfonic acid compound and a classic linear alkylbenzene-based surfactant. Different from branched alkylbenzene sulfonic acid (BAS), LABSA features a straight-chain alkyl molecular structure, which endows it with superior environmental degradability and stable surfactant properties.

In industrial chemical classification, LABSA belongs to the category of anionic surfactants. It is primarily produced through the sulfonation reaction of linear alkylbenzene (LAB) with sulfur trioxide (SO₃). As a fundamental fine chemical raw material, it is not directly used in end products in most cases. Instead, it is neutralized with alkaline substances such as sodium hydroxide and ammonia water to form sulfonate salts, which are then applied in various formulation scenarios. Its low production cost and excellent comprehensive performance make it occupy a dominant position in the global surfactant market.

2. What is Linear Alkylbenzene Sulfonic Acid (Full Definition)?

Linear Alkylbenzene Sulfonic Acid (LABSA) is a mixture of homologous organic compounds with a linear alkyl chain grafted on a benzene ring and a sulfonic acid functional group (-SO₃H) attached to the benzene ring’s para position. Its alkyl chain is mainly composed of C10–C13 linear carbon chains, with C12 alkyl chain derivatives accounting for the highest proportion in mainstream industrial products.

Structurally, the linear alkyl chain provides strong lipophilicity, while the terminal sulfonic acid group provides excellent hydrophilicity. This typical amphiphilic molecular structure enables LABSA to significantly reduce the surface tension of water, with outstanding functions of wetting, emulsifying, foaming, dispersing, and decontaminating. Environmentally, LABSA meets international biodegradation standards; its linear molecular chain can be completely decomposed by microorganisms in natural water bodies, avoiding the environmental pollution problems caused by branched surfactant residues, which is a core advantage of its large-scale industrial promotion.

3. LABSA Chemical Formula & Molecular Weight

Due to the mixed homologous composition of industrial LABSA (C10–C13 alkyl chain mixtures), it has both a general structural formula and a mainstream average molecular formula, which are uniformly recognized in the chemical industry:

• General Structural Formula: $$R-C_6H_4-SO_3H$$ (R = linear alkyl group of C10–C13)
• Mainstream Average Chemical Formula: $$C_{18}H_{30}O_3S$$ (corresponding to C12 alkyl chain dominant industrial grade products)
• Average Molecular Weight: 320–330 g/mol (standard industrial product average value: 322 g/mol)

The slight fluctuation of molecular weight is caused by the different proportions of C10, C11, C12, and C13 alkyl homologs in the product. Conventional industrial LABSA is dominated by C12 components, so$$C_{18}H_{30}O_3S$$ is the unified representative formula for technical parameter labeling and industry documentation.

4. LABSA CAS Number & EINECS Number

CAS and EINECS numbers are core identification codes for chemical product authentication, trade, and safety management. The unified standard codes for industrial Linear Alkylbenzene Sulfonic Acid are as follows:

• CAS Registry Number: 27176-87-0 (universal global standard CAS number for industrial mixed LABSA)
• EINECS Number: 248-289-4

Note: Some raw material test reports may show CAS 68584-22-5, which is applicable to partial high-purity single-component LABSA and is not a universal identification code for conventional industrial-grade products. The CAS 27176-87-0 is the standard number for commercial LABSA in global industrial trade.

5. LABSA Chemical Structure

The molecular structure of LABSA consists of three core parts, with a highly regular and stable structural configuration:

1. Linear Alkyl Lipophilic Group: A straight saturated carbon chain with 10–13 carbon atoms, no branched structure. This linear structure ensures high biodegradability and low residue performance, distinguishing it from toxic and low-degradability branched alkylbenzene sulfonic acid.
2. Benzene Ring Intermediate Skeleton: The benzene ring acts as a stable connecting bridge between the alkyl chain and the functional group, enhancing the overall chemical stability of the molecule and improving the compound’s compatibility with organic substances.
3. Para-Substituted Sulfonic Acid Hydrophilic Group: The -SO₃H functional group is stably bonded to the para position of the benzene ring. This para-substituted structure has higher chemical stability than ortho and meta substitutions, with stronger hydrophilicity and more stable surfactant performance.

The overall amphiphilic structure (lipophilic alkyl chain + hydrophilic sulfonic acid group) is the fundamental reason why LABSA has excellent surface activity, enabling it to efficiently dissolve oil stains, disperse particles, and stabilize emulsions in aqueous systems.

6. Physical Properties of LABSA

LABSA has stable physical properties under normal temperature and pressure, with fixed appearance, density, solubility, and fluidity parameters. The standard physical indicators of industrial-grade products (25℃, standard atmospheric pressure) are summarized as follows:

• Appearance: Dark brown viscous oily liquid; high-purity grade presents light brown transparent liquid
• Odor: Slight characteristic sulfur-containing organic odor, no pungent strong odor
• Density: 1.07–1.08 g/mL (25℃)
• Solubility: Soluble in water, ethanol, and other polar solvents; insoluble in non-polar solvents such as benzene and petroleum ether
• Pour Point (1% Aqueous Solution): -12℃, excellent low-temperature fluidity, not easy to freeze in conventional low-temperature environments
• Viscosity: Moderate viscosity at room temperature, fluidity improves significantly with temperature rise
• Volatility: Non-volatile under normal temperature, low volatility under heating conditions

Its stable physical state ensures convenient transportation, storage, and industrial batching, and is compatible with most water-based formula systems.

7. Chemical Properties of LABSA

As an organic weak acid anionic surfactant, LABSA has stable chemical properties and typical acid and surfactant chemical characteristics. The core chemical properties are as follows:

• Acidity & Neutralization Reaction: LABSA is a weak organic acid, which can undergo complete neutralization reactions with alkaline substances such as NaOH, KOH, NH₃·H₂O, and triethanolamine to form corresponding alkylbenzene sulfonates. Neutralized products have better water solubility and are the main application forms in detergents.
• Stability: Stable under normal temperature and sealed storage, no decomposition, deterioration, or polymerization. Stable in weak acid and neutral environments; easy to undergo hydrolysis failure in strong alkaline high-temperature environments.
• Surface Activity: It can significantly reduce the surface tension of water, with excellent wetting, foaming, emulsifying, dispersing, and solubilizing capabilities. The foam is rich and stable, with strong dirt-removing and oil-removing power.
• Biodegradability: The linear alkyl chain structure can be completely biodegraded in natural environments, with a degradation rate of over 98%, meeting EU REACH and global environmental protection standards, belonging to environmentally friendly surfactants.
• Compatibility: Compatible with non-ionic surfactants and amphoteric surfactants, with good synergistic effects; cannot be mixed with cationic surfactants in high concentration to avoid precipitation and failure.
• Corrosivity: Slightly corrosive to carbon steel, non-corrosive to stainless steel, plastic, and glass materials. Industrial production and storage usually use plastic drums or stainless steel equipment.

8. LABSA Active Matter Content

Active matter content is the core indicator to measure LABSA purity and product grade, representing the effective surfactant component content in the product, directly determining the decontamination efficiency and formula usability of LABSA.

Conventional industrial-grade LABSA on the market has a standard active matter content of ≥96%, which is the mainstream universal grade in the industry. High-purity refined LABSA can reach 97%–98% active content, while low-grade recycled or crude LABSA is about 90%–95%.

The higher the active matter content, the fewer ineffective impurities (free oil, residual sulfuric acid, water) in the product, the more stable the formula performance, and the better the decontamination and emulsifying effect. Detergent-grade products used for high-end household cleaning products strictly require active matter ≥96%, which is the industry mandatory standard for qualified commercial LABSA.

9. Key Impurity Indicators: Free Oil, Free Acidity & Color

Impurity indicators determine the quality grade, color stability, and formula compatibility of LABSA, and are core detection items for factory inspection and incoming material acceptance. The standard parameters of qualified industrial products are as follows:

9.1 Free Oil Content

Free oil refers to unreacted linear alkylbenzene and organic neutral impurities in LABSA. Excessive free oil will cause product turbidity, weakened water solubility, and reduced foam stability. The standard qualified index:free oil ≤1.5%; high-end detergent-grade products require free oil ≤1.0%.

9.2 Free Acidity (Calculated as H₂SO₄)

Free acidity represents residual inorganic sulfuric acid impurities in the sulfonation reaction. Excessive free acidity will increase product corrosivity, affect the pH value of subsequent formulas, and cause product deterioration and odor. Industry standard: free acidity ≤1.0% (calculated as H₂SO₄).

9.3 Color (Klett Value)

The color of LABSA is measured by Klett colorimeter (5% aqueous solution, standard light source), reflecting the degree of product oxidation and impurity content. The lower the Klett value, the lighter the color and the higher the purity. Qualified industrial grade: Klett value ≤50; high-purity light-colored grade ≤30, suitable for preparing transparent and light-colored high-end detergents.

10. Mainstream Industrial Specifications of LABSA

Combined with national standard GB/T 8447-2008 and international universal industrial standards, LABSA is divided into three mainstream specifications according to purity and application scenarios, with complete parameter indicators as follows:

Packaging Specifications: Universal industrial packaging is 210kg plastic sealed drums; bulk logistics adopts 1050kg IBC ton drums, supporting customized packaging according to customer needs.

11. Industrial Applications of LABSA

With its excellent surface activity, low cost, and environmental friendliness, LABSA covers most surfactant application scenarios and is the core raw material of the global detergent and fine chemical industry. The main application fields are as follows:

11.1 Household Detergent Industry (Core Application)

After neutralization into sodium alkylbenzene sulfonate, LABSA is widely used in the production of laundry detergent, washing powder, dish soap, soap, and household cleaning agents. It provides strong decontamination, oil removal, and foaming functions, with mild formula performance and no irritation, meeting household daily cleaning needs. It accounts for more than 60% of LABSA’s total market demand.

11.2 Industrial Cleaning Field

Used in the preparation of industrial heavy-duty oil removers, metal cleaning agents, floor cleaners, and pipeline detergents. It has strong emulsifying and dispersing ability for industrial grease, mechanical oil, and dirt, and is suitable for high-temperature and high-concentration industrial cleaning environments.

11.3 Textile & Leather Auxiliaries

Applied as textile wetting agents, penetrating agents, emulsifiers, and leveling agents. It can improve the dyeing uniformity of textiles, enhance fiber water absorption and permeability, and reduce dyeing defects. In leather processing, it is used for degreasing and cleaning leather blanks, improving leather softness and finish.

11.4 Petrochemical & Mineral Processing

Used as crude oil demulsifiers, oil-water separation agents, and mineral flotation agents. Its excellent emulsifying and dispersing properties can effectively separate oil-water mixtures and improve mineral flotation efficiency, widely used in oilfield chemical and mineral processing industries.

11.5 Other Fine Chemical Fields

It can be used as an emulsifier for pesticide formulations, a dispersant for coating and ink systems, and a cleaning auxiliary for paper-making industry. It has good compatibility with various chemical systems and low application cost, with strong industrial versatility.

12. LABSA Manufacturer & Supplier Selection Considerations

As a bulk industrial chemical raw material, the purity stability, impurity control, and supply capacity of LABSA directly affect the quality of downstream formulated products. The core selection criteria for manufacturers and suppliers are summarized as follows:

12.1 Product Quality Stability

Prioritize suppliers with stable active matter content (≥96% for standard grade), strictly controlled free oil and free acidity indicators, and stable color. Avoid products with large batch-to-batch parameter fluctuations, which will cause formula proportion adjustment difficulties and end-product quality instability. It is necessary to require suppliers to provide factory inspection reports (COA) for each batch.

12.2 Production Qualification & Certification

Formal suppliers must have complete production licenses, safety production qualifications, and environmental protection certification. High-quality suppliers usually comply with GB/T 8447-2008 national standards and international REACH environmental certification, ensuring product compliance for export and high-end application scenarios.

12.3 Supply Capacity & Logistics Stability

LABSA is a bulk continuous supply raw material. It is necessary to select manufacturers with large-scale sulfonation production lines and sufficient inventory reserves to avoid supply shortages and delivery delays. At the same time, confirm professional chemical logistics transportation qualifications to ensure safe and compliant transportation of corrosive chemical products.

12.4 Technical Support & After-Sales Service

Excellent suppliers can provide professional formula guidance, product compatibility testing, and technical problem-solving services. For downstream enterprises with customized formula needs, suppliers with flexible grade adjustment capabilities can better meet personalized production demands.

12.5 Cost-Effectiveness

On the premise of meeting quality standards, comprehensively evaluate the comprehensive cost of product unit price, packaging cost, and logistics cost. Avoid low-price and inferior products with unqualified impurity indicators, which will lead to increased downstream formula failure rates and hidden quality costs.

13. Conclusion

Linear Alkylbenzene Sulfonic Acid (LABSA) is an indispensable core surfactant in the modern fine chemical industry. Its unique linear molecular structure, stable physical and chemical properties, excellent surface activity, and environmental friendliness make it occupy an irreplaceable dominant position in household cleaning, industrial cleaning, textile auxiliaries, and petrochemical fields. This guide comprehensively sorts out all core dimensions of LABSA including definition, molecular parameters, structural characteristics, performance indicators, industrial specifications, application scenarios, and supplier selection. As a core pillar article of LABSA chemical knowledge, it provides authoritative and systematic technical support for subsequent in-depth research, content derivation, and industrial application reference of LABSA-related products.