1. Introduction to Laureth-11 Carboxylic Acid
Laureth-11 Carboxylic Acid (CAS: 27306-90-7), an important chemical intermediate and surfactant, is a fatty acid derivative typically used in the formulation of cosmetic, personal care, and cleaning products. The compound is synthesized from lauryl alcohol (C12H25OH), which is derived from coconut oil or palm kernel oil, making it a relatively sustainable choice for many industries. It features an ethoxylated group (C12H25-O-CH2-CH2-) linked to a carboxyl group (COOH), combining the hydrophobic properties of the long alkyl chain with the hydrophilic characteristics provided by the ethoxylation and carboxylation process.
This combination of characteristics makes Laureth-11 Carboxylic Acid a valuable ingredient in various applications, from cleansing to emulsification, with a growing presence in sustainable formulations. In this article, we will explore its chemical properties, manufacturing process, and various industrial applications, providing insight into how it is used in real-world products.
2. Chemical Properties
Laureth-11 Carboxylic Acid, as the name suggests, is an ethoxylated lauric acid derivative. It features a long alkyl chain (C12), which contributes its hydrophobic properties, combined with polyethylene glycol (PEG) units resulting from the ethoxylation process. The carboxyl group at one end makes the compound an anionic surfactant, giving it both cleansing and emulsifying capabilities. The overall chemical structure is as follows:
C12H25(OCH2CH2)11COOH.
2.1. Molecular Structure
The molecular structure of Laureth-11 Carboxylic Acid consists of:
- A long-chain alkyl group (C12H25), which is hydrophobic and provides solubility in oil-based environments.
- Ethoxylated units (OCH2CH2) that make the molecule more water-soluble, contributing to the surfactant’s ability to interact with both water and oils.
- Carboxyl group (-COOH), which imparts anionic properties to the molecule and contributes to its surfactant activity.
2.2. Physical and Chemical Properties
- Appearance: Typically a clear, viscous liquid or pale yellow oily liquid.
- Solubility: Water-soluble, with solubility increasing with the number of ethoxylate groups.
- pH of Aqueous Solution: The compound is typically formulated to maintain a neutral to mildly acidic pH (around 5–6), depending on the formulation.
- Molecular Weight: Approx. 502 g/mol.
- Density: Typically around 1.02–1.05 g/cm³ (depending on formulation and temperature).
- Viscosity: Moderate viscosity due to the high ethoxylation content.
- Flashpoint: Typically above 200°C, indicating good thermal stability.
- Ionic Nature: Anionic due to the carboxyl group, but the compound is mild compared to typical strong acids, and its emulsifying and wetting properties are valuable in mild formulations.
2.3. Surfactant Behavior
As an anionic surfactant, Laureth-11 Carboxylic Acid functions through:
- Hydrophilic-lipophilic balance (HLB): It has an HLB value that places it in the mild to moderate surfactant category, making it suitable for use in products designed for sensitive skin, such as baby shampoos, facial cleansers, and other dermatologically-tested products.
- Cleansing and emulsifying capabilities: The ethoxylated chain allows for emulsification of oils and water, which aids in product stability, enhancing cleaning, and delivering conditioning benefits.
- Foam performance: It generates stable foam, which is useful in personal care formulations such as shampoos and body washes.
3. Production Process
Laureth-11 Carboxylic Acid is primarily produced through a multi-step process that involves the ethoxylation of lauryl alcohol followed by the introduction of a carboxyl group. The following is a simplified overview of the production process:
3.1. Ethoxylation of Lauryl Alcohol
The first step involves the ethoxylation of lauryl alcohol, a long-chain fatty alcohol derived from coconut oil or palm kernel oil. This process adds a number of ethoxy groups (-CH2CH2O-) to the lauryl alcohol molecule, making it water-soluble and changing its behavior to a mild surfactant.
- Reagents Required: Ethylene oxide (EO) as the ethoxylating agent, and catalysts (typically potassium hydroxide or sodium hydroxide).
- Reaction Conditions: Ethylene oxide is reacted with lauryl alcohol at elevated temperatures (100–150°C) under pressure in the presence of a catalyst to create the ethoxylated compound, known as Lauryl Ethoxylates.
- Product: The degree of ethoxylation can be controlled to produce different chain lengths. For Laureth-11 Carboxylic Acid, 11 ethoxy units are typically added to the lauryl alcohol backbone.
3.2. Carboxylation
Once the ethoxylated lauryl alcohol is synthesized, the next step involves the introduction of the carboxyl group (-COOH) to the ethoxylated chain. This is usually done through a reaction with phosgene or carbon dioxide under mild conditions.
- Reagents: Phosgene or carbon dioxide, depending on the specific route chosen by the manufacturer.
- Reaction Conditions: The ethoxylated alcohol is exposed to CO2 or phosgene in the presence of a catalyst at lower temperatures (50–100°C). The carboxyl group (-COOH) is then introduced, making the molecule an anionic surfactant.
3.3. Purification and Standardization
After the carboxylation step, the product is purified to remove any unreacted chemicals or byproducts, typically by washing with water, neutralization, and distillation.
The final product, Laureth-11 Carboxylic Acid, is then standardized to ensure consistency in active ingredient concentration and performance.
4. Applications of Laureth-11 Carboxylic Acid
Laureth-11 Carboxylic Acid is a versatile surfactant with a wide range of uses in personal care, industrial applications, and even household products. Below are some of the primary applications:
4.1. Personal Care and Cosmetics
4.1.1. Shampoos and Conditioners
Laureth-11 Carboxylic Acid is used in the formulation of shampoos and conditioners for its mildness, foaming capacity, and conditioning benefits. It helps to cleanse the hair and scalp without stripping essential oils, making it ideal for sensitive skin and dry hair.
- Benefits: It provides a rich lather, helps with detangling hair, and leaves a smooth, non-greasy feeling after rinsing.
- Formulation Levels: Typically used at 1–3% of the total formula, combined with other surfactants such as Sodium Lauryl Sulfate (SLES) or cocamidopropyl betaine.
4.1.2. Body Washes and Shower Gels
The compound is widely used in body wash and shower gel formulations, where it acts as a mild surfactant and foam stabilizer. It helps cleanse the skin without causing irritation, making it suitable for use in formulations targeting sensitive skin.
- Benefits: Non-drying, smooth application, and mild cleansing properties. It also provides a pleasant foam texture, increasing consumer satisfaction in personal care products.
4.1.3. Facial Cleansers
Laureth-11 Carboxylic Acid is commonly used in facial cleansers due to its gentle nature. It effectively removes dirt, makeup, and oil while maintaining the skin’s moisture balance.
- Benefits: Prevents over-drying of the skin, making it suitable for mild facial cleansers and makeup removers.
4.1.4. Baby Care Products
Due to its low irritation potential, Laureth-11 Carboxylic Acid is used in baby shampoos, body washes, and baby wipes. These products require extremely mild surfactants to avoid skin irritation.
- Benefits: Mildness, safety, and gentle cleansing for delicate skin.
4.2. Household Cleaners
Laureth-11 Carboxylic Acid is increasingly found in a variety of household cleaning products. Its mild, yet effective surfactant properties make it a popular choice for formulations that aim to combine cleaning power with skin safety.
4.2.1. Dishwashing Liquids
In dishwashing liquids, Laureth-11 Carboxylic Acid helps cut grease while ensuring that the product is gentle on the hands. The anionic nature of the molecule enables it to effectively emulsify and remove greasy residues, while the ethoxylated portion of the molecule ensures that the cleaner can easily rinse off without leaving a greasy or harsh residue behind.
- Benefits:
- High foaming ability, making it easier to spread the product across the surface.
- Reduced skin irritation, important for consumers who frequently wash dishes by hand.
- Good grease-cutting properties, allowing for effective cleaning with less product.
4.2.2. Surface Cleaners
In surface cleaning formulations, Laureth-11 Carboxylic Acid is used for mild degreasing and cleaning. Its ability to interact with both hydrophobic oils and hydrophilic water makes it effective at cleaning surfaces like countertops, kitchen appliances, and other home surfaces without damaging them.
- Benefits:
- Enhanced cleaning of oily stains without leaving behind harsh residues.
- Mild formulation, reducing the potential for skin irritation or harm to sensitive surfaces like wood, plastics, and polished countertops.
- Pleasant user experience due to its foaming nature, leading to more efficient application.
4.3. Industrial Applications
While most commonly used in consumer products, Laureth-11 Carboxylic Acid also has several industrial applications due to its mild surfactant and emulsifying properties.
4.3.1. Emulsifiers in Industrial Formulations
Laureth-11 Carboxylic Acid is widely used in emulsification processes in various industrial applications, such as in the production of lubricants, paints, coatings, and agricultural formulations. The carboxyl group and ethoxylated chain create a stable interface between oil and water, allowing for the creation of stable emulsions.
- Benefits:
- Enables the creation of stable emulsions with both water and oil-based components, allowing formulations to retain their consistency over time.
- Improves the spreadability and viscosity of emulsions.
- Helps control the rheological properties of the formulation, preventing phase separation.
4.3.2. Agricultural Chemicals
In the agricultural industry, Laureth-11 Carboxylic Acid is used as an emulsifier in pesticide and herbicide formulations. The surfactant properties enable better penetration of active ingredients into plant surfaces, improving the efficiency of pesticide delivery.
- Benefits:
- Improved spreadability on plant surfaces, ensuring more uniform application of pesticides.
- Enhanced stability of pesticide formulations, reducing the risk of separation over time.
- Increased effectiveness of active ingredients due to improved absorption.
4.3.3. Oil and Gas Industry
In the oil and gas industry, Laureth-11 Carboxylic Acid can be utilized as a dispersant and wetting agent. Its ability to emulsify oils and interact with both water and hydrocarbons makes it useful in various processes, such as drilling fluid formulations and enhancing the performance of oil recovery.
- Benefits:
- Acts as an effective dispersant for oils and particulates in drilling fluids, preventing clumping and ensuring smooth operations.
- Can reduce surface tension, allowing for better contact between fluids and rock formations, potentially improving extraction efficiency.
5. Benefits and Advantages of Using Laureth-11 Carboxylic Acid
5.1. Mildness and Skin Sensitivity
One of the most significant benefits of using Laureth-11 Carboxylic Acid in formulations is its mildness. Its ethoxylated structure and long alkyl chain make it less likely to irritate the skin compared to harsher surfactants like traditional sodium lauryl sulfate (SLES) or ammonium lauryl sulfate. This makes it an excellent choice for products designed for sensitive skin or for formulations used in baby care, dermatology, and personal care products.
- Key Advantages:
- Suitable for sensitive skin.
- Can be used in dermatologically tested products.
- Ideal for baby wipes, baby shampoos, and other gentle formulations.
5.2. Sustainable Sourcing
Since Laureth-11 Carboxylic Acid is often derived from natural sources like coconut oil or palm kernel oil, it offers a more sustainable and renewable option compared to some petrochemical-based surfactants. This feature supports the growing demand for eco-friendly formulations in the personal care and cleaning industries.
- Key Benefits:
- Derived from renewable resources, contributing to sustainability.
- Can be included in products marketed as natural or green.
- Reduced environmental impact compared to petrochemical alternatives.
5.3. Versatility in Formulation
Laureth-11 Carboxylic Acid’s mild surfactant and emulsifying properties make it extremely versatile. It can be used in a wide range of applications, from personal care products to industrial formulations. This versatility allows formulators to replace multiple ingredients with one compound, simplifying the overall formulation process and improving the cost-effectiveness of the product.
- Key Benefits:
- Acts as both a surfactant and emulsifier.
- Can be used across various industries including cosmetics, household cleaning, and agriculture.
- Offers cost-saving potential by replacing multiple ingredients.
5.4. Compatibility with Other Ingredients
Laureth-11 Carboxylic Acid is compatible with a broad range of anionic, nonionic, and amphoteric surfactants. This compatibility allows it to be formulated alongside other surfactants to enhance foam, cleaning power, or conditioning properties. Its mild nature also makes it suitable for synergistic formulations, improving the overall product efficacy without compromising performance.
- Key Benefits:
- Can be combined with other surfactants to enhance foam and cleaning properties.
- Suitable for mild formulations in combination with stronger surfactants.
- Enables customization of formulations to meet specific performance criteria.
6. Safety and Regulatory Considerations
6.1. Safety Profile
Laureth-11 Carboxylic Acid is generally recognized as safe for use in cosmetic and personal care products. It has a low toxicity profile, and formulations containing it have not shown significant irritancy or sensitization, even when used on sensitive skin. However, as with all surfactants, it is essential to use it within recommended concentrations to avoid potential skin irritation or eye contact.
- Skin Irritation: Low irritancy at typical usage concentrations.
- Eye Irritation: Can cause mild irritation in concentrated forms, so formulations should be appropriately diluted.
- Toxicity: Low toxicity when ingested or inhaled.
6.2. Regulatory Status
Laureth-11 Carboxylic Acid is widely approved for use in cosmetics and personal care products across several regulatory agencies:
- FDA (United States): Allowed for use in cosmetic formulations.
- European Union: Approved for use in cosmetics and personal care products under the Cosmetics Regulation (EC) No 1223/2009.
- INCI Classification: Recognized as Coceth-11 Carboxylic Acid under INCI (International Nomenclature of Cosmetic Ingredients).
It is crucial for formulators to adhere to recommended usage levels and comply with local regulations, especially when selling products in regulated markets like the EU or the US.
7. Future Trends and Innovations
As sustainability becomes a more significant concern for the chemical and cosmetic industries, there is growing interest in bio-based surfactants like Laureth-11 Carboxylic Acid. Researchers and formulators are focusing on improving bio-degradability, renewability, and ecological performance in surfactant formulations, driving innovations in natural, eco-friendly alternatives.
- Sustainability Focus: Increased demand for surfactants derived from renewable, plant-based sources, reducing reliance on petrochemicals.
- Green Chemistry: More research into reducing the carbon footprint of surfactant production and improving their biodegradability in the environment.
- Hybrid Formulations: Potential for combining Laureth-11 Carboxylic Acid with other natural surfactants to create next-generation mild, effective cleaning products for both personal care and industrial applications.
8. Conclusion
Laureth-11 Carboxylic Acid (CAS: 27306-90-7) is a versatile, sustainable, and mild surfactant and emulsifier with broad applications across various industries. From personal care products such as shampoos, conditioners, and body washes