Chemical Identity and Properties
Sodium methyl 2-sulfolaurate is an anionic surfactant of the alpha-sulfonated methyl ester family, derived from lauric acid, a renewable C12 fatty acid. Its molecule combines a fatty acid methyl ester backbone with a sulfonate group neutralised as the sodium salt, giving the formula C13H25NaO5S and CAS number 149458-07-1. The sulfonate head group is the key difference from sulfate-ester surfactants: it is chemically stable, remains charged over a wide pH range and does not hydrolyse in the way an alkyl sulfate can.
| Property | Typical value |
|---|---|
| CAS number | 149458-07-1 |
| Chemical family | Alpha-sulfonated methyl ester, anionic surfactant |
| Formula | C13H25NaO5S |
| Molecular weight | 316.4 g/mol |
| Feedstock | Lauric acid from renewable vegetable oils |
| Appearance | White to pale yellow solid or clear aqueous solution |
| Ionic character | Anionic |
| Sulfate content | Sulfate-free chemistry, sulfonate based |
The ingredient is supplied either as a powder or as an aqueous solution, depending on the formulation route of the customer. It is readily soluble in water, compatible with other anionic, non-ionic and amphoteric surfactants, and stable in the presence of hard-water ions, which makes it straightforward to incorporate into both liquid and solid products.
Personal Care and Skin Cleansing
Shampoos, body washes, facial cleansers, hand soaps and baby care products are the largest outlet for sodium methyl 2-sulfolaurate. It works as a primary or secondary surfactant, contributing foam volume, foam stability, cleansing and emulsification of oils and sebum. Because the molecule is derived from a mild fatty acid and carries a stable sulfonate group, it produces less stinging and irritation than many conventional anionic surfactants.
This mildness profile explains its wide use in sulfate-free and gentle formulations. Brands moving away from alkyl sulfates adopt sulfonate-based surfactants to keep lather quality while reducing the potential for scalp and skin dryness, and sodium methyl 2-sulfolaurate is frequently paired with amphoteric and non-ionic co-surfactants to fine-tune viscosity, foam texture and after-feel. It also aids the dispersion of conditioning agents and plant extracts in clear and pearlescent systems.
Household and Industrial Cleaning
In household cleaning products the surfactant helps break down grease, oils and particulate soil from hard surfaces, laundry and dishware without leaving the tacky residue associated with some high-foaming anionics. It is compatible with the bio-based surfactant systems used in formulations marketed as green or natural, and its biodegradability supports those environmental claims.
Industrial and institutional cleaners use the same chemistry where efficient soil removal and low irritation potential are both required. Typical applications include vehicle and car-wash detergents, metal cleaning and degreasing formulations, multi-surface cleaners, floor-care products and foam or spray cleaners, often as part of a surfactant blend chosen by the formulator to match the target substrate and cleaning mechanism.
Performance and Formulation Benefits
Effective wetting, emulsification and soil removal across a broad pH range.
Stable in hard water, so performance and foam do not collapse in mineral-rich supplies.
Sulfate-free, sulfonate-based structure that resists hydrolysis in acid and alkaline products.
Mild to skin and eyes compared with conventional anionics, allowing higher use levels in leave-on and rinse-off products.
Readily biodegradable, supporting environmental claims and discharge requirements.
Compatible with anionic, non-ionic, amphoteric and cationic systems when properly formulated.
Formulators typically set the surfactant level to achieve the required foam and cleaning performance and then adjust viscosity with electrolytes, betaines or amide-free thickeners. Because the sulfonate group remains ionised at low pH, sodium methyl 2-sulfolaurate is also suitable for acidic cleaners and low-pH personal care products where sulfate esters would hydrolyse and lose activity.
Safety, Environmental Profile and Handling
Sodium methyl 2-sulfolaurate has a favourable safety profile for a surfactant: it is not classified as a severe skin or eye irritant at normal use concentrations, has low acute toxicity, and is not a known sensitiser. As with any surfactant, concentrated material should be handled with eye protection and gloves, and dust or mist should be controlled where powders are weighed.
From an environmental standpoint the molecule is designed to biodegrade readily: the fatty acid backbone is mineralised by microorganisms, and the sulfonate group is ultimately released as sulfate. This behaviour, together with the renewable vegetable-oil feedstock, is why the ingredient is used in formulations carrying eco-labels and in products intended for discharge to municipal treatment systems. Bulk material is stored in closed containers in a cool, dry place; aqueous solutions should be protected from microbial contamination and extreme temperatures, and shelf life is normally declared by the manufacturer on the basis of assay and viscosity retention.
FAQ
Q: What is the CAS number of sodium methyl 2-sulfolaurate?
Sodium methyl 2-sulfolaurate is CAS 149458-07-1, with the formula C13H25NaO5S and a molecular weight of 316.4 g/mol.
Q: Is sodium methyl 2-sulfolaurate a sulfate?
No. It is a sulfonate-based anionic surfactant derived from lauric acid, so it contains no sulfate ester group and is used in sulfate-free formulations.
Q: What is it mainly used for?
It is used as a primary or secondary surfactant in shampoos, body washes, facial cleansers and baby care products, and in household and industrial cleaners such as car-wash and hard-surface formulations.
Q: Why is it considered mild?
The lauric acid backbone and the stable sulfonate head group give good cleaning performance with lower irritation potential than conventional anionics such as alkyl sulfates.
Q: Is it biodegradable?
Yes. The fatty acid chain is readily biodegraded and the sulfonate group is ultimately released as sulfate, which is why it suits environmentally positioned cleaning and personal care products.
Q: Does it work in hard water?
Yes. The sulfonate group remains fully ionised in the presence of calcium and magnesium ions, so foam and detergency are retained in hard-water supplies.