General chemical structure of α-olefin sulfonates
R= Alkyl, M= Na⁺, n = 1 or 2 α-Olefin sulfonates (also: alpha-olefin sulfonates or AOS) are a group of anionic

surfactant Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a Blend word, blend of "surface-active agent", coined in ...

s, which are used as

detergent A detergent is a surfactant or a mixture of surfactants with Cleanliness, cleansing properties when in Concentration, dilute Solution (chemistry), solutions. There are a large variety of detergents. A common family is the alkylbenzene sulfonate ...

s. The compounds contain a - mostly linear, primary -

alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl group is derived from a cy ...

R and a monovalent

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

M, preferably

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

. The most frequently used example of this group of substances is sodium α-olefin sulfonate (

INCI The International Nomenclature of Cosmetic Ingredients (INCI) are the unique identifiers for cosmetic ingredients such as waxes, oils, pigments, and other chemicals that are assigned in accordance with rules established by the Personal Care Pro ...

: Sodium C14-16 Olefin Sulfonate).External identifiers of or database links to ''Sodium C14-16 olefin sulfonate'': CAS-Number
68439-57-6
EC Number
270-407-8

ECHA The European Chemicals Agency (ECHA; ) is an agency of the European Union working for the safe use of chemicals. It manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, ...

-InfoCard
100.063.987

Wikidata Wikidata is a collaboratively edited multilingual knowledge graph hosted by the Wikimedia Foundation. It is a common source of open data that Wikimedia projects such as Wikipedia, and anyone else, are able to use under the CC0 public domain ...

: Q72507735.

Production and composition

α-Olefin sulfonates are produced by

sulfonation In organic chemistry, aromatic sulfonation is a reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid () group. Together with nitration and chlorination, aromatic sulfonation is a widely used electrophilic aromatic substi ...

alpha-olefin In organic chemistry, terminal alkenes (alpha-olefins, α-olefins, or 1-alkenes) are a family of organic compounds which are alkenes (also known as olefins) with a chemical formula , distinguished by having a double bond at the primary, Alpha an ...

s, typically using

sulfur trioxide Sulfur trioxide (alternative spelling sulphur trioxide) is the chemical compound with the formula SO3. It has been described as "unquestionably the most conomicallyimportant sulfur oxide". It is prepared on an industrial scale as a precursor to ...

. Subsequent alkaline

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

gives a mixture of alkene sulfonates (60-65%) and hydroxyalkane sulfonates (35-40%). The commercially available olefin sulfonates are mostly solutions with about 40% active ingredient content.

Description

In addition to a longer

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...

chain in which there must be at least one

double bond In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betw ...

(hence the name "olefin"), it has an anionic sulfonate headgroup with a sodium ion as a counterion. The sulfonate group is negative in aqueous solution, which is why the α-olefin sulfonates are among the anionic surfactants. In contrast to most other surfactants in which the C₁₂-alkyl chains have the highest surface activity, olefin sulfonates shows maximal activity when using C₁₄and C₁₆-olefins.

Usage

α-Olefin sulfonates with linear alkenyl radicals from C₁₂ to C₁₈ are used as anionic surfactants in various areas of application due to their and foam stability (even with high

water hardness Hard water is water that has a high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, which are largely made up of calcium and magnesium carbonates, bicar ...

), excellent fat-dissolving power and oil dissolving power as well as a favorable ecological profile and low aquatic toxicity and human

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...

. They are typically used in detergents and cleaning agents, for degreasing, in the

emulsion polymerization In polymer chemistry, emulsion polymerization is a type of radical polymerization that usually starts with an emulsion incorporating water, monomers, and surfactants. The most common type of emulsion polymerization is an oil-in-water emulsion, in ...

, the conditioning of

concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...

and mortar as well as in the formulation of

pesticides Pesticides are substances that are used to pest control, control pest (organism), pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for a ...

. Sodium C14-16 olefin sulfonate is being introduced in some shampoos as an alternative to

sodium laureth sulfate Sodium laureth sulfate (SLES), an accepted contraction of sodium lauryl ether sulfate, also called sodium alkylethersulfate, is an anionic detergent and surfactant found in many personal care products (soaps, shampoos, toothpaste, etc.) and for ...

. Some groups and sellers suggest that it is healthier, but this claim lacks evidence.

References

{{DEFAULTSORT:Olefin sulfonates, α- Alkene derivatives Sulfonates Anionic surfactants