Sulfonic acids, C14-17-sec-alkane, sodium salts
[CAS 97489-15-1]

Identification

• Classification: Chemical reagent >> Organic reagent >> Sulfonate / sulfinate
• Name: Sulfonic acids, C14-17-sec-alkane, sodium salts
• CAS Registry Number: 97489-15-1
• EC Number: 307-055-2

Safety Data

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	4	H302
Serious eye damage	Eye Dam.	1	H318
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411

chemBlink Chemical Story

A detergent molecule can begin with something as chemically unremarkable as a straight-chain paraffin. Sulfonic acids, C14-17-sec-alkane, sodium salts are better known as C14-17 secondary alkane sulfonates, or SAS. They are not one pure molecule but a commercial mixture of closely related chain lengths and positional isomers in which a sulfonate group is attached to an internal carbon of a largely linear C14-C17 hydrocarbon chain.

That mixture is a consequence of how SAS can be made. In the classical sulfoxidation route, linear paraffins react with sulfur dioxide and oxygen in the presence of water under ultraviolet irradiation. A hydrocarbon that would normally prefer oil is thereby given a strongly hydrophilic sulfonate head group. Neutralization with sodium hydroxide yields the sodium salts used as anionic surfactants. Because sulfonation can occur at different secondary positions and the paraffin feed contains several chain lengths, the product is inherently a family rather than a single structural formula.

The chemistry gives SAS the two-part architecture that makes surfactants work. The long hydrocarbon portion prefers oils and greasy soils, while the sulfonate group remains strongly hydrated in water. At an interface the molecules can lower surface tension; above suitable concentrations they can assemble into micelles whose hydrophobic interiors help disperse oily material into the wash water. Secondary alkane sulfonates have therefore been used in dishwashing, laundry, and other cleaning formulations. Sulfonate groups are also resistant to hydrolysis, so the surfactant remains chemically stable across conditions that would cleave some ester-based amphiphiles.

A detergent, however, does not disappear when the foam goes down the drain. Environmental fate is therefore part of the SAS story. Studies of wastewater and sediments have found substantial biological removal and have identified degradation pathways in which the linear alkyl chain is progressively oxidized. Research has even shown anaerobic degradation in marine sediments, although longer-chain homologues can sorb more strongly and degrade more slowly. That is why regulatory databases treat C14-17 SAS as a defined UVCB-type substance rather than pretending that one structural drawing represents every molecule in the product.

The memorable idea is the transformation itself: take an inert paraffin chain, place an ionic sulfonate group somewhere along it, and the behavior of the material changes completely. What began as an oil-like hydrocarbon becomes a water-compatible cleaning agent able to organize at interfaces and carry hydrophobic soil away.

References:
1. European Chemicals Agency (ECHA), Sulfonic acids, C14-17-sec-alkane, sodium salts, EC 307-055-2, CAS 97489-15-1.
2. Lara-Martin P.A. et al. Reactivity and fate of secondary alkane sulfonates (SAS) in marine sediments. Environmental Pollution. 2014, 188, 1-9.
3. Gonzalez-Mazo E. et al. Determination and occurrence of secondary alkane sulfonates (SAS) in aquatic environments. Environmental Pollution. 2013.
4. EP4204396A1, Surfactant and detergent composition; description of SAS manufacture by paraffin sulfoxidation.

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