Database/Cleansing/Sodium Laureth-13 Carboxylate
Mostly petroleum · ISO 16128

Is Sodium Laureth-13 Carboxylate natural?

Mostly not. The INCI name is authoritative for the ethoxylation count, so 13 units are used even though the CosIng description quotes 12. The coconut-derived lauryl chain and the mineral sodium are natural origin; the ethoxylate chain and the chloroacetate cap are petrochemical.

INCI nameSodium Laureth-13 Carboxylate
CAS33939-64-9
FormulaC16H32O4 · 288.42 Da
FunctionCleansing · Emulsifying Surfactant
FeedstockLauryl alcohol from coconut or palm is ethoxylated…

How we scored it

The INCI name fixes the ethoxylation at 13 units. Natural origin is the lauryl-oxy fragment C12H25O (185.33 Da) plus the sodium counter-ion (22.99 Da) = 208.32 Da. Petrochemical is 13 ethylene oxide units (13 x 44.05 = 572.69 Da) plus the carboxymethyl cap CH2COO (58.04 Da) = 630.73 Da. Total 839.05 Da, so 208.32/839.05 = 0.25.
What counts. ISO 16128-2 scores the atoms that remain in the final ingredient. Reagents, solvents, catalysts and protecting groups used during manufacture leave no mass behind and are not counted.

How it’s made

Williamson ether synthesis: laureth alkoxide displaces chloride from sodium chloroacetate (SN2). Each curved arrow moves one electron pair, and the film ends on the score above.

Where it comes from

Lauryl alcohol from coconut or palm is ethoxylated with 13 moles of ethylene oxide per the INCI name, capped with a carboxymethyl group from chloroacetic acid and neutralised with sodium. The CosIng entry quotes a 12-mole average, but the name was treated as authoritative.

In plain English

A mild foaming cleanser used in shampoos and body washes. It starts from coconut-derived alcohol but is heavily modified with a petroleum-derived chemical (ethylene oxide) to make it gentle and water-soluble.

CosIng definition: Poly(oxy-1,2-ethanediyl), .alpha.-dodecyl-.omega.-carboxymethoxy-, sodium salts (12 mol EO average molar ratio)

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Structure

2D structure of Sodium Laureth-13 Carboxylate

2-(2-dodecoxyethoxy)acetic acid

PubChem CID 154267 ↗

References

  1. 1ISO 16128-1:2016 and ISO 16128-2:2017 — Guidelines on technical definitions and criteria for natural and organic cosmetic ingredients and products. ISO, Geneva.
  2. 2Sodium Laureth-13 Carboxylate. PubChem CID 154267. National Center for Biotechnology Information. pubchem.ncbi.nlm.nih.gov ↗
  3. 3SODIUM LAURETH-13 CARBOXYLATE. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
  4. 4SODIUM LAURETH-13 CARBOXYLATE. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=SODIUM%20LAURETH-13%20CARBOXYLATE