Database/Antistatic/Quaternium-18 Methosulfate
Mostly natural · ISO 16128

Is Quaternium-18 Methosulfate natural?

Mostly. The hydrogenated tallow chains and the SO3 of the methyl sulfate are natural origin; the nitrogen (from ammonia), its two methyl groups and the methoxy group of the methyl sulfate are petrochemical.

INCI nameQuaternium-18 Methosulfate
CAS61789-81-9
FunctionAntistatic
FeedstockHydrogenated tallow fatty acids are converted to a…

How we scored it

Two hydrogenated tallow alkyls (avg C17.3) 488 Da + SO3 80 Da (mineral) = 568 natural; N 14 + two N-CH3 30 + CH3O 31 (from dimethyl sulfate) = 75 petrochemical; total 643 Da; 568 / 643 = 0.88. Methosulfate quats credit the SO3 but not the methoxy group, as for Behentrimonium Methosulfate (0.81).
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.

Where it comes from

Hydrogenated tallow fatty acids are converted to a nitrile, then a secondary amine using ammonia, and quaternised with dimethyl sulfate to give the methosulfate salt. Vegetable-derived fatty chains are possible; the tallow mix gives about the same fraction.

In plain English

A conditioning agent that coats hair and fabric with a thin, positively charged layer, reducing static and flyaway. It is made from tallow-derived fatty chains attached to a nitrogen atom, methylated, and paired with methyl sulfate.

CosIng definition: Quaternary ammonium compounds, bis(hydrogenated tallow alkyl)dimethyl, Me sulfates.

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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. 2QUATERNIUM-18 METHOSULFATE. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
  3. 3QUATERNIUM-18 METHOSULFATE. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=QUATERNIUM-18%20METHOSULFATE