This technical presentation explains the chemistry and properties (both physical and chemical) of the range of mild anionic surfactants we supply, including Alkyl Sarcosinates, Alkyl Methyl Taurates, and Alkyl Isethionates. Written by Norman Lowe, Senior Technical Consultant HPC and Industrial, October 2025.
These products were originally developed for the textile industry as cloth scouring agents, replacing ‘soap’ in hard water areas. They are sometimes referred to as ‘interrupted soaps’ and have excellent detergency and high foaming capabilities. In cosmetics, they are all considered ‘mild’ anionic surfactants compared to soap, SLES, and SLS types. They are mainly used as co-surfactants in shampoos, body washes, and oral product systems.
Sarcosinates
These are produced by the reaction of an Acyl chloride (fatty acid chloride) with the amino acid N-Methyl Glycine (Schotten-Bauman reaction), as shown:
R-COCl + CH3NHCH2COOH = R – CO-N(CH3).CH2COOH + HCl
Here, R = C8-C18 (e.g., coco or various cuts).
The product is normally neutralised with Sodium Hydroxide, giving a stoichiometric level of Sodium Chloride. It is usually sold as a ca. 30% Sodium salt, such as Sodium Coco Methyl Sarcosinate.
Taurates
These are made by the reaction of an Acyl chloride with N-Methyl Taurine (2-aminoethanesulfonic acid), a sulfurous amino acid, via the Schotten-Bauman reaction:
R-COCL + CH3NH-(CH2)2 SO3H = RCO(CH3)N-(CH2)2SO3H + HCl
Generally, these are Sodium neutralised, leading to a high salt content.
However, an alternative production method is direct amidation:
R-COOH + CH3NH-(CH2)2.SO3H = RCOCH3N-(CH2)2SO3H.
This is neutralised by caustic soda to give the Sodium salt (or you can use the Sodium salt of N-Methyl Taurine). This route utilizes a Zinc catalyst (or similar) and offers the main advantage of producing low to no salt.
The two routes result in products with differing physical properties. The Acyl chloride route produces a product that is a paste at 30%, while the alternative route results in a clear liquid at 30%.
We supply Geropon® TC 95, a high-active Coco Methyl Taurate powder with low salt content, and Geropon® TC Clear, a ca. 30% active clear liquid version. We also offer Oleyl Methyl Tauride, a high-active powder called Geropon® T-77. You can find out more about these ingredients by Syensqo in our dedicated blog posts: one for Geropon® TC 95 and Geropon® T-77, and another for Geropon® TC Clear.
Alkyl Isethionates
These days, Alkyl Isethionates are produced by direct esterification, as opposed to the Acyl chloride route used in the past. This method is very similar to the alternative route described above for Taurates. In this case, fatty acid is reacted with Sodium Isethionate:
R-COOH + HO(CH2)2SO3Na = RCO-O(CH2)2SO3Na + H2O
Normally produced as the cocoyl variant and as a powder (ca. 80 to 85%), and with an added Stearic acid content as a 65% active flake for use in syndet beauty bars to replace soap bars.
Properties & Applications
All three products are considered mild, high-foaming anionic surfactants. Applications for all include high-foaming shampoos, hand and body washes. The Isethionate in particular provides a very creamy, silky feel foam with good skin after-feel, making it suitable for the production of syndet beauty bars and cream body washes. Due to its lower solubility, it is not recommended for clear systems.
The Taurides produce a high, close-celled foam and are mild compared to SLES, SCS, or SLS type surfactants, aligning with the ‘sulfate-free’ trend for mild shampoos. At HARKE UK & Ireland, we can offer the following Taurides:
- Geropon® TC 95: a very fine Coco Methyl Tauride powder that requires customers to have powder handling equipment
- Geropon® TC Clear: a ca. 30% active version that is a clear liquid, making it easy to process in clear wash systems
- Geropon® T-77: the Oleyl variant, comes as a high-purity, high-active fine powder
The Sarcosinate is also high foaming and mild to the skin, and like the Taurate, it is less susceptible to hard water salts. It is available from HARKE UK as Geropon® LS30 (Sodium Lauroyl Sarcosinate) by Syensqo.
In Summary
As a general overview, Taurates and Sarcosinates are suitable for mild shampoos, clear body washes, facial washes, infant shampoos, hand washes (liquid, gels, and mousse), and as mild foaming agents in toothpastes, replacing the harsher Sodium Lauryl Sulfate. Isethionates are ideal for syndet beauty bars, cream shampoos, body washes, and facial washes.
We should not forget industrial uses – both Taurates and Sarcosinates were developed for cloth scouring, so they possess good detergency. They can be applied to laundry detergents (travel wash and wool wash) and eco surface cleaners.
More data is available on all the ingredients and products mentioned here. To discuss mild anionic surfactants in more detail, please contact the technical team at HARKE UK & Ireland.
