Kwan CC, Chu WH, Shimabayashi S. Effect of polyvinylpyrrolidone and sodium lauroyl isethionate on kaolinite suspension in an aqueous phase. Chem Pharm Bull (Tokyo). 2006 Aug;54(8):1082-7. doi: 10.1248/cpb.54.1082.

Abstract. Suspension of concentrated kaolinite (20 g/30 ml-medium) in the presence of polyvinylpyrrolidone (PVP) and sodium lauroyl isethionate (SLI) was allowed to evaluate its degree of dispersion based on their rheological studies. Flow curves at low shear rate, measured by means of cone-plate method, showed a non-Newtonian flow. Plastic viscosity and Bingham yield value were derived from the flow curves. Relative viscosity, effective volume fraction and void fraction of secondary particle were also obtained. Results of dispersity and fluidity of the suspension were explained. PVP acted as a flocculant at a concentration lower than 0.1% but as a dispersant at a higher concentration. The presence of SLI could decrease both the Bingham yield value and suspension viscosity. Cooperative and competitive effects of PVP and SLI were found. Results indicated that SLI enhanced the degree of dispersion of kaolinite when PVP was less than 0.1%. The suspension, however, showed a maximum flocculation (i.e., aggregation) at 4 mM SLI when the concentration of PVP was higher than 0.1%.

Gibson WT, Teall MR. Interactions of C12 surfactants with the skin: studies on enzyme release and percutaneous absorption in vitro. Food Chem Toxicol. 1983 Oct;21(5):581-6. doi: 10.1016/0278-6915(83)90144-8. 

Abstract. Using an in vitro penetration cell, it has been shown that enzymes (acid phosphatase, lactate dehydrogenase and N-acetylglucosaminidase) are released from rat-skin slices in response to contact with two irritant C12 surfactants, sodium laurate and sodium lauryl sulphate, but not with the non-irritant sodium lauroyl isethionate. About 3-5 hr contact of the stratum corneum with surfactant and a long incubation time (24 hr) were required for enzyme release. Adsorption and penetration of the two effective surfactants was also studied and the results for sodium lauryl sulphate suggested a relationship between enzyme release and adsorption of surfactant. However, no such simple relationship was observed for sodium laurate, emphasizing the complex nature of surfactant interactions with the skin.

Jeraal, M. I., Roberts, K. J., McRobbie, I., & Harbottle, D. (2018). Process-focused synthesis, crystallization, and physicochemical characterization of sodium lauroyl isethionate. ACS Sustainable Chemistry & Engineering, 6(2), 2667-2675.

Abstract. There is a notable lack of published data concerning sodium cocoyl isethionate despite widespread application in the personal care industry. A specific homologue, sodium lauroyl isethionate (SLI), was therefore synthesized, purified by recrystallization, and then subjected to a detailed physicochemical examination. A purity of 98% was achieved via repeat recrystallization in methanol. A turbidimetric solubility analysis was then executed to identify both its crystallizability and metastable zone width as a function of temperature. Thermogravimetric analysis yielded decomposition onsets of 330 °C for the purified SLI. A dynamic vapor sorption study also demonstrated reversibility in the 2.3% mass gained when it was exposed to sustained humidity of 87%. Surface tension measurements of purified SLI yielded a critical micellar concentration (CMC) of 5.4 mM and a plateau surface tension of 38 mN/m at 20 °C. Both values are lower than the previously reported values for SLI in water, thus indicating the performance benefits of purified isethionates in personal care formulations. The single step synthesis was chlorine-, catalyst-, and solvent-free, thus improving process efficiency, safety, and throughput over existing SLI syntheses. The succeeding physicochemical analysis crucially provides much needed insight into the purification, properties, and performance of isethionate ester surfactants, all of which are strongly applicable to their commercial manufacture from biorenewable sources.

Sodium lauroyl Isethionate is a chemical compound, a non aggressive, economical and ecological surfactant and is added in cosmetic products.

The name defines the structure of the molecule

• "Sodium". It's an alkali metal, symbol Na, with atomic number 11. It's an essential element for life and plays a key role in regulating blood pressure and plasma volume.
• "Lauroyl". Indicates the presence of a lauroyl group, which is the acid derivative of lauric acid. Lauric acid is a saturated fatty acid with 12 carbon atoms.
• "Isethionate". It's the salt or ester of isethionic acid, a sulfonic acid. It has the chemical formula C₂H₅O₃S.

Description of the raw materials used in its production:

• Lauric Acid - A medium-chain fatty acid found in various natural sources such as coconut oil and palm oil.
• Isethionic Acid (2-hydroxyethanesulfonic acid) - A sulfonic acid used in the synthesis of sodium lauroyl isethionate.

Industrial chemical synthesis of Sodium Lauroyl Isethionate, step by step:

• Esterification - Lauric acid is reacted with isethionic acid in the presence of an acid catalyst to form lauric isethionate ester.
• Neutralization - The lauric isethionate ester is then reacted with sodium hydroxide (NaOH) to neutralize the acid and form the salt, known as sodium lauroyl isethionate.
• Isolation - After the reaction reaches completion, the formed sodium lauroyl isethionate precipitates out and is isolated via filtration.
• Purification - The crude sodium lauroyl isethionate is purified through crystallization or other purification techniques.
• Quality control - Once Sodium Lauroyl Isethionate is obtained, it undergoes various quality checks to ensure it meets specifications.

It appears in the form of a white powder. 

What it is for and where

Cosmetics

Antistatic agent. Static electricity build-up has a direct influence on products and causes electrostatic adsorption. The antistatic ingredient reduces static build-up and surface resistivity on the surface of the skin and hair.

Cleansing agent. Ingredient that cleanses skin without exploiting the surface-active properties that produce a lowering of the surface tension of the stratum corneum

Foaming.  Its function is to introduce gas bubbles into the water for a purely aesthetic factor, which does not affect the cleaning process, but only satisfies the commercial aspect of the detergent by helping to spread the detergent. This helps in the commercial success of a cleansing formulation. Since sebum has an inhibiting action on the bubble, more foam is produced in the second shampoo. In practice, it creates many small bubbles of air or other gases within a small volume of liquid, changing the surface tension of the liquid.

Hair conditioning agent. A significant number of ingredients with specific and targeted purposes may co-exist in hair shampoo formulations: cleansers, conditioners, thickeners, matting agents, sequestering agents, fragrances, preservatives, special additives. However, the indispensable ingredients are the cleansers and conditioners as they are necessary and sufficient for hair cleansing and manageability. The others act as commercial and non-essential auxiliaries such as: appearance, fragrance, colouring, etc. Hair conditioning agents have the task of increasing shine, manageability and volume, and reducing static electricity, especially after treatments such as colouring, ironing, waving, drying and brushing. They are, in practice, dispersants that may contain cationic surfactants, thickeners, emollients, polymers. The typology of hair conditioning agents includes: intensive conditioners, instant conditioners, thickening conditioners, drying conditioners. They can perform their task generally accompanied by other different ingredients.

Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

Surfactant - Cleansing agent. Cosmetic products used to cleanse the skin utilise the surface-active action that produces a lowering of the surface tension of the stratum corneum, facilitating the removal of dirt and impurities. 

Safety

The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) gave a favorable opinion on the safety of Sodium lauroyl Isethionate, deeming this chemical compound safe in current use and concentration practices in cosmetics when formulated to be nonirritating (1).

Commercial applications 

Skin Cleansing Products. Used in facial cleansers, body soaps, and shower gels for its ability to remove dirt and oil from the skin.

Shampoo and Hair Products. Acts as a foaming and cleansing agent in shampoos and other hair care products.

Shaving Products. Can be found in shaving creams and gels to help create a stable foam.

Cosmetics. Used in some cosmetic products as an emulsifier to help mix water-based and oil-based ingredients.

Oral Care Products. It can be used in some toothpastes as a foaming agent.

"Sodium lauroyl Isethionate, studies"

• Molecular Formula   C₁₄H₂₇NaO₅S
• Molecular Weight   330.415 g/mol
• CAS  7381-01-3
• EC number   230-949-8

Synonyms:

• sodium 2-(dodecanoyloxy)ethanesulfonate
• Sodium 2-sulfoethyl laurate
• Sodium ethyl 2-sulfolaurate
• Sodium lauroylisethionate
• Sodium 2-sulfoethyldodecanoate
• Lauroyl isethionate, sodium salt
• Dodecanoic acid, 2-sulfoethyl ester, sodium salt
• 2-Sulfoethyl dodecanoate sodium salt
• Lauric acid, ester with 2-hydroxyethanesulfonic acid sodium salt

References_____________________________________________________________________

(1) Burnett, C. L., Heldreth, B., Bergfeld, W. F., Belsito, D. V., Hill, R. A., Klaassen, C. D., ... & Andersen, F. A. (2017). Amended safety assessment of isethionate salts as used in cosmetics. International journal of toxicology, 36(1_suppl), 5S-16S.