Is Sodium Lauroyl Methyl Isethionate natural?

Coconut lauric acid esterified with sodium methyl isethionate made from propylene oxide and sodium bisulfite.

The synthesis of Sodium Lauroyl Methyl Isethionate (SLMI) involves a multi-step process typically starting with the production of methyl isethionate. Sodium methyl isethionate (sodium 2-hydroxypropane-1-sulfonate) is made by reacting propylene oxide with sodium bisulfite. Propylene oxide is a petrochemical made from propylene; the sodium sulfonate group comes from mineral sulfur and sodium.

The second key component is lauric acid, which comes from coconut or palm-kernel oil. The lauric acid is then activated, often by converting it into lauroyl chloride or a similar reactive derivative. This activated lauric acid is then reacted with methyl isethionate in an esterification reaction. This reaction typically occurs under controlled temperature conditions, often in the presence of a base to neutralize the acid byproduct and drive the reaction to completion.

Following the esterification, the resulting Sodium Lauroyl Methyl Isethionate is purified. Purification steps commonly include washing, filtration, and drying to remove unreacted starting materials, byproducts, and solvents. The final product is typically a white to off-white powder or flake. By mass the lauroyl chain and the mineral sodium sulfonate group are natural origin and only the small three-carbon linker from propylene oxide is petrochemical, so the ingredient is mostly natural origin (286/344 = 0.83).

Sodium Lauroyl Methyl Isethionate is a type of cleansing agent, commonly known as a surfactant, used in many personal care products like shampoos, body washes, and facial cleansers. Its main job is to help water mix with oil and dirt, allowing them to be washed away from your skin and hair, creating lather and a clean feeling.

The fatty part comes from coconut or palm-kernel oil and the sulfonate part from mineral sources; only a small three-carbon linker is made from petroleum. By weight it is mostly natural origin, which is why it scores 0.83.