C13-15 Pareth-21 is a chemical compound, alkyl polyethylene glycol (PEG (Polyethylene glycol)) ether mixture of synthetic C13-15 fatty alcohol ethoxylated (21 mol).
The name defines the structure of the molecule:
- C13-15 refers to a range of carbon chain lengths in the compound. In this case, it indicates that the compound consists of alkyl chains with carbon atoms between 13 and 15. Alkyl chains are hydrocarbon chains that are commonly derived from fatty acids.
- Pareth-21. "Pareth" is a term used to describe a group of compounds that are polyethylene glycols ethers of fatty alcohols. The number "21" indicates the average number of units of ethylene oxide in the compound. Polyethylene glycol ethers are commonly used as surfactants and emulsifiers in personal care products.
The synthesis process takes place in several stages:
- Preparation of C13-15 alcohols synthesized from oil through a process known as olefin oligomerization.
- Polyoxylation. C13-15 alcohols are reacted with ethylene oxide in a process known as polyoxylation. This process attaches polyethylene glycol chains to alcohols, increasing their solubility in water and improving their surfactant properties. The number "21" in C13-15 Pareth-21 refers to the average number of units of ethylene glycol in the PEG chain.
C13-15 Pareth-21 is produced as a clear to slightly yellowish liquid.

What it is used for and where
C13-15 Pareth-21 is a compound consisting of alkyl chains with carbon atoms ranging from 13 to 15, combined with polyethylene glycol ether groups. It is commonly used in cosmetics and personal care products as a surfactant or emulsifier, providing functions such as cleaning, foam and emulsifier.
Cosmetics
Surfactant - Emulsifying agent. Emulsions are thermodynamically unstable. Emulsifiers have the property to reduce the oil/water or water/oil interfacial tension, improve emulsion stability and also directly influence the stability, sensory properties and surface tension of sunscreens by modulating their filmometric performance.
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 term 'eth' refers to the ethoxylation reaction with ethylene oxide after which residues of ethylene oxide and 1,4-dioxane, chemical compounds considered carcinogenic, may remain. The degree of safety therefore depends on the degree of purity of the compound obtained. At present, no manufacturer is known to provide this information on the label.
CAS: 64425-86-1