C12-15 Pareth-11 is the name used in the international database of cosmetic ingredients (INCI) for a surfactant structurally derived from the subgroup of ethoxylated fatty alcohols. Its structure is derived from fatty alcohol with a carbon content of C12-C15. It is a substance with the structure and properties typical for non-ionic surfactants. Thus, the molecule does not have any anionic or cationic determinants. Due to its excellent detergency properties, C12-15 Pareth-11 is a widely used ingredient in the formulation of many chemical cleansers. The global structure identifier, CAS, for C12-15 Pareth-11 is 68131-39-5.
Under normal conditions, i.e. at atmospheric pressure and at room temperature, C12-15 Pareth-11 is an oily liquid or a semi-solid paste. The colour of the liquid at approx. 30oC is max. 50 in the Hazen scale. This means that it is slightly yellowish, but not colourless. It has a light but characteristic odour. The consistency of C12-15 Pareth-11 results from, among others, its relatively high solidification point of 16oC. For this reason, it is recommended to lightly heat C12-15 Pareth-11 to obtain more homogeneous form during use or dissolving it in slightly warm water. Too much heating, however, may result in exceeding the cloud point. In a solution of 100g NaCl/l, the cloud point is around 60–64oC, which means that when it is exceeded, the substance spontaneously separates into two clearly different phases. This temperature is characteristic especially for non-ionic surfactants. Apart being a surfactant, C12-15 Pareth-11 is also an excellent emulsifier. The hydrophile-lipophile balance (HLB) calculated for this structure is 13.6. This value suggests high hydrophilicity, as well as very good solubility in water. C12-15 Pareth-11 also shows high solubility in lower aliphatic alcohols, which, too, are commonly used solvents in chemistry. The HLB also indicates that C12-15 Pareth-11 tends to produce and stabilize oil-in-water emulsions. This means that the emulsions produced by this chemical have two phases – a continuous water phase and a dispersed oil phase. In practice, they are subtle oil droplets suspended in the water phase. The pH of a 1% aqueous solution of Pareth-11 C12-15 can range from slightly acidic to neutral (between 5.0–7.0). The density of the substance at 25°C is approx. 1.02 g/ml. Many factors have no influence on the activity and use of C12-15 Pareth-11 as an active ingredient. An environment rich in oxidizing and reducing agents, high water hardness – none of them are able to disrupt the detergency and action of the substance. In addition, C12-15 Pareth-11 is stable in many types of environments – from acidic, neutral, to diluted alkalis. Of all the C12-C15 fatty alcohol derivatives, this one is the most resistant to strong bases such as NaOH, which makes it suitable for use in strongly alkaline environments. In comparison with other ethoxylated fatty alcohols, C12-15 Pareth-11 has a relatively strong effect of foam formation and stabilization. As the substance meets the criteria set out in Regulation (EC) No. 648/2004 on detergents, it is considered to be completely biodegradable.
One of the basic functions of C12-15 Pareth-11 is its role of a solubilizer, including in air fresheners and other fragrance compositions. The possibility of such use is exploited due to the structure of the surfactant, which allows the incorporation of insoluble or poorly soluble plant extracts and fragrance compositions into water. Therefore, C12-15 Pareth-11 helps to dissolve oils and other greasy ingredients in the water phase. High foaming capacity, combined with excellent wetting and degreasing properties, make the substance a valuable active ingredient in the formulation of agents for cleaning windows, cars and metal surfaces. Strong detergent and dispersing properties make it suitable for use in broadly understood household and institutional chemicals. For example, in cosmetics one may find it in wet wipes. Due to its emulsifying abilities, C12-15 Pareth-11 is a component of many cream compositions, such as moisturising creams, foundations for dry skin, body lotions, cream shampoos, masks and hair conditioners.
