scientist with beakers
Ethoxylation is a chemical process used in industry to create surfactants, compounds that lower the surface tension of liquids. The ethoxylation process involves adding ethylene oxide to an alcohol or phenol to produce products. Many products produced by ethoxylation have commercial applications, and some are used in biochemistry and medicine. While most surfactants can be used widely, others are dangerous to humans and the environment, and their use is restricted in some countries.
Commonly ethoxylated compounds include nonylphenol, amines, fatty acids, and fatty alcohols. Usually, a catalyst such as potassium hydroxide must be added along with ethylene oxide to help speed up the ethoxylation reaction. Some compounds, such as lactic acid and 12-hydroxystearic acid, can be ethoxylated without a catalyst.
In industrial plants, ethoxylation may involve a pre-treatment step in which water is removed to prevent the formation of foreign compounds and a post-treatment step in which the catalyst is neutralized and removed. The various steps of the reaction can take place in different vessels or in one large reactor. The design of the reaction depends on the efficiency. Industrial chemists often directly supervise the ethoxylation process and make modifications to increase productivity.
The ethoxylation products are known as ethoxylated materials or surfactants. These are organic compounds that contain hydrophilic (water-attracting) and hydrophobic (water-repelling) groups. Surfactants change the surface properties of liquids because their structure causes them to migrate to the liquid boundary interface. For example, in water, the surfactants will migrate to the air-water boundary, but in a mixture of oil and water, the surfactants will migrate to the oil-water boundary. The term surfactant is a shortened version of the term surfactant, reflecting this behavior.
Surfactants can be found in detergents, shampoos, paints, inks, pesticides, and many other commercial products. They are typically used as emulsifiers, causing unmixable liquids to mix, or as foaming agents and cleaning agents. Some surfactants have biochemical applications and are used to extract proteins from cells or make proteins soluble in solution.
A specific type of ethoxylation, known as PEGylation, is used in medicine to promote the distribution of drugs in the body. In PEGylation, polyethylene glycol chains are attached to a protein or therapeutic drug. This prevents the body’s immune system from recognizing and attacking the drug or protein and also allows normally insoluble drugs to become water soluble.
Some ethoxylated materials can be hazardous and are currently regulated by some government agencies. Nonylphenol ethoxylates (NPE), which are used in pesticides, industrial detergents, and some household cleaning products, can reach groundwater and soil through the sewage system. NPEs have toxic effects on aquatic life and also cause reproductive problems in animals. Concerns that NPEs may migrate across agricultural land for human consumption have limited their use in several countries.