How are fatty alcohols converted into anionic synthetic detergents?

Fatty alcohols are converted into anionic synthetic detergents through a process known as sulfation. While the term "sulfonation" is often used broadly, sulfation is the chemically precise term for the reaction involving fatty alcohols, which results in a sulfate molecular group (—OSO₃Na) being attached to the compound.1

The process typically involves the following steps:

• Reaction: Gaseous sulfur trioxide is used to attach the sulfate group to the fatty alcohol. This sulfur trioxide can be obtained by vaporizing liquid stabilized sulfuric acid anhydride or by burning sulfur.1
• Neutralization: Following the initial reaction, the resulting acidic products are neutralized using a caustic soda solution.1

This process transforms the fatty alcohol into a surface-active agent that is hydrophilic, or attracted to water. These detergents are distinct from those produced from alkylbenzene, which undergo a process of sulfonation to attach a sulfonate group (—SO₃Na) directly to a benzene ring.1