α-Sulfonated fatty acids and esters: Manufacturing process,properties, and applications

α-Sulfonated fatty acid esters, because of their wide-range of application and biological properties, represent an interesting class of surfactants. A technical method for the preparation of α-sulfonated fatty acid esters is described. By using special reaction conditions it is possible to α-sulfonate saturated fatty esters directly without the use of solvents. The use of gaseous SO₃ gives the product in greater than 97% yield. A process for the bleaching of the α-sulfonated fatty esters has been developed, whereby a product of faultless color is produced without the necessity of further purification or separation techniques. The sulfonation and bleaching processes operate continuously. The process has been tried successfully on a commercial scale using the methyl esters of technical fatty acids. Methods for the preparation of α-sulfonated fatty acids are given. The chemical, technical, and biological properties of the α-sulfonated fatty acids and their esters are discussed. α-Sulfonated fatty esters possess good washing and foaming properties, have good biological degradability, possess good skin compatibility and low acute toxicity. They can be considered as surfactant components for phosphate-free or low-phosphate detergents. α-Sulfonated fatty acids and esters also possess other favorable technical properties which allow them to be used in cosmetics, as auxiliary agents in the production of fibers, plastics, and rubber, and in leather manufacture.