Alkanolamides and other amide-group containing nonionics

Alkanolamides and other amide-group containing nonionics 

These practically important nonionic surfactants are produced by interaction of a fatty acid, its methyl ester, or another derivative and aminoalcohol. Thus, about equal mole fraction of lauric acid and 2-aminoethanol at 150 °C yield lauric ethanolamide  

The final substance contains aminoester of the formula C11H23COOCH2CH2NH2 and amidoester C11H23CONHCH2CH2OOCC11H23 as by-products. In addition, alkanolamides may contain some alkanolamine soaps as well. The reaction between the methyl ester of a fatty acid and alkanolamine proceeds under milder conditions and gives higher yield of the final products. 

Along with monoethanolamides (I), isopropanolamides (II) and diethanolamides (III), synthesized analogously, have a practical importance. Purer fatty acid mono- and diethanolamides containing some ethoxylated amides could be prepared by the reaction of fatty acid amides with controlled amounts of ethylene oxide. Ethoxylation of fatty acid amides results in mixtures of mono- and diethanolamides as well as polyethoxylated alkanolamides. 

Fatty acid ethanolamides and isopropanolamides are solid or waxy products insoluble in water. Diethanolamides are usually pastes or liquids and show better dispersibility in water. In institutional and household formulations, shampoos, bath and shower preparations, fatty alkanolamides play the role of foam stabiliser, thickener, corrosion inhibitor, and ancillary agent that improves the skin compatibility of anionic surfactants. Undecylenic ethanolamide and undecylenic diethanolamide act as fungicides also [47]. Use of diethanolamine derivatives has legislative limitations today in some countries (but not its amides) because they are proved to be precursors of carcinogenic nitrosoamines. The probability of the nitrosoamine formation is assumed to increase in the presence of formaldehyde and formaldehyde-releasing preservatives [44-46]. 

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