Surfactant Properties of Monoalkyl Ethanolamine Phosphate Esters

Monolauryl and monostearyl phosphoric acid esters were synthesized by phosphorylation of the corresponding long chain fatty alcohols which were subsequently neutralized with mono-, di- and tri-ethanolamines. Monoalkyl nature of phosphate derivatives was ascertained by evaluating phosphorus contents. All the phosphate derivatives displayed appreciable lowering of surface tension of water and the monoethanolamine compounds, in particular, showed lower CMC values compared to the conventional anionic surfactant, linear alkyl bezene sodium sulphonate. Monoethanolamine derivatives of lauryl and stearyl esters of phosphoric acid exhibited lower water solubility compared to diethanolamine and triethanolamine derivatives. Foam characteristics of all the compounds were, in general, poor. Monolauryl diethanolamine phosphate ester indicated superior wetting power.