Nonionic Surfactants Organic Chemistry Volume 72 PDF Free Download

A series of four homologous pure nonionic surfactants, all monoesters of tetra(ethylene glycol), were synthesized. The ester surfactants varied in the degree of substitution on the α-carbon of the acyl chain, from no substitution to 2-methyl, to 2-ethyl, and on to 2,2-dimethyl. All surfactants were based on C8-acids except the 2-methyl-substituted, which was based on a C7-acid. The ester surfactants were characterized by critical micelle concentration (CMC) and cloud point. Base-catalyzed hydrolysis was investigated by using 1H NMR and tensiometry. The surfactants showed a pronounced difference in hydrolytic reactivity; the nonsubstituted surfactant was 90 times more reactive than the disubstituted, and the reactivity of the methyl-substituted surfactant was 14 times more reactive than the ethyl-substituted. Hydrolysis studies above the CMC revealed that the ester bond of the aggregated surfactant is protected from attack by hydroxide ions; thus, only surfactants in monomeric form are being cleaved.