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Novel switchable gemini imidazolium surfactants with different carbon atoms in hydrophobic group were successfully synthesized by condensation of fatty acid with triethylene tetramine, then the intermediates were reacted with CO2 to give the imidazolinium bicarbonates. The structures of intermediates and products were identified by IR and 1H-NMR spectra. As the results show, the structures of the products obtained correspond to the target compounds designed. By surface tension measurements, these Gemini surfactants have excellent surface activity with low cmc and surface tension. The conductivity and surface tension cycles show that these surfactants could be switched from imidazoline (neutral form) to imidazolium bicarbonate (charged form ) reversibly and repeatedly. [ABSTRACT FROM AUTHOR]

In this paper, an improved method for the preparation of erucyl dimethyl amidopropyl betaine (EDAB) was provided. The syn-thesis conditions were investigated. N,N-dimethyl-N'-erucyl-l,3-propylenediamine was synthesized by the reaction of erucic acid with N,N-dimethyl-l,3-propylenediamine at 170°C for 7 h, and then the intermediate was reacted with sodium chloroacetate in the mixture of methanol and water (3:7 v/v) at 60 °C. The product was obtained after 6 h. The compounds were con-firmed by IR and 'H-NMR. The properties of EDAB acid solution were also studied. The results indicated that viscosity of acid so-lution increased with decreasing hydrochloric acid concentration and was mainly controlled by surfactant concentration and tem-perature. The viscosity of an acid solution was maximum when the concentration of hydrochloric acid was at 15 wt%. [ABSTRACT FROM AUTHOR]