The interfacial behavior of aqueous solutions of newly synthesized bis- and tris-ammonium salts (i.e., bis[2-hydroxy-3-(dodecyldimethylammonio)propyl]alkylamine dichlorides and bis[2-hydroxy-3-(dodecyldimethylammonio)propyl]dialkylammmonium trichlorides, respectively) was analyzed, both experimentally and theoretically. The dynamic and equilibrium surface tension of multiple ammonium salt solutions was measured by using a pendant drop shape analysis method. The determined surface tension isotherms indicated the lack of significant differences in surface activity between bis- and tris-ammonium salts, contrary to the expectations for divalent and trivalent surfactant ions. That effect was explained by assuming the formation of multiple surfactant ion-counterion associates. Taking into account the association process, a good correlation between experimental data and theoretical predictions was obtained by means of the "surface quasi two-dimensional electrolyte" (STDE) model of ionic surfactant adsorption. The degree of association necessary to explain the lack of difference in surface activity between bis- and tris-ammonium salts was in quantitative agreement with the results of measurements of the concentration of free chloride anions in the surfactant solution.

A series of new cationic surfactants, bis-quaternary ammonium salts, were prepared from tert-alkylamine and a product of the reaction of epichlorohydrin with decyl-and dodecylamine, and their surface-active properties were measured. Specifically, the critical micelle concentration (CMC), effectiveness of surface tension reduction (γ CMC ), surface excess concentration (Γ), area per molecule at the interface (A), and standard free energies of adsorption (∆G ads°) and of micellization (∆G mic°) were determined. All these surfactants showed good water solubility and low CMC, more than one order of magnitude lower than those of corresponding monoalkylammonium salts. They also showed good foaming properties but worse wetting capabilities. Many of these compounds had antimicrobial activities against gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and yeast (Candida albicans), but they were not active against molds.

A series of new cationic surfactants, bis-quaternary ammonium salts and tris-ammonium salts, were prepared from N,N-dimethyldodecylamine and a product of the reaction of epichlorohydrin with ethyl-, propyl-, butyl-, pentyl-, hexyl-, and octylamine (in the case of bis-ammonium salts) or the hydrochloride of diethyl-, dipropyl-, dibutyl-, or dihexylamine (in the case of tris-ammonium salts). The obtained multiple salts were examined with respect to their surface-active properties: Critical micelle concentrations (CMC), effectiveness of surface tension reductions (γ CMC ), and adsorption efficiencies (pC 20 ) were measured. All these surfactants showed good water solubility and low CMC of more than one order of magnitude lower than those of corresponding monoalkylammonium salts. They also showed good foaming properties, but worse wetting capability. The obtained multiple salts showed excellent antielectrostatic properties.Paper no. S1520 in JSD 9, 221-226 (Qtr. 3, 2006). KEY WORDS:Antielectrostatic effect, bis-quaternary ammonium salt, cationic surfactant, critical micelle concentration, surface-active property, tris-quaternary ammonium salt.Ammonium salts are an important class of chemicals used widely as cationic surfactants, herbicides, and biocides. They have been known for more than 100 years. The first conventional salts were synthesized with one hydrophilic part (with quaternary nitrogen) and one long hydrocarbon chain in a molecule. However, for the last 30 years (1) a new class of ammonium salts has been investigated: multiple ammonium salts, which are made up of two or three amphiphilic moieties connected by a spacer. They are named dimeric and trimeric ammonium salts, respectively. The dimeric (gemini) salts have been widely investigated and their properties are well known (2-8). However, trimeric salts that are synthesized in a low yield are investigated to a lesser extent and their surface activity, biological properties, antielectrostatic effect, and other physicochemical properties are poorly known (9-11).The present article reports the synthesis and surface-active and antielectrostatic properties of new bis-ammonium and tris-ammonium salts. Their properties are compared with monoquaternary salts and with dimeric and trimeric salts, which have been presented in previous articles. EXPERIMENTAL PROCEDURESMaterials. All reagents used were commercial grade. Amines: ethyl-, propyl-, butyl-, pentyl-, hexyl-, octyl-, diethyl-, dipropyl-, and dibutylamine (purity >98%) were purchased from Fluka (Buchs, Switzerland) except dihexylamine (purity >97%), which was purchased from Aldrich. Epichlorohydrin (purity >98%) was purchased from VEB Laborchemie (Apolda, Germany) and freshly distilled before synthesis. All hydrochlorides of dialkylamines were prepared by the authors from an appropriate dialkylamine and gaseous hydrochloride in solution of diethyl ether, and hydrochlorides of dialkylamines were recrystallized subsequently from ethanol.Synthesis of bis(2-hydroxy-3-chloropropyl)alkylamine. General procedure. Th...

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