A series of diquaternary ammonium bromides having phenyl groups with different (CH 2 /N + ) ratios were synthesized. The critical micelle concentration of each amphiphile was determined using equilibrium surface tension and equivalent conductance data. Air/water interfacial parameters were measured at 20, 35, and 50°C. The surface tension isotherms of the different diquaternary amphiphiles showed two region of discontinuity corresponding to two critical micelle concentrations. The first was related to the spherical nature of the micelles, whereas the second was related to the multiple loops of the lamellar aggregates. The prepared compounds were evaluated as a new class of diquaternary ammonium compounds for future application in protection of steel fabrics against aggressive media (2 N HCl). The results showed that the prepared amphiphiles offered good corrosion inhibition efficiency. Also, increasing the hydrophobic chain length and/or concentration increased their efficiency.In many industrial applications, aqueous solutions are used in various heat transfer systems where water comes in contact with metal surfaces. The drawback stems from the existence of carbon dioxide, sulfur dioxide, or sulfur trioxide contaminants that attack metal surfaces. Organic compounds, especially those containing nitrogen or sulfur, are very good inhibitors of steel corrosion by acids (1,2). Thiourea and most of its derivatives have been described as inhibitors of iron and steel corrosion in acidic solutions (3-5).In a previous study (6), diquaternary bola-form amphiphiles containing saturated chains and spacers were prepared. Physical, surface, and thermodynamic parameters of these amphiphiles were determined, and the surface phenomena of their aggregates were also discussed. In this study, the effect of the unsaturated spacer groups (benzene ring) on the surface and thermodynamic parameters was investigated. These compounds were also evaluated as corrosion inhibitors for steel in extremely acidic environments. MATERIALS AND METHODSSynthesis of dibromodimethylcarbonyl hydroquinone. Hydroquinone (0.1 mol, 11.0 g) (Adwic, Cairo, Egypt) and bromoacetic acid (0.2 mol, 27.8 g) (Aldrich, Milwaukee, WI) were esterified in the presence of p-toluene sulfonic acid (0.001 mol) as a dehydrating agent, in toluene as a solvent, until the azeotropic amount of water was removed (3.6 mL). The product was then dissolved in petroleum ether (60-80°C) to separate the used catalyst, after which the used solvents were then removed in a rotary evaporator under reduced pressure.Synthesis of fatty acid methyldiethanolamine derivatives. Methyldiethanolamine (0.1 mol, 11.9 g) (Aldrich) was esterified by lauric, palmitic, and stearic acids (0.1 mol 20, 25.6, and 28.4 g; Sigma, St. Louis, MO), respectively, in toluene under inert atmosphere (N 2 gas) using p-toluene sulfonic acid (0.001 mol) as a catalyst. After the complete removal of the produced water (0.1 mol, 1.8 mL), the reaction mixture was dissolved in petroleum ether (60-80°C) in a separatory funnel t...

Two series of gemini cationic surfactants were synthesized based on glucose and fructose molecules. Their chemical structures were confirmed using micro-elemental analysis, mass spectral fragmentation and FTIR spectroscopic analysis. The surface activities of these gemini amphiphiles were measured, including surface tension (c), critical micelle concentration (CMC), effectiveness (p cmc ), efficiency (pC 20 ), maximum surface excess (C max ) and minimum surface area (A min ) at 25°C. Adsorption and micellization free energies of these amphiphiles in their solutions showed a good tendency towards adsorption at the interfaces. The biological activity of the synthesized gemini amphiphiles showed good inhibition at concentrations of 1, 2.5 and 5 mg/mL. The synthesized amphiphiles showed antimicrobial activity on gram-positive and gramnegative bacteria and antifungal activity equal to or comparable to commercially available controls. The discussion rationalized the antimicrobial activities of these amphiphiles with the surface activity and the adsorption parameters. In addition, the effect of sugar nuclei was discussed based on the chemical structure of the bacterial and fungal cell membranes.

In this study, steps were taken toward the development of bactericidal and fungicidal synthetic cationic surfactants by reacting decyl, dodecyl or tetradecyl amine with acetic or hydrochloric acid to produce a series of amine salts which consequently converted to copper or cobalt cationic complexes via complexing the first series compounds with copper (II) or cobalt (II) ions. Surface properties such as interfacial tension and emulsifying power of these surfactants were investigated. The surface parameters including critical micelle concentration (CMC), maximum surface excess (C max ) and minimum surface area (A min ) were studied. Free energy of micellization (DG°m ic ) and adsorption (DG°a ds ) were calculated. The antimicrobial activity was determined via the inhibition zone diameter of the prepared compounds, which measured against five strains of a representative group of microorganisms. FTIR spectra, elemental analysis and H 1 NMR spectrum were performed to confirm compound structure and purity.

A novel series of mono-quaternary ammonium salts was prepared by the reaction of fatty esters of methyldiethanolamine with epichlorohydrin in the presence of amine hydrochloride. The ease of the reaction with epichlorohydrin was found to be due to the assistance of amine hydrochloride in opening the epoxide ring and to neighboring-group participation by the hydroxyl group of the mono-ammonium salt in the quaternization step. The surface properties of the prepared compounds and their biological activities were measured. The prepared compounds had good water solubility and showed characteristic surface active properties.

We report in this investigation the synthesis of a new series of amphiphilic ABA-triblock copolymers consisting of double-chain hydrophobic moieties (A) of different chain lengths attached to each end of polyethylene glycols of different molecular weights (B). The identities of the prepared compounds were confirmed by elemental and Fourier transform infrared analyses. The prepared compounds showed good water solubility. Some of their surface properties, such as the critical micelle concentration, effectiveness of water surface tension reduction, surface excess concentration, standard free energies of adsorption and micellization, and surface area per molecule, were determined.