Synthesis of novel N,N-di-n-alkylaldonamides and properties of their surface chemically pure adsorption layers at the air/water interface

Synthesis and Characterization of N-alkyl-N′-glucosylhexanediamine Surfactant

The synthesis and structural analysis of glucosamide surfactants of the general formula CnH2n+1NH(CH2)6NHCO(CHOH)4CH2OH (n = 8, 10, 12) were described, and the surface activity properties of the surfactants were studied, and the interfacial tensions between n-octane and the aqueous surfactant solution were measured. N-alkylhexanediamines were synthesized by the alkylation of the 1,6-hexanediamine with alkyl bromide. The glucosamide surfactants, N-alkyl-N′-glucosylhexanediamine (C n GA), were prepared by amidation of the precursor diamine with D-gluconic acid δ-lactone. They were structurally characterized by IR, 1H NMR and MS. They reduced the surface tension of water to approximately 28–33 mN · m−1 at concentration levels of (0.2–1.0) × 10−3 mol · L−1, and reduced the interfacial tensions between n-octane and the aqueous surfactant solution to approximately 1–2 mN · m−1 at concentration levels of (0.3–4.2) × 10−3 mol · L−1.

From D-xylose to terminal polyols: a simple synthetic route

A simple and efficient synthetic approach toward different terminal alkyl tetraols and triols, starting from D-xylose, is described. The opening of the oxetane ring in a suitably protected 3,5-anhydro-D-xylose derivative with Grignard reagents leads to D-xylose-derived 5-deoxy-5-C-alkyl derivatives, which are suitable for reduction to terminal polyols after protecting group hydrolysis.

Synthesis of amphiphilic galactopyranosyl diamines and amino alcohols as antitubercular agents

Mono- and diacylated derivatives of galactopyranosyl amines were obtained from d-galactose, via aminated intermediates prepared by reaction of 6-deoxy-6-iodo-1,2:3,4-di-O-isopropylidene-alpha-d-galactopyranose with 1,3-propanediamine, 1,2-ethanediamine or ethanolamine. Monoacylated derivatives displayed antitubercular activity.

Investigations on foamability of surface-chemically pure aqueous solutions of functionalized alkylaldonamides

The foamability of the aqueous solutions of functionalized, surface-chemically pure surfactants of the nonionic saccharide-type: N,N-di-n-alkylaldonamides, N-alkyl-N-(2-hydroxyethyl)aldonamides, and N-cycloalkylaldonamides, derivatives of D-glucono-1,5-lactone and/or D-glucoheptono-1,4-lactone, were investigated. The approach of Lunkenheimer and Małysa for the characterization of the foamability and foam stability of these surfactant solutions was applied for these investigations. Using standard parameters related to the different physical stages of the foaming process, foam stability can be described in a simple and easy manner. In general, the investigated alkylaldonamides form foams of medium stability. However, for some homologues a transition from unstable to stable foam systems is observed with increasing concentration. Modifications of the molecular structure of the alkylaldonamides are distinctly reflected in their foam properties. This fact concerns not only changes of the hydrophobic moiety and its functionalization but also slight variations of the saccharide residue. Each homologous series reveals an exceptional foam behavior. In the case of the N,N-di-n-alkylaldonamides the increase of the n-alkyl chain length is accompanied by an increase of the foam stability. The aqueous solutions of the N-alkyl-N-(2-hydroxyethyl)aldonamides reveal most favorable foaming properties for homologues with average alkyl chain lengths. Moreover, it was found that the occurrence of a phase transition in the adsorption layers of the N-cyclooctylgluconamides previously observed by surface tension and surface potential measurements is also remarkably reflected in their foam stability.

Adsorption behavior of surface chemically pure N-cycloalkylaldonamides at the air/water interface

Equilibrium surface tension (sigma(e)) and electric surface potential (DeltaV(e)) versus concentration isotherms of the homologous series of N-cycloalkylaldonamides synthesized from cycloalkylamines (from cyclopentyl- to cyclododecylamine) and D-glucono-1,5-lactone (c-C(n)GA) or D-glucoheptono-1,4-lactone (c-C(n)GHA) (c-n(C) = 5-12) were investigated at the air/water interface. The measurements were performed with aqueous, surface chemically pure surfactant solutions. Equilibrium surface tension vs concentration isotherms were evaluated to get the adsorption parameters, i.e., standard free energy of adsorption, DeltaG degrees (ads), saturation surface concentration, Gamma(infinity), minimum surface area demand per molecule adsorbed, A(min), and interaction parameter, H(s). Increasing the size of the cycloalkyl moiety leads to a significant increase of the minimum surface area demand per molecule adsorbed. This fact, together with a decrease of the intermolecular interaction parameter suggests that the introduction of a more bulky cycloalkyl ring (c-n(C) = 7 and 8) causes an attenuation of the hydrogen-bond network. This goes in line with the exceptional finding that the higher homologues revealed improved solubility in water. In addition, surface tension investigations suggest occurrence of a phase transition for the N-cyclooctylaldonamides at relatively small surface coverage. This observation is well supported by the surface potential measurements, for which the effect of possible changes in the molecules' surface orientation is even more pronounced. Moreover, the concentration intervals of N-cyclooctylaldonamide in which the change in orientation is observed for either the surface tension or the surface potential isotherms are in very good agreement.

Stereoselective Synthesis of Polyhydroxyl Surfactants. Stereochemical Influence on Langmuir Monolayers

Herein is described the synthesis of surfactants featuring polyhydroxylated head groups. Three head groups were prepared via consecutive stereoselective dihydroxylations of a diene. By coupling of these with lipophilic tail groups six novel surfactants have been prepared. The monolayers prepared from four of these have been investigated at the air-water interface. Significant differences were observed between monolayers consisting of enantiomerically pure surfactants contra racemates as well as between diastereomers.