Alkyl Xylosides: Physico‐Chemical Properties and Influence on Environmental Bacteria Cells

A group of four selected non‐ionic surfactants based on carbohydrates, namely octyl d ‐xyloside (C₈X), nonyl d ‐xyloside (C₉X), decyl d ‐xyloside (C₁₀X) and dodecyl d ‐xyloside (C₁₂X), have been investigated to accomplish a better understanding of their physico‐chemical properties as well as biological activities. The surface‐active properties, such as critical micelle concentration (CMC), emulsion and foam stability, the impact of the compounds on cell surface hydrophobicity and cell membrane permeability together with their toxicity on the selected bacterial strains have been determined as well. The studied group of surfactants showed high surface‐active properties allowing a decrease in the surface tension to values below 25 mN m^?1 for dodecyl d ‐xyloside at the CMC. The investigated compounds did not have any toxic influence on two Pseudomonas bacterial strains at concentrations below 25 mg L^?1. The studied long‐chain alkyl xylosides influenced both the cell inner membrane permeability and the cell surface hydrophobicity. Furthermore, the alkyl chain length, as well as the surfactant concentration, had a significant impact on the modifications of the cell surface properties. The tested non‐ionic surfactants exhibited strong surface‐active properties accompanied by the significant influence on growth and properties of Pseudomonas bacteria cells.     

Preparation,Characterization and Properties of Novel Cationic Gemini Surfactants with Rigid Amido Spacer Groups

A series of novel cationic gemini surfactants with rigid amido groups inserted as the spacers, named C ₁₂ ‐PPDA‐C ₁₂ , C ₁₄ ‐PPDA‐C ₁₄ and C ₁₆ ‐PPDA‐C ₁₆ , were synthesized by a two‐step reaction with dimethyl terephthalate, N,N‐dimethyl propylene diamine and alkyl bromide as raw materials. The chemical structures of the prepared compounds were confirmed by IR, ¹H and ¹³C NMR and element analysis. Surface activity properties of the synthesized compounds were investigated by surface tension, electrical conductivity and fluorescence. Increasing the number of carbon atoms in the hydrophobic alkyl chain, decreased the critical micelle concentration (CMC), surface tension at the CMC and the minimum surface area. Other relevant properties including foaming ability and emulsion stability were investigated. The results indicated that the synthesized gemini surfactants possess good surface properties, emulsifying properties and steady foam properties.     

Preparation and properties of double- or triple- chain surfactants with two sulfonate groups derived fromN- Acyldiethanolamines

Bis(sulfonate) types of amphipathic compounds with three long- chain alkyl groups were prepared by the reaction ofN- (long- chain acyl)diethanolamine diglycidyl ethers with long- chain fatty alcohols, followed by the reaction with propanesultone. The diglycidyl ethers were easily obtained from the correspondingN- acyldiethanolamines and epichlorohydrin in the presence of a phasetransfer catalyst. The same types of compounds with two longchain alkyl groups were also prepared from Nacetyldiethanolamine according to similar procedures. All these new double- or triple- chain surfactants were soluble in water and showed much better micelle forming and ability to lower surface tension than general types of single- chain surfactants with one sulfonate group. The critical micelle concentration (CMC) and γ_CMC values of the triple- chain compounds were still much smaller than those of the corresponding double- chain compounds with two common alkyl groups. The efficiency of adsorption at the water/air interface (pC₂₀) of these surfactants was very high. Their foaming properties, wetting ability toward a felt chip, and lime- soap dispersing ability were measured. To whom correspondence should be addressed at Department of Applied Chemistry, Faculty of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565, Japan.     

Chemical structure/property relationships in surfactants. 17. N-substituted-N-acyl glycinates in pure and synthetic hard river water

The surface properties [effectiveness of surface tension reduction (γ_CMC), critical micelle concentration (CMC), efficiency of surface tension reduction (pC ₂₀), maximum surface excess concentration (Γ_CMC), minimum area/molecule at the interface (A _min), and the CMC/C ₂₀) ratio] of well-purified N-substituted glycine derivatives, having the structural formula RC(O)N(R′)CH₂COONa, where RC(O)=lauroyl, myristoyl, or oleoyl, and R′=Et, Pr, Bu, CH₂CH₂OH or CH₂CH₂CH₂OCH₃, were investigated at 25°C in hard river water and distilled water. These surfactants show greater surface activity in hard river water than in distilled water. The effect of both the main alkyl chain R and the N-substituent R′ on surface properties was elucidated, the oleoyl group showing properties equivalent to that of a C₁₆ saturated acyl group. A linear relationship was observed between the pC ₂₀ or CMC values and the number of carbon atoms in the alkyl chain R or in R′ when it was alkyl. With increase in the number of carbon atoms in either R or the N-substituent R′ when it is alkyl, both pC ₂₀ and micelle-forming ability increase, although the effect of R′ on the foregoing two surface properties is lower than that of R. When R′ is (CH₂)₃OCH₃, however, the results suggest that R′ is only partly removed from contact with the aqueous phase either upon adsorption at the water/air interface or upon micellization. It increases A _min, is equivalent only to an ethyl group in its effect on pC ₂₀ and to a methyl group in its effect on CMC, and, in contrast to the effect of R′ when it is alkyl, produces no increase in the CMC/C ₂₀ ratio. As a result, γ_CMC increases with R when R′ is alkyl and decreases with R when R′ is (CH₂)₃OCH₃.     

Surface Properties and Biological Activity of Select Cationic Surfactants

A series of cationic surfactants, N-(decyl N-tri-ethanol ammonium Bromide) (C₁₀), N-(dodecyl N-triethanol ammonium Bromide) (C₁₂), N-(hexadecyl N-triethanol ammonium Bromide) (C₁₆) were synthesized. These compounds have been evaluated by studying their surface properties, surface parameters, biodegradability and antimicrobial and antifungal activities.

Synthesis and Properties of 1,1-bis{[3-(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylamino)propyl]amido}alkane-di-<Emphasis Type="Italic">N</Emphasis>-oxides

A homologous series of new surface-active 1,1-bis{[3-(N,N-dimethylamino)propyl]amido}alkane-di-N-oxides were synthesized in the reaction of an appropriate diethyl 2-alkylmalonate with N,N-dimethylamino-1,3-propanediamine followed by oxidation with aqueous hydrogen peroxide. The adsorption isotherms of their aqueous solutions were measured and evaluated to obtain adsorption parameters: critical micelle concentration (CMC), surface excess concentration (Γ_CMC), equilibrium surface tension at the CMC (γ_CMC), cross-sectional area of the adsorbed surfactant molecule (A _CMC), efficiency of surface adsorption (pC₂₀), standard free energies of adsorption (ΔG°_ads), and micellization (ΔG°_CMC). All investigated di-amidoamines and di-N-oxides were practically non-toxic to selected bacteria and yeasts. These compounds are readily biodegradable in the Closed Bottle Test inoculated with activated sludge. Surface and biological properties showed that this group of N-oxide-type compounds has high surface activity and fulfills requirements for environmental acceptance.

Preparation and surface-active properties of telomer-type anionic surfactants from maleic anhydride

Maleic acid alkyl ester and N-alkyl maleamic acid monomers (R_nMa and R_nMaAm; n is alkyl chain length; n=6, 8, 10, 12, 14) were synthesized by the reaction of maleic anhydride with alkyl alcohol or alkylamine. The telomerization of R_nMa or R_nMaAm in the presence of alkanethiol as a chain transfer agent gave telomer-type anionic surfactants (xR_nMa, xR_nMaAm; x is total average number of alkyl chains; x=2.8–3.3) having multialkyl chains and multicarboxylate groups. Their surface-active properties were investigated by several techniques such as surface tension, foaming property, and emulsification power measurements. Critical micelle concentrations (CMC) of xR_nMa were 1/110–1/14 of those of R_nMa with the same alkyl chain length. xR_nMa and xR_nMaAm gave higher efficiencies in lowering the surface tension than R_nMa and R_nMaAm in aqueous solutions. In particular, the surface tension of 3.2R₁₂MaAm was 24.4 mN m⁻¹ at the CMC. Foaming abilities and foam stabilities of xR_nMa and xR_nMaAm were higher than those of R_nMa and R_nMaAm. The addition of 300 ppm of Ca²⁺ to the aqueous solutions rendered the telomers less surface active. Shaking the aqueous solutions of telomers with toluene emulsified them. The highly stable oil-in-water type emulsion was formed by using 3.0R₁₀MaAm and 3.2R₁₂MaAm, and the degree of emulsification was kept at a level of about 80% after 60 min of standing. Thus, telomer-type surfactants showed excellent surface activities that were superior to the corresponding monomers as well as to conventional surfactants. The relationship between alkyl chain length of the telomers and the properties of surface tension, foaming, and emulsification was unclear.     

Synthesis and properties of N-(α-carboxyalkyl)acrylamide telomer-type surfactants having multihydrocarbon chains

N-(α-Carboxyalkyl)acrylamide telomer-type surfactants (xC _n−1 AmAc where n is alkyl chain length=6, 8, 10, 12; and x is degree of polymerization=3.3–13.1) were synthesized by the telomerization of monomer (C _n−1 AmAc) in the presence of the corresponding alkanethiol as a chain transfer agent and then investigated for their surface-active properties. xC _n−1 AmAc telomers lowered the surface tension of aqueous solutions that were at pH 9–10. The critical micelle concentrations (CMC) of the telomers were lower than those of the monomers with the same alkyl chain length, and the CMC values shifted to lower concentrations with both increasing alkyl chain length and polymerization degree. xC₉AmAc with x=3.3–6.3 gave the highest efficiencies in lowering the surface tension. The cross-sectional molecular areas per molecule of xC _n−1 AmAc telomers were smaller than the values estimated on the assumption that they are assemblies of C _n−1 AmAc monomer units. The foaming abilities and the foam stabilities were both in the orders of xC₇AmAc>xC₉AmAc>xC₅AmAc>xC₁₁AmAc. Mixtures of aqueous solutions of xC _n−1 AmAc telomers and toluene formed oil-in-water emulsions. The emulsion-stabilizing abilities were in the orders of xC₇AmAc>xC₅AmAc>xC₉AmAc=xC₁₁AmAc. The addition of Ca²⁺ to the mixed solutions of telomers and toluene resulted in formation of water-in-oil type emulsions. Thus, the surface-active properties of the telomers were influenced significantly by the alkyl chain length and the polymerization degree of the telomers. In addition, these properties could be correlated with the hydrophilic-lipophilic balance (HLB); the highest surface activities were observed by using xC _n−1 AmAc with HLB of 14–18.     

Synthesis and surface measurements of surfactants derived from dehydroabietic acid

Dehydroabietates with poly(ethylene oxide) chains of average m=12, 17, and 45 units [DeHab(E) _m ] were synthesized. The adsorption at the liquid-vapor interface was measured, and the adsorbed amount and critical micelle concentrations (CMC) were determined. The foamability, the foam stability, wetting properties, and cloud points, with and without salt content, were studied. The results were compared with common linear alkyl ethoxylates, nonylphenol ethoxylates, and cholesterol ethoxylates. The dehydroabietic acid as hydrophobe was found to result in the same CMC as a linear dodecyl chain. DeHab(E)₄₅ was found to be insoluble above 400 mg/L, but the surface tensions at lower concentrations were similar to those of the C_11–13E_38–40 surfactants, which exhibit CMC in aqueous media. The foaming behavior of the DeHab(E)₁₂ and DeHab(E)₁₇ surfactants was about the same as for common linear C _n E _m surfactants. The foamability as well as the foam stability increased with ethylene oxide (EO) chain length. The cloud point was depressed by increased salt concentration and increased with the number of EO units in the head group. The cloud point was significantly lower than for the corresponding surfactant with a dodecyl chain with similar EO chain length. The wetting results, obtained by measuring the contact angle at similar surface tensions, indicate that surfactants of the DeHab(E) _m type are more efficient wetting agents than both disaccharide sugar surfactants and C _n E _m type surfactants.     

Synthesis and Properties of Novel Phenylenediamine Gemini Surfactants

In the present work, a two-step method was adopted to synthesize a series of novel Gemini surfactants using N,N-dimethylalkyl amines (alkyl length = C₁₂, C₁₆ and C₁₈), epichlorohydrin, and n-phenyllenediamine as starting materials. The products were characterized using mass spectroscopy (MS) and nuclear magnetic resonance spectroscopy (¹H NMR). Systematic experiments were conducted to evaluate their surface activity, foaming properties, and antibacterial performance. Results showed the critical micelle concentrations (CMC) of the C₁₂-based, C₁₆-based, and C₁₈-based phenylenediamine surfactants were 3.295 × 10⁻³, 2.532 × 10⁻⁴, and 3.140 × 10⁻⁴ mol L⁻¹ at 298 K, respectively, with corresponding surface tension (γ_cmc) values of 28.24, 31.95, and 35.06 mN m⁻¹ under the same conditions. The Gemini surfactants showed not only good surface activity and foaming properties, but also demonstrated good antimicrobial performance against Gram-positive and Gram-negative bacteria and fungi.     

Synthesis,Surface Activity,Thermodynamic Parameters,and Performance Evaluation of Branched Carboxylate Gemini Surfactants

Three novel carboxylate gemini surfactants (3C_ntaDA, n = 8, 10, and 12) were synthesized by two simple steps, and their structures were characterized using FT-IR and ¹H NMR. The surface activities of these surfactants were obtained from surface tension measurements at different temperatures, and the surface parameters containing the critical micelle concentration (CMC), surface tension (γ), minimum surface area per molecule ( A_min ), and maximum surface excess concentration ( Γ_max ) were obtained from surface tension measurements. The experimental results show that 3C_ntaDA surfactants have higher surface activities compared with the corresponding conventional surfactants. The thermodynamic parameters of the micellization process were investigated, and the calculated results show that it was an exothermic and spontaneous process. The emulsification and foam performance of these surfactants were also evaluated at different concentrations at 298.15 K.     

Synthesis and Properties of Functionalized Alkylaldonamides

Application studies of novel saccharide-type nonionic surfactants were performed. The homolog series of N-alkyl-N-(2-hydroxyethyl)gluconamides and N-alkyl-N-(2-hydroxyethyl)glucoheptonamides (alkyl: n-C₁₀H₂₁, n-C₁₂H₂₅, and n-C₁₄H₂₉) were synthesized and their structures were confirmed by means of elemental analysis and ¹H-NMR spectroscopy. The investigations showed that the application of N-alkyl-N-(2-hydroxyethyl)aldonamides as surfactants in an aqueous media can be limited. This is because of their relatively high Krafft point temperature. However, some variants can be successfully applied in mixtures with an anionic surfactant: sodium salt of n-dodecyl sulfate (SDS). The addition of SDS causes significant improvement of the Krafft point temperatures. In some cases a synergistic effect was observed, i.e., the Krafft point temperature of the binary mixture was lower that the corresponding values for the solutions containing individual compounds. It is also remarkable, that the aqueous solutions of binary surfactant mixtures were characterized by improved foaming properties, as compared to that of pure SDS.

Surface properties of N-alkanoyl-N-methyl glucamines and related materials

The surface properties [effectiveness of surface tension reduction (γ_CMC) critical micelle concentration (CMC), efficiency of surface tension reduction (pC ₂₀), maximal surface excess concentration (Γ_max), minimal area/molecule at the interface (A _min), and the (CMC/C ₂₀) ratio] of some well-purified N-alkanoyl-N-methyl glucamines and related polyol-based N-methyl amide-type surfactants, having the structural formula RC(O)N(Me)CH₂(CHOH)_xCH₂OH, where RC(O)=undecanoyl, lauroyl, tridecanoyl, myristoyl, and x=1,3, and 4, were investigated at 25°C in distilled water and 0.1 M NaCl. Water solubility of these compounds does not simply depend on the number of hydroxyl groups in the molecule but is associated with the balance between intermolecular hydrogen bonds and hydrogen bonds formed with water molecules. The fundamental interfacial properties, such as CMC and γ_CMC and two thermodynamic parameters, standard free energy of adsorption and standard free energy of micellization, were found to be significantly dependent on the hydrophobic acyl chain rather than on the number of CHOH groups in the hydrophilic moieties. By contrast, the practical performance properties were greatly dependent on the nature of the hydrophilic group. As a whole, these surfactants had desirable foaming properties and efficient wetting abilities. Furthermore, synergism in foaming and wetting abilities was observed in a binary mixture of these surfactants with an alkyloxyethylene sulfate.     

Synthesis and Properties of Alkylbetaine Zwitterionic Gemini Surfactants

A series of alkylbetaine zwitterionic gemini surfactants, 1,2-bis[N-methyl-N-carboxymethyl-alkyl-ammonium]ethane (C _n Ab, n = 8, 10, 12, or 14), were synthesized by alkylation of N,N′-dimethylethylenediamine with an alkyl bromide, followed by reaction with sodium 2-bromoacetate. Their solution properties were characterized by surface tension, steady-state fluorescence, and rheological measurements. Surface-tension measurements showed C _n Ab had lower critical micelle concentration (CMC) and higher efficiency in lowering the surface tension than their corresponding monomeric surfactants. The logCMC of C _n Ab decreased linearly with increasing chain lengths up to 12. Viscosity measurements showed only C₁₀Ab could enhance aqueous solution viscosity at high concentrations.     

Glucamine-based gemini surfactants I: Gemini surfactants from long-chain <Emphasis Type="Italic">N</Emphasis>-alkyl glucamines and α,ω-diepoxides

N-Alkyl glucamines can be reacted with α,ω-diepoxides to yield gemini (dimeric) surfactants similarly to the reaction of glucamine with terminal epoxides. Under the conditions chosen for this work, epoxides were quantitatively converted in the presence of an equimolar amount of amine to gemini surfactants. Reactions could be carried out under mild conditions (70°C) in methanol, and products were obtained quantitatively by removing the solvent. The combination of N-octyl glucamine, N-decyl glucamine, or N-dodecyl glucamine with diepoxides of α,ω-diolefins having chain lengths of C₈, C₉, C₁₀, or C₁₄ resulted in gemini surfactants differing in spacer length and length of hydrophobic alkyl chains. Surface-active properties were studied by measuring surface tension and evaluating foaming properties. Tensiometric studies showed the reduction of surface tension down to 29–33 mN/m and critical micelle concentrations often in the range of 3–150 mg/L. Comparison of a selected gemini surfactant [1,8-bis(N-dodecyl glucamino-2,7-octane diol] with its corresponding “single surfactant” demonstrated the enhancement of surface-active properties afforded by the gemini structure.     

Influence of Spacer Nature on the Aggregation Properties of Anionic Gemini Surfactants in Aqueous Solutions

A series of anionic gemini surfactants with the same structure except the spacer nature have been studied. Their solution properties were characterized by the equilibrium surface tension and intrinsic fluorescence quenching method. The critical micelle concentrations (CMC), surface tension at cmc, C₂₀, and the micelle aggregation number (N) were obtained. The surface tension measurements indicate that these gemini surfactants have much lower cmc values and great efficiency in lowering the surface tension of water compared with those of conventional monomeric surfactants. Furthermore, the standard free energy of micellization for anionic gemini surfactants was also determined. The results showed that the nature of the spacer has an important effect on the aggregation properties of gemini surfactants in aqueous solutions. The surfactant with a hydrophilic, flexible spacer was more readily able to form micelle compared with the surfactant with a hydrophobic, rigid spacer, which leads to a lower CMC value, larger N, more negative free energy of micellization, and a more closely packed micelle structure.     

Synthesis and evaluation of micellar properties and antimicrobial activities of imidazole‐based surfactants

The synthesis of two types of imidazole‐based surfactants, [(ROCOCH₂MIm)Br] and [(RNHCOCH₂MIm)Br], of varying chain lengths (C₁₀, C₁₂ and C₁₆), was conducted in the present work. The synthesis involves an initial reaction of bromoacetic acid with fatty alcohols or fatty amines, followed by quaternization with N‐methyl imidazole. The micellar properties of all the synthesized compounds were determined using surface tensiometry and compared with [(RMIm)Br], a well‐studied alkyl‐substituted imidazole‐based surfactant. Within the same homologous series, a decrease in critical micelle concentration (cmc) was observed with increasing alkyl chain length in all three types of cationic surfactants. Introduction of an ester [(ROCOCH₂MIm)Br] or an amide group [(RNHCOCH₂MIm)Br] in the alkyl chain lowers the cmc when compared to a cationic surfactant without functional group, [(RMIm)Br]. The synthesized surfactants were also assayed for antimicrobial activities and found to possess good activities against selected strains.     

Synthesis and Properties of Surface Chemically Pure Alkylamidoamine-N-oxides at the Air/Water Interface

A homologous series of surface active 2-(alkanoylamino)ethyldimethylamine-N-oxides, EDA-p(O), and 3-(alkanoylamino)propyldimethylamine-N-oxides, PDA-p(O), were synthesized. Their aqueous stock solutions were processed by the automatically operating apparatus to remove surface-active contamination and provide chemical purity at the air/water interface. In case of 3-(tetradecanoylamino)propyldimethylamine-N-oxide, PDA-14(O), the difference between equilibrium surface tension values of the purified surfactant solutions and the corresponding values of the solutions prepared from the “as received” compounds amounts to 15 mN m⁻¹. Moreover, in presence of the surface-active contaminants time needed to reach equilibrium surface tension values is over 2 h. For the solution of the “surface-chemically pure” grade the change of the surface tension within adsorption time is negligible and the equilibrium is reached instantaneously. Physicochemical properties of obtained surface-chemically pure aqueous solutions of N-oxides of alkylamidoamines and adsorption parameters (standard free energy of adsorption, ΔG°_ads, surface excess by saturation surface concentration, Γ_∞, minimum surface area demand per molecule adsorbed, A _min) were evaluated from the equilibrium surface tension versus concentration isotherms at the air/water interface using Gibbs’s equation. The introduction of the CH₂ moiety into the intermediate part of molecule causes a slight decrease of the hydrophobic character of surfactant. Also the minimum surface area demand, A _min, is slightly greater for PDA series than for the corresponding EDA derivatives. Surface potential measurements were performed in addition to surface tension studies. Electric surface potential versus concentration isotherms was determined. Surface potential increases with increasing surfactant’s bulk concentration for all investigated compounds. At highest concentrations, where interface is almost saturated, changes of surface potential become almost negligible.

Synthesis and Characterization of Glucosamide Surfactant

The synthesis and structural analysis of glucosamide surfactants of the general formula C_nH_2n+1NH(CH₂)₂NHCO(CHOH)₄CH₂OH (n = 8, 10, 12) are described, and the surface activity properties of the surfactants are studied. N‐alkylethylenediamines were synthesized by the alkylation of the ethylenediamine with alkyl bromide. The glucosamide surfactants, N‐alkyl‐N′‐glucosylethylenediamine (C_nGA), 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 26–27 mN m^?1 at concentration levels of (0.5–1.6) × 10^?3 mol L^?1.     

Surfactant properties of purified polyglycerol monolaurates

A series of purified polyglycerol monolaurates (PGML), such as di-, tri-, tetra-, and pentaglycerol monolaurates, were synthesized, and their surfactant properties in aqueous solutions were examined. The surfactant properties of PGML were compared with those of n-dodecyl polyoxyethylene monoethers (C₁₂EO_n) to examine the function of the hydrophilic part of these compounds. The critical micelle concentration (CMC) values and the surface tension at CMC of PGML and C₁₂EO_n increased linearly with an increase in the number of glycerol and oxyethylene units, respectively; the slope of the increase was greater for PGML than C₁₂EO_n. The minimum surface area per molecule of PGML was smaller than that of C₁₂EO_n at the air/aqueous solution interface. The initial foam heights of the surfactants at the CMC increased with an increase in the number of glycerol or oxyethylene units, and the foam heights of PGML were consistently higher and more stable than those of C₁₂EO_n. Detergency depended on a reduction in interfacial tension. Triglycerol monolaurate showed the lowest interfacial tension and the highest detergency among all the surfactants tested. Overall, the PGML showed better performance in all the surfactant properties tested than C₁₂EO_n. It is noteworthy that the surfactant properties of PGML having few glycerol units (di- to tetraglycerol monolaurates) are on par with those of C₁₂EO_n having many oxyethylene units (hexa- and octaoxyethylene). These results suggest that PGML having a secondary hydroxyl group on every glycerol unit of the hydrophilic part could be more hydrophilic than C₁₂EO_n; this characteristic feature guaranteed the superior surfactant properties of PGML.