Hydrotropic properties of some short‐chain alkylbenzene‐ and alkylnaphthalene sulfonates

Long-chain alkylnaphthalene sulfonates were synthesized by means of a Wurtz-Fittig reaction, and the basic properties were studied in water at 30°C. Through surface tension measurements, the following values were determined: the critical micelle concentration (CMC) and the surface tension at the CMC (γ CMC ). The following values were calculated: area per molecule at the CMC (A CMC ), standard free energy change of micellization (∆G°m ic ), standard free energy of adsorption (∆G°a d ), and the "efficiency" of a surfactant in reducing surface tension (pC 20 ). The micelle aggregation numbers were measured through steady-state fluorescence-quenching methods. As the chain length of the hydrocarbon of n-alkylnaphthalene sulfonate increased, the Krafft temperature increased, the surface tension decreased, the value of CMC decreased, pC 20 increased, ∆G°a d and ∆G°m ic became more negative, and the micelle aggregation number increased. The results showed that sodium α-(n-decyl)naphthalene sulfonate (DNS) had a high pC 20 , low Krafft temperature, and lower CMC than other surfactants in this study. Thus, DNS and the other n-alkylnaphthalene surfactants studied exhibit desirable properties that may be of value in some fields such as detergency, oil recovery, and dyes.Paper no. S1333 in JSD 7, 135-139 (April 2004).KEY WORDS: CMC, micelle aggregation number, sodium α-(n-decyl)naphthalene sulfonate, sodium α-(n-hexyl)naphthalene sulfonate, sodium α-(n-octyl)naphthalene sulfonate, standard free energy of adsorption, standard free energy change of micellization, surface tension, surfactant.

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“…White crystals. 1 1 H NMR, IR, and MS gave results consistent with the desired product and the purity was greater than 95%.…”

Section: Methodsmentioning

confidence: 56%

Synthesis and study of the surface properties of long‐chain alkylnaphthalene sulfonates

Tan

Zhang

Zhao

et al. 2004

J Surfact & Detergents

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“…28,29 Hydrotropes, like alkanols, 30 increase the surfactant solubility in water as they break the liquid crystalline phases formed at high surfactant concentration.…”

Section: Hydrotrope-surfactant Mixturesmentioning

confidence: 99%

Action of hydrotropes and alkyl-hydrotropes

2011

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Hydrotropes are small molecule amphiphiles, having considerable industrial importance as agents for solubilization of hydrophobic substances in aqueous systems. The physico-chemical origin and mechanism of hydrotrope action has been a subject of academic debate and controversy for many years. One important issue is how close the solution physical chemistry of hydrotropes resembles that of common surfactants. This article seeks to improve the appreciation of this field by comparing thermodynamic, phase, spectroscopic and scattering studies of hydrotrope aqueous solutions. In addition, alkyl-hydrotropes are discussed, which represent a structural evolution from classic hydrotropes towards common surfactants, having solution properties more reminiscent of surfactants.

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“…Alkyl naphthalene sulfonates are generally considered to be hydrotropes (10,11). Hydrotropes are amphiphile molecules with a short lipophilic moiety that can improve the aqueous solubility of lipophiles and reduce the viscosity and cloudiness of an aqueous solution containing a sparing amount of soluble components (10)(11)(12).…”

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confidence: 99%

The role of hydrophilic linkers

Acosta

Uchiyama

Sabatini

et al. 2002

J Surfact & Detergents

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In microemulsion formulations, linker molecules are additives that can enhance the surfactant-oil interaction (lipophilic linkers) or the surfactant-water interaction (hydrophilic linkers). In this paper, the role of the hydrophilic linker is elucidated through solubilization studies, interfacial tension studies, and by studying the partitioning of the hydrophilic linker into an optimum middle phase. This research used alkyl naphthalene sulfonates as the hydrophilic linkers, sodium dihexyl sulfosuccinate as the surfactant, and trichloroethylene as the oil phase. The hydrophilic linkers were found to have interfacial properties between a hydrotrope and a cosurfactant. More specifically, the data show that a hydrophilic linker is an amphiphile that coadsorbs with the surfactant at the oil/water interface but that has negligible interaction with the oil phase. The role of the hydrophilic linker can thus be interpreted as opening "holes" in the interface. Based on the characteristics of alkyl naphthalene linkers, carboxylic molecules were evaluated as hydrophilic linkers. For trichloroethylene microemulsions, sodium octanoate was found to be an alternative hydrophilic linker to sodium mono-and dimethyl naphthalene sulfonates.Paper no. S1269 in JSD 5, 151-157 (April 2002).Microemulsions are thermodynamically stable isotropic emulsions with nanometer-sized aggregates (1,2). A microemulsion can be oil solubilized in water (Winsor Type I), water in oil (Type II), or bicontinuously in oil and water (Winsor Type III middle phase). Microemulsions are characterized by ultralow interfacial tensions and a high capacity to dissolve oil and water into single clear phases. The transitions among the different types of microemulsions can be achieved under certain formulation conditions that change the hydrophilic/lipophilic balance (HLB) of the surfactant at the oil/water interface. More detailed descriptions of microemulsion systems can be found elsewhere (1-4). Figure 1 shows an example of the Winsor phase transitions discussed above, where salinity is used to produce the phase transition. By increasing salinity, the microemulsion phase changes from Type I to Type III (middle phase) to Type II. The point at which the same amount of oil and water are solubilized in Type III is known as the optimum formulation. At the optimum formulation, the interfacial tension between the excess oil and water reaches a minimal value. The solubilization and formulation results presented later will be for such optimum conditions. Microemulsion formulations often use additives such as hydrotropes, cosurfactants, cosolvents, and electrolytes to affect the HLB of the amphiphile at the interface. The spectrum of additives can range from very hydrophobic to very hydrophilic. Figure 2 illustrates the relative hydrophilic/ lipophilic character of different types of additives relative to their location at the oil/water interface. Graciaa et al. (5,6) introduced the lipophilic linker effect to characterize the role of long-chain alcohols in surfactant formu...

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Hydrotropic properties of some short‐chain alkylbenzene‐ and alkylnaphthalene sulfonates

Cited by 17 publications

References 1 publication

Synthesis and study of the surface properties of long‐chain alkylnaphthalene sulfonates

Synthesis and study of the surface properties of long‐chain alkylnaphthalene sulfonates

Action of hydrotropes and alkyl-hydrotropes

The role of hydrophilic linkers

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