An efficient method for synthesis of stable phosphorus ylides and 1,4-diionic organophosphorus compounds in the presence of sodium dodecyl sulfate in aqueous media

Stable crystalline phosphorus ylides and 1,4-diionic organophosphorus compounds were obtained in good to excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates and β-dicarbonyl or heterocyclic compounds, such as diethyl malonate, acetyl acetone, 1,3-diphenyl propane-1,3-dione, 1,3-dimethylbarbituric acid, meldrum’s acid, 2-benzoxazolinone, benzotirazole, and 2-thiazoline-2-thiol in the presence of sodium dodecyl sulfate as a surfactant in water. Green synthesis, mild conditions, decreasing timescale of reaction, low cost, and easy workup are the main advantages of this method.     

Comparison of dye (oxazine and thiazine) materials as a photosensitizer for use in photogalvanic cells based on molecular interaction with sodium dodecyl sulphate by spectral study

The photochemistry of dye is playing a significant role for understanding the mechanism of electron transfer reactions in photoelectrochemical devices such as photogalvanic cells, DSSC, semiconductor photo-catalysis, photoconductors, etc. Oxazines (Brilliant Cresyl Blue and Nile Blue O) and thiazines (Azur A, Azur B, Azur C, Methylene Blue and Toluidine Blue O) dyes have been used widely as a photosensitizer with and without surfactants in the photogalvanic cells for solar power conversion and storage. Since, the stability and solubility of photosensitizers (dyes) are increased in the presence of surfactant and these properties lead to enhance the electrical output of the photogalvanic cells. Therefore, here we have studied the extent of interaction of different dyes with sodium dodecyl sulphate (SDS), find out the order of stability of dye–SDS on the basis of magnitudes of shifting in λ_max of dye monomer and try to correlate order of dye–SDS interaction with already reported electrical output data of photogalvanic cells. Brilliant Cresyl Blue, Nile Blue O, Azur A and TB O have shown red shifting while Azur B, Azur C and MB have shown blue shifting in their λ_max value with SDS, which indicates formation of dye–surfactant complex. But, the extent of formation of complex for different dyes with SDS was different due to change in their alkyl groups. Dyes with red shifting have greater stability in excited state as well as higher electrical output data of the cell than dye with blue shifting. On the basis of both red and blue shifting, order of stability of dyes–SDS complex was found as: Brilliant Cresyl Blue?>?Toluidine Blue O?>?Azur A?>?Nile Blue?>?Azur B?>?Methylene Blue?>?Azur C. The order of electrical output values of these dyes in photogalvanic cells have also been supported by literature data in the presence of SDS. Hence, the dye–surfactant complex which would have greater stability in excited state might be more useful for improvement of conversion efficiency and storage capacity of photogalvanic cells in the future.     

Interactions between gelatin and sodium dodecyl sulphate: binding isotherm and solution properties

The interaction between sodium dodecyl sulphate (SDS) and gelatin was studied at pH 4.5 and 6.5 where the gelatin is positively charged (i.e.p. 8). At pH 4.5 a SDS/gelatin concentration range was found where gelatin precipitates. At pH 6.5 the SDS-gelatin complex remains soluble although three SDS concentration domains were distinguished where the SDS-gelatin complex had very different affinities for the solvent. Below C₁ the complex was highly surface active but other measurements (viscosity, potentiometry, protons uptake) did not reveal any particular consequence of binding. Between C₁ and C₂ the molecular size decreased (viscosity lowering) upon charge neutralization and collapse about small SDS aggregates (17 SDS molecules per gelatin molecule). Above C₂ a cooperative binding mechanism lead to the formation of SDS aggregates; the complex stretched out and turned strongly hydrophilic (the viscosity increases, low surface activity). At saturation one gelatin molecule bound about 200 SDS molecules. Above the overlap concentration (about 3 wt%) SDS aggregates formed between several gelatin molecules, the viscosity increased continuously with SDS concentration and the binding ratio was lower than in dilute gelatin solutions. A very good correspondence was found between the different analytical data including turbidity, viscosity, surface tension, protons uptake and direct potentiometric SDS binding measurements.     

Swelling of poly(ethylene oxide) gel in aqueous solutions of sodium dodecyl sulfate with added sodium chloride

The swelling behavior of poly(ethylene oxide) (PEO) gels in aqueous solutions of sodium dodecyl sulfate (SDS) with and without NaCl was investigated. In the absence of NaCl, PEO gels with different degrees of cross-linking began to swell from a concentration lower than the critical micelle concentration (cmc) of SDS, then showed sigmoidal enhancements of swelling in a higher SDS concentration region until the degrees of swelling reached maximum values. The SDS concentration at which the swelling began to appear was in reasonable agreement with the critical aggregation concentration (cac) value reported for the aqueous PEO system. For the cases where NaCl was present, the swelling behavior of PEO gel was different from that when NaCl was absent in the following way. The concentrations where the swelling begins to appear, and hence those where the degree of swelling rises steeply, decreased with an increase in NaCl concentration. The ultimate degrees of swelling at higher concentration regions also decreased with an increase in the NaCl concentration. The lowering of the SDS concentrations at which the PEO gel began to swell is in line with the decreases in the cmc of SDS solutions containing NaCl and also with the decreases in the cac of PEO solution. Electronic Publication     

Thermodynamic and aggregation properties of sodium dodecyl sulfate in aqueous binary mixtures of isomeric butanediols

The effect of aqueous binary mixtures of isomeric butanediols on the micellization of sodium dodecyl sulfate has been investigated. Conductivity and fluorescence techniques were employed to determine the critical micellar concentration, the degree of dissociation of the counterions and the aggregation numbers of the surfactants in these binary blends. Differential conductivity plots were employed to distinguish between the cooperative and the stepwise aggregation process of the surfactant in each solvent system. The mass-action model was employed to calculate the hydrophobic and the electrostatic contributions to the Gibbs energy of micellization as well as the monomer and the counterion concentrations in the postmicellar region. The thermodynamic parameters calculated for each system indicate that the micellization process occurs more readily in the presence of cosolvent owing to the formation of mixed micelles. Received: 5 July 2000 Accepted: 25 July 2000     

Hydrophobically end-capped poly (ethylene oxide) urethanes. Part 3: Effect of sodium dodecyl sulphate on their association in aqueous solution

The interactions between sodium dodecyl sulphate (SDS) and three autoassociative polymers (hydrophobically end-capped poly(ethylene oxide) urethanes) are studied by conductimetry, fluorescence, and viscometry. By the first two techniques the interactions are found to increase with the hydrophobicity of the polymer and to be stronger than those observed for a polyethylene oxide (PEO) of the same order of molecular weight. The results seem to be consistent with a model where SDS micelles are formed around hydrophobic chain ends in a first stage, and along the main chain in a second stage. For the more hydrophobic sample already self-aggregated in water and of relatively large reduced viscosity, the addition of SDS induces a loss in viscosity contrary to the less hydrophobic ones and PEO. Such effect may be attributed to the destruction of the chain end association by the formation of SDS micelles around one end in the first stage of the interaction.     

Determination of lead in the presence of morin-5′-sulfonic acid and sodium dodecyl sulfate by adsorptive stripping voltammetry

A simple and sensitive electroanalytical method is developed for the determination of lead by adsorptive stripping voltammetry (AdSV) in the presence of morin-5′-sulfonic acid (MSA) and sodium dodecyl sulfate (SDS). The Pb-MSA complex accumulates on the surface of a hanging mercury drop electrode (HMDE) and peak current is measured by square wave voltammetry (SWV). The complex is reduced at −0.48 V and peak current increases when low concentrations of SDS are added to the sample solution. The experimental variables pH, MSA concentration (C_MSA); accumulation time (t_acc); accumulation potential (E_acc), and SDS concentration (C_SDS), as well as potential interferences, are investigated. Under the optimized conditions (pH 3.2; C_MSA: 0.5 μmol L⁻¹; t_acc: 60 s; E_acc: −0.35 V, and C_SDS: 20 μmol L⁻¹), peak current is proportional to the concentration of Pb(II) over the 0.1-32.0 μg L⁻¹ range, with a detection limit of 0.04 μg L⁻¹. The relative standard deviation for a solution containing 5.0 μg L⁻¹ of Pb(II) solution was 1.5% for seven successive assays. The method was validated by determining Pb(II) in synthetic sea water (ASTM D665) spiked with ICP multi-element standard solution and in certified reference water (GBW08607). Finally, the method was successfully applied to the determination of Pb(II) in tap water and sea water after UV digestion.     

Photoprocesses in sodium decyl sulphate micellar media

The absorption and fluorescence behaviour of thionine dye in sodium decyl sulphate (sds) medium has been studied in detail. The transient spectra and kinetics of decay of semithionine species produced by photoreduction of thionine by ferrous ions has-been studied using flash photolysis technique. The results have been compared with those in neat aqueous medium and in sodium lauryl sulphate (sls) media published earlier. It was found that the decay of semithionine which is kinetically second order in neat aqueous medium becomes pseudo first order as in thesls medium; however unlike in the latter case, the pseudo first order rate decreases with increasing surfactant concentration at all concentrations of ferric ion. The effect of electrolyte concentration on transient semithionine spectra and decay kinetics has also been studied. It was found that with increasing NaCl concentration the transient absorbance decreases and the decay slowly reverts back to second order as in aqueous medium. Insds medium as compared tosls a much higher concentration of NaCl is needed for the reaction to become second order which is attributed to stronger binding of ferric ions to thesds micelles.     

Determination of berberine by measuring the enhanced total internal reflected fluorescence at water/tetrachloromethane interface in the presence of sodium dodecyl benzene sulfonate

A highly sensitive method for determination of berberine is proposed based on the measurements of total internal reflected fluorescence (TIRF) at water/ tetrachloromethane (H₂O/CCl₄) interface. In the pH range of 2.6–5.7, the co-adsorption of the berberine with the anionic surfactants such as sodium dodecyl benzene sulfonate (SDBS), sodium dodecylsulfonate (SDS), and sodium lauryl sulfate (SLS) occurs at the H₂O/CCl₄ interface, resulting in greatly enhanced TIRF signal characterized by the emission at 526 nm when excited with a 351 nm light beam. The enhanced TIRF intensity is in proportion to the berberine concentration in the range 0.2–10.0×10^-7 mol L^-1. The limit of detection is 1.7×10^-9 mol L^-1 (3). It was found that ions such as Ca(II), Cu(II), Fe(III), Cd(II), Mg(II), Zn(II), Pb(II), and Al(III) can be allowed larger than 1.0×10^-4 mol L^-1. Meanwhile, the organic compounds such as vitamin B, saccharine, and amino acid do not display any effect for the present TIRF method even if they are larger than 1.0×10^-2 mol L^-1in high concentration levels (larger than 1.0×10^-5 mol L^-1). The results of determination for synthetic samples were agreement with the desired values, and the ones for tablets were identical with those obtained according to the method of Chinese Pharmacopoeia.     

Synthesis and characterisation of a novel surfactant, sodium geranyl sulphate

An anionic surfactant, sodium geranyl sulphate (sodium 3,7-dimethyl-2,6-octadienyl sulphate), was synthesised from the natural extracted monoterpenol, geraniol. The final product yield is 51.5% after recrystallisation. The cis/trans isomer reduced the surface tension of water to 33 ± 0 mN m⁻¹ and yielded a critical micelle concentration of 89 ± 7 mM.     

Conformational study of papain in the presence of sodium dodecyl sulfate in aqueous medium

The interactions between a globular protein, papain and the anionic surfactant, sodium dodecyl sulfate (SDS) have been investigated in aqueous medium using fluorimetric, circular dichroism, Fourier transform infra-red, UV-vis spectrophotometric, dynamic light scattering, and nuclear magnetic resonance techniques. The conformational change of papain in aqueous solution has been studied in the presence of SDS. The results show the high alpha-helical content and unfolded structure of papain in the presence of SDS due to strong electrostatic repulsion leading to a "necklace and bead model" in protein-surfactant complexes.     

Alterations in phospholipid bilayers caused by sodium dodecyl sulphate/triton X-100 mixed systems

The mechanisms governing the subsolubilizing and solubilizing interaction of sodium dodecyl sulphate (SDS)/Triton X-100 mixtures and phosphatidylcholine liposomes were investigated. Permeability alterations were detected as a change in 5(6)-carboxy-fluorescein (CF) released from the interior of vesicles and bilayer solubilization as a decrease in the static light-scattered by liposome suspensions. Three parameters were described as the effective surfactant/lipid molar ratios (Re) at which the surfactant system a) resulted in 50% of CF release (Re _50%CF); b) saturated the liposomes (Re _SAT;c) led to a complete solubilization of these structures (Re _SOL). From these parameters the corresponding surfactant partition coefficientsK _50%CF,K _SAT andK _SOL were determined. The free surfactant concentrationsS _W were lower than the mixed surfactant CMCs at subsolubilizing level, whereas they remained similar to these values during saturation and solubilization of bilayers in all cases. Although theRe increased as the mole fraction of the SDS rose (X _SDS), theK parameters showed a maximum atX _SDS values of about 0.6, 0.4 and 0.2 forK _50%CF,K _SAT andK _SOL respectively. Thus, the higher the surfactant contribution in surfactant/lipid system, the lower theX _SDS at which a maximum bilayer/water partitioning of mixed surfactant systems added took place and, consequently, the lower the influence of the SDS in this maximum bilayer/water partitioning.Abbreviations PC Phosphatidylcholine - PIPES piperazine-1,4 bis (2-ethanesulphonic acid) - SDS sodium dodecyl sulphate - X _SDS mole fraction of sodium dodecyl sulphate in the mixed system - CF 5(6)-carboxyfluorescein - Re effective surfactant/lipid molar ratio - Re _50%CF effective surfactant/lipid molar ratio for 50% CF release - Re _SAT effective surfactant/lipid molar ratio for bilayer saturation - Re _SOL effective surfactant/lipid molar ratio for bilayer solubilization - S _W surfactant concentration in the aqueous medium - S _{W, 50%CF} surfactant concentration in the aqueous medium for 50% CF release - S _{W, SAT} surfactant concentration in the aqueous medium for bilayer saturation - S _{W, SOL} surfactant concentration in the aqueous medium for bilayer solubilization - S _B surfactant concentration in the bilayers - K bilayer/aqueous phase surfactant partition coefficient - K _50%CF bilayer/aqueous phase surfactant partition coefficient for 50% CF release - K _SAT bilayer/aqueous phase surfactant partition coefficient for bilayer saturation - K _SOL bilayer/aqueous phase surfactant partition coefficient for bilayer solubilization - PL phospholipid TLC-FID, thin-layer chromatography/flame ionization detection system - PI polydispersity index - CMC critical micellar concentration - r ² regression coefficient     

Denaturation of jack-bean urease by sodium n-dodecyl sulphate: a kinetic study below the critical micelle concentration

Kinetics of urease denaturation by anionic surfactant (sodium n-dodecyl sulphate, SDS) at concentrations below the critical micelle concentration (CMC) is investigated spectrophotometrically at neutral pH and the corresponding two-phase kinetic parameters of the process are estimated from a three-state reversible process using a binomial exponential relation based on the relaxation time method as: Using a prepared computer program, the experimental data are properly fitted into a binomial exponential relation, considering a two-phase denaturation pathway including a kinetically stable folded intermediate formed at SDS concentration of 1.1 mM. Forward and backward rate constants are estimated as: k(1)=0.2141+/-4.5 x 10(-3), k(2)=5.173 x 10(-3)+/-8.3 x 10(-5), k(-1)=0.09432+/-3.6 x 10(-4) and k(-2)=2.079 x 10(-3)+/-5.6 x 10(-5)s(-1) for the proposed mechanism. The rate-limiting step as well as the reaction coordinates in the denaturation mechanism are established. The mechanism involves formation of a kinetically stable folded native like intermediate through the electrostatic interactions. The intermediate was found to be more stable even than the native form (by about 9 kJmol(-1)) and still hexamer, because no loss of amplitude was observed. Electrophoresis experiments on the native and surfactant/urease complexes indicated a higher mobility for the kinetically folded native like intermediate.     

Resonance light-scattering method for the determination of BSA and HSA with sodium dodecyl benzene sulfonate or sodium lauryl sulfate

A new resonance light-scattering (RLS) assay of proteins such as bovine serum albumin (BSA) and human serum albumin (HSA) is presented. In the medium of phosphoric acid (pH=2.6), the weak RLS of sodium dodecyl benzene sulfonate (SDBS) or sodium lauryl sulfate (SLS) can be greatly enhanced by proteins, owing to interaction between the protein and the anionic surfactant and formation of an associate. The RLS intensity of the SDBS–protein system is stronger than that of the SLS–protein system under same experimental conditions. It is considered that the synergistic resonance caused by the absorption of both protein and SDBS could produce strong RLS, while absorption of protein only in the SLS system could cause relatively weak RLS. The enhanced intensity of RLS is proportional to the concentration of the protein. If SDBS is used as the probe the linear range is 7.5×10^–9–1.5×10^–5 g mL^–1 for BSA and 1.0×10^–8–1.0×10^–5 g mL^–1 for HSA. The detection limits are 1.8 and 2.8 ng mL^–1, respectively. When SLS is used as the probe the linear range is 2.0×10^–8–1.0×10^–5 g mL^–1 and 2.5×10^–8–1.0×10^–5 g mL^–1 for BSA and HSA, respectively, and the detection limits are 12.8 and 21.6 ng mL^–1, respectively. The biological mimics samples are synthetic concoctions of BSA and HSA with some interferents. In these samples, the concentration of interferents is higher than the concentration normally existing in organisms. The samples were determined satisfactorily.     

十二烷基硫酸钠与羟乙基纤维素的相互作用

本文用表面张力(γ)和电导率(κ)方法研究了阴离子表面活性剂十二烷基硫酸钠(SDS)与天然纤维素的水溶性改性物羟乙基纤维素(HEC)的相互作用.实验结果表明,SDS-HEC溶液的γ-lgcSDS曲线和κ～CSDS曲线均呈现双拐点特征,并且γ-lgcSDS曲线上两个SDS临界浓度值(c1 )γ及(c2)γ,与κ～CSDS...     

The dissolution of microcrystalline cellulose in sodium hydroxide-urea aqueous solutions

It has been reported that cellulose is better dissolved in NaOH-water when a certain amount of urea is added. In order to understand the mechanisms of this dissolution and the interactions between the components, the binary phase diagram of urea/water, the ternary urea/NaOH/water phase diagram and the influence of the addition of microcrystalline cellulose in urea/NaOH/water solutions were studied by DSC. Urea/water solutions have a simple eutectic behaviour with a eutectic compound formed by pure urea and ice (one urea per eight water moles), melting at −12.5 °C. In the urea/NaOH/water solutions, urea and NaOH do not interact, each forming their own eutectic mixtures, (NaOH + 5H₂O, 4H₂O) and (urea, 8H₂O), as found in their binary mixtures. When the amount of water is too low to form the two eutectic mixtures, NaOH is attracting water at the expense of urea. In the presence of microcrystalline cellulose, the interactions between cellulose and NaOH/water are exactly the same as without urea, and urea is not interacting with cellulose. A tentative explanation of the role of urea is to bind water, making cellulose-NaOH links more stable. Member of the European Polysaccharide Network of Excellence (EPNOE),     

Concentration of polyaromatic hydrocarbons in water to sodium dodecyl sulfate-gamma-alumina admicelle

Polyaromatic hydrocarbons (PAHs) in water were concentrated into sodium dodecyl sulfate (SDS)-gamma-alumina and di-2-ethylhexyl sodium sulfosuccinate (Aerosol-OT, AOT)-gamma-alumina admicelles. The comparison of the binding constants (Kad[={adsorbed concentration of the solute (mol/g surfactant)}/{the concentration in the bulk aqueous phase (mol/ml)}] indicated almost the same extraction abilities of the both admicelles. However, better and more reproducible recovery was obtained in the concentration of PAHs into the SDS-gamma-alumina admicelle. PAHs in tobacco smoke that were trapped in water were successfully concentrated into SDS-gamma-alumina admicelle for the HPLC analysis.     

A direct calorimetric determination of denaturation enthalpy for lysozyme in sodium dodecyl sulfate

Thermodynamics of the interaction between sodium dodecyl sulfate (SDS) with lysozyme were investigated at pH 7.0 and 27 °C in phosphate buffer by isothermal titration calorimetry. A new method to follow protein denaturation, and the effect of surfactants on the stability of proteins was introduced. The new solvation model was used to reproduce the enthalpies of lysozyme–SDS interaction over the whole range of SDS concentrations. The solvation parameters recovered from the new equation, attributed to the structural change of lysozyme and its biological activity. At low concentrations of SDS, the binding is mainly electrostatic, with some simultaneous interaction of the hydrophobic tail with nearby hydrophobic patches on the lysozyme. These initial interactions presumably cause some protein unfolding and expose additional hydrophobic sites. The enthalpy of denaturation is 160.81 ± 0.02 kJ mol⁻¹ for SDS.     

水溶性壳聚糖降血脂作用的化学机理 (II)水溶性壳聚糖及其氨化衍生物对硬脂酸钠、十二烷基硫酸钠结合能力

体外测定了水溶性壳聚糖及其氨化衍生物对硬脂酸钠、十二烷基硫酸钠的结合能力及其影响因素．结果表明，水溶性壳聚糖结合硬脂酸钠、十二烷基硫酸钠的能力主要取决于其阳离子化程度．修饰后的壳聚糖对硬脂酸钠、十二烷基硫酸钠结合能力的增强，说明引入更多的胺基或铵基有利于对硬脂酸钠、十二烷基硫酸钠的结合，氨基上烷基与硬脂酸钠、十二烷基硫酸钠碳链之间也应当产生疏水相互作用．