Comparative Study on the Structure of Water in Reverse Micelles Stabilized with Sodium Bis(2-ethylhexyl) Sulfosuccinate or Sodium Bis(2-ethylhexyl) Phosphate in n-Heptane

The microstructure of water solubilized in H(2)O/surfactant/n-heptane ternary systems has been investigated by employing (1)H-NMR and FT-IR spectroscopic techniques. Two reverse micellar systems were prepared and studied, i.e., sodium bis(2-ethylhexyl) sulfosuccinate in n-heptane (H(2)O/AOT/n-heptane) and sodium bis(2-ethylhexyl) phosphate in n-heptane (H(2)O/NaDEHP/n-heptane). (1)H-NMR data showed that the chemical shift of water protons for the AOT and NaDEHP reverse micelles varied downfield and upfield, respectively, with an increase of the water content. The opposite shift directions with increasing water content are interpreted as due to a composition change of the solubilized water associated with head-groups and sodium counterions in reverse micellar systems. On the basis of deconvolution results of FT-IR spectra, a four-component model is proposed to interpret the FT-IR and (1)H-NMR results. Copyright 2000 Academic Press.     

Properties of Fluids Composed of Polyelectrolyte and Double-Chain Anionic Surfactant: Branched Polyethyleneimine and Sodium bis(2-ethylhexyl) Sulfosuccinate

The properties of fluids composed of branched polyethyleneimine (PEI) and sodium bis(2-ethylhexyl)sulfosuccinate (AOT) were investigated by steady-state fluorescence, dynamic light scattering, turbidity, conductivity, and pH measurements. Light scattering studies show that addition of PEI into AOT solution can significantly decrease the aggregate size of AOT, however, the aggregate volume of AOT/PEI complexes slightly changes with the [AOT] or [PEI]. ¹H NMR spectroscopy measurements show the line shape and chemical shifts of the protons around the head of AOT severely change with increase of [PEI] or [AOT]. It indicates that the interaction of AOT and PEI mainly occurs around the head of AOT.     

傅立叶变换红外光谱对琥珀酸-2-乙基己基磺酸钠非极性溶液中 反胶束结构的研究

利用衰减全反射傅立叶变换红外光谱(ATR-FTIR), 对琥珀酸-2-乙基己基磺酸钠(AOT)的反胶束结构进行了研究. 通过对红外光谱进行二维相关分析, 可以分辨出AOT分子在CCl4溶液中具有旁式和反式两种结构, 随着温度的升高, 旁式结构向反式结构转变, 反胶束体系能量降低, 38 ℃时, 反式结构所占比例达到最大值, 此时反胶束具有最大尺寸, 并处于最稳定的能量状态. 随着温度的进一步升高, 反式结构开始向旁式结构转变, 反胶束尺寸变小, 直至最后反胶束被破坏.     

琥珀酸二油脂磺酸钠的合成、结构及水合作用

通过增加磺化反应时间, 补加NaHSO3, 以液液萃取法代替重结晶法提纯产品, 大幅度提高了合成琥珀酸二油酯磺酸钠(SDSS)的产品得率. 用量子化学密度泛函理论以及B3LYP/6-31G*方法全优化计算了SDSS阴离子的几何和电子结构, 确证其反反-异构体较为稳定, 解释了以相关反胶束提取蛋白质的实验事实. 还在B3LYP/6-31G*水平上研究了SDSS阴离子的水合作用, 报道了SDSS阴离子水合物的几何、电子结构和水合能, 阐述了SDSS阴离子的亲水机理.     

丁二酸二异辛酯磺酸钠对微乳液毛细管电泳分离蛋白质的影响

本研究探讨了在生理条件下,同时分离酸性和碱性蛋白质的毛细管电泳方法。在120mmol/L十二烷基硫酸钠(SDS) 5mmol/L丁二酸二异辛酯磺酸钠(AOT) 110mmol/L正辛烷 500mmol/L正丁醇 3mmol/LNa2B4O7 3mmol/LNaH2PO4(pH6.7)的微乳体系中,分离电压20kV,25min内完成核糖核酸A、细胞色素C、牛血清蛋白、α-淀粉酶和β-乳球蛋白5种不同酸、碱性蛋白质基线分离;分离效率为7.8×105～4.4×105/m;迁移时间的RSD为1.5%(n=11)。并讨论了蛋白质在AOT组成的复配微乳体系中的分离机制。     

Raman spectra of bis(2-ethylhexyl) hydrogen phosphorodithioate

Conclusions The Raman spectra of bis(2-ethylhexyl) hydrogen phosphorodithioate were studied. The frequencies of the principal vibrations of the acid phosphorodithioate were assigned.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1267–1271, June, 1976.The authors thank coworkers of the extraction laboratory for the samples and I. K. Korobeinicheva for making it possible to record the spectra on the PH-1 instrument.     

An experimental setup for isobaric heat capacities for viscous fluids at high pressure: Squalane,bis(2-ethylhexyl) sebacate and bis(2-ethylhexyl) phthalate

A high-pressure flow calorimeter has been used to determine highly accurate isobaric heat capacities for different viscous fluids, squalane (SQN), bis(2-ethylhexyl) sebacate (DEHS) and bis(2-ethylhexyl) phthalate (DEHP) from T = (293.15 to 353.15) K and up to 30 MPa. The experimental device was adapted for viscous liquids at high pressure and it can measure heat capacities with an estimated total uncertainty better than 1%. The isobaric heat capacity values were analysed together with their temperature and pressure dependences. In addition, a fitting equation of the experimental molar isobaric heat capacity for these viscous fluids as a function of temperature and pressure was proposed.     

Gel formation in extraction of terbium by bis(2-ethylhexyl) hydrogen phosphate

Gel formation has been studied in the bulk of the organic phase and in the interphase of the Tb(OH)₃ (Tb(NO₃)₃)-bis(2-ethylhexyl) hydrogen phosphate-decane-water systems. In the Tb(OH)₃-HDEHP-decane-water system, gel formation is observed over the bulk of the organic phase when $c_{HDEHP} /c_{Tb(OH)_3 } $ ≤ 1.8. A structured layer several tens of micrometers thick is formed when an aqueous Tb(NO₃)₃ solution is in contact with an HDEHP solution in decane. The share of the structured layer in the interphase increases from 0 to about 90% as the terbium concentration increases. The structured layer that appears during the extraction of terbium by HDEHP in decane consists of both amorphous portions and portions dominated by acicular crystals.     

Sodium and strontium extraction by di(2-ethylhexyl)phosphate: Mechanisms and equilibria

Extraction of sodium and strontium by di(2-ethylhexyl)phosphoric acid (HA or HDEHP) in benzene was examined over the complete loading range from trace concentration to reagent saturation, i.e., formation of the normal salt NaA (NaDEHP) or SrA₂ (Sr(DEHP)₂). Trace strontium extraction from 0·50 and 4·00 M NaNO₃ by mixtures of HA and its sodium salt, NaA, was examined from zero to 100% NaA. Extraction equilibrium curves (organic vs. aqueous concentration), hydrogen ion and reagent-concentration dependences have been examined in all cases, and, for strontium extraction by mixed HA-NaA, sodium-ion dependence was examined. The data indicate that the reaction for sodium extraction by the acid dimer, (HA)₂, is Na⁺ + 2(HA)₂·3HA + H⁺ up to 25% NaA. Additional sodium extraction results in tetramer destruction to yield the salt NaA. The reaction for strontium extraction by (HA)₂ is similar: Sr²⁺ + SrA₂·4HA + 2H⁺. Also similarly, ultimate loading leads to the salt SrA₂. Both these salts are polymerized. Trace strontium extraction by mixed HANaA is most readily described by the equation: Sr²⁺ + (n/y)(aHA·bNaA)_y (1/x)(SrA₂·(n − 2))(αHA·βNaA))_x + iH⁺ + jNa⁺, where the extractant is characterized as a mixed, y-fold polymer containing a fraction of HA and b fraction of NaA. The data indicate that strontium extracts as SrA₂·4HA at least up to organic-phase compositions of 40% NaA. At higher NaA concentrations the interpretation is less certain but suggests the extraction of strontium into NaA micelles.     

Separation of niobium and tantalum by extraction chromatography with bis(2-ethylhexyl)phosphoric acid

A novel method is developed for the reversed-phase extractive chromatographic separation of niobium and tantalum with bis(2-ethylhexyl)phosphoric acid. Niobium is extracted from 1-10M hydrochloric acid and can be stripped with 3M sulphuric acid containing 2% hydrogen peroxide. Tantalum is extracted from 0.1-2M hydrochloric acid and can be stripped with 0.1M hydrochloric acid containing 2M tartaric acid. It is possible to separate niobium and tantalum, in different ratios, from multicomponent mixtures.     

Structure and composition of the polymeric products of UO2SO4 extraction by benzene solutions of uranyl bis(2-ethylhexyl) phosphate

UO₂SO₄ extracts obtained from neutral aqueous solutions of this compound and benzene solutions of uranyl bis(2-ethylhexyl) phosphate have been studied by³¹P NMR and IR spectroscopy. It has been found that in the presence of donor-active additions L=TBP or DOSO the recurrent unit of the polymer (UO₂X₂)_p adds one or two UO₂SO₄ molecules to form {UO₂X₂·UO₂SO₄·2L} and {UO₂X₂·2UO₂SO₄·6L} units. The structure of these units has been established. It has been shown that the distribution of UO₂SO₄ molecules along the polymer chain is random. Institute of Catalysis, Siberian Branch, Russian Academy of Sciences. Translated fromZhumal Struktumoi Khimii, Vol. 36, No. 4, pp. 682–689, July–August, 1995. Translated by L. Smolina     

Extraction equilibria of some transition metal ions by bis(2-ethylhexyl)phosphinic acid

Measurements of dimerization constants (K(d,HR)) and distribution constants (K(D,HR)) of bis(2-ethylhexyl)phosphinic acid (PIA-8) in three kinds of organic diluents were carried out by a potentiometric two-phase titration technique at 298 +/- 0.1 K. Extraction of iron(III), zinc(II), copper(II), manganese(II), cadmium(II), cobalt(II) and nickel(II) by PIA-8 from 1.0 mol dm(-3) ammonium sulfate solution into heptane was investigated as a function of pH and extractant concentration. The data have been analyzed both graphically and numerically to determine the stoichiometry of extracted species and their extraction constants. The extracted metal species were found to be FeR(3) . 2HR for iron(III), ZnR(2) and ZnR(2) . 3HR for zinc(II), CuR(2) . HR and CuR(2) . 5HR for copper(II), MnR(2) . 2HR and MnR(2) . 3HR for manganese(II), CdR(2) . 3HR for cadmium(II), CoR(2) . HR and CoR(2) . 4HR for cobalt(II) and NiR(2) . 3HR and NiR(2) . 6HR for nickel(II), respectively.     

Solvent extraction of rare-earth metals with bis(2-ethylhexyl)phosphinic acid

 The extraction behavior of tervalent rare-earth metals (Ln) using a heptane solution containing bis(2-ethylhexyl)phosphinic acid (PIA-8, HR) from 0.1 mol/dm³ sodium perchlorate media was studied. The pH_0.5 values and separation factors obtained were compared among the metals. The stoichiometry of the extracted species and the extraction constants for the present aqueous/heptane system were determined by slope analysis. It is demonstrated that the rare-earth metals were extracted as monomers LnR₃⋅mHR (m=3, 4, 5 or 6), and the extracted species could be stripped into a relatively low concentrated hydrochloric acid. PIA-8 was found to be the most selective extractant for the mutual separation of rare-earth metals among the other phosphinic acids reported. Received: 27 February 1996/Revised: 13 May 1996/Accepted: 21 May 1996     

Integral physicochemical properties of reverse micelles of sodium bis(2-ethylhexyl) sulfosuccinate (AOT)

The effect the degree of hydration has on optical and electrophysical properties of water/AOT/n-hexane system is studied. It is found that AOT reverse micelles form aggregates whose dimensions grow along with the degree of hydration and temperature. Aggregation enhances their electrical conductivity and shifts the UV spectrum of AOT reverse emulsions to the red region. Four states of water are found in the structure of AOT reverse micelles.     

Gas-Phase Stability of Negatively Charged Organophosphate Metabolites Produced by Electrospray Ionization and Matrix-Assisted Laser Desorption/Ionization

The formation mechanisms of singly and multiply charged organophosphate metabolites by electrospray ionization (ESI) and their gas phase stabilities were investigated. Metabolites containing multiple phosphate groups, such as adenosine 5'-diphosphate (ADP), adenosine 5'-triphosphate (ATP), and D-myo-inositol-1,4,5-triphosphate (IP₃) were observed as doubly deprotonated ions by negative-ion ESI mass spectrometry. Organophosphates with multiple negative charges were found to be unstable and often underwent loss of PO₃ ^–, although singly deprotonated analytes were stable. The presence of fragments due to the loss of PO₃ ^– in the negative-ion ESI mass spectra could result in the misinterpretation of analytical results. In contrast to ESI, matrix-assisted laser desorption ionization (MALDI) produced singly charged organophosphate metabolites with no associated fragmentation, since the singly charged anions are stable. The stability of an organophosphate metabolite in the gas phase strongly depends on its charge state. The fragmentations of multiply charged organophosphates were also investigated in detail through density functional theory calculations.

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