Solubilization of Cationic Hemicyanine Dyesin Anionic Surfactant Micelles: A Partitioning Study

Summary.  Cationic hemicyanine dyes of the 1-methyl-4-(4-(di-n-alkylamino)-styryl) pyridinium betain type (alkyl group=methyl to butyl) have been investigated by differential spectroscopy in order to ascertain their solubilization in aqueous micellar solution of sodium dodecylbenzene sulfonate (SDBS). The differential absorption spectra were recorded as a function of surfactant concentration at 25.0°C. Thermodynamic parameters were calculated from partition coefficient data. The results show that cationic hemicyanine dyes are solubilized at the micellar surface, indicating an electrostatic interaction between dyes and surfactant micelles. Received October 15, 1999. Accepted February 14, 2000     

Effect of Crown Ether Macrocycle on the Methylation of the Thioamide Derivatives of Benzo-15-crown-5 and Veratrole

It was shown that benzo-15-crown-5 ether has an effect on the methylation of the thioamide derivatives, leading to the formation of the nitriles of carboxylic acids.     

pH Induced Partitioning and Interactions of Ciprofloxacin Hydrochloride with Anionic Surfactant Sodium Dodecyl Sulfate Using Ultraviolet and Fourier Transformed Infrared Spectroscopy Study

Ultraviolet (UV) and Fourier transformed infrared (FTIR) spectra of ciprofloxacin hydrochloride (Cpf) were studied under different pH conditions. The effect of aqueous, strong acidic, (pH 0.5–1.0) and a basic (pH 9.2) conditions on spectral behavior of Cpf was investigated in aqueous as well as in micellar environment of sodium dodecyl sulfate (SDS). Cpf shows partitioning from aqueous to micellar phase in a strong acidic as well as in a basic environment. Cpf shows no partitioning or binding to micelle in aqueous phase. Conductivity studies show that critical micelle concentration of SDS is increased with increasing concentration of Cpf. Different sites are responsible for binding under different pH conditions.     

Shape and Structure Formation of Mixed Nonionic–Anionic Surfactant Micelles

Aqueous solutions of a nonionic surfactant (either Tween20 or BrijL23) and an anionic surfactant (sodium dodecyl sulfate, SDS) are investigated, using small-angle neutron scattering (SANS). SANS spectra are analysed by using a core-shell model to describe the form factor of self-assembled surfactant micelles; the intermicellar interactions are modelled by using a hard-sphere Percus–Yevick (HS-PY) or a rescaled mean spherical approximation (RMSA) structure factor. Choosing these specific nonionic surfactants allows for comparison of the effect of branched (Tween20) and linear (BrijL23) surfactant headgroups, both constituted of poly-ethylene oxide (PEO) groups. The nonionic–anionic surfactant mixtures are studied at various concentrations up to highly concentrated samples (ϕ ≲ 0.45) and various mixing ratios, from pure nonionic to pure anionic surfactant solutions. The scattering data reveal the formation of mixed micelles already at concentrations below the critical micelle concentration of SDS. At higher volume fractions, excluded volume effects dominate the intermicellar structuring, even for charged micelles. In consequence, at high volume fractions, the intermicellar structuring is the same for charged and uncharged micelles. At all mixing ratios, almost spherical mixed micelles form. This offers the opportunity to create a system of colloidal particles with a variable surface charge. This excludes only roughly equimolar mixing ratios (X≈ 0.4–0.6) at which the micelles significantly increase in size and ellipticity due to specific sulfate–EO interactions.     

Effect of Surfactant Concentration and Operating Temperature on the Drop Size Distribution of Silicon Oil Water Dispersion

The effect of sodium lauryl sulphate (SLES) surfactant and the operating temperature on the drop size distribution of a 350 cSt Dow Corning 200 series oil water dispersion was successfully studied. The dispersion was prepared in a standard 6 litres mixing tank at different impeller speeds. A measurement of the SLES critical micelle concentration (CMC) at 25°C was carried out. The interfacial tension of silicon oil water under various SLES concentration at a temperature range of 25 to 80°C was accomplished. Results showed that the interfacial tension of the silicon oil water decreased as the operating temperature increased and as the surfactant concentration increased. When the operating temperature was increased at the highest SLES concentration tested, a decrease of d ₃₂ was observed. This was attributed to the possibility of hydration of the surfactant at high temperature. Same behavior was observed when measuring the drop size distribution at constant temperature but different SLES concentration. It was found that the mean drop size decreases with mixing time. Different slopes of the change of the median drop size with time were obtained for different SLES concentration. For the same concentration, the slope changes after 1 hour. The degree change of the slope is due to the change of interfacial area of the oil water as mixing time elapsed and the depletion of the surfactant concentration.     

Determination of Anionic Surfactant in Fresh Water and in Sea Water

Ion pairs formed from suitable cationic dye and anionic surfactant in water were separated by solvent extraction. The extracts were used subsequently for spectrophotometric determinations. The extraction of ion pairs with various combinations is described. Of the dyes and solvents examined, ethyl violet and p-xylene are the most useful combination as the cationic dye and extraction solvent. The extracts are determined spectrophotometrically at 611.5 nm; the molar absorptivity is 1, 01 × 10⁵ M^?1 cm^?1. The detection limit is 1.4 ppb in water. The method is simple, rapid and sensitive. It can also be applied to the determination of anionic surfactants in sea water.     

新型阴离子表面活性剂的合成及其反胶束体系的酶催化性能

合成了未见文献报道的新型阴离子表面活性剂磷酸二[(2-乙基己氧基)乙基]酯钠(sodium di-[(2-ethylhexyloxy)ethyl] phosphate,DEEPA);以核磁共振氢谱和红外光谱表征了它的结构;在DEEPK/异辛烷反胶束体系中进行了脂肪酶催化橄榄油水解反应实验.结果表明,该反胶束体系的催化活性优于AOT反胶束体系,更优于油-水双相中的酶催化反应,最大活性是油-水双相体系的1.86倍.     

Nafion功能化介孔催化剂上苯甲醚/苯甲酰氯酰基化反应研究

苯甲醚/苯甲酰氯的酰基化产物4-甲氧基二苯甲酮是多种精细化工产品的重要中间体. 本工作主要介绍了Nafion负载型SBA-15, SBA-16及Me-SBA-15介孔超强酸催化剂的制备及其在苯甲醚/苯甲酰氯酰基化反应中的应用. 实验结果表明, 单位时间单位Nafion活性位上的苯甲酰氯转化数高于传统HBeta沸石和硫酸氧化锆, 且载量的增加能显著提高酰基化催化性能. 甲基修饰的Me-SBA-15介孔材料明显改善了催化剂表面的疏水性能, 有效减缓了多聚芳烃副产物的生成, 反应的转化率得到大幅提高. 相对一维孔道结构的介孔SBA-15而言, 三维笼状结构的SBA-16对反应物及产物分子具有更好的扩散性能, 该结构优势由酰基化反应的高初始活性得以充分体现. 在整个反应过程中, 该类催化剂对4-甲氧基二苯甲酮具有专一的选择性.     

Effect of Protic Ionic Liquid and Surfactant Structure on Partitioning of Polyoxyethylene Non‐ionic Surfactants

The partitioning constants and Gibbs free energies of transfer of poly(oxyethylene) n‐alkyl ethers between dodecane and the protic ionic liquids (ILs) ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) are determined. EAN and PAN have a sponge‐like nanostructure that consists of interpenetrating charged and apolar domains. This study reveals that the ILs solvate the hydrophobic and hydrophilic parts of the amphiphiles differently. The ethoxy groups are dissolved in the polar region of both ILs by means of hydrogen bonds. The environment is remarkably water‐like and, as in water, the solubility of the ethoxy groups in EAN decreases on warming, which underscores the critical role of the IL hydrogen‐bond network for solubility. In contrast, amphiphile alkyl chains are not preferentially solvated by the charged or uncharged regions of the ILs. Rather, they experience an average IL composition and, as a result, partitioning from dodecane into the IL increases as the cation alkyl chain is lengthened from ethyl to propyl, because the IL apolar volume fraction increases. Together, these results show that surfactant dissolution in ILs is related to structural compatibility between the head or tail group and the IL nanostructure. Thus, these partitioning studies reveal parameters for the effective molecular design of surfactants in ILs.     

Rheological Study of Interactions between Anionic Guar and Oppositely Charged Surfactant

We have studied the interactions between anionic carboxymethyl guar (CMG) and oppositely charged surfactant: dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), cetyltrimethylammonium bromide (CTAB), and gemini surfactants (16-4-16), using rheological measurements. In the present study, two competing forces, electrostatic interaction and hydrophobic interaction, have been identified as important factors. Various types of structure formed on the anionic CMG chains are qualitatively discussed in comparison. For example, C₁₂TAB and gemini surfactant tend to form polymer-bound aggregates, whereas the C₁₆TAB tend to form the polymer-associated architecture. Furthermore, possible mechanisms based on the experimental results to elucidate these interesting phenomena have been proposed and discussed.     

Solubilization and Separation of Dicarboxylic Acids by Surfactant Micelles and Polyelectrolytes

Semi‐equilibrium dialysis (SED) and micellar enhanced ultra filtration (MEUF) methods are used to determine the extent of solubilization of water‐insoluble compounds by surfactant and polyelectrolyte. In this study, solubilization of ortho‐, meta‐ and para‐phthalic acids (OPA, MPA and TPA), 1,4‐ and 2,6‐naphthalene dicarboxylic acids (1,4‐NDCA and 2,6‐NDCA) into hexadecylpyridinium chloride (CPC), and the behavior of these acids to bind to the polyelectrolyte ionizable groups were investigated at 25 °C, using SED and MEUF methods. Polydimethyldiallylammonium chloride (PDMDAAC) is used in this study. It was found that the solubilization of organic acids decreases with increasing the solute mole fractions in micelles. Also, the best separation occurs at the lowest concentration of the phthalate ions and high concentrations of either CPC or PDMDAAC. The results support the idea of charge interaction between the anionic dicarboxylate groups and cationic surfactant or polyelectrolyte. The results also show that the presence of a second phenyl ring does not greatly affect the solubilization behavior of the acids.     

Ionization by pH and Anionic Surfactant Binding Gives the Same Thickening Effects of Crosslinked Polyacrylic Acid Derivatives

Physical properties of aqueous solutions of hydrophobically modified crosslinked polyacrylic acids change quite extensively as the polymer is charged up. A study is carried out concerning the similarities between two polymer ionization processes, that is, by pH increment and anionic surfactant addition. The two processes charge the polymer by distinctly different mechanisms. At sufficiently high pH the carboxylic groups of the polymer are virtually all ionized and the polymer is, therefore, fully charged. The effective repulsion among the charged groups due to the entropy of the counterions promotes an increased stiffness as well as an expansion of the polymer particles. We investigate here how the ionization and swelling will be if, instead of high pH, the polymer is at low pH conditions but associated to ionic surfactants. Surfactants associate to the polymer both in a noncooperative way by the binding of individual surfactant molecules and in a cooperative way as micelles since the polymer promotes surfactant self-assembly. This binding leads to a highly charged polymer-surfactant complex and leads to an osmotic swelling as well. The swelling and the gelation were monitored by rheology and dynamic light scattering, of polymer solutions by varying the pHs and adding ionic surfactants at low pH. The results show that ionization by surfactants and by pH lead to approximately the same gelation degree, as can be seen by similar viscosity values. Both processes result in dramatic viscosity increases, up to 8 orders of magnitude. More hydrophobic surfactants, with longer alkyl chain, are shown to be more efficient as enhancers of swelling and gelation. The network that is formed at high pH or at sufficiently high concentration of surfactant can be weakened or even disrupted if monovalent or divalent salts are added, demonstrating the role of counterion entropy.     

Synthesis of Trinorditerpenoid Derivatives and Evaluation of Antimicrobial and Cytotoxic Activity

The synthesis of optically active trinorditerpenes was carried out, and their antimicrobial and antitumor activity was tested. The synthetic derivative 12-hydroxypodocarpa-8,11,13-triene (7) showed GI₅₀ at 6.6 µM against breast cancer MDA-MB-435 (LC₅₀ = 50.9 µM and log10 GI₅₀ = −5.18). The 12-acetyloxypodocarpa-8,11,13-triene (8) showed GI₅₀ at 12.1 µM against leukemia RPMI-8226 (LC₅₀ = 76.1 µM and log₁₀GI₅₀ = −4.92).__________Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 255–259, May–June, 2005.     

Extraction Separation of BSA in Aqueous Two-Phase Systems of Anionic and Cationic Surfactant Mixtures

Aqueous two-phase systems (ATPS) are formed in mixtures of sodium dodecylsulfate (SDS), cetyltrimethyl ammonium bromide (CTAB), and sodium bromide (NaBr). Two different kinds of ATPS appear when CTAB and SDS surfactants are in excess, respectively. Such ATPS may provide a new, useful partitioning system for separation of bovine serum albumin (BSA). The partitioning of BSA was studied in these systems. The results show that the partitioning is affected by the electrical property, the hydrophobicity and the structure of liquid crystal (LC), which exists in the top phase of the ATPS. BSA is extracted into the top phase with higher distribution coefficient when LC and BSA are oppositely charged. The hydrophobicity of LC, which can be improved by increasing the length of alkyl group, enhances the distribution coefficient. The hydrophobicity of lamellar LC and hexagonal LC is stronger than that of cubic LC, which causes extractive capability of the former is higher than the latter.     

阴阳离子型表面活性剂双水相萃取色氨酸衍生物和牛血清白蛋白

溴化十二烷基三乙胺（Ｃ１２ＮＥ）和十二烷基硫酸钠（ＳＤＳ）在一定条件下混合可以形成具有清晰界面的两个水相，称为阴阳离子型表面活性剂双水相。作者研究了利用该双水相萃取３种色氨酸衍生物和牛血清白蛋白的可能性．文中采用工作曲线校正扣除表面活性剂背景的影响，萃取结果准确可信。     

阴阳离子表面活性剂混合体系对原油的乳化及增粘行为

利用阴阳离子表面活性剂复配技术,实现了高含水量原油体系的乳化及增粘. 通过调整表面活性剂分子结构,解决了阴阳离子表面活性剂复配体系在油田模拟水中的溶解度问题. 确定了相关体系高含水量油包水（W/O）乳状液的表面活性剂浓度,研究了可以产生高含水量油包水乳状液的油水混合体积比范围,并研究了温度、pH值、油水混合比例和离子强度对乳化及增粘作用的影响. 获得了一系列具有优良乳化效果和乳状液稳定性的体系,其中部分体系粘度可增大80倍. 这对于三次采油提高采收率有重要意义.     

Phase Diagrams and Solubilization of Chlorocarbons in Chlorocarbon/Water/Anionic Surfactant/Alcohol Microemulsion Systems

The solubilization abilities of various chlorocarbons were investigated in a middle phase microemulsion system anionic surfactant sodium dodecyl sulfate (SDS) or sodium dodecyl sulfonate (AS)/n-butanol/chlorocarbon/brine with a ε-β fishlike phase diagram. The composition of the balanced interfacial layer of the microemulsion and some other parameters are calculated. The result shows that surfactant little dissolves in water and chlorocarbon phases, while alcohol mainly dissolves in water and oil phases besides in the interfacial layer. The order of the solubilization ability is dichloromethane (CH₂Cl₂) ～ carbon tetrachloride (CCl₄) > tetrachloroethylene (PCE) > o-dichloro-benzene. The solubility of the alcohol decreases with the increase in NaCl concentrations, which should be compensated by the increase in the amount of alcohol as cosolvent (Cs), so as to maintain the balanced interfacial layer. Salinity has little effect on the partition of surfactant between phases.     

阴阳离子表面活性剂混合体系对原油的乳化及增粘行为

利用阴阳离子表面活性剂复配技术,实现了高含水量原油体系的乳化及增粘.通过调整表面活性剂分子结构,解决了阴阳离子表面活性剂复配体系在油田模拟水中的溶解度问题.确定了相关体系高含水量油包水(W/O)乳状液的表面活性剂浓度,研究了可以产生高含水量油包水乳状液的油水混合体积比范围,并研究了温度、pH值、油水混合比例和离子强度对乳化及增粘作用的影响.获得了一系列具有优良乳化效果和乳状液稳定性的体系,其中部分体系粘度可增大80倍.这对于三次采油提高采收率有重要意义.     

Synthesis of Thiazolidine and Thiophene Derivatives for Evaluation as Anticancer Agents

The non-isolated adducts (3a,b) were used as key intermediates to synthesize some novel thiazolidine and thiophene derivatives. Compound (4) exhibited a remarkable antitumor activity against EAC cells compared with the Doxorubicin as a positive control.