有机铵盐对FC-SAA表面活性及溶度的影响

测定了一系列有机铵盐与一种全氟烷磺酸盐１：１混合体系水 溶液的表面张力，由此研究有机铵盐对碳氟表面活性剂表面活性及溶度的影响，导出应用于此种混合体系的Ｇｉｂｂｓ吸附公式，并讨论了混合体系中两表面活性组分的表面分子相互作用和表面层的结构。     

Prediction of thermodynamic properties of heavy hydrocarbons by Monte Carlo simulation

In this study, Monte Carlo simulation techniques based on the anisotropic united atom (AUA) potential have been used to predict thermodynamic properties, comprising saturation pressures, vaporization enthalpies and liquid densities, at different temperatures for several isoalkanes (2,3-dimethylpentane, 2,4-dimethylpentane), alkylbenzenes (propylbenzene and hexylbenzene), alkyl-substituted cycloalkanes (propylcyclohexane and propylcyclopentane), polycyclic alkanes (trans-decalin), and naphtenoaromatics (tetralin and indan), representing gasoil range fractions of hydrocarbons. This variety of hydrocarbons with different molecular structures served to demonstrate the transferability of the AUA potential parameters. For this purpose, two types of Monte Carlo algorithm were used: the Gibbs ensemble algorithm to predict equilibrium properties at high temperatures, and the NPT algorithm followed by the thermodynamic integration to extend the prediction to lower temperatures. Techniques increasing the efficiency of the algorithms such as configuration bias, reservoir bias, and parallel tempering were also implemented in the algorithms. Based on available experimental information, good predictions of equilibrium properties were obtained for all the hydrocarbon families studied, and small differences between isomers were represented with a good accuracy.     

Synthesis and Surface Properties of N-Alkyl-N-methylgluconamides and N-Alkyl-N-methyllactobionamides

Three series of nonionic N-alkylaldonamides, N-alkyl-N-methylgluconamides (Cn-MGA, Cn: n-C(10)H(21), n-C(12)H(25), n-C(14)H(29), n-C(16)H(33), and n-C(18)H(37)), N-alkyl-N-methyllactobionamides (Cn-MLA, alkyl as above-mentioned), and N-oleyl-N-methylglucon/lactobionamide, were synthesized in the reaction of an appropriate N-alkyl-N-methylamine with delta-D-glucolactone and lactobionic acid, respectively. Krafft temperatures of aqueous solutions and surface properties of these surfactants at 20 degrees C, i.e., surface excess concentration, Gamma(cmc), surface area demand per molecule, A(min), efficiency in surface tension reduction, pC(20), effectiveness in surface tension reduction, Pi(cmc), critical micelle concentration, CMC, and CMC/C(20) parameter as well as standard free energies of adsorption, DeltaG degrees (ads), and of micellization, DeltaG degrees (mic), were determined. It was shown that introduction of the methyl group to the amide nitrogen increased the solubility of the surfactants, which was confirmed by their Krafft temperatures. Lactobionamides are more water soluble than gluconamides. On the other hand, the Cn-MGA surfactants are more surface active than the respective Cn-MLA ones. This observation is based on the determined adsorption and micellization parameters. The presence of one double bond in a hydrocarbon chain as in oleyl-amides increases their hydrophilic character compared with that of saturated C18 derivatives. No distinct differences were observed between the A(min) values obtained for both series studied, although they differ markedly in the size of the hydrophilic groups. Copyright 2001 Academic Press.     

Adsorption behavior of surface-chemically pure N-alkyl-N-(2-hydroxyethyl)aldonamides at the air/water interface

N-alkyl-N-(2-hydroxyethyl)aldonamides (alkyl: n-C6H13, n-C8H17, n-C10H21, n-C12H25, and n-C14H29) were obtained in the reaction of long-chain N-alkyl-N-(2-hydroxyethyl)amines with D-glucono-1,5-lactone and D-glucoheptono-1,4-lactone. The adsorption isotherms were obtained from surface tension measurements of aqueous solutions of surface-chemically pure surfactants. The experimental equilibrium surface tension versus concentration isotherms were evaluated by the Frumkin adsorption equation to get the adsorption parameters, namely, standard free energy of adsorption, deltaG(o)ad, saturation adsorption, gammainfinity minimum surface area demand per molecule adsorbed, Amin, and interaction parameter, Hs. The investigated functionalized alkylaldonamides show improved solubility in comparison with the corresponding sugar derivatives of the primary amines. The introduction of the -CHOH moiety into the saccharide headgroup causes a noticeable increase of the hydrophobic character of surfactant. The minimum surface area demand, Amin, is slightly greater for glucoheptonamides than for the corresponding gluconamides. The practically constant Amin value within the homologue series of the aldonamides indicates that the obtuse hydroxyethyl residue is the determining factor for the arrangement of the adsorbed surfactants in the interfacial layer.     

Wetting behavior of mixtures of water and nonionic polyoxyethylene alcohol

Five binary water + C4Ej mixtures, water + n-C4E0, water + 2-C4E0, water + iso-C4E0, water + n-C4E1, and water + iso-C4E1, were chosen to perform the surface/interfacial tension measurements over the experimental temperature range from 10 to 85 degrees C at the normal pressure by using a homemade pendent drop/bubble tensiometer. The symbol CiEj is the abbreviation of a nonionic polyoxyethylene alcohol CiH(2i+1)(OCH2CH2)jOH. The wetting behavior of the CiEj-rich phase at the interface separating gas and the aqueous phase is systematically examined according to the wetting coefficient resulting from the experimental data of surface/interfacial tensions measurements. For those systems with a lower critical solution temperature, for example, water + n-C6E2, water + n-C4E1, and water + iso-C4E1, a wetting transition from partial wetting to nonwetting is always observed when the system is brought to close to its lower critical solution temperature. On the other hand, to start with a partial wetting CiEj-rich phase, a wetting transition from partial wetting to complete wetting is always observed when the system is driven to approach its upper critical solution temperature. The effect of hydrophobicity of CiEj on the wetting behavior of the CiEj-rich phase at the interface separating gas and the aqueous phase was carefully investigated by using five sets of mixtures: (1) water + n-C4E0, water + n-C5E0, and water + n-C6E0; (2) water + 2-C4E0 and water + 2-C5E0; (3) water + 2-C4E0 and water + n-C4E0; (4) water + n-C4E1, water + n-C5E1, and water + n-C6E1; (5) water + n-C4E0 and water + n-C4E1. The CiEj-rich phase would tend to drive away from complete wetting (or nonwetting) to partial wetting with an increase in the hydrophobicity of CiEj in the binary water + CiEj system. All the wetting behavior observed in the water + CiEj mixtures is consistent with the prediction of the critical point wetting theory of Cahn.     

n-C_3H_7I和i-C_3H_7I在266nm的光解:烷基自由基分支化对C—I解离动力学的影响(英文)

结合共振增强多光子电离(REMPI)方案,利用离子影像技术研究了n-C3H7I和i-C3H7I分子的光解动力学.分析和比较了它们光解过程中所涉及的能量分配和解离态间的非绝热跃迁信息.它们的I(2P3/2)产物通道的内能所占百分比要大于I*(2P1/2)产物通道的.随着烷烃自由基变得更加的分支化,一方面,原子碎片(I和I*)的能量分布明显变宽,暗示了α-碳原子上的烷基具有更复杂的振转模式;另一方面,在266nm光子的泵浦下,尽管两分子3Q0邝X跃迁的谐振强度表现出很小的差别,但是,产生I*碎片的几率明显降低,从n-C3H7I的0.72降到i-C3H7I的0.46.这可以归因于在光解i-C3H7I过程中弯曲振动模式对产生I和I*的贡献要比n-C3H7I光解过程中弯曲振动模式对I和I*的贡献更明显,使得3Q0与1Q1态之间的非绝热跃迁得到增强.此外,n-C3H7I和i-C3H7I的3Q0邝X跃迁并不完全是平行跃迁,对应的跃迁偶极矩与键轴间的夹角分别约为15°和18°.     

Structures, electron affinities, and harmonic vibrational frequencies of the simplest alkyl peroxyl radicals and their anions

The molecular structures and electron affinities of the R-OO/R-OO(-) (R = CH3, C2H5, n-C3H7, n-C4H9, n-C5H11, i-C3H7, t-C4H9) species have been determined using seven different density functional or hybrid Hartree-Fock density functional methods. The basis set used in this work is of double-zeta plus polarization quality with additional diffuse s-type and p-type functions, denoted DZP++. The geometries are fully optimized with each density functional theory method. Harmonic vibrational frequencies were found to be within 3.1% of available experimental values for most functionals. Two different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity and the vertical detachment energy. The most reliable adiabatic electron affinities obtained at the DZP++ BP86 level of theory are 1.150 (CH3OO), 1.124 (C2H5OO), 1.146 (n-C3H7OO), 1.173 (n-C4H9OO), 1.184 (n-C5H11OO), 1.145 (i-C3H7OO), and 1.114 eV (t-C4H9OO). Compared with the experimental values, the average absolute error of the BPW91 method is 0.05 eV.     

Surface and micellar properties of new nonionic gemini aldonamide-type surfactants

A new group of gemini aldonamide-type surfactants-N,N'-bisalkyl-N,N'-bis[(3-gluconylamide)propyl]ethylenediamines, N,N'-bisdodecyl-N,N'-bis[(3-glucoheptonylamide)propyl]ethylenediamine, and N,N'-bisalkyl-N,N'-bis[(3-lactobionylamide)propyl]ethylenediamines, (alkyl: n-C(8)H(17), n-C(12)H(25)), were synthesized and characterized. The surface properties, such as surface excess concentration, Gamma(cmc), surface area demand per molecule, A(min), efficiency in surface tension reduction, pC(20), the effectiveness of surface tension reduction, gamma(cmc), critical micelle concentration, cmc, and a measure of the tendency of the surfactant to adsorb at the aqueous/air interface relative to its tendency to form micelles in the bulk surfactant solution, cmc/C(20), and standard free energy of micellization, DeltaG(mic)(0), have been obtained by means of surface tension measurements. The standard fluorescence shift technique using PRODAN as a probe provide confirmation of the cmc values by an alternative method. Additionally, the micellar properties for the concentration near above the cmc have been characterized by the aggregation number, N(agg). The presence of the dimeric segments with the aldonamide hydrophilic units in the surfactant molecule is found to be the source of their unusual physicochemical behavior. They are very efficient at adsorbing at the free surface and at forming micelles in water. Their critical micelle concentration values are remarkably low. They reveal remarkably low A(min) values in relation to conventional nonionic surfactants, which is unexpected from the molecular dimensions for the molecule but which is possible if one assumes some type of multilayer structure or a coherent interfacial film.     

Selective methylative homologation: an alternate route to alkane upgrading

InI3 catalyzes the reaction of branched alkanes with methanol to produce heavier and more highly branched alkanes, which are more valuable fuels. The reaction of 2,3-dimethylbutane with methanol in the presence of InI3 at 180-200 degrees C affords the maximally branched C7 alkane, 2,2,3-trimethylbutane (triptane). With the addition of catalytic amounts of adamantane the selectivity of this transformation can be increased up to 60%. The lighter branched alkanes isobutane and isopentane also react with methanol to generate triptane, while 2-methylpentane is converted into 2,3-dimethylpentane and other more highly branched species. Observations implicate a chain mechanism in which InI3 activates branched alkanes to produce tertiary carbocations which are in equilibrium with olefins. The latter react with a methylating species generated from methanol and InI3 to give the next-higher carbocation, which accepts a hydride from the starting alkane to form the homologated alkane and regenerate the original carbocation. Adamantane functions as a hydride transfer agent and thus helps to minimize competing side reactions, such as isomerization and cracking, that are detrimental to selectivity.     

Wettability of a Polymethylmethacrylate Surface by Extended Anionic Surfactants: Effect of Branched Chains

The adsorption behaviors of extended anionic surfactants linear sodium dodecyl(polyoxyisopropene)₄ sulfate (L-C₁₂PO₄S), branched sodium dodecyl(polyoxyisopropene)₄ sulfate (G-C₁₂PO₄S), and branched sodium hexadecyl(polyoxyisopropene)₄ sulfate (G-C₁₆PO₄S) on polymethylmethacrylate (PMMA) surface have been studied. The effect of branched alkyl chain on the wettability of the PMMA surface has been explored. To obtain the adsorption parameters such as the adhesional tension and PMMA-solution interfacial tension, the surface tension and contact angles were measured. The experimental results demonstrate that the special properties of polyoxypropene (PO) groups improve the polar interactions and allow the extended surfactant molecules to gradually adsorb on the PMMA surface by polar heads. Therefore, the hydrophobic chains will point to water and the solid surface is modified to be hydrophobic. Besides, the adsorption amounts of the three extended anionic surfactants at the PMMA–liquid interface are all about 1/3 of those at the air–liquid interface before the critical micelle concentration (CMC). However, these extended surfactants will transform their original adsorption behavior after CMC. The surfactant molecules will interact with the PMMA surface with the hydrophilic heads towards water and are prone to form aggregations at the PMMA–liquid interface. Therefore, the PMMA surface will be more hydrophilic after CMC. In the three surfactants, the branched G-C₁₆PO₄S with two long alkyl chains exhibits the strongest hydrophobic modification capacity. The linear L-C₁₂PO₄S is more likely to densely adsorb at the PMMA–liquid interface than the branched surfactants, thus L-C₁₂PO₄S possesses the strongest hydrophilic modification ability and shows smaller contact angles on PMMA surface at high concentrations.     

Effect of architecture on the formation of surface multilayer structures at the air-solution interface from mixtures of surfactant with small poly(ethyleneimine)s

The impact of ethyleneimine architecture on the adsorption behavior of mixtures of small poly(ethyleneimines) and oligoethyleneimines (OEIs) with the anionic surfactant sodium dodecylsulfate (SDS) at the air-solution interface has been studied by surface tension (ST) and neutron reflectivity (NR). The strong surface interaction between OEI and SDS gives rise to complex surface tension behavior that has a pronounced pH dependence. The NR data provide more direct access to the surface structure and show that the patterns of ST behavior are correlated with substantial OEI/SDS adsorption and the spontaneous formation of surface multilayer structures. The regions of surface multilayer formation depend upon SDS and OEI concentrations, on the solution pH, and on the OEI architecture, linear or branched. For the linear OEIs (octaethyleneimine, linear poly(ethyleneimine) or LPEI(8), and decaethyleneimine, LPEI(10)) with SDS, surface multilayer formation occurs over a range of OEI and SDS concentrations at pH 7 and to a much lesser extent at pH 10, whereas at pH 3 only monolayer adsorption occurs. In contrast, for branched OEIs BPEI(8) and BPEI(10) surface multilayer formation occurs over a wide range of OEI and SDS concentrations at pH 3 and 7, and at pH 10, the adsorption is mainly in the form of a monolayer. The results provide important insight into how the OEI architecture and pH can be used to control and manipulate the nature of the OEI/surfactant adsorption.     

Experimental and theoretical study of hydrogen atom abstraction from n-butane by lanthanum oxide cluster anions

Lanthanum oxide cluster anions are prepared by laser ablation and reacted with n-C(4)H(10) in a fast flow reactor. A time-of-flight mass spectrometer is used to detect the cluster distribution before and after the reactions. (La(2)O(3))(m=1-3)OH(-) and La(3)O(7)H(-) are observed as products, which suggests the occurrence of hydrogen atom abstraction reactions: (La(2)O(3))(m=1-3)O(-) + n-C(4)H(10) → (La(2)O(3))(m=1-3)OH(-) + C(4)H(9) and La(3)O(7)(-) + n-C(4)H(10) → La(3)O(7)H(-) + C(4)H(9). Density functional theory (DFT) calculations are performed to study the structures and bonding properties of La(2)O(4)(-), La(3)O(7)(-), and La(4)O(7)(-) clusters. The calculated results show that each of La(2)O(4)(-) and La(4)O(7)(-) contains one oxygen-centered radical (O(-?)) which is responsible for the high reactivity toward n-C(4)H(10). La(3)O(7)(-) contains one oxygen-centered radical (O(-?)) and one superoxide unit (O(2)(-?)), and the O(-?) is responsible for its high reactivity toward n-C(4)H(10). The O(-?) and O(2)(-?) can be considered to be generated by the adsorption of an O(2) molecule onto the singlet La(3)O(5)(-) with electron transfer from a terminally bonded oxygen ion (O(2-)) to the O(2). This may help us understand the mechanism of the formation of O(-?) and O(2)(-?) radicals in lanthanum oxide systems. The reaction mechanisms of La(2)O(4)(-) + n-C(4)H(10) and La(3)O(7)(-) + n-C(4)H(10) are also studied by the DFT calculations, and the calculated results are in good agreement with the experimental observations.     

Photofragment translational spectroscopy of n-C3H7I and i-C3H7I near 280 and 304 nm

The photodissociation dynamics of propyl iodides n-C3H7I and i-C3H7I near 280 and 304 nm has been investigated with our mini-TOF photofragment translational spectrometer. When a single laser is applied for both the photodissociation of parent molecules and the REMPI of I atom photofragments, the TOF spectra of photofragments I*(2P1/2) and I (2P3/2) are obtained at four different wavelengths for these two iodides. For n-C3H7I, some small vibrational peaks are partially resolved (with separation of approximately 522 cm-1, corresponding to the RCH2 deformation frequency of the fragment n-C3H7) at 281.73, 279.71, and 304.67 nm. These results show that the RCH2 deformation is mostly excited. For i-C3H7I, we obtain some partially resolved vibrational peaks (with separation of approximately 352 cm-1, corresponding to the HC(CH3)2 out-of-plane bending frequency of the fragment i-C3H7) at 281.73 nm only. For n-C3H7I, the partitioning values of the available energy Eint/Eavl are 0.48 at 281.73 nm and 0.49 at 304.02 nm for the I* channel, and 0.52 at both 279.71 and 304.67 nm for the I channel. These energy partitioning values are comparable with the previous results at different wavelengths in the literature. For i-C3H7I, the Eint/Eavl values are 0.61 at 281.73 nm, 0.65 at 304.02 nm for the I* channel, and 0.62 at 279.71 nm, 0.49 at 304.67 nm for the I channel. The potential-energy-surface crossing and the beta values have also been discussed.     

Characterization and comparison of Cm(III) and Eu(III) complexed with 2,6-di(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine using EXAFS, TRFLS, and quantum-chemical methods

The complexation of Cm(III) and Eu(III) with 2,6-di(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine (n-C3H7-BTP) in nonaqueous organic solution is studied with extended X-ray absorption spectroscopy. Bond lengths are the same in both complexes. Quantum-chemical calculations performed at different levels support this finding. On the other hand, the Cm.(n-C3H7-BTP)3 complex is formed at much lower ligand-to-metal concentration ratio than the Eu.(n-C3H7-BTP)3 complex, as shown by time-resolved laser-induced fluorescence spectroscopy. This is in good agreement with n-C3H7-BTP's high selectivity for trivalent actinides over lanthanides in liquid-liquid extraction.     

Evaluation of asphaltene degradation on highly ordered TiO2 nanotubular arrays via variations in wettability

Photocatalytic degradation of both aquatic and atmospheric organic pollutants on titanium dioxide has been extensively investigated in the past decades, but research on direct photocatalytic degradation of solid-phase organic pollutants is rather limited. In this work, photocatalytic degradation of n-C(7) asphaltene, which is composed of solid-phase organic substances found in crude oil, on highly ordered TiO(2) nanotubular arrays (TNAs) was studied using the wettability as an indicator. It was observed that the water contact angle rose linearly with increasing the concentration of n-C(7) asphaltene solution up to 0.02 g mL(-1). Further increasing the concentration of n-C(7) asphaltene only caused small augment in the contact angle, which eventually became stable around 98°. It is demonstrated that the water contact angle can be used as an indicator to reflect the residual solid-phase organic pollutants within a certain range of pollutant concentration. As observed, n-C(7) asphaltene film degraded on TNAs under UV illumination for 60 min, showing complete mineralization of ～80% of n-C(7) asphaltene that was released into air finally. The remaining 20% of asphaltene was partially decomposed into smaller organic molecules, e.g., -C(═O)- and -C(═O)-OH, confirmed by high-resolution X-ray photoelectron spectra analysis. TNAs can be reused to degrade the solid-phase n-C(7) asphaltene for a number of cycles without further treatment.     

辅酶B_(12)模型化合物的研究(V)RCo(Salen)L配合物Co—C键断裂的动力学

运用光度法研究了RCo(Salen)L配合物在甲醇中热分解反应动力学;测定了Co—C键断裂的速率常数及活化能,得到表观速率常数顺序为i-C3H7>i-C4H9>n-C4H9>n-C3H7>C2H5,活化能顺序为i-C3H7相似文献   

有机膦、胂、(月弟)合钨、钼聚多酸盐的研究 Ⅳ.烷基膦合钼聚多酸盐的制备

本文是作者在合成了一系列有机胂、有机(月弟)的钨、钼聚多酸盐后,有关若干有机膦合钼聚多酸“柄状”化合物的合成报导以及一些光学性质的测定。有关有机基团是C_2H_5,n-C_3H_7,n-C_4H_9,n-C_5H_(11)及C_6H_5CH_2。发现pH为3～5时,在不同的投料比例下都只形成一种类型的化合物[(RP)_2Mo_5O_(21)]~(4-),与相应的有机胂衍生物既可形成[(RAs)_2Mo_5O_(21)]~(4-)又可形成[(RAs)_2Mo_6O_(24)]~(4-)有较大的差异。     

L-天冬氨酸与阴离子表面活性剂SDS的相互作用

用电导法、表面张力法和荧光探针法测定了L-天冬氨酸(L-Asp)对十二烷基硫酸钠(SDS)胶束聚集性能的影响以及L-Asp在SDS胶束中的定位, 用循环伏安法研究了SDS/H₂O体系中L-Asp的电化学特性. 结果表明, L-Asp的加入能使SDS的临界胶束浓度cmc减小、胶束的聚集数增加. SDS表面胶束和SDS/n-C₄H₉OH/表面混合胶束均对L-Asp电化学氧化具有一定的催化作用.     

Amphiphilic and mesogenic carbohydrates IX. Perfluoroalkyl substituted monosaccharides: a new group of amphiphilic liquid crystals

The thermal properties of twelve 'single-tailed' carbohydrate-based liquid crystal materials which have a perfluoroalkyl chain (n-C4F9, n-C6F13, n-C8F17) linked to the polar sugar head group are described. All reported amphiphiles, the 6-deoxy-6-C-perfluorohexyl-L-altrose 1, the (5R)-xylopentoses 2, 3 and 4, the 5,6-dideoxy-6-C-perfluoroalkyl-D-glucofuranoses 5 and 6, the 2,3-O-perfluoroalkylidene-D-gulopyranoses 7, 8 and 9 and the 3,4-O-perfluoroalkylidene- D-altropyranoses 10 and 11 form mesophases of the smectic A type. Even a C4F9-chain (compounds 2, 7, and 10) is long enough to cause liquid crystalline behaviour.     

Intrinsic viscosities of four homopolymers and one copolymer in nonpolar solvents. II. Effect of solvent steric hindrance

Intrinsic viscosities at 25°C of an ethylene-propylene copolymer containing 81% ethylene (81% E) of polypentenamer (PPmer), polyisobutylene (PIB), polypentene-1 (PP-1), and polydimethylsiloxane (PDMS) have been measured in n-C₉ and three branched nonanes and n-C₇ and five branched heptanes. The effect of the solvent steric hindrance on the free energy, i.e., on the χ parameter was investigated. The highly sterically hindered, cruciform molecules 3,3-dimethylpentane and 3,3-diethylpentane are the best solvents for four of the five polymers. The enhancement of solvent quality due to the steric hindrance diminishes when the polymer free volume increases. The difference in [η] between 2,4-dimethylpentane and 2,3-dimethylpentane is ?50%, ?35%, ?2% for PPmer, PIB, PDMS, and can be correlated to a measure of the polymer free volume, i.e., the lower critical solubility temperature. The χ, χH, and χS are calculated from [η] using the Stockmayer-Fixman relation and from h, the heat of mixing at infinite dilution of the polymer, obtained previously. With each polymer, a good correlation is found between h and [η] obtained with the six heptanes and four nonanes. The correlation points to the same effect being at the origin of χH and χS but of different magnitude. In cases showing the steric hindrance effect, a negative contribution occurs in h (or χH) which is larger in magnitude than the corresponding negative entropic contribution leaving a net negative effect in χ itself. Probably due to their very compact shape and fewer degrees of freedom, the cruciform solvents lose less entropy than the chain solvents in mixing.