A novel way for ethoxylation with basic catalysts

Ethoxylation of dodecyl alcohol catalyzed by alkali hydroxides are accelerated by adding complexing agents for the alkali ions. The rate of ethoxylation could be increased by crown ether and dodecyl alcohols of a higher degree of ethoxylation. The effect is more pronounced with the crown ether; thus, reactions not taking place under other circumstances could also be carried out. The complexing additives have no significant effect on the molar mass distribution, The reaction could also be accelerated by using more bulky organic cations (e.g., triethylbenzylammonium ion) instead of the alkali cation.     

PEP聚醚型非离子表面活性剂的合成与性能分析

以聚乙二醇和环氧丙烷为原料 ,用氢氧化钾和少量冠醚为催化剂 ,在常压条件下合成了一系列“PO -EO -PO”嵌段共聚醚 ,并对产物的表面活性性能进行了测定分析     

黄酮类冠酸钾离子选择电极的研制及其对陶瓷原料含钾量的测定

黄酮类取代基能加强冠醚对钾离子的敏感性和络合选择性。本工作研制了以两种结构相似的黄酮类冠醚为电活性物质的钾离子选择电极，探讨了它们的响应功能及在测定陶瓷原料的应用。在ｐＨ＝６的酸度下，以乙酸锂为离子强度调节剂，按一次标准添加法和Ｇｒａｎ添加法进行分析处理，结果表明，该化学传感器应用于长石、高岭土等陶瓷原料中的氧化钾测定具有足够高的选择性和准确度。     

Polyaza crown ethers as non-nucleosidic building blocks in DNA conjugates: synthesis and remarkable stabilization of dsDNA

The synthesis of amphiphilic polyaza crown ether monomers X (benzyl-substituted), Y (palmityl-substituted) and Z (cholesteryl-substituted) and their incorporation into oligonucleotides are described. Their effects on thermal duplex stability were investigated by UV melting curve analysis in different alkaline metal buffer solutions. Thermal-denaturation experiments showed remarkable stabilization of dsDNA by polyaza crown ether monomers when incorporated in opposite positions. The series of polyaza crown ether monomers (X, Y and Z) with different overall lipophilicities showed a trend of increased stability of the corresponding dsDNA with increasing lipophilicity of the polyaza crown ether monomer. Multiple incorporations of benzyl-substituted polyaza crown ether monomer X as dangling ends on both sides of dsDNA resulted in strongly increased stability of the corresponding duplex.     

Studies on the properties of glass fiber reinforced epoxy composites of DGEBA / epoxidized polyhydric alcohols with or without fortifier

Differential scanning calorimetry (DSC) technique was used to study the curing reaction of diglycidyl ether of bisphenol A (DGEBA) resin and different di- and trifunctional polyhydric alcohols with phthalic anhydride as curing agent and triethylamine as catalyst with or without fortifier. The thermal stability of the cured products was also studied by thermogravimetric analysis (TGA). Using these data, different glass fiber reinforced epoxy composites were fabricated and their mechanical and electrical properties and their resistance to chemicals were studied as well. Activation energies of curing reactions range within 75.1 to 88.3 kJ mol^?1. The cured products have good thermal stability; the composites have good mechanical strength, electrical insulation properties and chemical resistance. 36 to 53% improvement in flexural strength has been observed when fortifier was added to the DGEBA-diluent systems.     

Ether alcohol sulfates. The effect of oxypropylation and oxybutylation on surface active properties

The reaction of 1,2-butylene oxide with fatty alcohols of 12 to 18 carbon atoms was investigated and products were compared with those from the propylene oxide reaction. A 60% yield of the first derivative was obtained for the butylene oxide reaction compared with a maximum yield of 50% for the propylene oxide reaction. First and second derivatives were fractionally distilled from the reaction mixtures and characterized as pure ether alcohols and their acetates. Sulfation of the pure ether alcohols permitted some interesting comparisons of the effect of structural change on surface active properties. Oxybutylation gave slightly greater solubility increases than oxypropylation and both reactions were more effective than oxyethylation. Dioxyalkylated products had lower Krafft points than monooxyalkylated products. A low degree of oxyalkylation had only minor effects on the detergency of alcohol sulfates but polyoxybutylation caused significant reductions in foam height for the 16 and 18 carbon alcohol sulfates. Critical micelle concentration was reduced both by increasing degree of oxyalkylation and molecular weight of epoxide. All of the ether alcohol sulfates were effective lime soap dispersing agents. Presented at the AOCS Meeting in Philadelphia, October 1966. E. Utiliz. Res. Dev. Div., ARS, USDA.     

Crosslinking behaviour of diolmodified epoxies

Summary Diglycidyl ether of bisphenol A (BADGE) reacts with aliphatic alcohols to form different products, depending on the type of accelerator. In the presence of magnesium perchlorate the reaction mechanism is nearly independent of the temperature. Using N,N-dimethylbenzylamine (DMBA) as accelerator, different reaction mechanisms can be observed with increasing temperature. These conclusions were drawn by kinetic investigations of the system BADGE/butane-1-ol/accelerator involving HPLC-measurements of reaction products.     

Crosslinking behaviour of diolmodified epoxies

Summary Diglycidyl ether of bisphenol A (BADGE) reacts with aliphatic alcohols to form different products, depending on the type of accelerator and the alcohol mole fraction. Using liquid state C-13 NMR different reactive groups as oxirane rings, primary and secondary hydroxyl groups were detected in dependence of the epoxide consumption. Crosslink and junction point resonances were identified by varying the cure state.     

Synthesis,characterization and spectroscopic studies of two new schiff-base bithienyl pendant-armed 15-crown-5 molecular probes

Two new ligands provided with a 15-crown-5 as a receptor unit and bithiophen unit as an emissive probe have been synthesized and characterized in order to evaluate the coordination capabilities and their sensor effect. Ligand L1 presents an aromatic crown ether moiety that is directly linked to the imine-2,2′-bithiophene π–conjugated system, and ligand L2 is constituted by an aliphatic crown ether moiety that is linked to the same imine-2,2′-bithiophene system through a methylene unit. Solid metal complexes of Ni(II), Pd(II), Hg(II) and Na(I) have been synthesized using both macrocyclic compounds, and have been studied in solution in the presence of the same metal ions. All solid compounds have been characterized by common analytical and spectroscopic techniques. The sensorial effect has been studied using absorption, emission and MALDI-TOF-MS spectroscopies.     

醚链桥接二芳醛缩氨基硫脲类化合物的合成

开链冠醚基二芳醛在酸性条件下与氨基硫脲反应,合成了链状冠醚二芳醛缩氨硫脲类化合物,产率80%以上,产物经由IR,MS和元素分析鉴定了其结构。     

开链冠醚衍生物的合成

开链冠醚基二芳醛在酸性条件下与氨基脲反应,合成了链状二芳醛缩氨脲类化合物,产率高达90%以上,产物由IR、MS和元素分析鉴定了其结构。     

Influence of process parameters on extraction equilibria for the chiral separation of amines and amino‐alcohols with a chiral crown ether

Reactive extraction is studied as a promising chiral separation technique for commercial production scale. For chiral separation of amines and amino alcohols, a chiral crown ether was identified as a versatile enantioselective extractant. In this paper, the influence of various process conditions on the extraction performance is studied experimentally, and a predictive model is constructed based on the chemical and physical equilibria. It was found that the operational selectivity in one extraction step is mainly determined by the complexation constants between crown ether and enantiomers (which are dependent on solvent and temperature) and by the extractant concentration, whereas the distribution ratio is also strongly influenced by the pH. The model gives an excellent prediction of the operational selectivity and a good explanation for the system's responses to changes in process conditions. The model can be used as a basis for a multistage equilibrium extractor model and for conceptual process design. Under optimal process conditions, an operational selectivity >1.5 was obtained for five out of seven model compounds, with satisfying distribution ratios (D ～ 1–10). Copyright © 2006 Society of Chemical Industry     

Studies of the Size-Selective Extraction of Alkali Metal Ions by the Synergistic Extraction System,Crown Ether-DI(2-Ethylhexyl) Phosphoric Acid-Benzene

Abstract

In order to take practical advantage of the size-selective cation-coordinating ability of the cyclic polyethers (crown ethers), experiments seeking a means of avoiding the problem of solubilizing a mineral-acid anion in a nonpolar organic diluent were performed. Mixtures of several known extractants and crown ethers were tried. Results presented indicate that organic soluble cation exchangers mixed in solution with crown ethers produce a synergistic extractant mixture that largely exhibits the size-selective properties expected of the crown ether. Data are presented for the extraction of macro concentrations of alkali metals by di(2-ethylhexyl) phosphoric acid—dicyclohexyl-18-crown-6 mixtures at a single pH, and at nonloading condition(σ metal cone < 0.04 M) as a function of pH, 2 to 6. In both cases potassium is synergized most strongly presumably because of its best fit to the crown ether cavity. Other data indicate, however, that the size-fit principle is not as consistent for all alkali metal ions and crown ethers as for potassium and dicyclohexyl-18-crown-6. Other effects such as competition for ion hydration and aqueous-phase distribution of the complex may have important effects that have not been elucidated.     

冠醚化合物对乳剂晶体外延生长的调变作用

本工作研究了冠醚化合物在外延乳剂生长过程中的调变作用。结果表明，１，４，７，１０，１３，１６－六氧杂环十八烷对ＡｇＢｒ八面体乳剂无侵蚀作用，对非同晶系晶体之间的外延不起调变作用。１，７，１０，１６－四氯－４，１３－二氮代杂环十八烷均使ＡｇＢｒ八面体乳剂的棱角产生了不同程度的侵蚀，可充当不同晶系晶体外延生长的调变剂，对晶体的溶解侵蚀能力依２Ｓ－１８－Ｃ－６，２Ｎ－１８－Ｃ－６，１８－Ｃ－６的次序降低     

Ligands for selective metal ion extraction: A molecular modeling approach

We present a density functional theory (DFT) based study on interaction of alkali metal cations (Li⁺ and Na⁺) with macrocyclic crown ethers of different ring sizes. The minimum energy structures, binding energies, and binding enthalpies of crown ether–cation complexes have been determined with a correlated hybrid density functional, namely Becke’s three-parameter functional, B3LYP using a split valence basis function, 6-311++G(d, p). Geometry optimizations for all the crown ether–cation complexes were carried out with several initial guess structures based on semi-empirical PM3 optimized results. For both metal ions, the calculated values of binding energy and binding enthalpy increase with the increase in size of the crown ether ring, i.e. with the increase in the number of donor oxygen atoms in crown ether. The calculated values of gas phase binding energy for lithium ions are always higher than those for sodium ions in the case of all macrocyclic crown ethers studied at present. The calculated values of binding enthalpy are in good agreement with the reported experimental data.     

Emulsifiers derived from linseed oil and their potential use in coatings

In the development of a stable linseed oil emulsion paint, a series of emulsifiers were prepared from linseed, oil and its fatty acids and alcohols: (a) linseed monoglycerides, (b) mono-and dilinseed fatty sorbitan esters and a mixed ester obtained by the transesterification of linseed oil with sorbitol, (c) polyoxyethylene ether adducts formed by reacting, ethylene oxide with these sorbitan esters, and (d) linseed polyoxyethylene ether made by ethoxylation of linseed alcohols. Another series of surfactants was prepared by esterifying a polyoxyethylene ether of sorbitol with various amounts of linseed fatty acids. Conditions of preparation and pertinent physical, and chemical properties of the emulsifiers are given. Some of these emulsifiers demonstrated filmforming properties. Combinations were formulated into linseed oil emulsion paints with and without zinc oxide. Paints containing zinc oxide have been relatively stable in viscosity for about 2 yr.     

Synthesis and adsorption properties for metal ions of mesocyclic diamine‐grafted chitosan‐crown ether

A new type of grafted chitosan‐crown ether was synthesized using mesocyclic diamine crown ether as the grafting agent. The C2 amino group in chitosan was protected from the reaction between benzaldehyde and chitosan to form N‐benzylidene chitosan (CTB). After reaction with mesocyclic diamine crown ether of the epoxy propane group to give mesocyclic diamine‐N‐benzalidene chitosan (CTBA), the Schiff base was removed in a dilute ethanol hydrochloride solution to obtain chitosan‐crown ether (CTDA). Its structure was confirmed by FTIR spectra analysis and X‐ray diffraction analysis. Its static adsorption properties for Pb(II), Cu(II), Cd(II), and Cr(III) were studied. The experimental results showed that the grafted chitosan‐crown ether has high selectivity for the adsorption of Cu(II) in the presence of Pb(II), Cu(II), and Cd(II) and its adsorption selectivity is better than that of chitosan. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1255–1260, 2000     

Synthesis of surfactants from 1-olefins wo bromoalkoxylation reaction

Alkyl β-bromoalkyl ether derivatives (I) (isomeric mixture) were prepared by the bromoalkoxylation reaction of olefins withN-bromosuccinimide (NBS) and appropriate alcohols. A series of nonionic surfactants was obtained by the reaction of I with glycols or ethanolamines. The distribution of two isomers (Markovnikov-type and anti-Markovnikov-type) in products was found to be slightly different from that in the starting material (I). Surface properties of several nonionic surfactants, which were prepared from I, were presented and discussed based on the difference in the structures.     

Benzylsulfonic acid functionalized mesoporous Zr-TMS catalysts: An efficient and recyclable catalyst for the preparation of coumarin derivatives by Pechmann condensation reaction

Benzylsulfonic acid functionalized mesoporous Zr-TMS (Zr-TMS-BSA, Zr-TMS, zirconia based transition metal oxide mesoporous molecular sieves) catalyst is used as an alternative to conventional acid catalysts in the von Pechmann condensation of aromatic alcohols with ethyl acetoacetate leading to the formation of coumarin derivatives in solvent free condition at 150 °C. Three types of coumarins, 7-hydroxy-4-methylcoumarin (β-methylumbelliferone), 7-methoxy-4-methylcoumarin (Methyl-4-methylumbelliferyl ether) and 7,8-benzo-4-methylcoumarin derivatives have been prepared using resorcinol, 3-methoxyphenol and 1-naphthol, respectively. The catalytic activity and the recycle studies of the catalyst in all the three reactions proved the superior performance of the catalyst. Further the products were confirmed by GC, elemental analysis, melting point and NMR techniques. Finally, the probable mechanism for Pechmann condensation using Zr-TMS-BSA catalyst has been reported.     

Liquid transport through membranes prepared by grafting of polar monomers onto poly(tetrafluoroethylene) films. I. Some fractionations of liquid mixtures by pervaporation

The separation of various liquid mixtures including systems of chloroform–hydrocarbons or ethyl ether, water–alcohols and water–nucleophilic organic solvents have been investigated by the pervaporation technique. Membranes were obtained by grafting Lewis base onto poly(tetrafluoroethylene) (PTFE) films. The PTFE backbone has been chosen for its mechanical and chemical resistance. N-Vinylpyrrolidone and 4-vinylpyridine were selected because of their great affinity for the electrophilic compounds. In all cases, the compound which has the greatest affinity for the membrane pervaporates selectively through modified PTFE films. Selectivity and rates were studied. It is concluded that because selectivity is very important, total separation of different mixtures is possible at a good yield, with a faster rate when the temperature is increased or the thickness of the membrane is decreased.