REACTIVITY AND STEREOSELECTIVITY IN THE DIELS-ALDER REACTIONS BETWEEN CYCLOPENTADIENE AND SOME α, β-UNSATURATED THIOESTERS

Abstract

Some new norbornene thioester derivatives of endo configuration are sinthesized. Proofs are provided that thioester group has more preference for endo configuration than the ester group.     

Salinity Controlled Vesicle Formation and Growth in Aqueous Mixture of Aerosol OT/Triton X‐100

Mixed vesicles can be formed spontaneously from aqueous mixture of the double‐tailed anionic surfactant sodium bis(2‐ethylhexyl) sulfosuccinate (AOT) and the nonionic surfactant octylphenoxypolyethoxyethanol (Triton X‐100) under the inducement of salt, the formation mechanism of which should be attributed to the compression of salt on the electric bilayers of the head groups. The stability and the polydispersity of the vesicles are superior to single‐component AOT vesicles, which can be proved by the TEM image and visual observation. The vesicle region was presented in a pseudo‐ternary diagram of AOT/TX‐100/brine. The size of the vesicle was measured using dynamic light scattering. It is found that the vesicle size increases with the salinity but decreases with the content of TX‐100 in the mixture at the same salinity. Especially, the vesicle size is independent of the surfactant concentration at fixed salinity.     

Soluble polymer-supported catalysts containing pendant quaternary onium salts for the addition reaction of oxiranes with carbon dioxide

The addition reaction of oxiranes ( 15a-d ) with carbon dioxide (CO₂) was carried out using 1 mol % of soluble polymer-supported quaternary onium salts as catalysts under atmospheric pressure. The reaction of 15a-d with CO₂ proceeded very smoothly to give the corresponding five-membered cyclic carbonates ( 16a-d ) in high yields at 90-100°C. The catalytic activity of the soluble polymer-supported quaternary onium salts was strongly affected by the following factors: kind of reaction solvent, degree of introduction of the pendant onium salt residues in the polymer chain, and type of alkyl group on the onium salts due to the balance between lipophilicity and steric hindrance of the onium salt residue. Furthermore, these soluble polymer-supported quaternary onium salts were found ordinarily to have higher catalytic activity than low molecular weight quaternary onium salts under the same reaction conditions. It was also found that the rate of reaction was proportional both to catalyst concentration and to oxirane concentration. © 1995 John Wiley & Sons, Inc.     

离子色谱法测定醇胺脱硫溶液中热稳定盐

为了控制热稳定盐(HSS)对天然气净化装置造成的危害,建立了一种同时检测醇胺脱硫溶液中的乙酸根离子、甲酸根离子、氯离子、硫酸根离子、草酸根离子、硫代硫酸根离子和硫氰酸根离子的离子色谱方法。该方法利用膜过滤、反相固相萃取和稀释3个步骤对工业样品进行前处理,采用氢氧化钾梯度淋洗和电导检测的方式,实现了7种离子的分离与检测。方法的线性范围为0.01～0.5 mmol/L,检出限(以信噪比(S/N)为3计)小于0.1 mg/L,回收率为80.0%～100.3%。在5个不同添加浓度下分别测定了上述7个离子,色谱峰面积的重复性良好(相对标准偏差(RSD, n=10)为0.94%～3.99%。通过3个实验室比对试验,表明该方法再现性良好,色谱峰面积的RSD小于5%。应用该方法成功地检测了8家天然气净化厂、3家石油炼厂和1家煤制油工厂的脱硫溶液样品中的HSS,并连续监测某天然气净化装置15 d。该方法具有良好的可靠性和实用性。     

Fluorinated polymerizable phosphonium salts from PH3: Surface properties of photopolymerized films

An array of highly fluorinated polymerizable phosphonium salts (HFPPS) were synthesized from PH₃ and utilized in UV‐curable formulations. Inclusion of these salts at very low loading (0.1–1 wt %) into hexanediol diacrylate (HDDA) resulted in hydrophobic surfaces. The water repellency was achieved with short C₄F₉ fluorocarbon appendages in the monomer as opposed to the bioaccumulative C₈F₁₇ appended polymers. The physical properties of these new monomers were also characterized. The molecular architecture of the monomers had a pronounced effect on both their physical properties along with the degree of hydrophobicity imparted in the polymer. Salts utilizing the bis(trifluoromethylsulfonyl)imide anion displayed excellent compatibility with HDDA, while the chloride salts were insoluble. Time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) confirmed the presence of the HFPPS at the surface of the polymer coating. For the first time this demonstrates how these salts may be used to functionalize the surface of a UV‐cured film with ionic species. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2782–2792     

Amine Salt–Catalyzed Synthesis of 5-Substituted 1H-Tetrazoles from Nitriles

The [3 + 2] cycloaddition reaction between sodium azide and various organic nitriles proceeds smoothly in the presence of amine salts as catalyst in dimethylformamide. The corresponding 5-substituted 1-H tetrazoles were obtained under mild condition in good to excellent yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Synthesis,characterization, and application of silver nanoparticle‐thiophenol nanocomposite film on the glassy carbon surface

In this study, 4‐thiophenol modified glassy carbon electrode was prepared by the reduction of 4‐diazothiophenol tetrafluoroborate salt. Silver nanoparticles were attached to the thiophenol modified surface to prepare a thiophenol‐silver nanoparticle composite film. 4‐Aminothiopenol molecules were deposited by self‐assembling technique to form multi‐layered nanofilms of TP/SNP/PhNH₂ on glassy carbon substrate. These surfaces were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, X‐ray photoelectron spectroscopy, reflectance‐absorption infrared spectroscopy, and ellipsometry at each multilayer film growth process. Atomic force microscopic images of GC/TP/SNP/PhNH₂ surfaces were also acquired. The characterization methods show that the amine group containing surface permits the subsequent modification by a variety of coupling reactions for the immobilization of more complex systems. An application of the electrode modification for the determination of uric acid with a significantly lower detection limit is described. Copyright © 2013 John Wiley & Sons, Ltd.     

Ionic Polymerization of α, α -Disubstituted Vinyl Monomers

Alkyl α-chloroacrylates and p-substituted α-methylstyrenes were investigated for the effect of polymerization conditions on tacticity, molecular weight, and distribution, and for the relationship between tacticity, glass temperature, and crystalline properties.     

Design of Chitosan-5Fu Conjugate Exhibiting Antitumor Activity

In order to provide a macromolecular prodrug of 5-fluorouracil (5FU) reducing the side effects, having an affinity for tumor cells, and exhibiting strong antitumor activity, the covalent attachments of 5FUs to chitosan and chitosamino-oligosaccharide (COS) through hexamethylene spacer groups via urea, urea bonds were carried out. The effect of prolongation of life was tested in vivo against p388 lyrnphocytic leukemia in female CDF, mice by intra-peritoneal (i.p.) transplantation/i.p. injection and the growth-inhibitory effect on Meth-A fibrosarcoma or MH-134Y heputoma was evaluated in vivo in SPF-C3H/He scl male or Balb/c male mice by subcutaneous (s.c.) implantation/intravenous (i.v.) injection. The effects of the degree of polymerization of chitosan and