Bisorthoesters as polymer intermediates. I. Synthesis of bisorthoesters

Derivatives of three types of bisorthoesters, hexaalkyl orthoisophthalates, hexaalkyl orthoterephthalates, and hexaethyl orthooxalate, were synthesized. The orthoesters of isophthalic and terephthalic acid were prepared from α, α, α, α′, α′, α′ -hexachloro-m-xylene or hexachloro-p-xylene, respectively. It was found more advantageous to prepare initially the hexamethyl orthoesters by reacting the hexachloro compounds with sodium methoxide in methanol either at the boiling point of methanol or under pressure at temperatures up to 200°C. Transesterification with higher alcohols, for example, ethanol or propanol, with the aid of molecular sieves gave the higher bisorthoesters in high yield and high purity. Attempts to synthesize orthoisophthalates and orthoterephthalates of higher alcohols directly from the hexachloroxylenes and alkoxides of higher alcohols gave only low yields of impure products. The Pinner synthesis of the bisorthoesters from the corresponding dinitriles was also ineffective. The ease of purification of hexa-n-propyl orthoisophthalate and orthoterephthalate makes these orthoesters the favored candidates for use in polymer syntheses. Hexaethyl orthooxalate was prepared in a three-step synthesis from triethyl orthoformate by a convenient, but low yield reaction. All bisorthoesters were purified to give compounds which were monomer grade materials free of normal esters.     

Regular copolyamides. I. A facile method for the preparation of diamine-oxamides

α,ω-Diamine-oxamides with 2–12 CH₂ groups between the two amino groups were obtained by the reaction of the diamines and diethyl or dimethyl oxalate. Diethyl oxalate is added slowly to a substantial excess of diamine in the proper solvent over a period of time under controlled temperature conditions. All variables are very important for each individual diamine in order to obtain optimal conversions to the diamine-oxamides under the most favorable conditions. Diamine-oxamides were obtained in approximately 80% yield with only small amounts (5–10%) of the corresponding polyoxamides as the side product. Diamine-oxamides from diamines with less than six methylene groups are water-soluble. All diamine-oxamides show an alternation of their melting points and are useful intermediates for the preparation of regular copolyoxamides.     

A facile and general method for the preparation of diaryltellurium dicarboxylates

Diaryltellurium dicarboxylates can be prepared by treatment of the corresponding dichlorides with carboxylic acids in the presence of silver oxide. The conversion of the dichlorides to the carboxylates can also be achieved through a more practical method employing a carboxylate anionic exchange resin. IR and PMR data are given.     

A facile and convenient method for the preparation of macrocyclic diamides

A number of macrocyclic diamides have been synthesized from the reaction of a diacid dicarboxylic dichloride with primary diamino compound in the presence of magnesium oxide-silica gel at room temperature in good yields. Using urea and thiourea as well as diamines to produce the corresponding macrocycles in the range of 52–56% yields are also included in this paper. One of the major advantages of this method is simple regeneration of inorganic solid and its reuse through several cycles without a decrease in activity.     

A facile and environment-friendly method for fabrication of polymer brush

A novel environment-friendly system is proposed tofabricate polymer brush, which has the advantages including non-toxic and inexpensive initiator(eosin Y), visible-light exposure(λ= 515 nm), water medium and ambient environment. The experimental results from UV-Vis spectroscopy, AFM-based single molecule force spectroscopy(SMFS) and other measurements indicate thata polymer brush with a living nature is fabricated via free radical polymerization. This polymer brush may find applications incoatings, bio-interfaces and so forth.     

A facile method for preparing sticky, hydrophobic polymer surfaces

Textured surfaces consisting of nanometer- to micrometer-sized lightly sulfonated polystyrene ionomer (SPS) particles were prepared by rapid evaporation of the solvent from a dilute polymer solution-cast onto silica. The particle textured ionomer surfaces were prepared by either spin-coating or solution-casting ionomer solutions at controlled evaporation rates. The effects of the solvent used to spin-coat the film, the molecular weight of the ionomer, and the rate of solvent evaporation on the surface morphology of cast films were investigated. The surface morphologies were consistent with a spinodal decomposition mechanism, where the surface first existed as a percolated-like structure and then ripened into droplets if molecular mobility was retained for sufficient time. The SPS particles or particle aggregates were robust and resisted separation from the surface even after annealing at 120 °C for 1 week. The water contact angles on as-prepared surfaces were relatively low, ～90°, due to the polar groups in the ionomer, but when the surface was modified by chemical vapor deposition of 1H,1H,2H,2H-perfluorooctyltrichlorosilane, the surface contact angles increased to ～109° on smooth surfaces and up to ～140° on the textured surfaces. Although the surfaces were hydrophobic, the contact angle hysteresis was relatively high and water droplets stuck to these surfaces even when the surface was turned upside down.     

A facile method for the preparation of bishomopropargylic alcohols from acyl chlorides

Controlled dilithiation of propargyl bromide with two equivalents of n-butyllithium, in the presence of TMEDA, produces the operational equivalent of the dianion 1,3-dilithiopropyne. The latter reacts efficiently with acid chlorides to produce bishomopropargylic alcohols in a single step route and with high regioselectivity and moderate yields.     

Simple and facile method for the preparation of vinyl azides

A synthetic utility of [bis(trifluoroacetoxy)iodo]benzene on α,β-unsaturated carboxylic acid is described. This is the first example of preparation of vinyl azide using α,β-unsaturated carboxylic acids directly by using hypervalent iodine reagent. The advantage of this protocol is characterized with non-toxicity of starting material and shorter reaction times to obtain good preparative yields. The method is also useful for the preparation of acyl azides.     

A facile method for preparation of graphene film electrodes with tailor-made dimensions with Vaseline as the insulating binder

This communication describes a facile but effective method to prepare graphene film electrodes with tunable dimensions with Vaseline as the insulating binder. Cyclic voltammetry (CV) studies reveal that the as-prepared graphene film electrodes have tunable dimensions ranging from a conventional electrode to a nanoelectrode ensemble, depending on the amount of graphene dispersed into the insulting Vaseline matrix. A large amount of graphene (typically, 10.0 μg/mL) leads to the formation of the film electrodes with a conventional dimension, while a small amount of graphene (typically, 1.0 μg/mL) essentially yields the graphene film electrodes like a nanoelectrode ensemble. As one new kind of carbon-based film electrodes with tailor-made dimensions and a good electrochemical activity as well as a high stability, the graphene film electrodes are believed to be potentially useful for fundamental electrochemical studies and for practical applications.     

A facile preparation method for nanosized MOFs as a multifunctional material for cellular imaging and drug delivery

Tb-based metal-organic framework nanoparticles (Tb-MOF NPs) with good colloidal stability and stable fluorescence properties in an aqueous solution were prepared by a simple mechanical grinding of Tb-MOF with a biocompatible polymer surfactant (F127). The characteristic fluorescence property of Tb-MOF NPs allowed us to use this nanomaterial as a cell imaging probe. Efficient cellular uptake of Tb-MOF NPs apparently via an energy-dependent endocytosis was observed by confocal laser scanning microscopy. By taking advantage of the porous nature of the Tb-MOF NPs an anticancer drug (doxorubicin) was successfully loaded and delivered to kill cancer cells to demonstrate their usage as a drug delivery vehicle. This simple grinding method afforded a nanosized, multifunctional biomaterial that was used for cell imaging and drug delivery, and it can be extended to other MOFs to widen their applications.     

A new method for preparation of magnetic polymer particles

Synthesis of magnetic polymer particles (MPP) was carried out through two steps. Firstly, the iron oxide particles carrying vinyl groups were synthesized, and in the second step, styrene (ST), divinyl benzene (DVB), and 2-hydroxyethyl methacrylate (HEMA) were polymerized on the surface of modified iron oxide through an emulsifier-free emulsion polymerization technique. The final particles were characterized by a Fourier transform infrared spectroscopy (FTIR), Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR), X-ray diffractometer (XRD), thermal gravimetry analysis (TGA), Fritsch particle sizer, scanning electron microscope (SEM), and vibrating sample magnetometer (VSM). Experimental analysis confirmed that all the iron oxide particles were embedded in a polymer phase and the final particles have more than 67 % iron oxide content. According to magnetometry data, the shape of the hysteresis loops evidences the ferromagnetic character of the particles.     

A facile method for the preparation of thermally remendable cross‐linked polyphosphazenes

Novel cross‐linked polyphosphazenes with remendable capacity have been synthesized through the Diels‐Alder reactions. Their structure and properties were characterized by NMR, FT‐IR, GPC, DSC, TGA SEM, and polarizing microscope. The process of Diels‐Alder reaction (D‐A reaction) and retro‐Diels‐Alder reaction (retro‐D‐A reaction) have been investigated by FT‐IR, UV, and DSC. The cross‐linked polyphosphazenes exhibited remendable capability only need a thermal treatment when they were cut by blade, any other treatments such as additional monomer or catalyst, surface treatment or pressure were not needed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

A facile preparation of some novel class II mesoionic xanthine acyclonucleosides

The synthesis of the first examples of Class II mesoionic xanthine acyclonucleosides is described. A series of mesoionic anhydro-(8-methoxyalkyl-5-hydroxy-7-oxothiazolo[3,2-a]pyrimidinium hydroxides), Class II mesoionic analogs isoconjugate with xanthine, were prepared by the thermal condensation of methoxyalkyl-2-aminothiazoles with substituted bis(2,4,6-trichlorophenyl)malonic esters. The memoxyalkyl-2-aminothiazoles were prepared via an aromatic nucleophilic substitution reaction between 2-bromothiazole and the appropriate methoxyalkylamine in excess. The resulting 8-methoxyalkyl-substituted mesoionic xanthines were demethylated using iodotrimethylsilane in acetonitrile at room temperature to afford the corresponding mesoionic anhydro-(8-hydroxyalkyl-5-hydroxy-7-oxothiazolo[3,2-a]pyrimidinium hydroxides) as the Class II mesoionic xanthine acyclonucleosides.     

A facile spectrophotometric method for the determination of selenium.

A rapid and sensitive spectrophotometric method is described for the determination of trace amounts of selenium using Variamine Blue (VB) as a chromogenic reagent. The proposed method is based on the reaction of selenium with potassium iodide in an acidic medium to liberate iodine, which oxidizes Variamine Blue to form a violet-colored species having an absorption maximum at 546 nm. Beer's law is obeyed in the range 2-20 g of selenium in a final volume of 10 ml. The molar absorptivity and Sandell's sensitivity were found to be 2.6 x 10(4) l mol-1 cm-1 and 0.003 microgram cm-2, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The effect of interfering ions on the determination is described. The proposed method has been successfully applied to the determination of selenium in real samples of water, soil, plant materials, human hair, and synthetic samples of cosmetics and pharmaceutical preparations.     

The use of 2-0xazolidinone as a latent aziridine equivalent. I. A facile method for the preparation of 2-substituted oxazolines

Ring-opening reaction of 2-oxazolidinone with acid chlorides followed by treatment with aqueous sodium hydroxide yields 2-substituted oxazolines.     

无水稀土氯化物的新制备方法: 从稀土氧化物出发制备无水稀土氯化物

本文报道从稀土金属氧化出发, 在THF中与TMSCl/CH3OH反应, 制备无水稀土氯化物LnCl3.nTHF的方法。此法具有产物纯度高, 产率好, 制备条件温和, 操作方便等优点, 因而具有一定的实用性。     

A facile method for the preparation of monodisperse hollow silica spheres with controlled shell thickness

This article presents a facile, effective, mild synthesis process for well‐defined hollow spheres by using cationic polystyrene (PS) submicro‐particles as templates. In this approach, the cationic PS templates can be first prepared via emulsifier‐free polymerization by using the cationic monomer 2‐(methacryloyloxy) ethyltrimethylammonium chloride as comonomer, then, the silica shells from the sol‐gel process of tetraethoxysilane were coated on the surfaces of template particles via electrostatic interaction, finally the PS was dissolved in situ by modification of the reaction conditions in the same medium to form monodisperse hollow silica spheres with controlled shell thickness. Fourier transform‐infrared spectroscopy, thermogravimetric analysis, Brunauer‐Emmett‐Teller, transmission electron microscopy, and scanning electron microscope measurements were used to characterize these hollow silica spheres. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1332–1338, 2010     

A new and facile method for measurement of apparent density of monodisperse polymer beads

The apparent density, an intrinsic physical property of polymer beads, plays an important role in the application of beads in micro-total analysis systems and separation. Here we have developed a new, facile and milligram-scale method to describe the motion of beads in aqueous solution and further detect the apparent density of beads. The motion of beads in solutions is determined by the viscosity of solutions and the density difference between beads and solutions. In this study, using various glycerol aqueous solutions with certain viscosities and densities, the motion time (i.e. floating or sedimentation time) of hybrid polymer beads was experimentally measured and theoretically deduced, and consequently, the apparent density of monodisperse beads can be quickly and easily calculated. The results indicated that the present method provided a more precise way to predict the movement of hybrid beads in aqueous solution compared with the approach for commercial use. This new method can be potentially employed in flow cytometry, suspension stability, and particle analysis systems.