Stereoselective Synthesis of Alkenyl Alcohols Using Dissolving Metal (Ca,Na) Reduction

Use of the calcium-ethylenediamine and sodium-liquid ammonia reduction systems for the ring opening of dihydropyran derivatives was studied. (Z)-Alkenyl alcohols and (E)-alkenyl alcohols were stereoselectively synthesized respectively.     

Reductive Cleavage of S-S Bond by Samarium Diiodide: A Novel Method for the Synthesis of Disulfides

Samarium diiodide reductively cleaves the S-S bond of sodium alkyl thiosulfates to give the corresponding disulfides in moderate to good yields under mild and neutral conditions.     

Dual template method to prepare hierarchical porous carbon nanofibers for high-power supercapacitors

Hierarchical porous carbon nanofibers serving as electrode materials are prepared through carbonization and hydrofluoric acid treatment of polyacrylonitrile-based electrospinning involving dual templates. The hierarchical porous structures are synergistically tailored by varying template contents in the spinning solution. The carbon nanofibers prepared from the electrospinning of polyacrylonitrile containing 15/15 wt.% polymethylmethacrylate/tetraethyl orthosilicate exhibit the largest specific surface area (699 m² g^?1) and microporous volume (0.196 cm³ g^?1). In 6 M KOH electrolyte, a symmetrical supercapacitor equipped with the hierarchical porous carbon nanofibers demonstrates its high-end specific capacitance of 170 F g^?1, superior rate capability, and high-power density output up to 14.7 kW kg^?1. Cycling evolution indicates capacitance fading is only 5.8 % of initial capacitance at a current density of 1 A g^?1 even after 8,000 cycles. The excellent electrochemical performances of the carbon nanofiber are mainly ascribed to the optimized pore size distributions of both micropores and mesopores and the unique hierarchical pore structures possessed by abundant micropores.     

Novel Synthetic Approach Toward C‐Substituted Piperazine Derivatives via C‐N Bonds Formation of α‐Bromoarylethanones and Ethanolamine

A new method for the synthesis of novel C‐substituted piperazine derivatives bearing aryl substituents on 2,6‐C positions has been developed by one‐pot three‐component sequential reaction of α‐bromoarylethanones with ethanolamine in the presence of formic acid. The structure of the novel compounds was established by nuclear magnetic resonance (NMR), mass spectrometry (MS), and elemental analysis. In addition, the crystal structure of 4e was determined by single X‐ray crystallography and a possible reaction mechanism was proposed.     

An analytical method for the determination of stress and strain concentrations in textile-reinforced GF/PP composites with elliptical cutout and a finite outer boundary and its numerical verification

Stress concentrations in the vicinity of cutouts can often be regarded to be the limiting factor for a whole structure. As a further development of prior research at the Institute of Lightweight Engineering and Polymer Technology, an analytical method for the determination of the whole stress-strain fields in the vicinity of holes in multilayered textile-reinforced composites has been developed, which takes into consideration the influences of a finite outer boundary of the specimen. The analytical method is based on the classical laminate theory and the use of complex-valued potential functions. To account for the shape of the specimen, the method of conformal mappings is applied for the inner boundary, while a combination of boundary collocation and least squares method is used for the outer boundary. The method allows a layer-by-layer analysis of stress concentrations. For the verification of the developed calculation model, extensive experimental and numerical finite-element (FE) studies have been carried out on multilayered GF/PP plates with different laminate layups, notches, and specimen dimensions. The comparison of the experimentally or numerically determined results with the analytically calculated ones shows a very good correlation, of which the numerical studies are presented here for the first time. In a second step, the applicable boundary conditions on the outer boundary have been extended in such a way that varying stress and moment resultants can be applied, so that the calculation method can be used as an analytical sub-model in combination with FE techniques.     

Synthesis of novel side‐chain triphenylamine polymers with azobenzene moieties via RAFT polymerization and investigation on their photoelectric properties

Two novel and well‐defined polymers, poly[6‐(5‐(diphenylamino)‐2‐((4‐methoxyphenyl)diazenyl)phenoxy)hexyl methacrylate] (PDMMA) and poly[6‐(4‐((3‐ethynylphenyl)diazenyl) phenoxy)hexyl methacrylate] (PDPMMA), which bear triphenylamine (TPA) incorporated to azobenzene either directly (PDMMA) or with an interval (PDPMMA) as pendant groups were successfully prepared via reversible addition‐fragmentation chain transfer polymerization technique. The electrochemical behaviors of PDPMMA and PDMMA were investigated by cyclic voltammograms (CV) measurement. The hole mobilities of the polymer films were determined by fitting the J‐V (current‐voltage) curve into the space‐charge‐limited current method. The influence of photoisomerization of the azobenzene moiety on the behaviors of fluorescence emission, CV and hole mobilities of these two polymers were studied. The fluorescent emission intensities of these two polymers in CH₂Cl₂ were increased by about 100 times after UV irradiation. The oxidation peak currents (I_OX) of the PDMMA and PDPMMA in CH₂Cl₂ were increased after UV irradiation. The photoisomerization of the azobenzene moiety in PDMMA had significant effect on the electrochemical behavior, compared with that in PDPMMA. The changes of the hole mobility before and after UV irradiation were very small for both polymers. The HOMO energies (E_HOMO, HOMO: the highest occupied molecular orbital) of side chain moieties of TPA incorporated with cis‐isomer and trans‐isomer of azobenzene in PDMMA and PDPMMA were obtained by theoretical calculation, which are basically consistent with the experimental results. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Novel ether-functional spiro-tetronic acid derivatives: molecule design, convenient synthesis and biological evaluation

A novel series of ether functionalization of spiro-tetronic acid derivatives have been designed and conveniently synthesized via three steps, including esterification, one-pot heterocyclization, and etherification reactions. The target molecules have been identified on the basis of analytical spectra data. All newly synthesized compounds have been screened for their potential insecticidal activity against Heliothis armigera and Plutella xylostella compared with spirodiclofen by standard method.