Morphological,thermal, and conductivity studies of poly(methyl methacrylate)/polyaniline dodecylbenzenesulfonate blends

Soluble in organic solvent polyaniline (PANI) was prepared using DBSA as a functional dopant. Miscibility was maximized for PMMA with hydroquinone. Transmission electron micrographs showed lowest level of phase separation. Thermal studies by differential scanning calorimetry show some peak shifts which indicate the miscibility of two polymers. The formations of new bonds are also confirmed by Fourier transformation infrared spectroscopy. Electroconductivity increased with increase of content of doped PAN1, showing percolation threshold at 3 wt %.     

Selective monotetrahydropyranylation of symmetrical diols using P_20_5/Si0_2 under solvent-free conditions and their depyranylation

Selective protection of one of the hydroxyl group in 1,n-symmetrical diols is achieved by P_2O_2/SiO_2-catalyzed reaction of the diol with dihydropyran under solvent-free conditions at room temperature.This selective protection is simple and it occurred under economically cheap conditions in high yield.The deprotected diol is simply obtained by refluxing of this compound in methanol using the same catalyst without any byproduct formation or additional purifications.     

Diethyl 1-(p-fluoro­phenyl)-5-oxo-3-(2-thienyl)­pyrrolidine-2,2-di­carboxyl­ate

In the title compound, C₂₀H₂₀FNO₅S, the pyrrolidine ring adopts an envelope conformation. The fluoro­phenyl and thio­phene rings are individually planar. The molecular and crystal structures are stabilized by intra- and intermolecular C—H⋯O interactions.     

Structure determination of salisomide and salisoflavan,two new secondary metabolites from Salsola imbricata,by 1D and 2D NMR spectroscopy

Chromatographic analysis of the alcoholic extract from Salsola imbricata yielded two new secondary metabolites, salisomide (1) and salisoflavan (2). Their structures were established with the help of spectroscopic techniques including COSY, HMQC and HMBC NMR experiments. Copyright © 2008 John Wiley & Sons, Ltd.     

Convergence and Voronovskaja-type theorems for derivatives of generalized Baskakov operators

In the present paper our aim is to establish convergence and Voronovskaja-type theorems for first derivatives of generalized Baskakov operators for functions of one and two variables in exponential and polynomial weight spaces.      

The effect of proton irradiation on the melting and isothermal crystallization of poly(ether‐ether‐ketone)

Amorphous poly(ether‐ether‐ketone) (PEEK) progressively crosslinks on irradiation with 11.0 MeV protons, and this has a marked effect on the extent of crystallinity that subsequently develops and on the kinetics of the high temperature isothermal crystallization. The extent of crystallinity with time was analyzed using the Avrami equation, and the temperature dependence of the rate constants was analyzed in terms of nucleation theory. While irradiation inhibits the overall rates of crystallization by the reduction in the mobility of the chain segments as observed by the progressive increase in the glass transition temperature, it also alters the fold surface free energy. The observed melting points were consistent with depression of the equilibrium melting point by the crosslinks produced by irradiation. These two effects alone are sufficient to account for the inhibition of crystallization on irradiation of PEEK by protons. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1094–1103, 2008     

Thermodynamic properties of CO2 absorption in hydroxyl ammonium ionic liquids at pressures of (100–1600) kPa

Solubility of CO₂ in six hydroxyl ammonium ionic liquids 2-hydroxyethanaminium acetate [hea], bis(2-hydroxyethyl)ammonium acetate [bheaa], 2-hydroxy-N-(2-hydroxyethyl)-N-methylethanaminium acetate [hhemea], 2-hydroxyethanaminium lactate [hel], bis(2-hydroxyethyl)ammonium lactate [bheal], 2-hydroxy-N-(2-hydroxyethyl)-N-methylethanaminium lactate [hhemel] at temperatures (298.15, 313.15, and 328.16) K and pressures ranging from (100 to 1600) kPa was determined. From the experimental solubility data, the Henry’s constant of CO₂ for each hydroxyl ammonium ionic liquids was estimated and reported as a function of temperature. Furthermore, enthalpy and entropy of absorption were obtained from estimated Henry’s constant. The results showed that the solubility increase with increasing pressure and decrease with increasing temperature and the solubility of CO₂ in these six hydroxyl ammonium ionic liquids was in sequence: [hea] > [bheaa] > [hel] > [bheal] > [hhemel] > [hhemea].     

Conversion of iminoacyl quinolinylpalladium (II) complexes into novel oxo‐pyrrolo[3,4‐b] quinolines via depalladation reactions

Oxidative addition reactions of quinolines 1a , b with Pd(dba)₂ in the presence of PPh₃ (1:2) in acetone gave dinuclear palladium complexes [Pd(C,N‐2‐C₉ H₄N‐CHO‐3‐R‐6)Cl(PPh₃)]₂ [(R = H ( 2a ), R = OMe ( 2b ), which were reacted with isocyanide XyNC (Xy = 2,6‐Me₂C₆H₃) to give novel iminoacyl quinolinylpalladium complexes 3a , b in good yields (81 and 77%). Cyclopalladated complexes 3a , b were also obtained in low yields (39 and 33.5%) via one‐pot reaction of 1a , b with isonitrile XyNC:Pd(dba)₂ (4:1). The reaction of 3a , b with Tl(TfO) (TfO = triflate, CF₃SO₃) in the presence of H₂O or EtOH causes depalladation reactions of complexes to provide the corresponding organic compounds 4a , b , 5a , b and 6a , b in yields of 41, 27 and 18 ? 19%, respectively. The products were characterized by satisfactory elemental analyses and spectral studies (IR, ¹H, ¹³C and ³¹P NMR). The crystal structures 2a , 3a and 3b were determined by X‐ray diffraction studies. Copyright © 2008 John Wiley & Sons, Ltd.     

Copolyesteramides: synthesis and kinetic analysis

The synthesis of copolyesteramides using para-acetamido benzoic acid (PABA) and polyethylene terephthalate (PET) by melt polymerization has been studied in detail. The performance of three transesterification catalysts are assessed for three different initial compositions, PABA 60 mol%/PET 40%, PABA 50 mol%/PET 50% and PABA 40 mol%/PET 60%. The polycondensations are found to obey second order kinetics, irrespective of whether the reaction was catalysed or not. The mechanism of initial stage polymerization kinetics of the copolymers has been fully explained.It is suggested that acetic acid is evolved only by the homopolymerization of PABA and that the insertion of a monomer of homopolymer of PABA into PET does not yield any acetic acid. A set of differential equations containing three different rate constants, k₁ for homopolymerization of PABA, k₂ for PET reaction with dimer of PABA and k₃ for PABA reaction with copolymer of PABA and PET has been developed and numerically solved, to study the initial stage kinetics. The computed values of acetic acid are compared with the experimentally collected amount and the three rate constants are optimized using a differential algebraic optimization technique. The present model represents the data with an acceptable accuracy with an average % error of less than 5% between experimental and computed values for the entire experimental range. The correlation coefficient values range between 0.988 and 0.999.Differential scanning analysis of the copolyestermides indicates that 40 mol% PABA and 60% PET had the highest enthalpy values of the order of 18 kJ/mol. It is found that within the copolyesteramide series the degree of crystallinity increased with the increase of PET contents in the feed mixture to the batch reactor.