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Polyphosphoric Acid (polyphosphoric + acid)
Selected AbstractsChemInform Abstract: Synthesis of Bipyridyls by the Reaction of Allylpyridines with 1,3,5-Triazine in Polyphosphoric Acid.CHEMINFORM, Issue 33 2010A. V. Aksenov No abstract is available for this article. [source] ChemInform Abstract: Unexpected Result from the Interaction of 1,8-Diaminonaphthalene with Aromatic Nitriles in Polyphosphoric AcidCHEMINFORM, Issue 5 2008I. V. Aksenova Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Acylation of Perimidine with 1,3,5-Triazines in Polyphosphoric Acid.CHEMINFORM, Issue 52 2007A. V. Aksenov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis of 5(6)-Arenesulfonyl Derivatives of 2-Aminobenzimidazole in Polyphosphoric Acid.CHEMINFORM, Issue 16 2006E. B. Mel'nikova Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Anomalous Beckmann Reaction of 4-Aryl-2,7,7-trimethyl-5-oxo-5,6,7,8-tetrahydroquinoline Oximes in Polyphosphoric Acid.CHEMINFORM, Issue 42 2004Part 1. Abstract For Abstract see ChemInform Abstract in Full Text. [source] Asymmetric Synthesis of (S)-Mirtazapine: Unexpected Racemization through an Aromatic ipso -Attack MechanismEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2008Marco van der Linden Abstract An asymmetric synthesis of (S)-mirtazapine has been achieved from the synthesis of the racemate by using (S)-1-methyl-3-phenylpiperazine as the starting material. Unfortunately, significant racemization was encountered in the final step, which involved an electrophilic aromatic ring closure of a alcohol by concentrated sulfuric acid. A significantly higher ee was observed when polyphosphoric acid (PPA) was used instead. A remarkable correlation between the amount of PPA used and the ee of the product was revealed, namely, an increase in the ee upon decreasing the amount of PPA. This trend was paralleled by the formation of an increasing amount of a side-product upon lowering the amount of PPA. The racemization and formation of a side-product can be explained by an ipso -attack mechanism during the electrophilic aromatic ring-closure reaction. This mechanism was supported by a mechanistic study using a deuterium-labeled substrate.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] NMR Studies of Proton Transport in Anhydrous Polymer Electrolytes for High Temperature Fuel Cells,FUEL CELLS, Issue 3-4 2008H. A. Every Abstract This paper presents an NMR study of the dynamic processes related to proton transport in a new polymer consisting of two blocks , poly(2,6-diphenylphenol) (P3O) and an imidazole functionalised poly(2,6-dimethylphenol) (imi-PPE) , and subsequently doped with polyphosphoric acid (PPA). From 1H and 31P NMR relaxation and diffusion measurements of the individual homopolymers and block copolymer, it was observed that addition of PPA significantly enhanced the mobility of imi-PPE and the imi-block copolymer, but not of P3O. The similarity in 1H T2 values between imi-PPE and the imi-block copolymer suggests that the relaxation behaviour in the block copolymer is dominated by the imi-PPE phase. 1H diffusion in P3O and the imi-block copolymer were comparable to pure PPA, suggesting that the proton diffusion is similar in each case. For imi-PPE, the diffusion coefficients were several orders of magnitude lower, reflecting a restricted diffusion process that is not indicative of the proton mobility. For all three polymers, the 31P T2 relaxation behaviour and inability to measure 31P diffusion coefficients imply hindered translational motion of the phosphonate groups. From these results, it can be concluded that hydrogen bonds between the phosphoric acid and the polymer form a network that facilitates proton transport via a hopping mechanism. [source] Original recyclization of S-phenacyl derivatives of 4-acylamino-2-mercapto-1,3-oxazoles and their analoguesHETEROATOM CHEMISTRY, Issue 4 2007Andrei G. Balia Readily accessible acylamino(chloro)acetophenones, if treated with sodium rhodanide and ,-halogenocarbonyl compounds, provide 4-acylamino-5-aryl-2-mercapto-1,3-oxazole derivatives which undergo recyclization on heating in polyphosphoric acid to give substituted 1,3-thiazol-2(3H)-ones or 1,3-thiazolidin-2,4-diones containing 2-alkyl(aryl)-5-aryl-1,3-oxazol-4-yl residues at the N3 atom. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:432,437, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20317 [source] Thermal, catalytic, antimicrobial, and chelating aspects of phenolic resin and its polychelates with f-block elementsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008M. M. Patel Abstract The polymeric ligand (resin) was synthesized by condensation of 2-hydroxy-4-ethoxybenzophenone with ethane diol in the presence of polyphosphoric acid as a catalyst at 145°C for 10 h. The synthesized resin was used to study its ion exchange efficiency and to synthesize its polychelates with 4f-block elements. The resin and its polychelates were characterized on the basis of elemental analyses, electronic spectra, magnetic susceptibilities, IR, NMR, and thermogravimetric analyses. The molecular weight was determined using number,average molecular weight (Mn) by a vapor pressure osmometry (VPO) method. Ion-exchange studies at various concentrations of different electrolytes, pH, and rate have been carried out for f-block elements. Antimicrobial activity of all polychelates and catalytic activity of selected polychelates in organic synthesis have been studied. It is observed that resin can be used as an ion-exchanger and polychelates are found to be an efficient catalysts and antimicrobial agents. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] A new method for the synthesis of substituted indeno[1,2- b]thiophene with subsequent ring expansion to form substituted thieno[3,2- c]quinolineJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2006Lyle W. Castle 2-Phenacylindan-1,3-dione (3) was treated with Lawesson's reagent (2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide) to form 2-phenyl-4H -indeno[1,2- b]thiophene-4-one (4). Compound 4 was subsequently reacted with hydroxyl amine to form the oxime (5), which, upon treatment with polyphosphoric acid, underwent ring expansion (Beckmann rearrangement) to give 2-phenylthieno[3,2- c]quinoline-4(5H)one. [source] Synthesis and characterization of high molecular weight hexafluoroisopropylidene-containing polybenzimidazole for high-temperature polymer electrolyte membrane fuel cellsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2009Guoqing Qian Abstract A high molecular weight, thermally and chemical stable hexafluoroisopropylidene containing polybenzimidazole (6F-PBI) was synthesized from 3,3,-diaminobenzidine (TAB) and 2,2-bis(4-carboxyphenyl) hexafluoropropane (6F-diacid) using polyphosphoric acid (PPA) as both the polycondensation agent and the polymerization solvent. Investigation of polymerization conditions to achieve high molecular weight polymers was explored via stepwise temperature control, monomer concentration in PPA, and final polymerization temperature. The polymer characterization included inherent viscosity (I.V.) measurement and GPC as a determination of polymer molecular weight, thermal and chemical stability assessment via thermo gravimetric analysis and Fenton test, respectively. The resulting high molecular weight polymer showed excellent thermal and chemical stability. Phosphoric acid doped 6F-PBI membranes were prepared using the PPA process. The physiochemical properties of phosphoric acid doped membranes were characterized by measuring the phosphoric acid doping level, mechanical properties, and proton conductivity. These membranes showed higher phosphoric acid doping levels and higher proton conductivities than the membranes prepared by the conventional membrane fabrication processes. These membranes had sufficient mechanical properties to be easily fabricated into membrane electrode assemblies (MEA) and the prepared MEAs were tested in single cell fuel cells under various conditions, with a focus on the high temperature performance and fuel impurity tolerance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4064,4073, 2009 [source] A new intumescent flame-retardant: preparation, surface modification, and its application in polypropylenePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2008Xingyi Wang Abstract Melamine salt of tripentaerythriol phosphate (MTP), as a new intumescent flame-retardant, was prepared from tripentaerythritol (TPE), polyphosphoric acid, phosphoric pentoxide, and melamine, and then incorporated into polypropylene (PP) to obtain flame-retarded PP-MTP. FT-IR analysis showed that MTP was in the form of cage structure. The flammability, combustion behavior, and thermal degradation and stability of flame-retarded PP were characterized by using LOI, UL-94 test, cone calorimetry, and TGA, respectively. By SEM, the char structure of PP-MTP was analyzed. XRD diffraction tests showed that PP-matrix of PP-MTP presented better crystallized phases, when MTP was modified by methyl hydrogen siloxane. The relations of the dispersion of MTP in PP matrix to the compatibility between PP and MTP, and to the flame retardancy were discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Synthesis, spectral properties and application of novel disazo disperse dyes derived from polyester wasteCOLORATION TECHNOLOGY, Issue 2 2010V S Palekar Terephthalic dihydrazide was obtained through aminolytic depolymerisation of polyester bottle waste by using hydrazine hydrate. It was further reacted with 4-aminobenzoic acid in the presence of polyphosphoric acid to obtain a cyclic compound, 4,4,-[5,5,-(1,4)-phenylene)bis(1,3,4-oxadiazole-5,2-diyl)dianiline, having a heterocyclic moiety. Diazotisation of this compound followed by coupling with various N,N -disubstituted anilines afford a series of novel disazo disperse dyes. The structures of these synthesised dyes were confirmed by elemental analysis and Fourier Transform,infrared, proton nuclear magnetic resonance and mass spectroscopy. Ultraviolet,visible spectra of these azo dyes in different polar solvents showed considerable variation in the wavelength of maximum absorbance (,max). Application of these dyes on polyester and nylon fabrics using high-temperature dyeing methods gave brilliant yellowish red hues with fair to moderate light fastness and very good to excellent wash fastness and sublimation fastness. [source] | |||||||||||||