Topic
Phosphotungstic acid
About: Phosphotungstic acid is a research topic. Over the lifetime, 1925 publications have been published within this topic receiving 38059 citations. The topic is also known as: Phosphowolframic acid.
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TL;DR: In this article, five heteropoly acids (HPAs), which are thermally stable homogeneous strong acid catalysts, were used to promote carbonization of phloroglucinol (PG) without losing the controllability of functional groups and the dispersibility.
Abstract: Oxygen-containing carbon materials such as graphene oxide have been extensively studied because of their high dispersibility. However, the oxygen-containing functional groups in most carbon materials are not controlled. Uncontrollability of the synthesis is also one of factors that prevent industrialization. Carbon materials derived from phloroglucinol (PG), which show high solubility/dispersibility and controllability of functional groups, have been developed recently by our group. The high performance of carbonized PG originates from the thermally stable backbone structure of the benzene ring with hydroxy groups of PG. However, the degree of carbonization was low. In this study, five heteropoly acids (HPAs), which are thermally stable homogeneous strong acid catalysts, were used to promote carbonization of PG without losing the controllability of functional groups and the dispersibility. HPAs promoted etherification of hydroxy groups followed by C=C coupling reactions (furan cyclization) at 523 K. Furthermore, it was confirmed that particularly furan structures, which contribute to solubility/dispersibility in solvents, and thermal stability in air, could be maintained at 673 K as suggested by spectroscopies and thermogravimetric-differential thermal analysis. Among five HPAs, phosphotungstic acid worked as the excellent catalyst to promote carbonization of PG containing furan structures, exhibiting high solubility/dispersibility and high thermal stability in air.
8 citations
TL;DR: In this paper, a graphite electrode coated with a PVC matrix membrane containing the benzyldimethyltetradecylammonium-phosphotungstate ion association complex as electroactive material and dioctyl phthalate as plasticizer was constructed and used in conjunction with a Ag-AgCl double-junction reference electrode to detect the end point of the titration.
Abstract: A method for the determination of micro-amounts of vitamin B1 by direct potentiometric titration in aqueous medium with a standard phosphotungstic acid solution is described. A graphite electrode coated with a PVC matrix membrane containing the benzyldimethyltetradecylammonium–phosphotungstate ion association complex as electroactive material and dioctyl phthalate as plasticizer was constructed and used in conjunction with a Ag–AgCl double-junction reference electrode to detect the end-point of the titration. This method gave very satisfactory results in the range 1–4 mg of vitamin B1, also in comparison with other methods; the recoveries were 100.00 ± 0.25% and the mean relative standard deviation was 0.22%. The method was successfully applied to the analysis of pharmaceutical preparations.
8 citations
TL;DR: In this article, the thermal decomposition of 2-methylpyridine N -oxide was studied at temperatures between 190°C and 220°C using an Automatic Pressure Tracking Adiabatic Calorimeter.
8 citations
TL;DR: In this article, a material with low dielectric constant was produced using nanoparticle phosphotungstic acid (PWA) modified by the silane coupling agent γ-aminopropyltriethoxysilane (KH-550) dispersed in a poly(aryl ether ketone) containing (3-trifluoromethyl) phenyl side groups (FPEEK) matrix synthesized with (3,triflormethyl), phenyl hydroquinone (3FHQ) and 4,4′-dif
Abstract: A material with low dielectric constant was produced using nanoparticle phosphotungstic acid (PWA) modified by the silane coupling agent γ-aminopropyltriethoxysilane (KH-550) dispersed in a poly(aryl ether ketone) containing (3-trifluoromethyl) phenyl side groups (FPEEK) matrix synthesized with (3-trifluoromethyl) phenyl hydroquinone (3FHQ) and 4,4′-difluorobenzophenone. The material was fabricated using solution-blending. Moreover, the dielectric, thermal, and mechanical properties of this material were characterized using a precision impedance analyzer, thermal gravimetric analyzer, and universal tester, respectively. The results indicate that modified PWA (m-PWA)/FPEEK composites show obvious improvement in the dielectric properties compared to unmodified PWA (p-PWA)/FPEEK composites. This should be attributed to the good dispersion and compatibility of m-PWA in FPEEK, as proven by scanning electron microscope and wide-angle X-ray diffraction. Besides, m-PWA/FPEEK composites also exhibited the relatively good thermal and mechanical properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
8 citations
Patent•
01 Mar 1989
TL;DR: In this paper, a 2,3,5-trimethyl-p-benzoquinone is prepared by the catalytic oxidation of 2.3, 5- or 2, 3, 6-trIMethylphenol with hydrogen peroxide in an organic solvent, which is preferably acetic acid, in the presence of a catalyst which is a heteropolyacid having a silicon or phosphorus atom as the centre atom.
Abstract: 2,3,5-trimethyl-p-benzoquinone is prepared advantageously by the catalytic oxidation of 2,3,5- or 2,3,6-trimethylphenol with hydrogen peroxide in an organic solvent, which is preferably acetic acid, in the presence of a catalyst which is a heteropolyacid having a silicon or phosphorus atom as the centre atom, selected from phosphomolybdic acid, silicomolybdic acid, phosphotungstic acid and silicotungstic acid. The reaction proceeds rapidly even at room temperature to give the product in a high yield so that the method is industrially advantageous in addition to the advantages in respect of the inexpensiveness of the reactions and catalyst and the absence of any noxious by-products which may cause environmental pollution.
8 citations