Presence Of H2PtCl6 Research Articles

SYNTHESIS AND PROPERTIES OF 2-SUBSTITUTED ORGANOSILICON 1,4-DIENE EPOXIDES

The addition reaction of triorganosilanes to 1-(5-methylhexene-5-yn-2-yloxy)-2,3-epoxypropane in the presence of H2PtCl6.6H2O catalyst proceeds via a triple bond, but with an advantageous yield (75-85%) of the β-isomer (relative to the oxygen atom). The addition of dimethylamine to the epoxy ring leads to secondary amino alcohols, and the corresponding episulfide is obtained by the reaction of epoxysilane with thiocarbamide. Epoxy-1,4-dienes can be used as modifiers for phenol-formaldehyde resin

Oxygen vacancies enhanced photocatalytic activity towards VOCs oxidation over Pt deposited Bi2WO6 under visible light

A novel Pt assisted self-modified Bi2WO6 composites (Pt/Bi-BWO) with high oxygen vacancies concentration was successfully fabricated via a simple in-situ NaBH4 reduction method in presence of H2PtCl6•6H2O. The Pt/Bi-BWO performed excellent photocatalytic activity on the degradation of gaseous toluene under visible light illumination. The photocatalytic reaction rate of 0.15% Pt/Bi-BWO was 2.88 times higher than that of Bi2WO6. Over 90% gas phase toluene was removed by 0.15% Pt/Bi-BWO in one hour and over 80% of which was degraded into CO2 and H2O. The Pt/Bi-BWO also performed great stability confirmed by circulating runs test. The mechanism of the promotion was explored by electron paramagnetic resonance (EPR) and DFT calculations. The produced oxygen vacancies were below conduction band (CB) of Bi2WO6, leading to a narrowed band gap. Meantime, the generated oxygen vacancies could activate O2 to enhance the production of reactive oxygen species (ROS), such as O2− and OH. In addition, the added Pt could act as electron trap to suppress the recombination of electrons-holes pairs. In a word, this work produced a novel simply made photocatalyst to remove volatile organic compounds.

Hierarchical reduced graphene oxide supported dealloyed platinum–copper nanoparticles for highly efficient methanol electrooxidation

Exploiting highly efficient electrocatalysts through simple methods is very critical to the development of energy conversion technologies. Herein, we develop a hierarchical reduced graphene oxide supported dealloyed platinum–copper nanoparticle catalyst (Pt–Cu/RGO) by a facile one-step electrodeposition of graphene oxide in the presence of H2PtCl6 and copper ethylenediamine tetraacetate. The nanostructure and composition were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. Meanwhile, the electrocatalytic performance was investigated by cyclic voltammetry and chronoamperometry, showing that the Pt–Cu/RGO catalyst not only equips with an outstanding electrocatalytic activity for the methanol oxidation reaction (2.3 times that of commercial Pt/C catalyst), but also shows a robust durability and superior tolerance to CO poisoning. The excellent electrocatalytic performance could be attributed to the three-dimensional hierarchical structure, porous dealloyed nanoparticles and synergistic effect between each component.

Electroless deposition of Gold-Platinum Core@Shell Nanoparticles on Glassy Carbon Electrode for Non-Enzymatic Hydrogen Peroxide sensing#

A non-enzymatic hydrogen peroxide sensor was developed using gold@platinum nanoparticles (Au@PtNPs) with core@shell structure fabricated on glassy carbon electrode (GCE) by electroless deposition method. Initially, gold nanoparticles (AuNPs) were deposited on GCE by reducing HAuCl4 in the presence of NH2OH and the deposited AuNPs on GCE act as the nucleation centre for the deposition of platinum nanoparticles (PtNPs) in the presence of H2PtCl6 and NH2OH. SEM and AFM studies demonstrated that the electroless deposition of Pt on Au was isotropic and uniform. Further, Au@PtNP-modified substrates were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDAX) and cyclic voltammetry (CV). XPS showed characteristic binding energies at 71.2 and 74.4 eV for PtNPs and, 83.6 and 87.3 eV for AuNPs indicating the zero-valent nature in both of them. The electrocatalytic activity of Au@PtNP-modified electrode was investigated towards hydrogen peroxide (HP) reduction. The modified electrode exhibited higher electrocatalytic activity towards HP by not only shifting its reduction potential by 370 mV towards less positive potential but also by enhancing the reduction current when compared to bare and AuNP-modified GCE. The present method shows better sensitivity compared to the reported methods in literature and the detection limit was found to be 60 nM.

Monitoring isoniazid level in human fluids in the presence of theophylline using gold@platinum core@shell nanoparticles modified glassy carbon electrode

We report the electrochemical determination of anti-tuberculosis drug, isoniazid (INH) using gold–platinum core–shell nanoparticles (Au@PtNPs) modified glassy carbon electrode (GCE). The Au@PtNPs modified GCE was fabricated by electroless deposition of AuNPs by reducing HAuCl4 in the presence of NH2OH followed by the electroless deposition of PtNPs in the presence of H2PtCl6 and NH2OH. The initially deposited AuNPs act as the nucleation centre and catalyzed the deposition of PtNPs. Scanning electron microscopy (SEM) studies suggest that the electroless deposition of Pt on Au was isotropic and uniform. Then, the GC/Au@PtNPs electrode was exploited for the determination of INH in the presence of theophylline (TP). It was found that GC/Au@PtNPs electrode not only enhanced the oxidation currents of INH and TP but also shifted their potentials toward less positive potential in contrast to bare GCE. The present modified electrode was successfully used to determine these drugs simultaneously in a mixture. Selective determination of INH in the presence of 100-fold higher concentration of TP was also achieved at GC/Au@PtNPs electrode. The amperometric current response was increased linearly while increasing the concentration of INH from 50×10−9 to 100×10−6M with a correlation coefficient of 0.998 and the limit of detection was found to be 26×10−9M (S/N=3). Finally, the practical application of the present modified electrode was demonstrated by simultaneously determining the concentrations of INH and TP in human blood serum and urine samples.

Fabrication of Metal-Nanoparticle-Modified Semiconducting Copper- and Silver-TCNQ Materials as Substrates for the Reduction of Chromium(VI) Using Thiosulfate Ions at Ambient Temperature.

The formation of readily recoverable and reusable organic semiconducting Cu- and AgTCNQ (TCNQ=7,7,8,8-tetracyanoquinodimethane) microstructures decorated with Pt and Pd metallic nanoparticles is described for the effective reduction of CrVI ions in aqueous solution at room temperature using both formic acid and an environmentally friendly thiosulfate reductant. The M-TCNQ (M=metal) materials were formed by electrocrystallisation onto a glassy carbon surface followed by galvanic replacement in the presence of H2 PtCl6 or PdCl2 to form the composite material. It was found that loading of the surface with nanoparticles could easily be controlled by changing the metal salt concentration. Significantly, the M-TCNQ substrates facilitated the formation of well-isolated metal nanoparticles on their surfaces under appropriate galvanic replacement conditions. The semiconductor-metal nanoparticle combination was also found to be critical to the catalyst performance, wherein the best-performing material was CuTCNQ modified by well-isolated Pt nanoparticles with both formic acid and thiosulfate ions as the reductant.

Synthesis and characterization of polysiloxanes with pendant bicyclic fragments

AbstractThe hydrosilylation reactions of 5‐vinyl‐2‐norbornene with α,ω‐bis(trimethylsiloxy)methylhydrosiloxane catalyzed by platinum hydrochloric acid (0.1Msolution in tetrahydrofuran), Karstedt's catalyst (Pt2[(VinSiMe2)2O]3) and platinum on the carbon have been studied. Dependence of reaction rate and active SiH bonds' conversion depth on the catalyst was investigated. Even in the excess of the 5‐vinyl‐2‐norbornene, not all active SiH groups participate in the hydrosilylation reaction. The reaction order, activation energies, and rate constants have been determined for hydrosilylation reactions in the presence of H2PtCl6. The synthesized oligomers were characterized by Fourier transform infrared spectroscopy (FTIR),1H,13C,1H‐1H correlation spectroscopy (COSY), and C,H‐correlation NMR spectroscopy. Synthesized polysiloxanes were characterized by wide‐angle X‐ray, gel‐permeation chromatography, and DSC analyses. Calculations using the quantum‐chemical semi‐empirical AM1 method for modeling reaction between methyldimethoxysilane [Me(MeO)2SiH] and 5‐vinyl‐2‐norbornene were performed to evaluate possible reaction paths. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Trisyl modification of epoxy- and chloromethyl-polysiloxanes

The new bulky organosilicon compound HC(Me2SiCH2CH2CH2OCH2CycloCHCH2O)3 was synthesized by hydrosilylation of tris(dimethylsilyl)methane (HMe2Si)3CH and allyl glycidyl ether (AGE) in the presence of H2PtCl6 as a catalyst. Polysiloxanes containing 3-(2,3-epoxypropoxy)propyl and chloromethylphenethyl groups were synthesized by hydrosilylation of AGE and chloromethyl styrene (CMS) with hydrogen-containing polymethylsiloxane (PMHS). Both types of polymers could be modified by incorporation of the highly sterically-demanding tris(trimethylsilyl)methyl [trisyl = (Me3Si)3C] substituent. The trisyl (Tsi) groups were attached to the obtained polymers as side chains by reacting excess trisyl lithium with benzyl chloride and epoxy groups. The epoxy groups possess a higher reactivity for TsiLi than the chloromethyl groups. The ring opening reaction between the epoxy groups and TsiLi is fast. The modification increases the rigidity of the polymers as shown by differential scanning calorimetry analysis. The incorporation of the Tsi groups into the polymer structure creates macromolecules of novel architecture with potential use as membranes for fluid separation. All the resulting polymers were characterized by FT-IR and 1H NMR spectroscopy.

2- and 3-arylpropyl(ethynyl)dimethylsilanes

Hydrosilylation of ortho- and para-substituted 2-phenylpropenes and ortho-, meta-, and para-alkoxysubstituted 3-phenylpropenes with chlorodimethylsilane in the presence of H2PtCl6 was effected. The resulting adducts were reacted with ethyntlmagnesium bromide to synthesize 2- and 3-arylpropyl(ethynyl)silanes.

The synthesis and catalytic activity of poly(bis(imino)pyridyl) iron(II) metallodendrimer

The first and second generation carbosilane dendrimers with silicon hydride terminated were synthesized, and then reacted with bis(imino)pyridyl containing allyl [4-CH2==CHCH2-2,6-(Pr2C6H3N)-Pr-i==CMe(C5H3N)MeC==N(2,6-'Pr2C6H3)], in the presence of H2PtCl6 as a hydrosilylation catalyst, to afford the first and second generation carbosilane supported ligands. Complexation reactions with FeCl(2)(.)4H(2)O give rise to iron-containing carbosilane dendrimers with FeCl2 moieties bound on the periphery. The metallodendrimers were used as catalyst precursors, activated with modified methylaluminoxane, for the polymerization of ethylene. In the case of low Al/Fe molar ratio, the metallodendrimers display much higher catalytic activity towards ethylene polymerization and produce much higher molecule weight polyethylenes than the corresponding single-nuclear complex under the same conditions.

Hydrosilylation of 2‐(2‐Propynyl)‐2,3‐dihydro‐1,2‐benzothiazol‐3‐one 1,1‐Dioxide with 1‐Alkynyl(dimethyl)‐ and Bis(1‐alkynyl)methylsilanes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Hydrosilylation of 2-(2-Propynyl)-2,3-dihydro-1,2-benzothiazol-3-one 1,1-Dioxide with 1-Alkynyl(dimethyl)- and Bis(1-alkynyl)methylsilanes

Hydrosilylation of 2-(2-propynyl)-2,3-dihydro-1,2-benzothiazol-3-one 1,1-dioxide with 1-alkynyldimethyl- and bis(1-alkynyl)methylsilanes of the general formula MenHSi(C=-CR)3-n (n = 1, 2) in the presence of H2PtCl6 (Speier's catalyst) occurs in a nonregioselective but stereoselective fashion, yielding mixtures of the corresponding trans-β- and α-adducts. The fraction of the latter ranges from 50 to 70%, depending mainly on the substrate nature rather than on the nature of substituent at the triple bond of the reagent.

α‐Acetylene Hydrosilanes as Hydrosilylating Agents for Terminal Arylacetylenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

α-Acetylene Hydrosilanes as Hydrosilylating Agents for Terminal Arylacetylenes

The hydrosilylation of a number of acetylenes RC≡CH (R, R' = Ph, CH2OPh, CH2SPh) with α-ethynylhydrosilanes Me2SiHCH≡CR' in the presence of H2PtCl6 was investigated. The addition did not occur regioselectively, but was stereospecific and afforded a mixture of α- and trans-β-adducts. The replacement of phenyl substituent by phenoxymethyl both in the molecule of ethynylsilane and the acetylene substrate resulted in growing proportion of the α-adduct in the reaction mixture up to 10-60%.

AN ALTERNATE SYNTHESIS OF THE POTENT ANTIMUSCARINIC AGENT SILA-BIPERIDEN

Sila-biperiden, 9x(RS,SR ), i. e. racemic (SiRS, C2SR)-(exo-bicyclo[2.2.1]hept-5-en-2-yl)phenyl(2-piperidinoethyl)silanol, the silicon analogue of the antimuscarinic agent biperiden, is prepared by a seven-step synthesis. The first step consists in the hydrosilylation of 5-exo-bromobicyclo[2.2.1]-hept-2-ene (2) with dichloro(phenyl)silane (1) in the presence of H2PtCl6. The product of the last synthetic step is a mixture of four endo- (9n) and four exo-diastereomers (9x) of (bicyclo[2.2.1]hept-5-en-2-yl)phenyl(2-piperidinoethyl)silanol and of the (tricyclo[2.2.1.02,6]hept-1−yl)silanol derivative 9t. Eight-fold crystallization of the 9n/9x/9t-mixture gave pure sila-biperiden (racemate) in an overall yield of 5.3%, which represents a more than 30-fold improvement over the earlier synthesis.

ChemInform Abstract: Selective Hydrosilylation of Vinylcyclopropanes in the Presence of H2PtCl6×6 H2O

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Chemical separation for identification of new isotope202Pt

A separation procedure of trace platinum from large amounts of mercury and other interfering elements is described. After irradiation, the HgO target was dissolved in concentrated HCl solution. The thallium fraction was removed by solvent extraction with ether. In the aqueous phase after extraction the radioisotope of platinum produced by irradiation was precipitated as (NH4)2PtCl6 by adding a saturated solution of NH4Cl in the presence of H2PtCl6·6H2O as stable carrier. The decontamination factor of mercury, gold and thallium and the recovery of platinum in the process of separation are satisfactory.

Hydrosilation of ?,?,?-trichloroalkenes in the presence of H2PtCl6 � 6H2O

1. In the presence of H2PtCl6 · 6H2O, Et3SiH is readily added to 5,5,5-trichloropent-1-ene at room temperature. 2. Reaction of CCl3CH=CH2 with Et3SiH gives CCl2=CHCH3 as the main reaction product.

ChemInform Abstract: SYNTHESIS OF METHYLPHENYLBICYCLOCARBOSILOXANES AND STUDY OF THEIR PROPERTIES

AbstractBei der Umsetzung von 2 Mol (I) mit 1 Mol (II) erhält man die im Titel genannten Siloxane (III).

Synthesis of methylphenylbicyclocarbosiloxanes and study of their properties

1. A series of new organosiloxanes with end cyclotetrasiloxanylethyl fragments was obtained by hydrosilylation of heptamethylvinylcyclotetrasiloxane and hexamethylphenylvinylcyclotetrasiloxane withα,ω-dihydromethyl (methylphenyl)siloxanes in the presence of H2PtCl6. 2. The density, specific volume, and activation energy of viscous flow of organobicyclocarbosiloxanes depend on the ratio of the CH3 and C6H5 groups.