Triphenylphosphine Solution Research Articles

Ionic inverse vulcanized polymer cross-linked bio-based Eucommia ulmoides gum with reprocessibility, shape memory and low-frequency sound absorption capability

Imidazolium-based ionic sulfur-rich polymer with bromonium ion (SBIM) was synthesized via the vulcanization polymerization of sulfur and ionic diene monomer (VBIM) for the thermally cross-linking of EUG, to generate the modified EUG (EUG-SBIM-xs) with ionic bonds and polysulfide bonds. The CN bonds transalkylation exchange and polysulfide bonds rearrangement of SBIM endowed the EUG-SBIM-xs with good thermally induced reprocessibility. Furthermore, the cross-linked EUG-SBIM-11.5 could completely dissolve in triphenylphosphine solution (in chloroform) via breaking the polysulfide bonds. The existence of imidazolium endowed the EUG-SBIM-xs with damping performance at around 60 °C. In addition, the thermally stimulated shape memory transition process was observed. Finally, the sound absorption properties were also investigated, and the EUG-SBIM-xs displayed high sound absorption coefficient in low-frequency.

SRGO hydrotreating over Ni-phosphide catalysts on granulated Al2O3

Ni-phosphides present a promising alternative to the conventional hydrotreatment NiMo sulfides. The hydrotreatment catalysts are supported on Al2O3 granules, and the similarly Al2O3 supported Ni-phosphide catalysts provide an interesting case for comparison. In this work the Ni-phosphide catalysts supported on Al2O3 granules were prepared using two procedures: 1) temperature-programmed reduction of “phosphite”-type precursor in hydrogen flow (TPR_I catalyst), 2) treatment of Ni nanoparticles with triphenylphosphine solution at elevated temperature (LP catalyst). The catalysts were characterized by ICP-AES chemical analysis, N2 physisorption, XRD, TEM, XPS, 27Al MAS NMR. The Ni2P particles were found in LP samples, while TPR method gives the mixture of Ni12P5 and Ni2P particles and amorphous AlPO4 on the alumina surface. The behavior of granulated Ni phosphide and conventional sulfided NiMo/Al2O3 catalysts was compared in hydroprocessing of straight-run gas oil (SRGO) at 340 °C, 4 MPa, V(H2)/V(feed) - 400 Nm3/m3, LHSV - 1,5 h−1. Hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activity of nickel phosphide catalysts were shown to be lower in comparison with NiMo/Al2O3. Hydrotreating of S-containing model compounds (DBT, 4-MDBT, 4,6-DMDBT) was carried out over TPR_I catalyst, and a negative effect of dimethyl disulfide (DMDS) and acridin additions on the HDS activity was observed.

Iodometric Determination of Hydroperoxides in Hydrocarbon Autoxidation Reactions Using Triphenylphosphine Solution as a Titrant: A New Protocol

Hydroperoxides are important oxidants in epoxidation processes and play a central role in the industrial hydrocarbon autoxidation. This paper presents a new and water-free/low-water iodometric titration technique that can be utilized to quantify organic hydroperoxides. In this protocol, the aqueous thiosulfate titrant used in the conventional iodometric titration method was replaced with a new titrant (triphenylphosphine solution) in order to prevent the need for aqueous solutions. In addition, a comparison of two methods showed that titration time in this new method is shorter than that of thiosulfate titrant based one. It is predicted that a colorless charge-transfer complex is formed from interaction between triphenylphosphine and iodine. The proposed protocol can be utilized in the industrial processes that go through hydroperoxide intermediates.

A rapid method for peroxide value determination in edible oils based on flow analysis with Fourier transform infrared spectroscopic detection.

The development of an automated, rapid and highly precise method for determination of the peroxide value in edible oils based on a continuous flow system and Fourier transform infrared (FTIR) spectroscopic detection is described. The sample stream was mixed with a solvent mixture consisting of 25% (v/v) toluene in hexanol which contained triphenylphosphine (TPP). The hydroperoxides present in the sample reacted stoichiometrically with TPP to give triphenylphosphine oxide (TPPO) which has a characteristic and intense absorption band at 542 cm-1. A 10% (m/v) TPP solution in the solvent mixture and a 100 cm reaction coil were necessary for complete reaction. FTIR transmission spectra were recorded using a flow cell equipped with CsI windows having an optical pathlength of 100 microns. By using tert-butyl hydroperoxide spiked oil standards and evaluation of the band formed at 542 cm-1 a linear calibration graph covering the range 1-100 PV (peroxide value; mequiv O2 kg-1 oil) was obtained. The relative standard deviation was 0.23% (n = 11) and the throughput 24 samples h-1. The developed system was also applied to the determination of PV in olive, sunflower and corn oils, showing good agreement with the official reference method of the European Community which is based on titration using organic solvents. The results obtained clearly show that the developed method is superior to the standard wet chemical method, hence suggesting its application in routine analysis and quality control.

Electrochemical synthesis and structural characterization of the trinuclear copper(I)–copper(II) complex: bis[bis(triphenylphosphine)copper(I)] [bis(thiosalicylate)copper(II)

A novel, symmetrical trinuclear copper(I)–copper(II) com-plex, bis[bis(triphenylphosphine)copper(I)][bis(thiosalicylate)copper(II)], [{Cu(PPh3)2}2{Cu(C7H4O2S)2}], has been prepared by anodic dissolution of copper into a solution of triphenylphosphine and thiosalicylic acid in acetonitrile and characterized by single crystal X-ray structure determination as its acetonitrile solvate; characterized also is the 1:3 copper(I) complex, [tris(triphenylphosphine)(thiosalicylic acid-S)copper(I)], formed as an intermediate in the electrosynthesis.

Stoichiometric determination of hydroperoxides in fats and oils by fourier transform infrared spectroscopy

AbstractA primary Fourier transform infrared (FTIR) spectroscopic method for the determination of peroxide value (PV) in edible oils was developed based on the stoichiometric reaction of triphenylphosphine (TPP) with hydroperoxides to produce triphenylphosphine oxide (TPPO). Accurate quantitation of the TPPO formed in this reaction by measurement of its intense absorption band at 542 cm−1 provides a simple means of determining PV. A calibration was developed with TPPO as the standard; its concentration, expressed in terms of PV, covered a range of 0–15 PV. The resulting calibration was linear over the analytical range and had a standard deviation of ±0.05 PV. A standardized analytical protocol was developed, consisting of adding ∼0.2 g of a 33% (w/w) stock solution of TPP in hexanol to ∼30 g of melted fat or oil, shaking the sample, and scanning it in a 100‐µm KCI IR transmission cell maintained at 80°C. The FTIR spectrometer was programmed in Visual Basic to automate scanning and quantitation, with the reaction/FTIR analysis taking about 2 min per sample. The method was validated by comparing the analytical results of the AOCS PV method to those of the automated FTIR procedure by using both oxidized oils and oils spiked with tert‐butyl hydroperoxide. The two methods correlated well. The reproducibility of the FTIR method was superior (±0.18) to that of the standard chemical method (±0.89 PV). The FTIR method is a significant improvement over the standard AOCS method in terms of analytical time and effort and avoids solvent and reagent disposal problems. Based on its simple stoichiometry, rapid and complete reaction, and the singular band that characterizes the end product, the TPP/TPPO reaction coupled with a programmable FTIR spectrometer provides a rapid and efficient means of determining PV that is especially suited for routine quality control applications in the fats and oils industry.

Adsorption of organic monolayers on pyrite (FeS 2)(100)

A systematic study has been carried out in order to investigate the possibility to grow ultrathin organic films by self-assembly on pyrite (FeS 2) from solutions of triphenylphosphine, n-alkanethiols and n-alkylamines. The adsorption of the different molecules on pyrite(100) surfaces was studied with regard to chemical composition using X-ray photoelectron spectroscopy and with regard to molecular orientation by near-edge X-ray absorption fine structure and IR spectroscopy. Triphenylphosphine readily adsorbs from a solution in ethanol and forms dense monolayers. The adsorption of n-alkylamines is found to result in the formation of highly oriented films, n-alkanethiols, which form well defined monolayers on Au, Ag and Cu surfaces are not found to adsorb on pyrite from solutions in ethanol.

The coordination of mono- and diphosphines to the surface of cadmium selenide

Band edge photoluminescence (PL) of single-crystal n-CdSe provides evidence for adduct formation between the solid's surface and various mono- and diphosphines present in toluene solution. Relative to a toluene ambient, solutions of triphenylphosphine (PPh 3), ethyldiphenylphosphine (PEtPh 2), bis(diphenylphosphino)methane (dppm) and bis(diphenylphosphino)ethane (dppe) in toluene enhance the semiconductor's PL intensity. For all of the phosphines, the increases in PL intensity can be fit to a dead-layer model, allowing the estimation of the reduction in depletion width resulting from phosphine exposure; reductions in dead-layer widths are about 300–400 Å for all phosphines except PEtPh 2, which yields a reduction roughly twice as large. Fits of the PL changes to the Langmuir adsorption isotherm model yield formation constants for the phosphine/CdSe adducts of 30±7 M −1 for PPh 3 and 220± 30 M −1 for PEtPh 2; the diphosphines, which do not fit this simple model as well, give adsorption equilibrium constants of ∼ 100–200 M −1. The results suggest that the diphosphines do not coordinate to the surface in a chelating fashion, but in some combination of bridging and monodentate bonding modes at lower effective surface coverages than the monophosphines.

Revrsed Phase High Performance Liquid Chromatographic Analysis of Triphenylphosphine in a Reaction Mixture

Abstract An isocratic reversed phase high performance liquid chromatographic method is described for monitoring concentrations of triphenylphosphine (TPP) and other compounds involved in an oxygen-transfer reaction catalyzed by a molybdenum complex. Using an inexpensive octadecylsilane column and a mobile phase consisting of aqueous acetonitrile, good separations and linear chromatographic responses were achieved for solutions of TPP, pyridine and each of their oxides in the mobile phase with concentrations in the range of 0.0012 – 0.12 grams/100 mL. No evidence for TPP precipitation was observed during the analysis of supersaturated solutions containing TPP at concentrations as high as 0.27 grams/100 mL. Chromatograms of more concentrated TPP solutions exhibited a second peak corresponding in retention time to TPP-oxide. Contrary to the interpretation of a similar effect in a previous study, evidence is presented indicating that this second peak is not the result of decomposition of TPP to its oxide, but...

A kinetic study of the reaction of diazoalkanes with triphenylphosphine: structure and reactivity in a biphilic process

Second-order rate coefficients and activation parameters are reported for the reaction in solution of triphenylphosphine with a series of diazoalkanes (Ar2CN2) having two aromatic groups attached to the diazo-carbon atom, 9-diazofluorene (DAF), 5-diazo-5H-dibenzo[a,d]cycloheptene (DBSE), its 10,11-dihydro analogue (DBSA), and diazodiphenylmethane (DDM). Although the product phosphazine Ar2CNNPPh3 arises formally by nucleophilic attack of phosphorus on the terminal nitrogen atom of the diazoalkane, the pattern of reactivity approximates to that for proton transfer from acetic acid to the diazoalkane under similar conditions, highlighting the biphilic nature of the reaction. The results can be rationalised in terms of qualitative FMO theory taking into account both HOMO(Ph3P)–LUMO (Ar2CN2) and HOMO(Ar2CN2)–LUMO (Ph3P) interactions. This is lent qualified support by MNDO calculations on Ar2CN2 based on molecular parameters from the X-ray crystal structure of DAF itself and of the ketones corresponding to DBSE, DBSA, and DDM.The reactivity of DDM and the effect of 4,4′-disubstitution by CH3O–, CH3–, and Cl–, which gives rise to a U-shaped Hammett ρσ correlation, is not easily interpreted within the FMO framework. Conformational changes which affect the interacting orbitals as the reactants are transformed into transition states offer an alternative interpretation.

Extractive separation of platinum from macroamounts of palladium using triphenylphosphine oxide and its successive spectrophotometric determination by the stannous chloride method

Trialkylphosphine oxides extract more effectively chloride complexes of platinum than of palladium(II). Of the examined tributylphosphine (TBPO), trioctylphosphine (TOPO), and triphenylphosphine (TPPO) oxides the latter one makes possible best separation of these metals. The extraction of platinum with TPPO from solutions containing platinum and palladium unfavorably decreases with increasing palladium concentration. Using 0.1 M TPPO solution in dichloroethane, at HCl concentration 7.5 M, it is possible to separate 2–200 μg Pt/ml at a palladium concentration not higher than 10 mg/ml. Separation of platinum from macroamounts of palladium has been combined with spectrophotometric determination of platinum by means of stannous chloride. The method has been applied to the analysis of palladium for platinum content.

Extraction of platinum metals from hydrochloric acid medium with triphenylphosphine solution in 1,2-dichloroethane

Extraction of platinum metals with TPP in 1,2-dichloroethane from hydrochloric acid medium has been examined. At hydrochloric acid concentrations higher than 6 M, palladium, platinum and osmium are extracted, whereas at low acidity only palladium is quantitatively extracted. Addition of stannous chloride as labilizing agent makes possible a group separation of platinum metals (except osmium). Possible extraction mechanisms are discussed.

Determination of silver in copper ores by atomic-absorption spectrophotometry after extraction separation with triphenylphosphine

A procedure is proposed for determination of small amounts of silver in copper ores and processed products. The samples are dissolved in a Teflon bomb in a mixture of hydrofluoric and nitric acids, then evaporated in the presence of nitric and boric acids. Silver is extracted from the sample solution with a solution of triphenylphosphine in methyl isobutyl ketone, then determined by atomic-absorption spectrophotometry. The method is precise and accurate. The relative standard deviation for a silver content of 10−4% is about 4%.