Mixture Of Triphenylphosphine Research Articles

Paramagnetic Relaxation Agents for Enhancing Temporal Resolution and Sensitivity in Multinuclear FlowNMR Spectroscopy.

Sensitivity in FlowNMR spectroscopy for reaction monitoring often suffers from low levels of pre-magnetisation due to limited residence times of the sample in the magnetic field. While this in-flow effect is tolerable for high sensitivity nuclei such as 1 H and 19 F, it significantly reduces the signal-to-noise ratio in 31 P and 13 C spectra, making FlowNMR impractical for low sensititvity nuclei at low concentrations. Paramagnetic relaxation agents (PRAs), which enhance polarisation and spin-lattice relaxation, could eliminate the adverse in-flow effect and improve the signal-to-noise ratio. Herein, [Co(acac)3 ], [Mn(acac)3 ], [Fe(acac)3 ], [Cr(acac)3 ], [Ni(acac)2 ]3, [Gd(tmhd)3 ] and [Cr(tmhd)3 ] are investigated for their effectiveness in improving signal intensity per unit time in FlowNMR applications under the additional constraint of chemical inertness towards catalytically active transition metal complexes. High-spin Cr(III) acetylacetonates emerged as the most effective compounds, successfully reducing 31 P T1 values four- to five-fold at PRA concentrations as low as 10 mM without causing adverse line broadening. Whereas [Cr(acac)3 ] showed signs of chemical reactivity with a mixture of triphenylphosphine, triphenylphosphine oxide and triphenylphosphate over the course of several hours at 80° C, the bulkier [Cr(tmhd)3 ] was stable and equally effective as a PRA under these conditions. Compatibility with a range of representative transition metal complexes often used in homogeneous catalysis has been investigated, and application of [Cr(tmhd)3 ] in significantly improving 1 H and 31 P{1 H} FlowNMR data quality in a Rh-catalysed hydroformylation reaction has been demonstrated. With the PRA added, 13 C relaxation times were reduced more than six-fold, allowing quantitative reaction monitoring of substrate consumption and product formation by 13 C{1 H} FlowNMR spectroscopy at natural abundance.

New Molecular Niobium(IV) Complexes NbX4(OPPh3)2 (X = Cl, Br): Synthesis, Crystal and Electronic Structure

New molecular niobium(IV) complexes NbCl4(OPPh3)2(1) and NbBr4(OPPh3)2(2) are synthesized by heating respective niobium pentahalide with a mixture of triphenylphosphine and triphenylphosphine oxide. For the obtained compounds the crystal structure is solved: 1P-1, a = 13.3540(5) A, b = 9.4461(3) A, c = 9.5635(3) A, α = 93.084(1)°, β = 121.263(1)°, γ = 115.058(1)°, Z = 1, R1 = 0.0194; 2P-1, a = 13.308(2) A, b = 9.5934(8) A, c = 9.5556(9) A, α = 93.975(3),°, β = 119.391(4)°, γ = 114.740(4)°, Z = 1, R1 = 0.0184. The unpaired electron is mainly located on the niobium atom, which is supported by quantum chemical calculations and EPR spectroscopic results.

Phosphorus-Doped Carbon Nanocages for Simultaneous Detection of Dopamine and Uric Acid

Phosphorus-doped carbon nanocages are prepared from the mixture of triphenylphosphine and benzene through a chemical vapor deposition method. The as-prepared phosphorus doped sample displays a three dimensional nanosized hollow structure with high specific surface area. Based on these unique properties, phosphorus-doped carbon nanocages have been developed to fabricate an electrochemical sensor. The cyclic voltammetry experimental results indicate that the sensor possesses an excellent catalytic capacity. Compared with carbon nanotubes, the prepared sensor shows a higher sensitivity for dopamine and uric acid. The sensor also shows good selectivity for these analytes. With the acceptable reproducibility and stability, the sensor is applied for real samples with satisfactory results. The simple and efficient sensor in the present work implies that the phosphorus-doped carbon nanocages can be further used for other compounds determination.

Inclusion of Triphenylphosphine in the Supercage of Zeolite Y

A mixture of triphenylphosphine and zeolite Y was thermally treated in an autoclave (423 K, 24 h), resulting in the inclusion of PPh3 in the supercage of zeolite Y, up to 21 wt % (1.5 PPh3 molecule...

Studies on the Synthesis of Novel Four-Membered Cyclic Oxaphosphetanes via Intramolecular Mitsunobu Reaction of Bishydroxyalkylphosphinic Acids

Studies on the synthesis of novel four-membered cyclic oxaphosphetanes from bishydroxyphosphinic acids is reported. Investigations showed that the conversion proceeds through an intramolecular Mitsunobu cyclisation of bishydroxyphosphinic acids with a mixture of triphenylphosphine and diisopropylazodicarboxylate (DIAD) in toluene–CH2Cl2 at room temperature. The treatment of two diastereomers of bishydroxymethylphosphinic acids (dl pair and meso) with a mixture of triphenylphosphine and DIAD gives only one stereoisomer of the cyclic oxaphosphetane.

$$\hbox {Ph}_{3}\hbox {P/CCl}_{4}$$ Ph 3 P/CCl 4 as a highly efficient reagent for one-pot $$N$$ N -alkylation of sulfonamides from alcohols: a rapid route to $$N$$ N -alkyl sulfonamides synthesis

A mild, efficient, and selective protocol for the one-pot $$N$$ -alkylation of sulfonamides with alcohols using triphenylphosphine and carbon tetrachloride is described. In this method, treatment of alcohols with a mixture of triphenylphosphine, carbon tetrachloride, and potassium sulfonylamide salts in refluxing anhydrous DMF furnishes the corresponding $$N$$ -alkyl sulfonamides in good to excellent yields. This protocol is highly efficient for various structurally diverse alcohols and potassium sulfonylamide salts. In this paper the influence of solvents and various reagents as sources for electrophilic-halogen instead of carbon tetrachloride in combination with triphenylphosphine have been examined. This protocol demonstrates the selectivity between primary and secondary alcohols. A plausible mechanism for this protocol has been described.

Synthesis and characterization of segmented copolymers of polystyrene and thermotropic liquid crystalline poly(4-oxybenzoate-co-2,6-oxynaphthoate)

A series of segmented copolymers containing a thermotropic liquid crystalline poly(4-oxybenzoate-co-2,6-oxynaphthoate) and an amorphous polystyrene were created and analyzed. The segmented copolymers were prepared by solution polycondensation of α,ω-dicarboxylic acid-terminated polystyrene with 4-hydroxybenzoic acid and 2-hydroxy-6-naphtholic acid in a mixture of triphenylphosphine, hexachloroethane, and pyridine. The obtained polymers were fractionated to isolate the pure segmented copolymers. The segmented copolymers were characterized by FT-IR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, optical polarizing microscopy (OPM), and X-ray diffraction measurement. OPM and X-ray diffraction measurements verified the presence of a nematic liquid crystalline phase for the segmented copolymers. The experimental results indicate that the segmented copolymers have a microphase-separated morphology, that is both amorphous and liquid crystalline properties were shown by the polystyrene and liquid crystalline polyester segments respectively.

Synthesis of a New Class of Phosphinic Acids: Synthesis of Novel Four-Membered Cyclic Oxaphosphetanes by Intramolecular Mitsunobu Reaction of Bis(α-hydroxyalkyl)phosphinic Acids

A novel class of phosphinic acid derivatives, four-membered cyclic oxaphosphetanes, was synthesized by the reaction of bis(hydroxymethyl)phosphinic acids with a mixture of triphenylphosphine and diisopropyl azodicarboxylate in toluene-dichloromethane at room temperature via an intramolecular Mitsunobu reaction.

An Efficient One-Pot Synthesis of Oxime Ethers from Alcohols Using Triphenylphosphine/Carbon Tetrachloride

A convenient and efficient one-pot O-alkylation of oximes fromalcohols using triphenylphosphine in carbon tetrachloride is described.In this method, treatment of alcohols with a mixture of triphenylphosphine,carbon tetrachloride, oxime, and DBU in the presence of catalyticamounts of tetrabutylammonium iodide in refluxing acetonitrile regioselectivelyfurnishes the corresponding O-alkyl ethersin good yields. This methodology is highly efficient O-alkylationof oximes with various structurally diverse alcohols. Semiempiricalquantum-mechanic calculations (AM1) for unsymmetrical oxime ethers,indicated a lower heat of formation for Z-isomers.

One-Pot Synthesis of N-Alkyl Purine, Pyrimidine and Azole Derivatives from Alcohols using Ph3P/CCl4: A Rapid Route to Carboacyclic Nucleoside Synthesis

A facile and efficient method for one-pot N-alkylation of nucleobases and azole derivatives from alcohols using triphenylphosphine in carbon tetrachloride is described. In this method, treatment of alcohols with a mixture of triphenylphosphine, carbon tetrachloride, nucleobase or azole derivatives and potassium carbonate in the presence of catalytic amounts of tetra-n-butylammonium iodide (TBAI) in refluxing N,N-dimethylformamide, furnishes the corresponding N-alkyl derivatives in good yields. This methodology is highly efficient for various structurally diverse primary alcohols and also useful for N-alkylation of other N-heterocycles containing an acidic N―H bond.

An Efficient and Fast Method for the Preparation of Benzylic Bromides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

PPh3/DDQ as a Neutral System for the Facile Preparation of Diethyl α‐Bromo, α‐Iodo and α‐Azidophosphonates from Diethyl α‐Hydroxyphosphonates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

An Efficient and Fast Method for the Preparation of Benzylic Bromides

A mixture of triphenylphosphine and N‐bromosuccinimide system is found to promote efficient conversion of benzylic alcohols into benzylic bromides under microwave irradiation conditions.

PPh 3/DDQ as a neutral system for the facile preparation of diethyl α-bromo, α-iodo and α-azidophosphonates from diethyl α-hydroxyphosphonates

The mixture of triphenylphosphine (PPh 3) and 2,3-dichloro-5,6-dicyanobenzquinone (DDQ) as a neutral system has been used for the preparation of various types of diethyl α-bromo, α-iodo and α-azidophosphonates from their corresponding diethyl α-hydroxyphosphonates in the presence of n-Bu 4NBr, n-Bu 4NI and NaN 3 in good to high yields.

Synthesis of Pyrazole‐Fused Heterocycles by Thermal Rearrangement of N‐Aziridinylimino Ketenimines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of pyrazole‐fused heterocycles by thermal rearrangement ofN‐aziridinylimino ketenimines

AbstractThe reaction ofN‐aziridinylimino carboxamides 11 with a mixture of triphenylphosphine, carbon tetrachloride, and triethylamine in dichloromethane (Appel's condition) provides a new route to pyrazole‐fused heterocycles such as 2,3‐dihydro‐lH‐imidazo[1,2‐b]pyrazoles 15 and 9,10‐dihydro‐47H‐pyrazolo[5,l‐b]‐[1,3]benzodiazepines 17viathe thermal rearrangement of the expectedN‐aziridinylimino ketenimines12.

Triphenylphosphine/2,3‐dichloro‐5,6‐dicyanobenzoquinone as a New, Selective and Neutral System for the Facile Conversion of Alcohols, Thiols and Selenols to Alkyl Halides in the Presence of Halide Ions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Rapid and Facile Conversion of Primary Amides and Aldoximes to Nitriles and Ketoximes to Amides with Triphenylphosphine and N‐Chlorosuccinimide.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Triphenylphosphine/2,3-dichloro-5,6-dicyanobenzoquinone as a new, selective and neutral system for the facile conversion of alcohols, thiols and selenols to alkyl halides in the presence of halide ions

A mixture of triphenylphosphine (Ph 3P) and 2,3-dichloro-5,6-dicyanobenzoquinone in CH 2Cl 2 affords a complex which in the presence of R 4NX (X=Cl, Br, I) converts alcohols, thiols and selenols into their corresponding alkyl halides in high yields at room temperature. The method is highly selective for the conversion of 1° alcohols in the presence of 2° ones and also 1° and 2° alcohols in the presence of 3° alcohols, thiols, epoxides, trimethylsilyl- and tetrahydropyranyl ethers, 1,3 dithianes, disulfides, and amides.

A RAPID AND FACILE CONVERSION OF PRIMARY AMIDES AND ALDOXIMES TO NITRILES AND KETOXIMES TO AMIDES WITH TRIPHENYLPHOSPHINE AND N-CHLOROSUCCINIMIDE

ABSTRACT Primary amides and aldoximes are easily converted to their corresponding nitriles using a mixture of triphenylphosphine and N-chlorosuccinimide in dichloromethane at room temperature. The reaction of aldoximes occurs almost immediately and primary amides in 0.5 h by this method. By this procedure secondary amides are produced by Beckmann rearrangement of ketoximes.