Dialkyl Phosphine Research Articles

Selective Functionalization of White Phosphorus with Alkyl Bromides under Photocatalytic Conditions: A Chlorine-Free Protocol to Dialkyl and Trialkyl Phosphine Oxides.

A novel and efficient method for the direct selective alkylation of white phosphorus (P4) with alkyl bromides has been developed, utilizing 4DPAIPN as the photocatalyst and Hantzsch ester as the reductant. This method facilitates the synthesis of structurally diverse dialkyl phosphine oxides in good yields, offering a streamlined alternative to the traditional stepwise approach of chlorinating P4 with Cl2 and subsequently displacing the chlorine atom. Noteworthy features of this reaction include excellent product selectivity, remarkable functional group tolerance, and a broad substrate scope. Additionally, this method is effective for the synthesis of trialkyl phosphine oxides.

Manganese(II) complexes based on pyridyl- and quinolyl-containing dialkylphosphine oxides

New N,O-hybrid ligands with methylene fragment between coordinating nitrogen and oxygen donor centers namely, dialkyl(pyridine-2-ylmethyl)phosphine oxides and dialkyl(quinoline-2-ylmethyl)phosphine oxides were synthesized. During complexation with MnCl2 pyridyl-containing dialkylphosphine oxides act as chelating N,O-bidentate ligands, while quinoline-containing dialkylphosphine oxide acts as O-monodentate ligand. All compounds were structurally characterized by mass-spectrometry, IR spectroscopy, elemental analysis, the monocrystal and powder X-ray analyses. The photoluminescence, electrochemical properties and cytotoxicity of the synthesized compounds were studied. It was found that obtained ligands and their manganese(II) complexes exhibit green–blue and blue-violet luminescence. High catalytic activity of manganese(II) complex with diisopropyl(pyridine-2-ylmethyl)phosphine oxide in HER (hydrogen evolution reaction) was found. Manganese(II) complexes based on pyridyl-containing phosphine oxides demonstrate high cytotoxic activity towards HuTu80 cancer cell line.

Switchable ethylene tri-/tetramerization with high catalytic performance: Subtle effect presented by P-alkyl substituent of PCCP ligands

Electron-rich Ph2PC(R″) = CHPRR′ ligands with a P-alkyl group were prepared, and, in conjunction with chromium, showed very high activities in ethylene tri-/tetramerization, leading to, in most cases, a very low PE selectivity of ≤0.1 wt%. The electronic property of ligands has a remarkable influence on the catalytic activity: the stronger the σ-donor ability, the higher the activity. Dialkyl phosphine ligands show a stronger σ-donor ability, and thus exhibited higher activities than their mixed alkyl/Ph phosphine counterparts. Reducing the ligand steric bulk could convert the selectivity from predominant trimerization into mixed tri-/tetramerization with 1-octene:1-hexene ratio of >1 without compromising high combined 1-C6/1-C8 selectivity (>90 wt%). Furthermore, the ligands with a dialkyl phosphine showed high low-temperature activity at 25 °C with a relatively high 1-C8 selectivity. Notably, under a lower pressure of 20–30 bar, using PPhiPr-PCCP 7 showed almost no formation of PE with high activity and selectivity.

Design, Synthesis, and Applications of ortho -Sulfur Substituted Arylphosphanes

Design, Synthesis, and Applications of <i>ortho</i> -Sulfur Substituted Arylphosphanes

Cross-dehydrogenative Coupling of N-Aryl Tetrahydroisoquinolines Catalyzed by an Anthraquinone-containing Polymeric Photosensitizer.

This work reports the photocatalytic application of an anthraquinone-containing polymeric photosensitizer (AQ-PHEMA) in the visible light-induced cross-dehydrogenative-coupling of N-aryl tetrahydroisoquinolines with several nucleophiles, including nitromethane, 1-methyl-2-alkyl ketone and dialkyl (aryl) phosphine oxide. The results revealed that the reaction could be catalyzed by AQ-PHEMA efficiently to afford a series of 1-substituted-2-aryl-1,2,3,4-tetrahydroisoquinolines in good to excellent yields with nice substrate tolerance under aerobic conditions at room temperature. The practical application potential was also showcased by a gram-scale synthesis. More importantly, the utilization of AQ-PHEMA as a heterogeneous photosensitizer also showed nice recyclability and reusability of the catalyst, whereas AQ-PHEMA can be easily separated and reused for at least 8 times without significant loss of photocatalytic activity.

Double Ligands Enabled Ruthenium Catalyzed ortho‐C−H Arylation of Dialkyl Biarylphosphines: Straight and Economic Synthesis of Highly Steric and Electron‐Rich Aryl‐Substituted Buchwald‐Type Phosphines

AbstractA double‐ligands enabled ruthenium catalyzed C(sp2)−H arylation of dialkyl phosphines is described, which provides a straight access to aryl‐substituted dialkyl phosphine ligands. The combination of 1,3‐diketone and amino acid ligands is essential for this transformation. An important six‐membered cycloruthenium intermediate was successfully isolated and characterized by X‐ray diffraction. Mechanistic studies showed that the 1,3‐diketone promoted the process of oxidative addition of cycloruthenium intermediate. Some of modified CyJohnPhos ligands exhibited highly catalytic activity in palladium catalyzed C−N bond formation.magnified image

Effect of Buchwald-type ligands on platinum catalyzed hydrosilylation of vinyl terminated polydimethylsiloxane

The effect of Buchwald-type ligands on the platinum catalyzed hydrosilylation of vinyl-terminated polydimethylsiloxane has been studied by differential scanning calorimetry of platinum catalyst-containing silicone compositions. Dialkyl(biphenyl-2-yl)phosphines bearing bulky substituents at phosphorus atom are efficient inhibitors of the catalytic hydrosilylation process allowing one to increase the pot-life of silicone composition and to prevent the decomposition of the Pt-based catalyst.

Sorption and transport of aluminum dialkyl phosphinate flame retardants and their hydrolysates in soils

Aluminum dialkyl phosphinates (ADPs) are a class of promising phosphorus-containing flame retardants, but their environmental fate is not well understood. Sorption and transport behaviors of ADPs, and their hydrolysates dialkyl phosphinic acids (DPAs) were studied by batch and column experiments. ADPs are less mobile in soil columns with more than half (>52.6%) of ADPs retained in the soil and residues in the topmost 2-cm layer account for more than 57% of total residues. Dissolution and dispersion of fine grain ADPs were responsible for the transport of ADPs. Sorption DPAs (logKoc) was significantly related to the lipophilicity of DPAs (logD) (p < 0.05). Soil pH and clay content were the dominant factors governing the sorption and transport of DPAs in soils, indicating the importance of electrostatic interactions. The retardation factors (R) of DPAs derived from leaching experiments were pH-dependent with larger R values in the acidic soil (pH = 4.0) where anionic and neutral species of DPAs coexisted. Both physical and chemical non-equilibrium convection-dispersion equations (CDE) yield appropriate modeling for DPAs transport. In most cases, R values estimated from column tests differed from those derived from the batch experiments, which might be attributed to non-equilibrium sorption processes in dynamic conditions.

Construction of N-Heterocyclic Systems Containing a Fully Substituted Allylic Carbon by Palladium/Phosphine Catalysis.

The unique cyclization of benzamide derivatives that contain an alkyne by a Pd(0)/dialkyl(biaryl)phosphine catalytic system is reported. The reaction efficiently provides a variety of six-membered N-heterocyclic compounds that contain a fully substituted carbon center without the need for a stoichiometric additive. Mechanistic studies suggest that this unprecedented cyclization starts with the cleavage of a propargylic C-O bond, and a 1,3-diene has been identified as a relevant intermediate.

Phosphino-Triazole Ligands for Palladium-Catalyzed Cross-Coupling.

Twelve 1,5-disubtituted and fourteen 5-substituted 1,2,3-triazole derivatives bearing diaryl or dialkyl phosphines at the 5-position were synthesized and used as ligands for palladium-catalyzed Suzuki–Miyaura cross-coupling reactions. Bulky substrates were tested, and lead-like product formation was demonstrated. The online tool SambVca2.0 was used to assess steric parameters of ligands and preliminary buried volume determination using XRD-obtained data in a small number of cases proved to be informative. Two modeling approaches were compared for the determination of the buried volume of ligands where XRD data was not available. An approach with imposed steric restrictions was found to be superior in leading to buried volume determinations that closely correlate with observed reaction conversions. The online tool LLAMA was used to determine lead-likeness of potential Suzuki–Miyaura cross-coupling products, from which 10 of the most lead-like were successfully synthesized. Thus, confirming these readily accessible triazole-containing phosphines as highly suitable ligands for reaction screening and optimization in drug discovery campaigns.

Dialkyl(1,3-diarylimidazolin-2-ylidenamino)phosphines: Strongly Electron-Donating, Buchwald-Type Phosphines

The synthesis and properties of a series of strongly electron-donating, sterically demanding dialkyl(1,3-diarylimidazolin-2-ylidenamino)phosphines (IAPs) are reported. Determination of the TEP values shows that the bulky IAPs are better donor ligands than classical N-heterocyclic carbenes. The steric profiles of the IAPs in neutral and cationic gold(I) complexes were analyzed by X-ray diffraction studies and computational methods, revealing similar structural features to the Buchwald-type phosphines. The new phosphines were tested in the gold-catalyzed hydroamination of phenylacetylene with anilines.

Rhodium‐Catalyzed Synthesis of Dialkyl(Heteroaryl)Phosphine Sulfides by Phosphinylation of Heteroaryl Sulfides

AbstractDialkyl(heteroaryl)phosphine sulfides were synthesized by the rhodium‐catalyzed exchange reaction of heteroaryl aryl sulfides and tetraalkyldiphosphine disulfides. The reaction has a broad applicability, giving diverse dialkyl(heteroaryl)phosphine sulfides containing five‐ and six‐membered heteroaryl groups. Various dialkyl(heteroaryl)phosphines were obtained by desulfurization.magnified image

Preliminary test on the distribution, hydrolyzation and excretion of aluminum dialkyl phosphinate flame retardants in rats

Aluminum dialkyl phosphinates (ADPs) are a promising class of chemicals offering superior flame retardance. However, knowledge on their behavior in vivo is scarce. Hydrolysis has been suggested as one of the major routes of environmental degradation of ADPs. Herein, aluminum methylcyclohexyl phosphinic (AMHP), a kind of ADPs with industrial production in China, and its hydrolysate methyl cyclohexyl phosphinic acid (MHPA) were continuously exposed to Sprague Dawley (SD) rats for 28 days in this study. The same ratio of MHPA in organs to serum and the same daily excretion of MHPA were observed for AMHP exposure group and MHPA exposure group, suggesting the hydrolysis of AMHP in vivo. The hydrolysis of AMHP to MHPA was further confirmed by in vitro simulated human gastric intestinal juice. Therefore, both AMHP and MHPA distributed in liver, kidney and even brain in the form of MHPA. More than 80% of AMHP and MHPA could be excreted by feces and urine. Feces are the main route of excretion of AMHP and MHPA. The denseness of the inflammatory cell in the hepatic portal area and biochemical indexes showed the obvious dose-effect relationship. However, the toxicity of AMHP and MHPA was quite low even with exposure level up to 100 mg/kg dw/day. The low cumulative ability and mild toxicity indicated AMHP as a promising substitute for brominated flame retardant.

Buchwald-Hartwig Amination of Nitroarenes.

The Buchwald-Hartwig amination of nitroarenes was achieved for the first time by using palladium catalysts bearing dialkyl(biaryl)phosphine ligands. These cross-coupling reactions of nitroarenes with diarylamines, arylamines, and alkylamines afforded the corresponding substituted arylamines. A catalytic cycle involving the oxidative addition of the Ar-NO2 bond to palladium(0) followed by nitrite/amine exchange is proposed based on a stoichiometric reaction.

Buchwald–Hartwig Amination of Nitroarenes

AbstractThe Buchwald–Hartwig amination of nitroarenes was achieved for the first time by using palladium catalysts bearing dialkyl(biaryl)phosphine ligands. These cross‐coupling reactions of nitroarenes with diarylamines, arylamines, and alkylamines afforded the corresponding substituted arylamines. A catalytic cycle involving the oxidative addition of the Ar−NO2 bond to palladium(0) followed by nitrite/amine exchange is proposed based on a stoichiometric reaction.

Simultaneous determination of the lipophilicity and dissociation constants of dialkyl phosphinic acids by negligible depletion hollow fiber membrane-protected liquid-phase microextraction

Determination of the physicochemical properties, especially the lipophilicity (expressed as the logarithm of distribution coefficient, log D) and dissociation constant (pKa), is of great importance in the early stage of environmental risk assessment for an ionizable compound without these data. Currently, the log D and pKa values of dialkyl phosphinic acids (DPAs), the environmental hydrolysates of aluminum dialkyl phosphinates (ADPs) that is one class of emerging phosphorus-containing flame retardants, are not available. In this study, the log D and pKa values of three DPAs including methylethylphosphinic acid (MEPA), diethylphosphinic acid (DEPA) and methylcyclohexyl phosphinic acid (MHPA), were simultaneously determined by negligible depletion hollow fiber supported liquid phase microextraction (nd-HF-LPME) followed by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC–MS/MS). The pKa and log D of DPAs were determined by curve-fitting the experimental data with equations derived on the basis of the Henderson-Hasselbalch equation and compared with model calculated data. For MEPA, DEPA and MHPA, the pKa values were close and around 3, but the log Ds were strongly pH-dependent with values from −5.01 to 1.01. The log KOW of the neutral form (logKOW,HA) and ionic form (logKOW,A) were in the range of −0.67–1.02 and −3.86–−1.33, respectively. The experimentally determined pKa values were highly in good agreement with ACD/pKa predicted values and the measured log KOW,HA values were closely related to KOWWIN calculated ones, suggesting ACD/pKa and KOWWIN are good alternative methods to estimate pKa and log KOW of DPAs, respectively. As far as we know, this is the first report on the pKa and log D data for DPAs, which are fundamental for the product design and evaluating the environmental behavior and effects of DPAs and ADPs.

Biological effects of new-generation dialkyl phosphinate flame retardants and their hydrolysates in BALB/C mice.

Aluminum methylcyclohexylphosphinate (AMHP), calcium methylcyclohexylphosphinate (CMHP), aluminum diethylphosphinate (ADEP), and aluminum methylethylphosphinate (AMEP) are organic dialkyl phosphinates (DPs) and emerging phosphorus-based flame retardants. The broad-spectrum DPs flame retardants occupy high-end industrial markets, but their ecologic risk has been reported rarely. By exposing male BALB/c mice to DPs and dialkyl phosphinic acids, we studied the toxic effects of these chemicals, and measured AMHP and methylcyclohexylphosphinic acid (MHPA) in blood and feces. We found that DPs and their main hydrolysates had mild toxicity in BALB/c mice. Exposure to 10 and 50 mg/kg/d of AMEP and ADEP caused mild hepatotoxicity in mice. Toxicity of CMHP was in the liver and kidneys. Toxicity of AMHP and its hydrolysate MHPA was low and affected the liver. These data suggest that AMHP has lower toxicity than the other DPs that we tested. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1578-1586, 2017.

New binary extractants and prospects of their application

The distribution of chlorides and nitrates of lanthanides from aqueous solutions has been investigated in the absence of a salting out agent using a new binary extractant, methyl trioctyl ammonium dialkyl phosphinate compared with methyl trioctyl ammonium dialkyl phosphate. Isotherms of the extraction of lanthanides have ben obtained. The extraction stoichiometry of these metals in systems with binary extractants is determined. It has been found that, in the case of the extraction of nitrates of lanthanides by methyl trioctyl ammonium dialkyl phosphate and dialkyl phosphinate, extractable compounds of varying composition are formed. The extraction and separation of lanthanide chlorides by the conventional counter-current scheme and by the scheme based on the technology of free supported liquid membranes (FSLMs) have been experimentally and computationally investigated. It has been found that, when using the FSLM scheme, an increase in the degree of extraction and separation of lanthanides is observed.

ChemInform Abstract: Synthesis of New 2‐[2‐(Dialkyl(diaryl)‐phosphoryl)‐2‐methylpropyl]quinoline‐4‐carboxylic Acids

Abstractby Pfitzinger reaction of isatin with phosphine oxides (II)

Synthesis of new 2-[2-(dialkyl(diaryl)-phosphoryl)-2-methylpropyl]quinoline-4-carboxylic acids

A Pfitzinger reaction of isatin with 2-methyl-(4-oxopent-2-yl)dialkyl(diphenyl)phosphine oxides was used to synthesize new derivatives of 4-quinolinecarboxylic acids, containing a phosphine oxide fragment, and screening for antimicrobial activity was performed.