Search

Composite quantum chemical methods W1X-1 and CBS-QB3 are used to calculate the gas phase standard enthalpy of formation, entropy, and heat capacity of 38 phosphines and phosphine oxides for which reliable experimental thermochemical information is limited or simply nonexistent. For alkyl phosphines and phosphine oxides, the W1X-1, and CBS-QB3 results are mutually consistent and in excellent agreement with available G3X values and empirical data. In the case of aryl-substituted species, different computational methods show more variation, with G3X enthalpies being furthest from experimental values. The calculated thermochemical data are subsequently used to determine Benson group additivity contributions for 24 Benson groups and group pairs involving phosphorus, thereby allowing fast and accurate estimations of thermochemical data of many organophosphorus compounds of any complexity. Such data are indispensable, for example, in chemical process design or estimating potential hazards of new chemical compounds. © 2018 Wiley Periodicals, Inc.

Study of the liquid-liquid extraction of Ag(I) ions with a series of phosphine oxides (trioctylphosphine, tributylphosphine, triphenylphosphine, and octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide) and phosphorus-containing calix[4]arene by the well-known method of slope analysis and determination of the process parameters are presented employing CHCl3 and an ionic liquid, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C1C4im+][Tf2N−]) as diluents. The ligand effect on the complexation properties of Ag(I) is quantitatively assessed. The silver-containing extracts are examined by 1H, 31P NMR as well as by SEM and TEM approaches in order to viewing the cation coordination and ligands’ binding mode inside, in the organic phase solution at micro-scale level. A conclusion can be made about aggregation in micelle formation of the calix[4]arene under study upon extraction of Ag(I) ion. A method employing thermogravimetric analysis (TGA) is also exploited for the determination of the solubility of CMPO ligand diluted in [C1C4im+][Tf2N−]. Final conclusions are given highlighting the role of the diluent, molecular or ionic, in complexation processes and selectivity involving ligands with P=O donor group and various metal s-, p-, d- and f-cations. The Ag(I) ions have shown the best extraction behavior compared to the other ions in the +1 oxidation state. Indeed, the calix[4]arene derivative bearing four P=O functions at the lower rim, shows strongly enhanced extraction as well as pronounced separation abilities towards lanthanoids in an ionic liquid environment.

This review surveys the literature regarding the development of catalytic versions of the Wittig and aza-Wittig reactions. The first section summarizes how arsenic and tellurium-based catalytic Wittig-type reaction systems were developed first due to the relatively easy reduction of the oxides involved. This is followed by a presentation of the current state of the art regarding phosphine-catalyzed Wittig reactions. The second section covers the field of related catalytic aza-Wittig reactions that are catalyzed by both phosphine oxides and phosphines.

Octahedral cationic manganese(II) complexes having formulae [Mn(dppmO2)3]2+ and [Mn(dppeO2)3]2+, where dppmO2 and dppeO2 are respectively bis(diphenylphosphino)methane dioxide and 1,2-bis(diphenylphosphino)ethane dioxide, showed intense orange emission upon excitation with UV light, with photoluminescence lifetimes in the range 10–15 ms. The complexes maintain their luminescence features once dispersed in poly(methyl methacrylate) matrix.

In this study, Michaelis-Arbuzov-type reaction of 1-imidoalkyltriarylphosphonium salts with phosphites, phosphonites, and phosphinites was used in the synthesis of a wide range of phosphorus analogs of &alpha, amino acids such as 1-imidoalkylphosphonates, 1-imidoalkylphosphinates, and 1-imidoalkylphosphine oxides. Large differences were observed in the reactivity of substrates depending on their structure, especially on the type of phosphonium moiety and N-protecting group. The conditions under which the expected products can be obtained in good to excellent yields have been developed. Mechanistic aspects of the transformation have been provided.

Background: The Hirao reaction discovered ca. 35 years ago is an important P–C coupling protocol between dialkyl phosphites and aryl halides in the presence of Pd(PPh3)4 as the catalyst and a base to provide aryl phosphonates. Then, the reaction was extended to other Preagents, such as secondary phosphine oxides and H-phosphinates and to other aryl and hetaryl derivatives to afford also phosphinic esters and tertiary phosphine oxides. Instead of the Pd(PPh3)4 catalyst, Pd(OAc)2 and Ni-salts were also applied as catalyst precursors together with a number of mono- and bidentate P-ligands. Objective: In our review, we undertook to summarize the target reaction with a special stress on the developments attained in the last 6 years, hence this paper is an update of our earlier reviews in a similar topic. Conclusion: “Greener” syntheses aimed at utilizing phase transfer catalytic and microwave-assisted approaches, even under “P-ligand-free. or even solvent-free conditions are the up-to date versions of the classical Hirao reaction. The mechanism of the reaction is also in the focus these days.

The crystal structure of 4-(2,3,5,6-tetrafluoropyridyl)diphenylphosphine oxide (1) contains two independent molecules in the asymmetric unit. Although the molecules are virtually identical in all other aspects, the P=O bond distances differ by ca. 0.02 &Aring, In contrast, although tris(pentafluorophenyl)phosphine oxide (2) has a similar crystal structure, the P=O bond distances of the two independent molecules are identical. To investigate the reason for the difference, a density functional theory study was undertaken. Both structures comprise chains of molecules. The attraction between molecules of 1, which comprises lone pair&ndash, &pi, weak hydrogen bonding and C&ndash, H∙∙∙arene interactions, has energies of 70 and 71 kJ mol&minus, 1. The attraction between molecules of 2 comprises two lone pair&ndash, interactions, and has energies of 99 and 100 kJ mol&minus, 1. There is weak hydrogen bonding between molecules of adjacent chains involving the oxygen atom of 1. For one molecule, this interaction is with a symmetry independent molecule, whereas for the other, it also occurs with a symmetry related molecule. This provides a reason for the difference in P=O distance. This interaction is not possible for 2, and so there is no difference between the P=O distances of 2.

Tri- or tetrasubstituted furans have been prepared from terminal activated olefins and acyl chlorides or anhydrides by a multicomponental convergent synthesis mode. Instead of stoichiometric nBu3P, only catalytic nBu3P or nBu3P=O is needed to furnish the furans in modest to excellent yields with a good functional group tolerance under the aid of reducing agent silane. This synthetic method features a silane-driven catalytic intramolecular Wittig reaction as a key annulation step and represents the first successful application of catalytic Wittig reaction in multicomponent cascade reaction.

The geometries, energies, and nuclear magnetic resonance (NMR) chemical shifts of 3 bases (trimethylphosphine, trimethylamine, and trimethylphosphine oxide), their 3 protonated cations, and 15 hydrogen-bonded complexes (corresponding to the HF, HNC, HCN, HCCH, HO, and CHOH Brønsted acids) have been calculated at the B3LYP/6-311++G(d,p) level. The determination of hydrogen bond acidities by NMR is classically performed using the P chemical shifts MePO. This method is more reliable than the use of the N NMR chemical shifts of MeN. This work shows that the P NMR chemical shifts of MeP cannot be used. The raison of the difference between MeP on one hand and MePO and MeN on the other will be discussed., Ministerio de Economía y Competitividad (Spain), Grant/Award Number: CTQ2015‐63997‐C2‐2‐P; Comunidad Autónoma de Madrid, Grant/Award Number: S2013/MIT‐2841

© 2016 Elsevier LtdA new two-step synthesis of phosphonium salts from phosphine oxides using Grignard reagents is reported. This approach involves a cyclization of Z-dialkyl-(diaryl)[2-(5-chloro-2-hydroxyphenyl)-2-phenylvinyl]phosphine oxides under the action of sulfinyl chloride with the formation of 2,2-dialkyl(diaryl)-6-chloro-4-phenyl-2H-1,2-benzoxaphosphinin-2-ium chlorides followed by ring opening under the action of organomagnesium compounds. The method was successfully applied to prepare a series of a new phosphonium salts bearing phenolic moiety with a wide range of substituents at phosphorus atom. Synthesized phosphonium salts shows high antibacterial and antifungal in vitro activity and low toxicity towards human red blood cell.

A simple protocol is presented here for the use of inexpensive polymethylhydrosiloxane (PMHS), a waste product of the silicon industry, as stoichiometric reducing agent for phosphine oxides to phosphines, a highly desirable reaction to recover P-based ligands from their spent form. The reactions were studied by screening parameters, such as substrate to reductant ratio, temperature and reaction time, achieving good conversions and selectivities.

N-Phosphine oxide substituted imidazolylidenes (PoxIms) have been synthesized and fully characterized. These species can undergo significant changes to the spatial environment surrounding their carbene center through rotation of the phosphine oxide moiety. Either classical Lewis adducts (CLAs) or frustrated Lewis pairs (FLPs) are thus formed with B(C6 F5 )3 depending on the orientation of the phosphine oxide group. A strategy to reactivate FLPs from CLAs by exploiting molecular motions that are responsive to external stimuli has therefore been developed. The reactivation conditions were successfully controlled by tuning the strain in the PoxIm-B(C6 F5 )3 complexes so that reactivation only occurred above ambient temperature.

Secondary phosphine oxides react with vinyl sulfides (both alkyl- and aryl-substituted sulfides) under aerobic and solvent-free conditions (80 °C, air, 7–30 h) to afford 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides in 70–93% yields.

The synthesis of P-chirogenic (±)-phosphine oxides and phosphinates via selective nucleophilic ring opening of the corresponding oxaphospholanes is described. Two representative substrates: the phosphonate 2-ethoxy-1,2-oxaphospholane 2-oxide and the phosphinate 2-phenyl-1,2-oxaphospholane 2-oxide were reacted with various Grignard reagents to produce a single alkyl/aryl product. These products may possess further functionalities in addition to the phosphorus center such as the γ-hydroxypropyl group which results from the ring opening and π-donor moieties such as aryl, allyl, propargyl and allene which originates from the Grignard reagent.

P-Hydroxytetraorganophosphorane, the long-postulated intermediate in phosphonium salt and ylide hydrolysis, has been observed and characterised by low temperature NMR, finally definitively establishing its involvement in these reactions. The results require modification of the previously accepted mechanism for ylide hydrolysis: P-hydroxy-tetraorganophosphorane is generated directly by 4-centre reaction of ylide with water.

A mild method for the facile removal of phosphine oxide from the crude products of Wittig and Appel reactions is described. Work-up with oxalyl chloride to generate insol. chlorophosphonium salt (CPS) yields phosphorus-free products for a wide variety of these reactions. The CPS product can be further converted into phosphine. SB. 18/11/2013.

Molybdenum(V) and (VI) and tungsten (VI) complexes of formulae MoOX3.RPPh, MO2X2.RPPh and MoO2X2.RPOEt, where RPPh = bis[(diphenylphosphinyl)methyl]phenylphosphine oxide and RPOEt = bis[(diphenylphosphinyl)methyl]ethyl phosphinate, M = Mo or W and X = Cl, Br or I, have been isolated. Molar conductance, magnetic susceptibility, IR, electronic, 1H and 31P NMR measurements are discussed. All the complexes isolated have octahedral geometry in which the potentially terdentate ligands are coordinated to the metal through two P=O groups.