998-40-3Relevant articles and documents
An Electron Spin Resonance Study of Alkyl Radical Addition to Diethyl Vinylphosponate
Baban, Jehan A.,Roberts, Brian P.
, p. 161 - 166 (1981)
The irreversible addition of alkyl radicals to diethyl vinylphosphonate to give the α-phosphorylalkyl radicals (1) has been studied by e.s.r. spectroscopy at 233 K in hydrocarbon solvents.The rate constants for addition (kadd) have been determined relative to those (2kAt) for self-reaction of (1) for a series of addenda.The values of 2kAt have been measured in separate kinetic e.s.r. experiments for (1; R = Me) (2.0 x 1E9 dm3mol-1s-1) and (1; R = But) (5.0 x 1E8 dm3mol-1s-1) and thus absolute values of kadd were obtained.The rate constant kadd increases along the series R. = Me. (2.5 x 1E3 dm3mol-1s-1 ) prim. sec. t. (5.9 x 1E4 dm3mol-1s-1) and this order is interpreted in terms of the over-riding importance of polar effects in determining the size of the barrier for addition of these nucleophilic radicals to the electron deficient alkene.R. + H2C=CHP(O)(OEt)2 --> RCH2C.HP(O)(OEt)2 (1)
Kinetics and mechanism of the reaction of bis-μ-diethylphosphidobis(tetracarbonylmanganese) with tri-n-butylphosphine
Basato, Marino
, p. 173 - 180 (1993)
The dinuclear phosphido-bridged manganese complex undergoes thermal CO substitution by PnBu3 in decalin to give nBu3)> and nBu3P)(OC)3Mn(μ-PEt2)2Mn(CO)3(PnBu3)>.A kinetic study of the first CO/PnBu3 exchange indicates that all substitutions for the forward and reverse reactions occur via a dissociative mechanism.The rate of CO dissociation is rather low (k = 6.27 * 10-5 s-1 at 130 deg C), mainly as a consequence of a high activation enthalpy (ΔH* = 165 kJ mol-1).The discriminating ability ofthe resulting coordinatively unsaturated intermediate is only slightly in favour of attack of the more basic PnBu3 compared to CO, as indicated by the values of the competition rate ratio nBu3) = 0.36-0.47>.This behaviour is compared with that of the isostructural chromium complex and discussed in the light of the electronic and structural features related to the metal-metal distance in the two complexes (Mn-Mn = 3.675 Angstroem, Cr-Cr = 2.905 Angstroem, for the μ-PMe2 derivatives).
Reaktionen von Phosphanen und Arsanen mit Diselenkomplexen
Frank, Lutz-R.,Evertz, Kaspar,Zsolnai, Laszlo,Huttner, Gottfried
, p. 179 - 188 (1987)
The compound Se2 (1) reacts with primary arsanes and phosphanes, and migration of the carbonylmetal fragment Cp'Mn(CO)2 (Cp'=CH3C5H4) from the selenium to the arsenic or phosphorus center occurs.Products of these reactions are diselena-diarsetanes (4) or diselena-diphosphetanes (5).During the reaction of arsanes with 1, arsinidene complexes (2) are obtained in very good yields.Compounds with a P-Se-P unit (6) can be isolated as by-products of the reaction of phosphanes with 1.
New insights into the mechanism of reduction of tertiary phosphine oxides by means of phenylsilane
Demchuk, Oleg M.,Jasiński, Radomir,Pietrusiewicz, K. Micha?
, p. 441 - 448 (2015)
The mechanism of the reduction of phosphine oxides by PhSiH3 was established on the basis of kinetic measurements and Density Functional Theory (DFT) calculations. In particular, it has been proved that the model reaction between tri-nbutylphosphine oxide and phenylsilane occurs via a nonpolar mechanism. The data presented herein allow prediction and verification of the applicability of the new reduction reagents and conditions for industrially attractive processes.
The Trityl-Cation Mediated Phosphine Oxides Reduction
Landais, Yannick,Laye, Claire,Lusseau, Jonathan,Robert, Frédéric
supporting information, p. 3035 - 3043 (2021/05/10)
Reduction of phosphine oxides into the corresponding phosphines using PhSiH3 as a reducing agent and Ph3C+[B(C6F5)4]? as an initiator is described. The process is highly efficient, reducing a broad range of secondary and tertiary alkyl and arylphosphines, bearing various functional groups in generally good yields. The reaction is believed to proceed through the generation of a silyl cation, which reaction with the phosphine oxide provides a phosphonium salt, further reduced by the silane to afford the desired phosphine along with siloxanes. (Figure presented.).
Reversing Lewis acidity from bismuth to antimony
Balasubramaniam, Selvakumar,Jemmis, Eluvathingal D.,Kumar, Sandeep,Sharma, Deepti,Venugopal, Ajay
supporting information, p. 8889 - 8892 (2021/09/10)
Investigations on the boundaries between the neutral and cationic models of (Mesityl)2EX (E = Sb, Bi and X = Cl?, OTf?) have facilitated reversing the Lewis acidity from bismuth to antimony. We use this concept to demonstrate a higher efficiency of (Mesityl)2SbOTf(Mesityl)2BiOTf in the catalytic reduction of phosphine oxides to phosphines. The experiments supported with computations described herein will find use in designing new Lewis acids relevant to catalysis.
A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
supporting information, (2022/01/04)
The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
Reductive conversion of phosphoryl P(O) compounds to trivalent organophosphines R3P
Zhang, Jian-Qiu,Han, Li-Biao
supporting information, (2021/02/20)
By introducing trimethylsilyl chloride (TMSCl), the pentavalent phosphoryl P(V) compounds such as triphenylphosphine oxides, secondary phosphine oxides etc., were readily converted to the corresponding R2P(OTMS) intermediates, that can further react efficiently with an electrophile R'X or with a nucleophile R'Li to produce the corresponding trivalent phosphines R2PR’. Chiral phosphines could also be obtained stereospecifically by this strategy.
Convergent synthesis of polysubstituted furans via catalytic phosphine mediated multicomponent reactions
Fan, Xia,Chen, Rongshun,Han, Jie,He, Zhengjie
supporting information, (2019/12/25)
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.
Exploring an Umpolung strategy for quaternization of phosphorus
Vetter, Anna C.,Nikitin, Kirill,Gilheany, Declan G.
, p. 339 - 342 (2019/03/07)
We propose a new, potentially widely-applicable, Umpolung approach for the synthesis of quaternary phosphonium salts R3PR1 X (X = Cl, Br) from phosphine oxides R3PO. The new organic group R1 is introduced via nucleophilic attack on an intermediate halophosphonium salt using a Grignard reagent R1MgX and replaces the traditional phosphine quaternization approach. Consequently, the new method does not suffer from the limited availability of many parent phosphines and is much faster than standard quaternization.
