- On the mechanism of lead chalcogenide nanocrystal formation
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On the basis of evidence from 31P NMR spectroscopy, and using PbSe as a model, we propose two simultaneous mechanisms through which monomers are formed in preparations of lead chalcogenide nanocrystals (NCs). In one mechanism, selenium is delivered as a Se2- species, whereas in the other, Se0 reacts with metal already reduced by the organophosphine. This latter mechanism helps explain the sensitivity of NC preparations to the purity of organophosphines and allows the rational modification of batch NC reactions to increase yield. Copyright
- Steckel, Jonathan S.,Yen, Brian K. H.,Oertel, David C.,Bawendi, Moungi G.
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- Rapid Metal-Free Formation of Free Phosphines from Phosphine Oxides
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A rapid method for the reduction of secondary phosphine oxides under mild conditions has been developed, allowing simple isolation of the corresponding free phosphines. The methodology involves the use of pinacol borane (HBpin) to effect the reduction while circumventing the formation of a phosphine borane adduct, as is usually the case with various other commonly used borane reducing agents such as borane tetrahydrofuran complex (BH3?THF) and borane dimethyl sulfide complex (BH3?SMe2). In addition, this methodology requires only a small excess of reducing agent and therefore compares favourably not just with other borane reductants that do not require a metal co-catalyst, but also with silane and aluminium based reagents. (Figure presented.).
- Provis-Evans, Cei B.,Emanuelsson, Emma A. C.,Webster, Ruth L.
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supporting information
p. 3999 - 4004
(2018/09/21)
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- METHODS FOR PHOSPHINE OXIDE REDUCTION IN CATALYTIC WITTIG REACTIONS
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A method for increasing the rate of phosphine oxide reduction, preferably during a Wittig reaction comprising use of an acid additive is provided. A room temperature catalytic Wittig reaction (CWR) the rate of reduction of the phosphine oxide is increased due to the addition of the acid additive is described. Furthermore, the extension of the CWR to semi-stabilized and non-stabilized ylides has been accomplished by utilization of a masked base and/or ylide-tuning.
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Page/Page column 33; 34
(2014/09/29)
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- Breaking the ring through a room temperature catalytic wittig reaction
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One ring no longer rules them all: Employment of 2.5-10 mol % of 4-nitrobenzoic acid with phenylsilane led to the development of a room temperature catalytic Wittig reaction (see scheme). Moreover, these enhanced reduction conditions also facilitated the use of acyclic phosphine oxides as catalysts for the first time. A series of alkenes were produced in moderate to high yield and selectivity. Copyright
- O'Brien, Christopher J.,Lavigne, Florie,Coyle, Emma E.,Holohan, Andrew J.,Doonan, Bryan J.
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supporting information
p. 5854 - 5858
(2013/06/27)
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- Reduction of phosphine oxides to phosphines with the InBr3/TMDS system
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An efficient method for the reduction of phosphine oxide derivatives into their corresponding phosphines is described. The system InBr3/TMDS allows the reduction of different secondary and tertiary phosphine oxides as well as aliphatic and aromatic phosphine oxides.
- Pehlivan, Leyla,Métay, Estelle,Delbrayelle, Dominique,Mignani, Gérard,Lemaire, Marc
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supporting information; experimental part
p. 3151 - 3155
(2012/05/31)
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- General and selective copper-catalyzed reduction of tertiary and secondary phosphine oxides: Convenient synthesis of phosphines
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Novel catalytic reductions of tertiary and secondary phosphine oxides to phosphines have been developed. Using tetramethyldisiloxane (TMDS) as a mild reducing agent in the presence of copper complexes, PO bonds are selectively reduced in the presence of other reducible functional groups (FGs) such as ketones, esters, and olefins. Based on this transformation, an efficient one pot reduction/phosphination domino sequence allows for the synthesis of a variety of functionalized aromatic and aliphatic phosphines in good yields.
- Li, Yuehui,Das, Shoubhik,Zhou, Shaolin,Junge, Kathrin,Beller, Matthias
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scheme or table
p. 9727 - 9732
(2012/07/14)
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- A catalytic method for the reduction of secondary and tertiary phosphine oxides
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TMDS has been found to be an efficient hydride source for the reduction of tertiary and secondary phosphine oxides using a catalytic amount of Ti(Oi-Pr)4. All classes of tertiary phosphine oxides, such as triaryl, trialkyl, and diphosphine, were effectively reduced. Georg Thieme Verlag Stuttgart.
- Berthod, Mika?l,Favre-Réguillon, Alain,Mohamad, Jahjah,Mignani, Gérard,Docherty, Gordon,Lemaire, Marc
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p. 1545 - 1548
(2008/02/05)
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- Method for manufacturing acryloxypropysilane
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A method to manufacture acryloxypropylsilane to a high degree of purity is achieved by hydrosilation of (A) allyl acrylate or allyl methacrylate by (B) a hydrosilane compound, using (C) a platinum-containing compound as the catalyst and (D) an organic phosphorus compound as the promoter. The acryloxypropylsilane product is expressed by General Formula I where R1 represents a hydrogen or methyl group, R2 represents a hydrolyzable group, R3 represents an aryl, alkenyl or aryl group of carbon number 1-12, and n is 0, 1, 2, or 3.
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- Process for preparing organophosphines
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Olefins can be induced to react with phosphines at ambient temperature and pressure to produce organophosphines by free-radical addition. Suitable olefins include C1 to C4 alpha-olefins, cyclic olefins, polycycloalkenyl species, allyl alcohol and esters of vinyl phosphonic acid.
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- Diorganomagnesium Compounds from Magnesium, Hydrogen, and 1-Alkenes and Their Application in Synthesis
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1-Alkenes are converted in high yields to the corresponding primary diorganomagnesium compounds by transition metal-catalyzed hydromagnesation reaction using catalytically prepared suspended (MgH2*) or dissolved magnesium hydride (MgH2').The most active hydromagnesation catalysts have been found to be combinations of zirconium tetrahalides with MgH2* or MgH2'.The reaction is highly regio- and chemoselective.The diorganomagnesium compounds prepared in situ from magnesium, hydrogen, and 1-alkenes can be applied to the synthesis of organic and organometallic compounds just as Grignard compounds (Scheme 3, reactions 3-11).Dioctylmagnesium undergoes the growth reaction with ethene in the presence of quinuclidine and is oxidized by molecular oxygen in high yield to 1-octanol. Key Words: Magnesium hydride, catalytically prepared / Hydromagnesation reactions / Magnesium, diorgano compounds, preparation from magnesium, hydrogen and 1-alkenes / Magnesium, diorgano compounds, application in syntheses / Magnesium, diorgano compounds, oxidation of
- Bogdanovic, Borislav,Bons, Peter,Konstantinovic, Stanimir,Schwickardi, Manfred,Westeppe, Uwe
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p. 1371 - 1384
(2007/10/02)
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- THE CONVERSION OF 2-(METHYLTHIO)ETHANOL INTO 1-CHLORO-2-(METHYLTHIO)-ETHANE: A 13C-LABELLING STUDY WITH THE AID OF 13C NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
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The synthesis of 2-(methylthio)ethanol from acetic acid is described.This labelled alcohol and 13C NMR spectrocopy were used to evaluate the propensity for rearrangement of four methods for effecting the conversion ROH RCl.In every case the product observed at all stages of the reaction was a 1:1 mixture of 1-chloro-2-(methylthio)ethane and 1-chloro-2-(methylthio)ethane.It is proposed that activation of the hydroxy-group of 2-(methylthio)ethanol is followed by internal displacement by the methylthio-group giving the 1-methylthiiranium ion, which is captured by chloride.
- Billington, David C.,Golding, Bernard T.
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p. 341 - 348
(2007/10/02)
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