- Polymerized phosphonium-based ionic liquids as stationary phases in gas chromatography: performance improvements by addition of graphene oxide
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Eight new functionalized, polymerizable phosphonium ionic liquids were prepared and applied as polymeric stationary phases in gas chromatography (GC). These coated GC columns exhibit high thermal stability compared to other ionic liquids (220-380 °C), and column efficiencies between 2700 and 3700 plates per m. The new columns have been characterized using the Abraham model in order to understand the effects of the polymeric cations and anions on the behavior of the system. These stationary phases show unique selectivity for several types of organic compounds such as alcohols, amines, pesticides and polycyclic aromatic hydrocarbons (PAHs), with good peak symmetries in some cases. Moreover, graphene oxide (GO) sheets have been covalently bonded onto the inner wall surface of fused silica capillary columns using 3-aminopropyl-diethoxymethylsilane (3-AMDS) as a cross-linking agent. The use of GO in the preparation of the capillary columns enhances their efficiency, improving peak symmetries because of the reduction of the unspecific absorption.
- González-álvarez, Jaime,Arias-Abrodo, Pilar,Puerto, Marcos,Viguri, Maialen Espinal,Perez, Julio,Gutiérrez-álvarez, María Dolores
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- Studies on the efficient generation of phosphorus-carbon bonds via a rearrangement of PIII esters catalysed by trimethylhalosilanes
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Halotrimethylsilanes Me3SiX (X = Br, I) catalyse rearrangements of tricoordinate phosphorus esters R′R″P-OR into the corresponding phosphoryl systems R′R″P(O)R. This provides a simple and efficient route to a variety of structures containing phosphorus-carbon bonds, under mild conditions and with good yields. The reaction mechanism was investigated in detail by 31P NMR spectroscopy and independent synthesis of the reaction intermediates. It has been demonstrated that the primary products of this catalytic reaction are halogeno PIII structures R′R″PX and silyl ethers ROSiMe3 and that they subsequently react to give the corresponding phosphorus silyl esters - Me 3SiOPR′R″-and alkyl halides RX. At higher temperatures these intermediates then react to form R′R″P(P)R compounds. This paper also features the surprising observation that when esters Ph 2POR and halotrimethylsilanes Me3SiX (X = Br, I) are used in 2:1 ratio, phosphonium salts Ph2R2P+X - and trimethylsilyl diphenylphosphinate - Ph2P(O) OSiMe3 - are formed as the major products. Experimental evidence indicates that the mechanisms of both reactions are fundamentally different from that of the Michaelis-Arbuzov reaction. Me3SiCl is not reactive and this paper explains why.
- Dabkowski, Wojciech,Ozarek, Alfred,Olejniczak, Sebastian,Cypryk, Marek,Chojnowski, Julian,Michalski, Jan
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experimental part
p. 1747 - 1756
(2009/09/25)
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- Synthesis of Diphenyldialkylphosphonium Salts
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A general method for synthesis of the title compounds by a one-pot reaction is described.It consists in the double alkylation of lithium diphenylphosphide, obtained by the reaction of triphenylphosphine, lithium and tert-butyl chloride.This procedure can also be used for α-functional alkylating agents.
- Cristau, Henri-Jean,Ribeill, Yves
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p. 911 - 912
(2007/10/02)
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