- Highly Recoverable Pd(II) Catalysts for the Mizoroki-Heck Reaction Based on N-Heterocyclic Carbenes and Poly(benzyl ether) Dendrons
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Two series of bis(imidazolylidene)palladium complexes of general formula [PdBr2(NHC)2] have been prepared. The molecular weight of the complexes was enlarged by bonding poly(benzyl ether) dendrons of increasing size (G0 to G3) at the nitrogen atom of the NHC ligands. Complexes 1-4 contain monodentate NHC ligands coordinated in a trans mode, whereas complexes 9-12 contain a chelating ethylene-bridged bis(NHC) ligand. The complexes were recovered from the product stream of a Mizoroki-Heck reaction by nanofiltration through thermally and chemically stable ceramic membranes. The recoverability is better for larger complexes and chelate ligands. In particular, chelate G3 complex 12 maintained a constant activity during the 13 recovery cycles performed, affording an accumulated turnover number (TON) of 13a€000. On average, around 99.5% of the metal is recovered in each recovery cycle, and contamination by palladium is only 3 mg per kg of product. Several models to explain the efficiency of the recovery are discussed.
- Ortiz, Alba,Gómez-Sal, Pilar,Flores, Juan C.,De Jesús, Ernesto
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- Organoinorganic composites based on tetraethoxysilane and nitrogen polybases
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Hybrid organoinorganic composites insoluble in water and organic solvents were prepared by the hydrolysis of tetraethoxysilane in the presence of poly-1-vinylpyrazole, poly-1-vinylimidazole, and poly-4-vinylpyridine. The composition of the composites was determined by the nature of the polymeric nitrogen base and hydrolysis conditions. The composites synthesized showed high sorption activity in the extraction of the [PdCl4]2-, [PtCl6]2-, and [AuCl4]- ions from hydrochloric acid solutions. Nauka/Interperiodica 2007.
- Shaglaeva,Lebedeva,Pozhidaev,Sultangareev,Bochkareva,Es'Kova
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- Solvent-free copper/iron co-catalyzed N-arylation reactions of nitrogen-containing heterocycles with trimethoxysilanes in air
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A solvent-free copper/iron-catalyzed N-arylation of nitrogen-containing heterocycles with trimethoxysilanes method for the formation of C-N bonds has been developed. In the presence of Cu, FeCl3, TBAF, and air, a variety of nitrogen-containing heterocycles including imidazoles and triazoles were coupled with aryltrimethoxysilanes and vinyltrimethoxysilane to afford the corresponding products in moderate to excellent yields. It is noteworthy that the reaction is conducted under solvent-free and relatively low Cu/FeCl3 loadings conditions.
- Song, Ren-Jie,Deng, Chen-Liang,Xie, Ye-Xiang,Li, Jin-Heng
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- Synthesis of vinyl monomers with active azaaromatic groups. Phase-transfer catalytic approach
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An efficient method based on the alkylation-elimination reactions under solid-liquid phase transfer-catalysis conditions (S/L PTC) is reported for the preparation of N-vinyl derivatives of azaheterocyclic compounds.
- Bogdal, Dariusz,Jaskot, Krzysztof
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- Phosphine-Catalyzed Vinylation at Low Acetylene Pressure
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The vinylation of various nucleophiles with acetylene at a maximum pressure of 1.5 bar is achieved by organocatalysis with easily accessible phosphines like tri-n-butylphosphine. A detailed mechanistic investigation by quantum-chemical and experimental methods supports a nucleophilic activation of acetylene by the phosphine catalyst. At 140 °C and typically 5 mol % catalyst loading, cyclic amides, oxazolidinones, ureas, unsaturated cyclic amines, and alcohols were successfully vinylated. Furthermore, the in situ generation of a vinyl phosphonium species can also be utilized in Wittig-type functionalization of aldehydes.
- Bienewald, Frank,Comba, Peter,Hashmi, A. Stephen K.,Menche, Maximilian,Rominger, Frank,Schafer, Ansgar,Schaub, Thomas,Sitte, Nikolai A.,Tuzina, Pavel
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p. 13041 - 13055
(2021/09/18)
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- Direct N- and C-vinylation with trimethoxyvinylsilane
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Treatment of nucleobases, nucleosides, 5-membered N-heterocycles and terminal alkynes with trimethoxyvinylsilane in the presence of copper(II) acetate-TBAF system as catalyst affords the vinylation products.
- Arsenyan, Pavel,Petrenko, Alla,Paegle, Edgars,Belyakov, Sergey
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experimental part
p. 326 - 328
(2012/02/04)
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- METHOD OF PREPARING DIALKYLCARBONATES
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The present invention relates to a process of preparing dialkylcarbonates, and particularly to an improved process of preparing dialkylcarbonates, which comprises performing a reaction between an alcohol compound and a chloroformate derivative in the presence of an imidazole compound, thereby enabling to prepare dialkylcarbonates with high yield in a mild condition without using toxic raw materials and to easily separate impurities.
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Page/Page column 11; 12
(2008/06/13)
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- Synthesis of N-vinylazoles from vinyl acetate without using mercury catalysts
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N-Vinyl-substituted pyrazole, 3(5)-methylpyrazole, imidazole, and 1,2,4-triazole were synthesized by addition of the corresponding azoles to vinyl acetate under conditions of phase-transfer catalysis, followed by pyrolysis of N-(1-acetoxyethyl)azoles thus formed at 350-400°C in the presence of water.
- Attaryan,Baltayan,Sagatelyan,Takmazyan, K. Ts.
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p. 2176 - 2178
(2008/09/18)
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- METHOD OF PREPARING FLUORINATED ALKOXYTRIALKYLSILANES
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The present invention relates to a process for preparing alkoxytrialkylsilane, and in particular to a process, wherein an imidazole compound is added as a HCl scavenger and a reaction promoter, thereby enhancing the yield of fluorinated alkoxytrialkylsilanes and reducing corrosion problem.
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Page/Page column 11-12
(2008/06/13)
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- Separating material
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The present invention provides a separating material producable by a) providing a solid substrate, having amino-functional groups coupled to the substrate surface, b) covalently coupling of the amino-functional groups with a thermally labile radical initiator, c) contacting the substrate surface with a solution of polymerizable monomers under conditions, where thermally initiated graft copolymerization of the monomers takes place, to form a structure of adjacent functional polymer chains on the surface of the substrate. The present invention further provides a method for the production of a separating material by a) providing a solid substrate, having amino-functional groups coupled to the substrate surface, b) covalently coupling of the amino-functional groups with a thermally labile radical initiator, c) contacting the substrate surface with a solution of polymerizable monomers under conditions, where thermally initiated graft copolymerization of the monomers takes place, to form a structure of adjacent functional polymer chains on the surface of the substrate.
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- Purification of alkenyl compounds
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A process for purifying alkenyl compounds having a divalent or trivalent heteroatom in the à-position relative to the double bond by distillation comprises carrying out at least two distillations in which the purified alkenyl compounds are obtained from the gas phase by condensation, where the time between the first distillation after the synthesis of the alkenyl compounds and at least one further distillation is at least one day and the purified alkenyl compounds have an APHA color number of 30.
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Page column 8
(2008/06/13)
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- PURIFICATION OF ALKENYL COMPOUNDS
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A process for purifying alkenyl compounds having a divalent or trivalent heteroatom in the α-position relative to the double bond by distillation comprises carrying out at least two distillations in which the purified alkenyl compounds are obtained from the gas phase by condensation, where the time between the first distillation after the synthesis of the alkenyl compounds and at least one further distillation is at least one day and the purified alkenyl compounds have an APHA color number of 30.
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- Synthesis of N-vinyl-1,2,3-triazole derivatives
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Nitro-substituted N-vinyl-1,2,3-triazole derivatives were synthesized by the vinyl exchange reaction. The process was promoted by the catalytic system mercury(II) acetate-trifluoroacetic acid. This system is universal, and it can be used in the synthesis of vinylazoles having two, three, and four nitrogen atoms in the ring.
- Kizhnyaev,Pokatilov,Tsypina,Ratovskii,Vereshchagin,Smirnov
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p. 1056 - 1059
(2007/10/03)
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- N-Alkylation of anilines, carboxamides and several nitrogen heterocycles using CsF-Celite/alkyl halides/CH3CN combination
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It has been found that the N-alkylation of aniline, carboxamides and heterocyclic compounds bearing an acidic hydrogen atom attached to nitrogen can be accomplished with alkyl halides in acetonitrile and cesium fluoride-celite employed as a solid base. In this manner, pyrrole, indole, pyrazole, imidazole, benzimidazole, carbazole, phthalimide, indazole, indoline, 2-pyrrolidinone, piperidine and 1,2,4-triazole can be successfully alkylated. The procedure is convenient, efficient and generally gives rise to the N-alkylated product exclusively.
- Hayat, Safdar,Atta-Ur-Rahman,Iqbal Choudhary,Khan, Khalid Mohammed,Schumann, Wilhelm,Bayer, Ernst
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p. 9951 - 9957
(2007/10/03)
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- 1,2,3-Benzothiadiazole derivatives
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Novel 1,2,3-benzothiadiazole derivatives of the formula STR1 in which Het has the meanings set forth in the specification, and addition products thereof with an acid or metal salt are very effective for the control of undesired microorganisms. Novel intermediates of the formulae STR2 in which Het1 and R5 have the meanings given in the specification.
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- Triazole antifungal agents
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An antifungal compound of formula (I): STR1 or a pharmaceutically acceptable salt thereof, or a pharmaceutically acceptable solvate of either entity, wherein X is CH or N; R1 is phenyl substituted with 1 to 3 substituents each independently selected from halo and CF3 ; R2 is (hydroxy)C1 -C4 alkyl, CONH2, S(O)m (C1 -C4 alkyl), Ar or Het; m is 1 or 2; Ar is phenyl optionally monosubstituted with halo or CF3 ; and Het is a C-linked 6-membered nitrogen-containing aromatic heterocyclic group containing 1 or 2 nitrogen atoms, or a C- or N-linked 5-membered nitrogen-containing aromatic heterocyclic group containing from 2 to 4 nitrogen atoms, wherein either of said heterocyclic groups is optionally substituted with C1 -C4 alkyl or (C1 -C4 alkoxy)methyl.
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- PHASE TRANSFER CATALYSIS WITHOUT SOLVENT. SYNTHESIS OF BISAZOLYLALKANES
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The reaction of azoles and benzazoles with dihalomethanes and dihaloethanes was performed in the absence of solvent.This method provides a general procedure for the synthesis of bisazolylmethanes and ethanes.No solvent was used during the reaction and, when possible, during the work-up.
- Diez-Barra, Enrique,Hoz, Antonio de la,Sanchez-Migallon, Ana,Tejeda, Juan
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p. 1365 - 1373
(2007/10/02)
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- 3-Imidazolium cephalosporin derivatives
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A cephalosporin compound substituted by imidazolium ring in 3-position of cephem having the following formula (I), and pharmaceutically acceptable salt thereof, STR1 wherein R1 is an organic residue known in β-lactam antibiotics, R2 is hydrogen atom or methoxy, n is 0 or 1, A is a nitrogen-containing group constituting imidazolium ring, is useful as an agent for preventing and treating bacterial infections.
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- Synthesis and Physicochemical Studies on 1,2-Bisazolylethanes
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Twenty symmetrical and asymmetrical 1,2-bisazolylethanes have been obtained from azoles and 1,2-dibromoethane or 1-chloro-2-(pyrazol-1-yl)ethane by phase transfer catalysis (PTC).The 1H and 13C nmr properties are reported and the chemical shifts of the ethylene carbon atoms discussed using an additive model.
- Torres, J.,Lavandera, J. L.,Cabildo, P.,Claramunt, R. M.,Elguero, J.
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p. 771 - 782
(2007/10/02)
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- Process for the preparation of phosphonic acid dihalides
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Process for preparing phosphonic acid dihalides of the formula EQU1 wherein R is alkyl of 1 to 18 carbon atoms, cycloalkyl of 4 to 8 carbon atoms, alkenyl of 2 to 18 carbon atoms, phenyl, phenalkyl or alkyl-phenyl of 7 to 8 carbon atoms, phenyl, phenalkyl or alkyl-phenyl of 7 to 8 carbon atoms, all radicals R optionally being substituted by chlorine, bromine, cyano or lower acyloxy, and wherein X is halogen such as 2-chloroethane phosphonic acid dichloride, by reacting phosphonic or thio-phosphonic acids of the formula EQU2 wherein Y is oxygen or sulfur, their salts or functional derivatives, with acid halides of the formula wherein X is chlorine or bromine and n is 1 or 2, in the presence of 0.2 - 5% or in the presence of 0.01 to 0.2% by weight of 1. compounds containing at least one tri- to pentavalent nitrogen or phosphorus atom, which in the case of nitrogen is bound with 1 to 4, in the case of phosphorus with at least 3 valences to organic radicals having up to 20 carbon atoms, two of these valences optionally forming a double bond, or 2. mono-di- or tribasic organic or inorganic fully amidated acids or tri- or pentavalent phosphorus, the N atom of which optionally being substituted by aliphatic radicals having up to 20 carbon atoms, and the organic radicals of which contain up to 20 carbon atoms, If required, in the presence of an inert solvent.
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