2155-94-4Relevant academic research and scientific papers
218. INTRAMOLECULAR CYCLIZATION OF AN AMMONIUM SALT CONTAINING AN ALLYL SUBSTITUENT IN POSITION 1 OF THE DIENE FRAGMENT
Chukhadzhyan, E. O.,Chukhadzhyan, El. O.,Shakhatuni, K. G.,Manasyan, L. A.,Babayan, A. T.
, p. 192 - 195 (1994)
It has been shown that, under basic catalytic conditions, dimethylpropargylallyl-(1-allyl-3-phenylpropargyl)- and -(1-allyl-3-α-naphthylpropargyl)ammonium salts undergo diene synthesis type intramolecular cyclization to form condensed analogs of isoindolenium and dihydroindolenium salts with an allyl substituent at position 1.
Piperazine-promoted gold-catalyzed hydrogenation: The influence of capping ligands
Barbosa, Eduardo C. M.,Camargo, Pedro H. C.,Fiorio, Jhonatan L.,Hashmi, A. Stephen K.,Kikuchi, Danielle K.,Rossi, Liane M.,Rudolph, Matthias
, p. 1996 - 2003 (2020/04/22)
Gold nanoparticles (NPs) combined with Lewis bases, such as piperazine, were found to perform selective hydrogenation reactions via the heterolytic cleavage of H2. Since gold nanoparticles can be prepared by many different methodologies and using different capping ligands, in this study, we investigated the influence of capping ligands adsorbed on gold surfaces on the formation of the gold-ligand interface. Citrate (Citr), poly(vinyl alcohol) (PVA), polyvinylpyrrolidone (PVP), and oleylamine (Oley)-stabilized Au NPs were not activated by piperazine for the hydrogenation of alkynes, but the catalytic activity was greatly enhanced after removing the capping ligands from the gold surface by calcination at 400 °C and the subsequent adsorption of piperazine. Therefore, the capping ligand can limit the catalytic activity if not carefully removed, demonstrating the need of a cleaner surface for a ligand-metal cooperative effect in the activation of H2 for selective semihydrogenation of various alkynes under mild reaction conditions.
High-yield preparation method of high-purity dimethyl diallyl ammonium chloride monomer
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Paragraph 0060-0068; 0072-0080, (2019/03/31)
The invention belongs to the technical field of organic synthesis, and specifically relates to a high-yield preparation method of a high-purity dimethyl diallyl ammonium chloride monomer. According tothe preparation method provided by the invention, a segmented type chloropropene and sodium hydroxide solution alternative and dropwise adding method is adopted, the most suitable alternative and dropwise adding amount and the most suitable reaction time of the chloropropene and the sodium hydroxide solution can be found through a large amount of small-scale tests and by adopting an acid-base indicator, the chloropropene can be prevented from being located in strong base environment, a large amount of byproducts such as allyl alcohol can be effectively prevented from being generated, the utilization rate of the chloropropene can be effectively increased, and by adopting a pressure-proof closed reaction kettle, dimethylamine is enabled not to leak and can completely take part in reaction.A dimethyl diallyl ammonium chloride monomer solution obtained through the preparation method is light in color and less in impurities, activated carbon is not used for decoloring and removing the impurities, the purity is high, the contents of amine salt and chlorine ions are extremely low, the yield is approximate to ideal value, a product is used for homopolymerization experiments, a colorless,transparent and clear polymer solution is obtained, and the viscosity and the molecular weight of the colorless, transparent and clear polymer solution are far higher than those of like products.
Accessing Frustrated Lewis Pair Chemistry through Robust Gold@N-Doped Carbon for Selective Hydrogenation of Alkynes
Fiorio, Jhonatan Luiz,Gon?alves, Renato Vitalino,Teixeira-Neto, Erico,Ortu?o, Manuel A.,López, Núria,Rossi, Liane Marcia
, p. 3516 - 3524 (2018/04/14)
Pyrolysis of Au(OAc)3 in the presence of 1,10-phenanthroline over TiO2 furnishes a highly active and selective Au nanoparticle (NP) catalyst embedded in a nitrogen-doped carbon support, Au@N-doped carbon/TiO2 catalyst. Parameters such as pyrolysis temperature, type of support, and nitrogen ligands as well as Au/ligand molar ratios were systematically investigated. Highly selective hydrogenation of numerous structurally diverse alkynes proceeded in moderate to excellent yield under mild conditions. The high selectivity toward the industrially important alkene substrates, functional group tolerance, and the high recyclability makes the catalytic system unique. Both high activity and selectivity are correlated with a frustrated Lewis pairs interface formed by the combination of gold and nitrogen atoms of N-doped carbon that, according to density functional theory calculations, can serve as a basic site to promote the heterolytic activation of H2 under very mild conditions. This "fully heterogeneous" and recyclable gold catalyst makes the selective hydrogenation process environmentally and economically attractive.
Gold-Ligand-Catalyzed Selective Hydrogenation of Alkynes into cis-Alkenes via H2 Heterolytic Activation by Frustrated Lewis Pairs
Fiorio, Jhonatan L.,López, Núria,Rossi, Liane M.
, p. 2973 - 2980 (2017/05/31)
The selective hydrogenation of alkynes to alkenes is an important synthetic process in the chemical industry. It is commonly accomplished using palladium catalysts that contain surface modifiers, such as lead and silver. Here we report that the adsorption of nitrogen-containing bases on gold nanoparticles results in a frustrated Lewis pair interface that activates H2 heterolytically, allowing an unexpectedly high hydrogenation activity. The so-formed tight-ion pair can be selectively transferred to an alkyne, leading to a cis isomer; this behavior is controlled by electrostatic interactions. Activity correlates with H2 dissociation energy, which depends on the basicity of the ligand and its reorganization on activation of hydrogen. High surface occupation and strong Au atom-ligand interactions might affect the accessibility and stability of the active site, making the activity prediction a multiparameter function. The promotional effect found for nitrogen-containing bases with two heteroatoms was mechanistically described as a strategy to boost gold activity. (Graph Presented).
USE OF IONIC POLYSILOXANES AS A SOLVENT IN ORGANIC REACTIONS
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Page/Page column 16, (2013/03/26)
The invention concerns the use of ionic polysiloxanes as a solvent in organic reactions.
Activated carbon as a mass-transfer additive in aqueous organometallic catalysis
Kania, Nicolas,Leger, Bastien,Fourmentin, Sophie,Monflier, Eric,Ponchel, Anne
experimental part, p. 6138 - 6141 (2010/07/14)
(Figure Presented) Carbon, on active duty: The addition of activated carbon into the reaction medium appears to be a simple and efficient method to solve mass-transfer limitations in aqueous organometallic catalysis (see figure).
Production of acrylic monomers
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, (2008/06/13)
A process for the preparation of a mixture comprising a compound of formula (1) and a compound of formula (2) wherein R1is an optionally substituted C1-20alkyl, optionally substituted C3-4alkenyl, optionally substituted C5-7cycloalkyl or optionally substituted benzyl, R2is an optionally substituted C1-20alkyl, optionally substituted C3-4alkenyl or optionally substituted C5-7cycloalkyl, A is either S or NR3, R3is an optionally substituted C1-20alkyl, optionally substituted C3-4alkenyl or optionally substituted C5-7cycloalkyl, or R2and R3together form a 5-7 membered ring which can contain an oxygen atom, R4is hydrogen or methyl, R5is an optionally substituted C1-20alkyl, optionally substituted C3-4alkenyl, optionally substituted C5-7cycloalkyl or optionally substituted benzyl and, R6is hydrogen or an optionally substituted C1-20alkyl, optionally substituted C3-4alkenyl or optionally substituted C5-7cycloalkyl, or R5and R6together form a 5-7 membered ring which can contain an oxygen atom, which comprises reacting in an alkaline or base medium a compound of formula (3) wherein X?is an anion, R1, R2, R3, R4, R5and R6have the same meaning as above, A+is S+or N+R3.
Selective liquid-phase semihydrogenation of functionalized acetylenes and propargylic alcohols with silica-supported bimetallic palladium-copper catalysts
Spee,Boersma,Meijer,Slagt,Van Koten,Geus
, p. 1647 - 1656 (2007/10/03)
Silica-supported, bimetallic palladium-copper catalysts were prepared in solution under mild conditions by reacting lithium di(4-tolyl)cuprate with palladium acetate in the presence of silica particles. Small bimetallic palladium-copper particles were deposited on the silica surface as confirmed with TEM-EDAX and EXAFS. The new material has been applied as catalyst in the liquid-phase semihydrogenation of mono- and disubstituted alkynes and showed high selectivity toward the cis-alkenes. The influence of addition of quinoline or potassium hydroxide to the semihydrogenation reaction mixture and the effects of exposure of the catalyst to air before use have been investigated. Silica-supported, bimetallic palladium-copper catalysts were prepared in solution under mild conditions by reacting lithium di(4-tolyl)cuprate with palladium acetate in the presence of silica particles. Small bimetallic palladium-copper particles were deposited on the silica surface as confirmed with TEM-EDAX and EXAFS. The new material has been applied as catalyst in the liquid-phase semihydrogenation of mono- and disubstituted alkynes and showed high selectivity toward the cis-alkenes. The influence of addition of quinoline or potassium hydroxide to the semihydrogenation reaction mixture and the effects of exposure of the catalyst to air before use have been investigated.
A New Group of Compounds Derived from Nereistoxin - Synthesis of Bis-dimethylamino-tris-disulfanes
Muehlstaedt, M.,Heinicke, J.,Schubert H.
, p. 841 - 847 (2007/10/02)
The reaction of organo-thiosulfates, BUNTE-salts, with mercaptans is a convenient synthesis of disulfanes.Similarly bis-BUNTE-salt 7 and tert. butyl mercaptan give bis-disulfane 5c.By treating 7 with several aliphatic mercaptans we found the formation of the tris-disulfanes 8a-d in preparative amounts in addition to the bis-disulfanes 5a-d expected.This reaction was investigated.The preparation of the compounds 8 is described and a proposal is given for a mechanism of the formation of 8 as a thiol-disulfide-interchange.
