- Extractability and Reactivity of OH- in Low-Polarity Media under Phase-Transfer Catalysis Conditions: Dramatic Effect of the Aqueous Base Concentration
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In the chlorobenzene-aqueous NaOH two-phase system, an increase in NaOH concentration from 15percent to 50percent produces both a decrease in the extractability and an enhancement in the reactivity of OH- in the organic phase as quaternary ammonium hydroxide 1d.
- Landini, Dario,Maia, Angelamaria,Rampoldi, Alessandro
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- Role of Organic Fluoride Salts in Stabilizing Niobium Oxo-Clusters Catalyzing Epoxidation
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We present here that easily available organic salts can stabilize/modify niobium (Nb) oxo-clusters. The as-synthesized Nb oxo-clusters have been characterized by various methods. These Nb oxo-clusters were catalytically active for the epoxidation of allylic alcohols and olefins with H2O2 as an oxidant. Notably, Nb-OC@TBAF-0.5 appeared as highly dispersed nanosized particles and showed the highest catalytic activity, which can be attributed to the following reasons on the basis of characterization. First, the strong coordination of fluorine ions with Nb sites and the steric protection with bulky organic cations led to high stabilization and dispersion of the oxo-clusters in the course of the reaction. Second, a hydrogen-bond interaction between the coordinated fluorine atom and the -OH group of allylic alcohol favored the epoxidation reaction. Third, the electron density of Nb sites decreased due to the strong electron-withdrawing ability of F- adjacent to Nb sites, thus promoting the electrophilic oxygen transfer to the CC bond.
- Dai, Sheng,Ding, Bingjie,Gong, Xueqing,Hou, Zhenshan,Li, Difan,Tang, Xuan,Xu, Beibei,Yao, Yefeng,Zhang, Tong,Zheng, Anna,Zhou, Qingqing
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- BIOACTIVE PHENOLATE IONIC COMPLEXES
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The invention provides an isolated material, or a phenolate form of at least one phenol- containing active material, wherein the isolated material comprises one or more phenolate species and a counter ion (a cation) in the form of a metal salt, a phosphonium or an ammonium.
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(2021/10/30)
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- Novel ionic liquid with peroxyniobate-radical negative ions and preparing method thereof
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The invention relates to novel ionic liquid with peroxyniobate-radical negative ions and a preparing method thereof. The ionic liquid comprises imidazolium salt positive ions, quaternary ammonium salt positive ions and the peroxyniobate-radical negative ions. The preparing method of the ionic liquid includes the steps that 1, alkyl-replacing N-methylimidazole hydrochloride is prepared from N-methylimidazole; 2, alkyllimidazolium salt chloride and quaternary ammonium salt halogenide are subjected to ion exchange to obtain corresponding ethanol solutions of hydroxide; 3, ammonium peroxyniobate is prepared from commercial niobium pentoxide with the document method; 4, the brand-new-structure ionic liquid with the peroxyniobate-radical negative ions is obtained with the ion exchange (acid-base neutralization) method. According to the novel ionic liquid with the peroxyniobate-radical negative ions and the preparing method thereof, the ionic liquid is prepared for the first time, the preparing method is simple, the yield is high, and the characteristics of a niobium element can be fully used to carry out a certain catalytic oxidation reaction.
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Page/Page column 7
(2016/12/01)
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- Synthesis of high proton conducting nanoparticles by emulsion polymerization
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High ion-exchange capacity (IEC) sulfonated polystyrene nanoparticles were synthesized by an emulsion copolymerization of styrene, divinyl benzene and sulfonated styrene (SS). The effects of varying the counterion of the sulfonated styrene monomer, the SS concentration, the surfactant and the addition of a crosslinking agent on the ability to stabilize the emulsion nanoparticles to high IEC were studied. Water-insoluble nanoparticles, 20-160 nm in diameter, with IEC as high as 5.2 meq/g were achieved using sulfonated styrene with a quaternary alkyl ammonium cation, a non-ionic surfactant and a crosslinking agent in the emulsion formulation. That IEC corresponds to fully sulfonated crosslinked polystyrene.
- Pitia, Emmanuel,Shaw,Weiss
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p. 297 - 306
(2012/01/13)
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- Extraction of Highly Hydrophilic Anions in Low Polarity Media under Phase-transfer Catalysis Conditions: Dramatic Enhancement of the OH- Reactivity by Reduction of its Specific Hydration
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In the chlorobenzene-aqueous NaOH two-phase system, an increase in NaOH concentration from 5 to 20 M reduces the OH- hydration sphere of the tetrahexylammonium hydroxide (1a) dissolved in chlorobenzene from 11 to 3.5 molecules of water, thus producing a dramatic increase (up to 104 times) in OH- reactivity.
- Landini, Dario,Maia, Angelamaria
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p. 1041 - 1042
(2007/10/02)
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