- Selective N-Alkylation of Imidazole with Alcohols over Calcined Layered Double Hydroxides
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Vapor-phase N-alkylation syntheses of imidazole were carried out with MeOH and EtOH over a series of calcined MgII-AlIII layered double hydroxides (LDHs) selectively produced in high yields of N-methyl (70%) and N-ethyl (63%) imidazoles only on the 3 : 1 atomic ratio of MgII-AlIII calcined LDH. Attempts on C-alkylation and dialkylation reactions over the same catalysts proved to be unsuccessful.
- Santhanalakshmi, Jayadevan,Raja, Thirumalaiswamy
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Read Online
- Evaluation of decomposition products of EMImCl·1.5AlCl3 during aluminium electrodeposition with different analytical methods
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Ionic liquids are of great importance for electrodeposition of metals, which can't be deposited from aqueous electrolytes due to their negative standard potentials. In this paper non-woven polymers were coated with aluminium by electrodeposition from 1-et
- Poetz, Sandra,Handel, Patricia,Fauler, Gisela,Fuchsbichler, Bernd,Schmuck, Martin,Koller, Stefan
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Read Online
- Reactivity of Ionic Liquids: Reductive Effect of [C4C1im]BF4 to Form Particles of Red Amorphous Selenium and Bi2Se3 from Oxide Precursors
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Temperature-induced change in reactivity of the frequently used ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([C4C1im]BF4) is presented as a prerequisite for the rational screening of reaction courses in material synthesis. [C4C1im]BF4 becomes active with oxidic precursor compounds in reduction reaction at ?≥200 °C, even without the addition of an external reducing agent. The reaction mechanism of forming red amorphous selenium from SeO2 is investigated as a model system and can be described similarly to the Riley oxidation. The reactive species but-1-ene, which is formed during the decomposition of [C4C1im]BF4, reacts with SeO2 and form but-3-en-2-one, water, and selenium. Elucidation of the mechanism was achieved by thermoanalytical investigations. The monotropic phase transition of selenium was analyzed by the differential scanning calorimetry. Beyond, the suitability of the single source oxide precursor Bi2Se3O9 for the synthesis of Bi2Se3 particles was confirmed. Identification, characterization of formed solids succeeded by using light microscopy, XRD, SEM, and EDX.
- Knorr, Monika,Schmidt, Peer
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p. 125 - 140
(2020/12/17)
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- Crystallographic and spectroscopic analysis of 9,10-bis-alkyl imidazolium anthracene hexatungstate supramolecular complexes
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This article describes the ionic and supramolecular association of bis-dialkyl imidazolium anthracene dications with hexametalate cluster anions. In the relevant compounds, the length of the alkyl chain was varied to observe its effect on the crystal packing. Despite the endothermicity in the crystals due to structural incompatibility between planar anthracene and spherical polyoxometalate ion, packing stability is attained by coulombic interaction together with the supramolecular interactions between the components. The nature of supramolecular interactions depends on the number of carbon atoms in the alkyl chain in the organic counterparts of the crystals which ultimately modifies the packing pattern.
- Annapareddy, Gayatri,Mubeena, Shaik,N, Meghana,Sarma, Monima
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- Amphiphilic Polymeric Nanoparticles for Photoredox Catalysis in Water
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Photoredox catalysis has recently emerged as a powerful synthesis tool in organic and polymer chemistry. In contrast to the great achievements realized in organic solvents, performing photocatalytic processes efficiently in aqueous media encounters several challenges. Here, it is presented how amphiphilic single-chain polymeric nanoparticles (SCPNs) can be utilized as small reactors to conduct light-driven chemical reactions in water. By incorporating a phenothiazine (PTH) catalyst into the polymeric scaffold, metal-free reduction and C?C cross-coupling reactions can be carried out upon exposure to UV light under ambient conditions. The versatility of this approach is underlined by a large substrate scope, tolerance towards oxygen, and excellent recyclability. This approach thereby contributes to a sustainable and green way of implementing photoredox catalysis.
- Eisenreich, Fabian,Meijer,Palmans, Anja R. A.
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supporting information
p. 10355 - 10361
(2020/07/27)
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- N-Alkylation of Imidazoles with Dialkyl and Alkylene Carbonates
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Abstract: The reactions of imidazoles with a series of dialkyl and alkylene carbonatesafforded the corresponding N-alkyl- andN-(hydroxyalkyl)imidazoles with highyields. The reactivity of dialkyl carbonates decreases in the series dimethyl> diethyl > dibutyl carbonate. Ethylene carbonate is a more efficientalkylating agent than trimethylene carbonate. The mechanisms of alkylation ofimidazole with dimethyl carbonate and ethylene carbonate were studied by DFTquantum chemical calculations at the B3LYP/6-311++G(d,p) level of theory.
- Gabov,Khamidullina,Puzyrev,Ezhikova,Kodess,Pestov
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p. 2079 - 2086
(2021/02/09)
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- Molecular tunability of surface-functionalized metal nanocrystals for selective electrochemical CO2 reduction
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Organic ligands are used in homogeneous catalysis to tune the metal center reactivity; in contrast, clean surfaces are usually preferred in heterogeneous catalysis. Herein, we demonstrate the potential of a molecular chemistry approach to develop efficient and selective heterogeneous catalysts in the electrochemical CO2 reduction reaction (CO2RR). We have tailor-made imidazolium ligands to promote the CO2RR at the surface of hybrid organic/inorganic electrode materials. We used silver nanocrystals for the inorganic component to obtain fundamental insights into the delicate tuning of the surface chemistry offered by these ligands. We reveal that modifying the electronic properties of the metal surface with anchor groups along with the solid/liquid interface with tail groups is crucial in obtaining selectivities (above 90% FE for CO), which are higher than the non-functionalized Ag nanocrystals. We also show that there is a unique dependency of the CO2RR selectivity on the length of the hydrocarbon tail of these ligands, offering a new way to tune the interactions between the metal surface with the electrolyte and reactants.
- Pankhurst, James R.,Guntern, Yannick T.,Mensi, Mounir,Buonsanti, Raffaella
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p. 10356 - 10365
(2019/11/20)
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- Synthesis and structural, photophysical, electrochemical redox and axial ligation properties of highly electron deficient perchlorometalloporphyrins and selective CN- sensing by Co(ii) complexes
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A straightforward synthetic route has been adopted to synthesize highly nonplanar electron deficient perchlorometallo-porphyrins. Herein, we report the synthesis and characterization of MTPP(NO2)Cl7 where M = CoII, NiII, CuII and ZnII. Further, we examined their optical and electrochemical redox properties and the results are compared with MTPPCl8. MTPP(NO2)Cl7 exhibited red-shifted (~10-15 nm) absorption spectra relative to MTPPCl8 due to the strong electron withdrawing nature of the nitro group. Mixed β-substitution alters the electrochemical redox properties to such an extent that an appreciable increase in the anodic shift in reduction potential (200-300 mV) is observed for MTPP(NO2)Cl7 relative to MTPPCl8 whereas only a minimal shift (15-50 mV) in the oxidation potential is observed. Nonplanarity of the macrocyclic core was investigated by single crystal X-ray analysis and DFT calculations. A higher ΔCβ (0.706 ?) for 1d as compared to 2d (0.642 ?) undoubtedly signifies nonplanarity induced by the nitro group. To substantiate the effect of mixed substitution, we performed axial ligation studies of Zn(ii) complexes with nitrogenous bases and basic anions and found higher log:β2 values as well as a linear relation between log:β2 and pKa as compared to perbromoporphyrins. Highly electron deficient β-substituted Co(ii) porphyrins (1a and 2a) were utilized as novel sensors for selective rapid visual detection of CN- ions.
- Chaudhri, Nivedita,Butcher, Ray J.,Sankar, Muniappan
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p. 8190 - 8199
(2018/05/24)
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- Polyfunctional imidazolium surfactant and preparation method thereof
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The invention discloses a polyfunctional imidazolium surfactant and a preparation method thereof. The preparation method comprises the following steps: 1) preparing an alkyl-substituted imidazole intermediate; 2) preparing a bromo-oligomer intermediate; and 3) under nitrogen protection, adding the alkyl-substituted imidazole intermediate, the bromo-oligomer intermediate and acetonitrile in a reaction bottle, stirring the materials, heating the materials and performing backflow, reacting the materials, cooling the materials to room temperature, and removing a solvent to obtain the tri-imidazolium surfactant. Compared with the prior art, the tri-imidazolium surfactant has excellent performance, has three imidazolium groups, and greatly enhances the hydrophilic performance of the surfactant.The tri-imidazolium surfactant can adjust an amount of a monomer, effectively controls a size of a hydrophobic group in the surfactant molecules, and is in favor of regulating and controlling the performance of the surfactant. The preparation method of the tri-imidazolium surfactant has the advantage of simple process, and the obtained product has the advantages of easy separating and purifying, less by-product, and environmentally friendly performance.
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Paragraph 0022; 0025; 0026
(2018/09/12)
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- Alkylation method for nitrogen-hydrogen containing compounds and application thereof
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The invention discloses an alkylation method for nitrogen-hydrogen containing compounds and an application thereof, belonging to the technical field of synthesis of organic compounds. The invention provides a series of methods for a nitrogen alkylation reaction of N-H containing heterocyclic compounds (II) with N,N-dimethylformamide dialkyl acetal as an alkyl source under the condition of no participation of metals, and a product with a hydrogen atom on a nitrogen atom substituted by R1 is obtained. The method provided by the invention has the advantages of highly-efficient reaction, high yield, simple treatment after the reaction, simple and convenient operation, mild reaction conditions, no participation of the metals, high tolerance of functional groups of a reaction substrate, wide range and easy preparation of the substrate, high reaction efficiency after amplification of the reaction, and applicability to large-scale industrial production.
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Paragraph 0059; 0060; 0069; 0070
(2018/10/04)
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- Novel alkylimidazolium ionic liquids as an antibacterial alternative to pathogens of the skin and soft tissue infections
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Keeping in mind the concept of green chemistry, this research aims to synthesize and characterize new ionic liquids (ILs) derived from N-cinnamyl imidazole with different sizes of alkyl chains (1, 6, 8, and 10 carbon atoms), and evaluate their antibacterial activity against Skin and soft tissue infections (SSTIs) causative bacteria. The antibacterial screening was carried out by agar well diffusion and the Minimum Inhibitory Concentration (MIC) and Half Maximum Inhibitory Concentration (IC50) of the different ILs were determined by microdilution in broth, also Molecular dynamics simulations were performed to study the interaction mechanism between ILs and membranes. The MIC value in Gram-positive bacteria showed that as the hydrocarbon chain increases, the MIC value decreases with a dose-dependent effect. Furthermore, Gram-negative bacteria showed high MIC values, which were also evidenced in the antibacterial screening. The molecular dynamics showed an incorporation of the ILs with the longer chain (10 C), corresponding to a passive diffusion towards the membrane surface, for its part, the ILs with the shorter chain due to its lack of hydrophobicity was not incorporated into the bilayer. Finally, the new ILs synthesized could be an alternative for the treatment of Gram-positive bacteria causative of SSTIs.
- Doria, Oscar Forero,Castro, Ricardo,Gutierrez, Margarita,Valenzuela, Diego Gonzalez,Santos, Leonardo,Ramirez, David,Guzman, Luis
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- A 2 - mercapto - 1 - alkyl imidazole of preparation method (by machine translation)
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The invention discloses a 2 - mercapto - 1 - alkyl imidazole synthesis method, which belongs to the technical field of organic synthesis. Imidazole and alkyl halide in the presence of an inorganic base sealing reaction the temperature of the 1 - alkyl imidazole, then dissolved in ether in the solvent, the low temperature by adding 1 - 1.1 equivalent BuLi, then adding 0.9 - 0.95 equivalent powder reflux reaction, after cooling add acetyl chloride to obtain 2 - acetyl thio - 1 - alkyl imidazole; the final 2 - acetyl thio - 1 - alkyl imidazole dissolved in alcohol solvent, adding a catalytic amount of hydrogen chloride or potassium carbonate deprotection, to obtain 2 - mercapto - 1 - alkyl imidazole. The raw material of the invention is cheap, and more friendly to the environment, the advantages of easy operation, the quality of the product in accordance with the electronic chemicals using standard. (by machine translation)
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Paragraph 0024; 0025
(2018/01/19)
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- Method for catalytic synthesis of 1-methylimidazole
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The invention discloses a method for catalytic synthesis of 1-methylimidazole. By taking a glyoxal aqueous solution, paraformaldehyde, a methylamine aqueous solution and ammonia as reactants, and taking a supporting transition metal oxide as a catalyst, the method is used for catalytic synthesis of 1-methylimidazole under relatively mild reaction conditions within relatively short reaction time at relatively high yield. At the same time, the catalyst can be separated from a reaction system by easy filtration to be recycled.
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Paragraph 0018; 0019; 0020; 0021; 0022; 0023; 0024
(2017/11/18)
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- Method for preparing 1-methylimidazole
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The invention discloses a method for preparing 1-methylimidazole. The method comprises the steps of mixing a water solution of 1-methylamine, ammonia water and ammonium carbonate, then, carrying out heating, adding mixed aldehyde into the heated mixture, and then, carrying out a reaction; and after the reaction is completed, subjecting the obtained reaction solution to concentration and rectification, thereby preparing 1-methylimidazole. Compared with the prior art, the method has the advantages that 1-methylimidazole is synthesized in one step by adopting the traditional mixed aldehyde cyclization method, ammonium carbonate is adopted to replace part of ammonia water and serves as a reaction accelerant, meanwhile, the consumption of 1-methylamine and ammonia water can be lowered, and the production cost is reduced. Meanwhile, after ammonium carbonate is used, the yield of the method can be increased by 10% compared with that of the traditional synthesis methods.
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Paragraph 0017; 0023; 0024; 0025; 0026; 0027; 0028
(2017/03/28)
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- Coordination properties of μ-carbidodimeric iron(IV) 2,3,7,8,12,13,17,18-octapropyltetraazaporphyrinate and 5,10,15,20-tetraphenylporphyrinate in reactions with nitrogen-containing bases
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The equilibria of μ-carbidodimeric iron(IV) 2,3,7,8,12,13,17,18-octapropyltetraazaporphyrinate and 5,10,15,20-tetraphenylporphyrinate in reactions with nitrogen-containing bases in an inert solvent were studied spectrophotometrically. The equilibrium constants of the studied processes and the compositions of molecular complexes were determined. The effect of the electronic and conformation factors of a macrocycle and the nature of the base on the equilibrium constant was pointed out. A comparative analysis of the substrate specificity of the studied compounds was performed.
- Zaitseva,Zdanovich,Kudrik,Koifman
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p. 1257 - 1266
(2017/09/29)
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- CATALYST COMPOSITION, AND METHOD FOR PREPARING ALPHA-OLEFIN
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The present disclosure relates to a catalyst composition including an organic ligand compound of a specific chemical structure; and a chromium compound and a method for synthesizing alpha-olefin using the catalyst composition, and when the catalyst composition is used, alpha-olefin may be stably synthesized with high selectivity and reaction activity.
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Paragraph 0108-0110
(2017/08/07)
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- A planar anthracene–imidazolium/anthracene–benzimidazolium cation system in a spherical polyoxometalate matrix: Synthesis, crystallography and spectroscopy
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A series of ion–pair compounds, comprising of Lindqvist type isopolyanions viz., [Mo6O19]2?and [W6O19]2?as the counter anions and anthracene–imidazolium/anthracene–benzimidazolium as counter cations, have been described. Structures of the isolated stoichiometric solids have been unambiguously determined by single crystal X-ray diffraction analysis. In spite of the structural incompatibility between anthracene (planar) and the present polyoxometalate anions (spherical), coulombic and several intermolecular weak interactions, e.g. C–H?O, C–H?π, π–π, etc. compensate the destabilization energy raised due to presence of the structurally mis-matched components in the respective crystal lattices. Single-crystal- as well as powder X-ray-diffraction (PXRD) analyses reveal iso-structural relationship between the hexamolybdates- and hexatungstates-associated ion pair compounds. Conformational variation has been observed in the crystal structures containing benzyl benzimidazolium counter cations. Diffuse reflectance electronic absorption spectral studies are performed to understand the relatively intense color of the title compounds in their solid states in comparison to their respective solution states.
- Chatterjee, Tanmay,Kumar, N. Tanmaya,Das, Samar K.
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- Continuous preparation method of N-methylimidazole
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The invention discloses a continuous preparation method of N-methylimidazole. The method comprises the following steps: by taking an Hbeta molecular sieve as a catalyst, carrying out a gas phase catalytic reaction on mixed ammonia and mixed aldehyde in a tubular reactor, and performing rectification separation on the obtained reaction product, thereby obtaining the N-methylimidazole. The preparation method of the N-methylimidazole can be continuously operate, the conversion rate of glyoxal can be over 97.07 percent, the purity of N-methylimidazole can be over 99.0 weight percent, and the recovered mixed ammonia and mixed aldehyde can be recycled.
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Paragraph 0029-0040
(2017/01/02)
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- 1-production of aminoalkylimidazole compd.
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PROBLEM TO BE SOLVED: To provide a method for producing a 1-alkylimidazole in high efficiency and yield.SOLUTION: There is provided a method for producing a 1-alkylimidazole compound comprising vapor-phase reaction of glyoxal, formaldehyde, ammonia and a primary amine compound.
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Paragraph 0026
(2017/04/07)
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- METHOD FOR PRODUCING 1,2-DISUBSTITUTED IMIDAZOLE
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PROBLEM TO BE SOLVED: To provide a 1,2-disubstituted imidazole production method which can suppress production of by-products and efficiently produce high-purity 1,2-disubstituted imidazole in a shorter reaction time than that of the conventional one. SOLUTION: A 1,2-disubstituted imidazole production method includes a first stage reaction step of reacting an aldehyde compound with ammonia and/or a primary amine, and a second stage reaction step of reacting a glyoxal compound and ammonia and/or a primary amine with reaction products in the first stage reaction step. The primary amine is reacted in at least one of the first stage reaction step and the second stage reaction step to produce 1,2-disubstituted imidazole in a flow manner. The reaction in at least one of the first stage reaction step and the second stage reaction step is performed in a pressurized state at a pressure of 1-50 MPa. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2017,JPOandINPIT
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Paragraph 0051-0052
(2017/06/14)
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- Process for the preparation of 1-hexene and 1-oxtene
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The present invention relates to a manufacturing method of 1-hexene and 1-octene from an olefin under the presence of a catalyst composition. The catalyst composition comprises: at least one type of an organic ligand compound selected from the group consisting of a compound represented by chemical formula 1, a compound represented by chemical formula 2, and a compound represented by chemical formula 3; at least one type of transition metal or a transition metal precursor selected from the group consisting of group IV to group XII elements; and a promotor. The manufacturing method of the present invention reduces generation of byproducts, and can manufacture 1-hexene and 1-octene from an olefin with high selectivity and reaction activity.
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Paragraph 0137-0140
(2017/05/18)
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- Preparation method of 1-methylimidazole
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The invention discloses a preparation method of 1-methylimidazole obtained by firstly carrying out ring formation of 2-chloro-2-(((methylamino)methyl)imino)ethyl trifluoromethanesulfonate and then forming a double bond. Compared with the prior art, a by-product obtained in other process production lines is used as a raw material, so that the production cost is greatly reduced, and the productive rate can reach 91% and is far higher than that of a conventional process. At the same time, the preparation method is simple, and is prone to large-scale industrialized promotion.
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Paragraph 0026; 0027; 0028; 0029; 0030; 0031; 0039
(2016/10/08)
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- Synthesis of N-pyridyl azoles using a deprotometalation-iodolysis-N-arylation sequence and evaluation of their antiproliferative activity in melanoma cells
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N-Arylation of pyrrole with 3-iodo-4-methoxypyridine was investigated by copper catalysis under different conditions. The best conditions, that proved to be protocol A (CuI, DMEDA or TMEDA, K3PO4, DMF at 110?°C) and above all protocol B (Cu2O, Cs2CO3, DMSO at 110?°C), were applied to the synthesis of various N-(methoxypyridyl) pyrroles, indoles and benzimidazoles. The behavior of the different iodinated methoxypyridines was rationalized by evaluating the partial positive charge on the carbon bearing iodine from the1H NMR chemical shift of the corresponding deiodinated substrates. The reaction was next connected with the deprotometalation-iodolysis step generating iodinated methoxypyridines: straight involvement of the crude iodo intermediates in pyrrole N-arylation afforded the expected N-(methoxypyridyl) pyrroles in good yields. Several synthesized N-(methoxypyridyl) azoles exerted low to moderate antiproliferative activity in A2058 melanoma cells.
- Hedidi, Madani,Erb, William,Bentabed-Ababsa, Ghenia,Chevallier, Floris,Picot, Laurent,Thiéry, Valérie,Bach, Stéphane,Ruchaud, Sandrine,Roisnel, Thierry,Dorcet, Vincent,Mongin, Florence
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p. 6467 - 6476
(2016/09/23)
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- Reduction of (chloro)-μ-nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)] with organic N-bases
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The interaction of (chloro)-μ-nitrido-bis[(tetra-Tert-butyl-phthalocyaninato)iron(IV)] Cl(FePc)2N with organic N-bases L as electron-donors (L diethylamine, imidazole, 1-methylimidazole, 2-methylimidazole) with the formation of one-electron reduced species (L)PcFeIII-N?FeIVPc(L) was investigated in benzene at 298 K by UV-visible spectroscopy. The reaction was established to be stepwise process including fast reversible axial binding of two substrate molecules onto iron cations followed by slow one-electron metal-centered reduction. The results of IR, ESI-MS and EPR study support the formation of final product with Fe?3-N?Fe?4 unit and two substrate molecules in the first coordination sphere. The reaction kinetics was studied, the pre-equilibrium constants Keq and rate constants κ were obtained. The Keq and κ values were found to be linearly correlated with basicity of substrates pκa. The possibility of the transition Fe4?→Fe3??is promoted by electron-donor properties of substrate combined with the presence of both electron-rich macrocycle and φ-backdonation Fe →NPc.
- Zaitseva, Svetlana V.,Zdanovich, Sergei A.,Tyulyaeva, Elena Y.,Grishina, Ekaterina S.,Koifman, Oskar I.
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p. 639 - 646
(2016/07/11)
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- LIPOPHILIC BISPHOSPHONATES AND METHODS OF USE
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Disclosed herein are lipophilic bisphosphonate compounds and embodiments of a method for making the same. The compounds may inhibit FPPS and/or GGPPS enzymes. The compounds are useful for treating a disease, such as cancer, such as those with a KRAS mutation. In some embodiments, the compounds are used to prevent or treat a cancer, such as a lung cancer that has a KRAS mutation.
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Page/Page column 54
(2016/06/20)
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- Aldehyde acetal based processes for the manufacture of macrocyclic depsipeptides and new intermediates
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The invention relates to a method or process for the chemical manufacture of depsipeptides of the formula I employing an aldehyde acetal intermediate, wherein the symbols have the meaning defined in the description, to new intermediates and their manufacture, as well as related invention embodiments.
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Page/Page column
(2015/03/28)
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- Coordinating ability of rhodium(III) porphyrins toward organic bases
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Reactions of hydroxo(2,3,7,8,12,13,17,18-octaethylporphyrinato)rhodium(III) and acetylacetato-(5,10,15,20-tetraphenylporphyrinato)rhodium(III) with nitrogen-containing substrates were studied by spectrophotometry. The stability constants and compositions of the resulting molecular complexes were determined, and the effects of the macrocycle nature and substrate basicity on the stability constants were estimated. The structures of the isolated rhodium porphyrin molecules and their complexes with organic bases were optimized by the PM3 quantum chemical method. The degree of macrocycle deformation was found to change in the course of metal-substrate coordination. A correlation between the metal-substrate bond energy and equilibrium constant was revealed.
- Zaitseva,Zdanovich,Bryukhanova,Koifman
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p. 2786 - 2792
(2016/02/18)
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- Synthesis of methylal from methanol and formaldehyde catalyzed by Br?nsted acid ionic liquids with different alkyl groups
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The catalytic reaction of methanol with formaldehyde for the preparation of methylal was investigated in various Br?nsted acid ionic liquids with different carbon chain length of alkyl groups. The structures, acidities, and properties of ionic liquids were experimentally characterized and theoretically analyzed. The Br?nsted acidity-viscosity-activity correlation for the ionic liquids was studied. Among all these ionic liquids, [C6ImBS][HSO4] exhibited the best catalytic performance, which was ascribed to its strong Br?nsted acidity and low viscosity. The catalytic activity of the ionic liquid was near that of concentrated sulfuric acid. The influences of ionic liquid dosage, reaction temperature and molar ratio of methanol to formaldehyde were explored using [C6ImBS]HSO4 as the catalyst. Under the optimal conditions of n(methanol):n(formaldehyde):n(ILs) = 2.5:1:0.0258, 60 °C, and 4 h, the conversion of formaldehyde can reach 63.37%. The ionic liquid [C6ImBS]HSO4 could be reused.
- Sun, Jiahan,Li, Hansheng,Song, Haoran,Wu, Qin,Zhao, Yun,Jiao, Qingze
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p. 87200 - 87205
(2015/11/09)
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- Tris-imidazolium and benzimidazolium ionic liquids: A new class of biodegradable surfactants
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Based on imidazolium and benzimidazolium, two series of novel tris-cationic ionic liquid surfactants containing ester groups were synthesized simply from readily available starting materials in high yields. Biodegradability and surfactants properties of the tris-imidazolium and tris-benzimidazolium ionic liquids were investigated. Some compounds showed assembly behaviour in the pure form (i.e. absence of solvent) and in the presence of polar or nonpolar solvents. These surfactants are effectively reducing the surface tension of water in the range of 28-31 mN m-1. Through using the 'Closed-Bottle Test' OECD 301D, the incorporation of alkyl or phenyl side chains with ester groups in the same molecule significantly improved the biodegradation compared to sodium n-dodecyl sulphate (SDS) as a reference. The aliphatic alkyl side chain, i.e., butyl, hexyl, octyl, decyl and dodecyl, in both imidazolium and benzimidazolium ionic liquids have marked increasing biodegradation and phase behaviour results compared to aromatic side-chains.
- Al-Mohammed, Nassir N.,Duali Hussen, Rusnah Syahila,Alias, Yatimah,Abdullah, Zanariah
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p. 2869 - 2881
(2015/02/02)
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- Synthesis of polyoxymethylene dimethyl ethers from methylal and trioxane catalyzed by Br?nsted acid ionic liquids with different alkyl groups
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Br?nsted acid ionic liquids with different alkyl group carbon chain lengths and an alkane sulfonic acid group were synthesized through bromoalkane, imidazole and 1,4-butane sultone as raw materials. The structures and properties of the ionic liquids were experimentally characterized. Catalytic reaction of methylal (DMM) with trioxane (TOX) for preparation of polyoxymethylene dimethyl ethers (PODMEn, CH3O(CH2O)nCH3, where n > 1) was investigated in various Br?nsted acid ionic liquids with different carbon chain length of alkyl groups. The carbon chain length of alkyl groups and activity correlation for the ionic liquids was studied. It was found that the structures of ionic liquids were consistent with the designed structure and their purities were high. They possessed high thermal stability and wide liquid range. The hydrophobicity of ionic liquids became stronger with the increase of carbon chain length. With increasing the carbon chain length of ionic liquids, the selectivity of PODME3-8 is increased at first and then decreased. Among all the ionic liquids, [C6ImBS][HSO4] shows the best catalytic performance and the selectivity of PODME3-8 is 57.85%.
- Wu, Qin,Li, Weijiao,Wang, Min,Hao, Yu,Chu, Tonghua,Shang, Jiqing,Li, Hansheng,Zhao, Yun,Jiao, Qingze
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p. 57968 - 57974
(2015/07/20)
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- Tetrakis-imidazolium and benzimidazolium ionic liquids: A new class of biodegradable surfactants
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Novel series of tetra-cationic ionic liquids containing alkyl or phenyl side chains and ester groups within the same molecule were successfully prepared. Based on imidazolium and benzimidazolium, these ionic liquids were synthesized from readily available starting materials in high yield. Surfactant properties including liquid crystalline behaviour and surface properties as well as their biodegradability were investigated. Tetrakis-imidazolium ionic liquid compounds showed assembly behaviour in the pure form (i.e. spontaneously) and in the presence of polar or nonpolar solvents, while both imidazolium and benzimidazolium ionic liquids effectively reduced the surface tension of water in the range of 29-34 mN m-1. The incorporation of tetra alkyl or phenyl side chains into imidazolium and benzimidazolium ionic liquids with tetra-ester groups, significantly improved the biodegradation. 'Closed-Bottle Test' OECD 301D and sodium n-dodecyl sulphate (SDS) as a reference were used for evaluation. The linear alkyl side chains (i.e. butyl, hexyl, octyl, decyl and dodecyl) in both tetrakis-imidazolium and benzimidazolium ionic liquids promote the increasing in biodegradation and phase behaviour results comparing to aromatic side-chains.
- Al-Mohammed, Nassir N.,Duali Hussen, Rusnah Syahila,Ali, Tammar Hussein,Alias, Yatimah,Abdullah, Zanariah
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p. 21865 - 21876
(2015/11/27)
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- ALDEHYDE ACETAL BASED PROCESSES FOR THE MANUFACTURE OF MACROCYCLIC DEPSIPEPTIDES AND NEW INTERMEDIATES
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The invention relates to a method or process for the chemical manufacture of depsipeptides of the formula I employing an aldehyde acetal intermediate, wherein the symbols have the meaning defined in the description, to new intermediates and their manufacture, as well as related invention embodiments.
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Page/Page column
(2014/04/18)
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- Peroxopolyoxotungsten-based ionic hybrid as a highly efficient recyclable catalyst for epoxidation of vegetable oil with H2O2
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A peroxopolyoxotungsten-based ionic hybrid was synthesized by anion-change of peroxopolyoxometalate (POM) PW4O243- with dicationic long-chain alkyl imidazolium ionic liquids. The characterization was conducted by FT-IR, TGA, 1H-NMR and CHN Elemental analyses. Its catalytic performance was evaluated by the epoxidation of soybean oil with H2O2 under solvent-free condition, including testing of organic cations influence, catalytic reusability and reaction conditions. The catalyst was proved to be a highly efficient recyclable catalyst for epoxidation of various vegetable oils with H2O2, showing high H 2O2 utilization efficiency, high catalytic activity, convenient recovery and good reuse ability.
- Wu, Jianghao,Jiang, Pingping,Qin, Xiaojie,Ye, Yuanyuan,Leng, Yan
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p. 1675 - 1680
(2014/07/07)
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- Magnesium oxide as a heterogeneous and recyclable base for the N-methylation of indole and O-methylation of phenol using dimethyl carbonate as a green methylating agent
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This work reports a mild efficient and sustainable protocol for N-methylation of indole and O-methylation of phenol using dimethylcarbonate as an environmentally safe, non-toxic, biodegradable and green methylating agent under microwave conditions. Magnesium oxide (MgO) has been employed as a heterogeneous and recyclable base for clean N-methylation of indole and O-methylation of phenol with dimethylcarbonate. Basic properties of the fresh and recycled MgO were measured by temperature programmed desorption (CO2-TPD) analysis. The CO2-TPD runs suggested that both strong and moderately basic sites are present on the oxide, while only the moderately basic sites are responsible for the N-and O-methylation of indole and phenol, respectively, using DMC as a methylating agent. The CO2-TPD analysis showed that the basic sites on fresh and recycled MgO were comparable. The MgO was isolated by simple filtration and recycled efficiently without loss in activity and selectivity.
- Gadge, Sandip T.,Mishra, Ashish,Gajengi, Aravind L.,Shahi, Nileshkumar V.,Bhanage, Bhalchandra M.
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p. 50271 - 50276
(2014/12/10)
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- Synthesis and crystal structures of new 1,3-disubstituted imidazoline-2-thiones
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Two methods (MeOH=K2CO3, pyridine=Et3N) were assessed for the introduction of sulfur into the 2-position of 1,3-disubstituted quaternary imidazolium salts 1-9 (Cl, I, BF4, PF6, CH3OSO3 were used as anions) to yield nine 1,3-disubstituted imidazoline-2-thiones 10-18 (1, 10: R1 = CH 3, R2 = CH3; 2, 11: R1 = OCH 2Ph, R2 = CH3; 3, 12: R1 = OCH 3, R2 = CH3; 4, 13: R1 = OCH 3, R2 = OCH3; 5, 14: R1 = NH 2, R2 = CH2Ph; 6, 15: R1 = NCHPh, R2 = CH3; 7, 16: R1 = NH2, R 2 = CH3; 8, 17: R1 = NCHPh, R2 = NCHPh; 9, 18: R1 = NH2, R2 = OCH3). Compounds 11-18 represent N-alkyloxy and N-amino imidazoline-2-thiones, whereas 10 served as reference compound. The first method was advantageous for the conversion 1 → 10 due to faster reaction, whereas in the reaction 2 → 11 considerable amounts of by-products were formed. Pure thiones 11, 14, 16, 17, and 18 were obtained only by the second method. Both methods worked for the synthesis of the methoxy derivatives 12 and 13 from 3 and 4, and the benzylideneamino derivative 15 from 6. 1-Amino-3- methylimidazoline-2-thione (16) was also prepared by hydrolysis of the benzylideneamino derivative 15. Crystal structures of seven 1,3-disubstituted imidazoline-2-thiones were determined by singlecrystal X-ray diffraction. Intermolecular C-H...S contacts were identified and, additionally, N-H...S interactions in aminothiones 14 and 16. The 1H NMR shifts of 10 and 13 were satisfactorily correlated with the Kamlet-Abboud-Taft π* and β parameters in ten solvents. From the lack of correlation with the a parameter and from the C=S bond length (average 1.68 A ) a significant contribution of a mesoionic imidazolium-2-thiolate resonance structure seems unlikely.
- Laus, Gerhard,Kahlenberg, Volker,Wurst, Klaus,Mueller, Thomas,Kopacka, Holger,Schottenberger, Herwig
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p. 1239 - 1252
(2013/12/04)
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- On the mesophase formation of 1,3-dialkylimidazolium ionic liquids
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A series of seven different 1,3-dialkylimidazolium-based ion-pair salts with the same molecular weight and size but different symmetries was synthesized. For all salts, bromide was chosen as the counterion, giving the series ([CnIMCm][Br]), where IM = imidazolium and Cn and Cm are varying N-alkyl substituents with n + m = 13. Thus, the effect of symmetry on the physicochemical properties, such as thermal transitions, densities and viscosities and particularly mesophase formation, is investigated herein. All salts are fully characterized by NMR spectroscopy and mass spectrometry, and their physicochemical properties such as thermal transitions, densities, and viscosities are reported. Single crystal X-ray structure analysis is reported for 1-tridecylimidazolium bromide ([C0IMC13][Br]) and 1-ethyl-3- undecylimidazolium bromide ([C2IMC11][Br]). Salts 1-tridecylimidazolium bromide ([C0IMC13][Br]) and 1-dodecyl-3-methylimidazolium bromide ([C1IMC12][Br]) exhibit thermotropic liquid crystal behavior, confirmed by differential scanning calorimetry, polarized optical microscopy, and small-angle X-ray diffraction to be the SmA mesophase. A structure with interdigitation of alkyl chains is observed for all of [C0IMC13][Br], [C1IMC12][Br], and [C2IMC11][Br], despite the absence of thermotropic liquid crystalline behavior for the latter (and all other isomers with an alkyl chain length less than 12 carbon atoms). This allows us to draw the conclusion that for the liquid crystal phase of an ionic liquid to exist, not only are the calamitic shape and integral length of a molecule important but a minimal alkyl chain length of n = 12 is also required. Therefore, a dodecyl group could be considered as the functional group responsible for liquid crystalline behavior.
- Yang, Mei,Mallick, Bert,Mudring, Anja-Verena
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p. 3068 - 3077
(2013/07/26)
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- Electronic structure and biologically relevant reactivity of low-spin {FeNO}8 porphyrin model complexes: New insight from a bis-picket fence porphyrin
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Because of HNO's emerging role as an important effector molecule in biology, there is great current interest in the coordination chemistry of HNO and its deprotonated form, the nitroxyl anion (NO-), with hemes. Here we report the preparation of four new ferrous heme-nitroxyl model complexes, {FeNO}8 in the Enemark-Feltham notation, using three electron-poor porphyrin ligands and the bis-picket fence porphyrin H2[3,5-Me-BAFP] (3,5-Me-BAFP2- = 3,5-methyl-bis(aryloxy)-fence porphyrin dianion). Electrochemical reduction of [Fe(3,5-Me-BAFP)(NO)] (1-NO) induces a shift of ν(N-O) from 1684 to 1466 cm-1, indicative of formation of [Fe(3,5-Me-BAFP)(NO)]- (1-NO-), and similar results are obtained with the electron-poor hemes. These results provide the basis to analyze general trends in the properties of ferrous heme-nitroxyl complexes for the first time. In particular, we found a strong correlation between the electronic structures of analogous {FeNO}7 and {FeNO}8 complexes, which we analyzed using density functional theory (DFT) calculations. To further study their reactivity, we have developed a new method for the preparation of bulk material of pure heme {FeNO}8 complexes via corresponding [Fe(porphyrin)]- species. Reaction of [Fe(To-F 2PP)(NO)]- (To-F2PP2- = tetra(ortho-difluorophenyl)porphyrin dianion) prepared this way with acetic acid generates the corresponding {FeNO}7 complex along with the release of H2. Importantly, this disproportionation can be suppressed when the bis-picket fence porphyrin complex [Fe(3,5-Me-BAFP)(NO)]- is used, and excitingly, with this system we were able to generate the first ferrous heme-NHO model complex reported to date. The picket fence of the porphyrin renders this HNO complex very stable, with a half-life of ~5 h at room temperature in solution. Finally, with analogous {FeNO}8 and {FeNHO}8 complexes in hand, their biologically relevant reactivity toward NO was then explored.
- Goodrich, Lauren E.,Roy, Saikat,Alp, E. Ercan,Zhao, Jiyong,Hu, Michael Y.,Lehnert, Nicolai
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supporting information
p. 7766 - 7780
(2013/07/26)
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- Facile and scalable preparation of 2-imidazolylpyridines
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A novel method for the synthesis of 2-imidazolylpyridines is presented. The reaction of 2-halopyridines, potassium carbonate, and imidazole at high temperatures under inert gas atmosphere leads exclusively to the formation of 2-imidazolylpyridines in high yields. The synthesis is scalable, comparatively inexpensive, and the products are easily isolable.
- Raba, Andreas,Anneser, Markus R.,Jantke, Dominik,Cokoja, Mirza,Herrmann, Wolfgang A.,Kühn, Fritz E.
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supporting information
p. 3384 - 3387
(2013/07/11)
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- A safe and facile route to imidazole-1-sulfonyl azide as a diazotransfer reagent
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A facile approach to the diazotransfer reagent of imidazole-1-sulfonyl azide was reported. The procedure was well optimized to clarify potential explosion risks. A high production yield as well as small batch variation was achieved even without careful pretreatment of reagents and solvents. HPLC and NMR methods to monitor the process were provided. These features made this protocol suitable for large scale preparation in academia and industry as well.
- Ye, Hui,Liu, Ruihua,Li, Dongmei,Liu, Yonghui,Yuan, Haixin,Guo, Weikang,Zhou, Lifei,Cao, Xuefeng,Tian, Hongqi,Shen, Jie,Wang, Peng George
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supporting information
p. 18 - 21
(2013/03/29)
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- Probing the nature of the Co(III) ion in corrins: Comparison of reactions of aquacyanocobyrinic acid heptamethyl ester and aquacyano-stable yellow cobyrinic acid hexamethyl ester with neutral N-donor ligands
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Equilibrium constants (log K) for substitution of coordinated H 2O in aquacyanocobyrinic acid heptamethyl ester (aquacyanocobester, ACCbs) and aquacyano-stable yellow cobyrinic acid hexamethyl ester (aquacyano-stable yellow cobester, ACSYCbs), in which oxidation of the C5 carbon of the corrin interrupts the normal delocalized system of corrins, by neutral N-donor ligands (ammonia, ethanolamine, 2-methoxyethylamine, N-methylimidazole, and 4-methylpyridine) have been determined spectrophotometrically as a function of temperature. Log K values increase with the basicity of the ligand, but a strong compensation effect between ΔH and ΔS values causes a leveling effect. The aliphatic amines with a harder donor atom produce ΔH values that are more negative in their reactions with ACSYCbs than with ACCbs, while the softer, aromatic N donors produce more negative ΔH values with ACCbs than with ACSYCbs. Molecular modeling (DFT, M06L/SVP, and a quantum theory of atoms in molecules analysis of the electron density) shows that complexes of the aliphatic amines with SYCbs produce shorter and stronger Co-N bonds with less ionic character than the Co-N bonds of these ligands with the cobester. Conversely, the Co-N bond to the aromatic N donors is shorter, stronger, and somewhat less ionic in the complexes of the cobester than in those of the SYCbs. Therefore, the distinction between the harder Co(III) in ACSYCbs and softer Co(III) in ACCbs, reported previously for anionic ligands, is maintained for neutral N-donor ligands.
- Chemaly, Susan M.,Kendall, Louise,Nowakowska, Monika,Pon, Dale,Perry, Christopher B.,Marques, Helder M.
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p. 1077 - 1083
(2013/03/13)
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- Chemo-immunotherapeutic antimalarials targeting isoprenoid biosynthesis
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We synthesized 30 lipophilic bisphosphonates and tested them in malaria parasite killing (targeting parasite geranylgeranyl diphosphate synthase, GGPPS) and human γδ T cell activation (targeting human farnesyl diphosphate synthase, FPPS). Similar patterns of activity were seen in inhibiting human FPPS and Plasmodium GGPPS, with short to medium chain-length species having most activity. In cells, shorter chain-length species had low activity, due to poor membrane permeability, and longer chain length species were poor enzyme inhibitors. Optimal activity was thus seen with ~C 10 side-chains, which have the best combination of enzyme inhibition and cell penetration. We also solved the crystal structure of one potent inhibitor, bound to FPPS. The results are of interest since they suggest the possibility of a combined chemo/immuno-therapeutic approach to antimalarial development in which both direct parasite killing and γδ T cell activation can be achieved with a single compound.
- Zhang, Yonghui,Zhu, Wei,Liu, Yi-Liang,Wang, Hong,Wang, Ke,Li, Kai,No, Joo Hwan,Ayong, Lawrence,Gulati, Anmol,Pang, Ran,Freitas-Junior, Lucio,Morita, Craig T.,Oldfield, Eric
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supporting information
p. 423 - 427
(2013/06/05)
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- Weakly-basic anion exchange resin scavenges impurities in ionic liquid synthesized from trialkyloxonium salt
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A new purification method of ionic liquids made from trialkyloxonium salts (Meerwein reagents) has been established. 1H and 19F NMR spectroscopy clarified the presence of 1-methylimidazolium ([Hmim]+) and trifluoro(1-methylimidazole)boron ([BF3(mim)]) as impurities occurring in the crude ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim]BF4). The Lewis acidic parts of these impurities, that is, H+ and BF3, were demonstrated to be able to transfer to dimethylamino groups of the weakly basic anion exchange resin (DOWEX MARATHON WBA) in aqueous solutions, releasing 1-methylimidazole (mim). The adsorption isotherms of [Hmim]BF4 and [BF 3(mim)] resulted in the equilibrium constants (K) of the reactions with the resin ([Hmim]BF4: log K ≈ 1.7, [BF3(mim)]: log K = -0.17 ± 0.03), indicating that the impurities show a difference in the reactivity with the resin. The volatiles (mim and water) are possible to be removed by evaporation under reduced pressure. Although intense reddish brown color was given to the residual oil of [emim]BF4, further purification and decolorization have been achieved by using silica-gel column chromatography (eluent: acetone) and treatment with activated carbon in water. Finally, the purified [emim]BF4 was successfully obtained as an almost colorless oil. The resin after use can be regenerated simply by washing with 1 M NaOH aq and deionized water.
- Takao, Koichiro,Tsubomura, Taro
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p. 2497 - 2502,6
(2020/08/24)
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- Preparation of various xanthene derivatives over sulfonic acid functionalized imidazolium salts (SAFIS) as novel, highly efficient and reusable catalysts
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In this work, some novel sulfonic acid functionalized imidazolium salts (SAFIS), as a new category of ionic liquids, are synthesized by eco-friendly and simple procedures, and used as highly efficient and reusable catalysts to promote the following one-pot multicomponent organic transformations under solvent-free conditions: (i) the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes from β-naphthol (2 eq.) and arylaldehydes (1 eq.), (ii) the preparation of tetrahydrobenzo[a]xanthene-11-ones from β-naphthol, arylaldehydes and dimedone, and (iii) the synthesis of 1,8-dioxo-octahydroxanthenes from dimedone (2 eq.) and aromatic aldehydes (1 eq.). Environmentally benign, simple methodologies, easy workup procedure, clean reaction, short reaction time, high yield and easy preparation of the catalysts are some advantages of this work.
- Zolfigol, Mohammad Ali,Khakyzadeh, Vahid,Moosavi-Zare, Ahmad Reza,Zare, Abdolkarim,Azimi, Seyedeh Bahareh,Asgari, Zhila,Hasaninejad, Alireza
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body text
p. 719 - 736
(2012/10/08)
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- Kinetics and mechanism of organocatalytic aza-Michael additions: Direct observation of enamine intermediates
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The imidazoles 1a-g add to the CC-double bond of the iminium ion 2 with rate constants as predicted by the equation log k = sN(N + E). Unfavourable proton shifts from the imidazolium unit to the enamine fragment in the adduct 3 account for the failure of imidazoles to take part in iminium-activated aza-Michael additions to enals.
- Lakhdar, Sami,Baidya, Mahiuddin,Mayr, Herbert
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supporting information; experimental part
p. 4504 - 4506
(2012/05/19)
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- IONIC LIQUIDS, THE METHOD FOR PREPARING THE SAME AND METHOD FOR REMOVING ACETYLENES FROM OLEFIN MIXTURES USING THE IONIC LIQUIDS
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There are provided an ionic liquid having ether group(s) in which a copper(I) compound is included, a method for preparing the same, and a method for removing traces amounts of acetylene-based hydrocarbon compounds included in olefin by absorption or extraction using the same. When the disclosed solution is used, oxidation of Cu(I) to Cu(II) is prevented since CuX is stabilized by the ionic liquid. Thus, selective removal efficiency of acetylenic compounds is improved greatly while the removal performance is retained for a long period of time. Further, since the solution according to the present disclosure is applicable as an extractant as well as an absorbent, the associated operation is simple and apparatus cost can be decreased.
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Page/Page column 4
(2012/04/11)
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- A continuous methylation of phenols and N, H -heteroaromatic compounds with dimethyl carbonate
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The methylation of phenolic substrates has been reevaluated using sulfolane as solvent instead of DMF. The change of solvent gave in all cases cleaner production of the anisole products in very good yields. The reaction requires 0.1 equiv of DBU, 2-3 equiv of DMC, and 2-5 vols of sulfolane depending on the substrate. At 220 C the reaction time is 10 min. Sulfolane is completely stable under the reaction conditions, excluding unwanted impurities from the solvent. The reaction could also be extended to NH-indole and NH-imidazole derivatives utilizing 0.1 equiv of DBU and 2-3 equiv of DMC in 2 vols of sulfolane. All NH-heteroaromatic compounds gave clean N-methylation.
- Tilstam, Ulf
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p. 1974 - 1978
(2013/02/25)
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- On the reactivity of imidazole carbamates and ureas and their use as esterification and amidation reagents
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The optimization, substrate scope, and mechanism of esterification and amidation of carboxylic acids mediated by imidazole-based reagents are discussed. The innate reactivity of carbonylimidazole reagents with a range of nucleophiles is also explored. New reagents developed for the synthesis of α,β-unsaturated esters are described, as are reagents for the preparation of tertiary amides directly from carboxylic acids.
- Heller, Stephen T.,Sarpong, Richmond
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experimental part
p. 8851 - 8859
(2011/12/02)
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- Antithyroid drugs and their analogues protect against peroxynitritemediated protein tyrosine nitration-a mechanistic study
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In this paper, the effect of some commonly used antithyroid drugs and their analogues on peroxynitritemediated nitration of proteins is described. The nitration of tyrosine residues in bovine serum albumin (BSA) and cytochrome c was studied by Western blot analysis. These studies reveal that the antithyroid drugs methimazole (MMI), 6-n-propyl-2-thiouracil (PTU), and 6-methyl-2- thiouracil (MTU), which contain thione moieties, significantly reduce the tyrosine nitration of both BSA and cytochrome c. While MMI exhibits good peroxynitrite (PN) scavenging activity, the thiouracil com-pounds PTU and MTU are slightly less effective than MMI. The S- and Semethylated compounds show a weak inhibitory effect in the nitration of tyrosine, indicating that the presence of a thione or selone moiety is important for an efficient inhibition. Similarly, the replacement of N-H moiety in MMI by N-methyl or N-m-methoxybenzyl substituents dramatically reduces the antioxidant activity of the parent com-pound. Theoretical studies indicate that the substitution of N-H moiety by NMe significantly increases the energy required for the oxidation of sulfur center by PN. However, such substitution in the selenium analogue of MMI increases the activity of parent compound. This is due to the facile oxidation of the selone moiety to the corresponding selenenic and seleninic acids. Unlike N,N'-disubstituted thiones, the corresponding selones efficiently scavenge PN, as they predominantly exist in their zwitterionic forms in which the selenium atom carries a large negative charge.
- Bhabak, Krishna P.,Mugesh, Govindasamy
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experimental part
p. 1175 - 1185
(2010/06/19)
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- [(NHC)(NHCewg)RuCl2(CHPh)] complexes with modified NHCewg ligands for efficient ring-closing metathesis leading to tetrasubstituted olefins
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Imidazolium salts (NHCewg-HCl) with electronically variable substituents in the 4,5-position (H,H or C1,C1 or H,NO2 or CN 5CN) and sterically variable substituents in the 1,3-position (Me,Me or Et,Et or iPr,iPr or Me,iPr) were synthesized and converted into the respective [AgI(NHC)ewg] complexes. The reactions of [(NHC)RuCl 2(CHPh)(Py)2] with the [AgI(NHQw8)] complexes provide the respective [(NHC)(NHCewg)RuCl2(CHPh)] complexes in excellent yields. The catalytic activity of such complexes in ring-closing metathesis (RCM) reactions leading to tetrasubstituted olefins was studied. To obtain quantitative substrate conversion, catalyst loadings of 0.2-0.5 mol% at 80°C in toluene are sufficient. The complex with the best catalytic activity in such RCM reactions and the fastest initiation rate has an NHCewg group with l,3-Me,iPr and 4,5-Cl,Cl substituents and can be synthesized in 95 % isolated yield from the ruthenium precursor. To learn which one of the two NHC ligands acts as the leaving group in olefin metathesis reactions two complexes, [(FL-NHC)-(NHCcwg)RuCl2(CHPh)] and [(FLNHCewg)(NHC)RuCl2(CHPh)], with a dansyl fluorophore (FL)-tagged electron-rich NHC ligand (FL-NHC) and an electron-deficient NHC ligand (FLNHCewg) were prepared. The fluorescence of the dansyl fluorophore is quenched as long as it is in close vicinity to ruthenium, but increases strongly upon dissociation of the respective fluorophore-tagged ligand. In this manner, it was shown for ring-opening metathesis ploymerization (ROMP) reactions at room temperature that the NHCewg ligand normally acts as the leaving group, whereas the other NHC ligand remains ligated to ruthenium.
- Sashuk, Volodymyr,Peeck, Lars H.,Plenio, Herbert
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experimental part
p. 3983 - 3993
(2010/07/04)
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- Thermal stability of ionic liquids assessed by potentiometric titration
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The long-term thermal stability of imidazolium-based ionic liquids is addressed here. We have found that potentiometric titration is a precise, low-cost and quick analytical method to assess the quality changes occurring during the thermal aging of ionic liquids. Using this protocol, we have discovered that imidazolium-based ionic liquids start to decompose, to a small extent, at much lower temperatures than those inferred from thermogravimetric analysis.
- Meine, Niklas,Benedito, Flavio,Rinaldi, Roberto
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body text
p. 1711 - 1714
(2011/02/22)
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- PRODRUGS OF FUSED HETEROCYCLIC INHIBITORS OF D-AMINO ACID OXIDASE
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The invention relates to prodrugs of fused heterocyclic inhibitors of D-amino oxidase (DAAO) and methods of treating diseases and conditions, wherein modulation of D- amino acid oxidase activity, D-serine levels, D-serine oxidative products and NMDA receptor activity in the nervous system of a mammalian subject is effective.
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Page/Page column 112-113
(2010/04/03)
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