- Binary ionic liquid system for direct cellulose etherification
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Etherification of cellulose was performed using a mixture of ionic liquids (ILs) playing roles in both cellulose dissolution and catalysis. We investigated the effects of the reaction time and the ratio of these ILs in the mixture. Cellulose etherification was performed in these IL mixtures. The proportion of propoxy cellulose exceeded 2.5 after 24 h.
- Kakibe, Takeshi,Nakamura, Satoshi,Amakuni, Kiyokazu,Kishi, Hajime
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- Poly(oxyalkylene) synthesis in Bronsted acid ionic liquids
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The polyetherification of diols with 4-12 methylene units was studied in Bronsted Acid Ionic Liquids (BAILs). High molar mass poly(oxyalkylene)s were obtained at relatively low temperatures (130 °C), except in the cases of 1,4-butanediol and 1,6-hexanediol where cyclic ether formation was observed.
- Zhang, Shaodong,Feret, Aurelie,Lefebvre, Herve,Tessier, Martine,Fradet, Alain
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- Influence of Bronsted acid ionic liquid structure on hydroxyacid polyesterification
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Bronsted acid ionic liquids (BAILs) based on the 4-(3′-butyl-1′-imidazolio)-1-butanesulfonic acid cation were found to be very efficient polyesterification solvents and catalysts. Only 5-30 min at 90-110 °C was required to obtain high molar mass poly(12-hydroxydodecanoic acid) (Mw up to 40000 g mol-1). The polyesterification was faster in BAILs with the bis(trifluoromethylsulfonyl)imidide anion (Tf 2N), but small amounts of ethers and double bonds arising from side reactions were detected in the final polymer. On the other hand, no side reactions took place in the BAIL with the hydrogen sulfate anion, except for the formation of a sulfonate ester intermediate that can further react with carboxylic acid groups to yield the expected ester. This intermediate, not observed in Tf2N-based BAILs, might be involved in the protection of hydroxy end groups from etherification side reactions in HSO4 --based BAILs. To explain the different behaviors of these BAILs, and since the acidity of H2SO4 is much higher than that of Tf2NH, it is suggested that the structure of these BAILs could be different: alkylsulfonic acid-substituted imidazolium for the former, while the latter could be just a mixture of imidazolium-sulfonate zwitterion and Tf 2NH. The influence of reaction temperature, water elimination method and BAIL concentration on polyesterification are also discussed.
- Zhang, Shaodong,Lefebvre, Herve,Tessier, Martine,Fradet, Alain
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- Ionic liquid-assisted synthesis of dihydropyrimidin(thi)one Biginelli adducts and investigation of their mechanism of urease inhibition
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Twenty-six Biginelli adducts were synthesized through an ionic liquid-assisted synthesis with up to 92% yield. Sixteen of these Biginelli adducts were then assayed to determine their antiureolytic activity against purified urease from jack beans. The substances BA7-S, BA9-S and BA11-S were shown to be as efficient inhibitors as hydroxyurea, a positive control used in in vitro screening assay against urease. Fluorescence studies revealed that BA7-S, BA9-S, BA11-S and BA5-S possessed high binding constant values of 5.95, 6.72, 4.55, and 4.28 M-1, respectively, while BAS12-S, without substituents, showed a low value of log Kb = 2.16 M-1. In addition, in the most thermodynamically favorable BA5-S and BA7-S urease complexes, the corresponding Biginelli adducts were capable of interacting with the active site of urease through non-ionic interactions, such as hydrophobic interactions, or hydrogen and van der Waals interactions, respectively. In silico studies also supported that the BAs interact with the active site, confirming the fluorescence and kinetic assay studies, which clearly indicate that BA5-S and BA7-S are competitive inhibitors (Ki = 0.96 and 0.57 mM, respectively). In silico studies also showed that the substituents in the aromatic ring interact with Ni atoms to form a stable complex.
- Braga, Taniris Cafiero,Silva, Thamara Ferreira,MacIel, Thamilla Maria Silva,Da Silva, Edjan Carlos Dantas,Da Silva-Júnior, Edeildo Ferreira,Modolo, Luzia Valentina,Figueiredo, Isis Martins,Santos, Josué Carinhanha Caldas,De Aquino, Thiago Mendon?a,De Fátima, ?ngelo
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p. 15187 - 15200
(2019/10/08)
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- Olefin oligomerization via new and efficient Br?nsted acidic ionic liquid catalyst systems
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Olefin oligomerization reaction catalyzed by new catalyst systems (a Br?nsted-acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co-catalyst) has been investigated. The synthesized Br?nsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV), 1H nuclear magnetic resonance (NMR), and 13C NMR to analyze their structures and acidities. The influence of different ionic liquids, ionic liquid loading, different co-catalysts, catalyst ratios (mole ratio of ionic liquid to co-catalyst), reaction time, pressure, temperature, solvent, source of reactants, and the recycling of catalyst systems was studied. Among the synthesized ionic liquids, 1-(4-sulfonic acid)butyl-3-hexylimidazolium hydrogen sulfate ([HIMBs]HSO4) exhibited the best catalytic activity under the tested reaction conditions. The conversion of isobutene and selectivity of trimers were 83.21% and 35.80%, respectively, at the optimum reaction conditions. Furthermore, the catalyst system can be easily separated and reused; a feasible reaction mechanism is proposed on the basis of the distribution of experimental products.
- Wang, Guoqin,Song, Heyuan,Li, Ruiyun,Li, Zhen,Chen, Jing
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p. 1110 - 1120
(2018/05/28)
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- Chemical Analysis of Ionic Liquids Using Photoelectron Spectroscopy
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The feasibility of utilizing X-ray photoelectron spectroscopy (XPS) to analyze roomerature ionic liquids (RTILs) was investigated in this study. Conventionally, the chemical structure of organic compounds is identified by nuclear magnetic resonance (NMR) spectroscopy. The properties of RTILs, especially their low vapor pressure, make it possible to analyze RTILs by using XPS. The usefulness of XPS on RTILs was confirmed by commercial RTILs. All atoms in RTILs were detected in survey XPS spectra, and the calculated atomic percentages matched well with theoretical values. After the verification of commercial RTILs by XPS, we synthesized three RTILs and investigated them with XPS. The atomic ratio and chemical environment of carbon in RTILs were verified by XPS. By adapting XPS to the investigation of RTILs, carbon atoms in different chemical environments were distinguishable by the binding energy shift, and the atomic ratio of the constituent atoms was identifiable after peak deconvolution. In addition, inorganic constituents were detected by XPS unlike in the case of NMR spectroscopy.
- Seo, Sungyong,Park, Juyun,Kang, Yong-Cheol
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p. 355 - 360
(2016/03/15)
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- Selective palladium-catalysed arylation of 2,6-dibromopyridine using N-heterocyclic carbene ligands
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A selective palladium-catalysed arylation of 2,6-dibromopyridine has been developed by employing N-heterocyclic carbene ligands. Selective mono-arylation was performed in water/acetonitrile solvent system at ambient temperature with catalyst loading of 0.1 mol%. This reaction was also found to proceed smoothly in water although at a slightly elevated temperature of 80 °C. 2,6-Disubstituted and diversely substituted 2,6-pyridines were also obtained in high yields which will be of importance to organic and medicinal chemists.
- Prajapati,Schulzke,Kindermann,Kapdi
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p. 53073 - 53085
(2015/06/25)
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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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- Synthesis and thermophysical properties of imidazolium-based bronsted acidic ionic liquids
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A range of imidazolium-based Bronsted acidic ionic liquids (ILs) have been synthesized by varying the side chain length of the alkyl and alkyl sulfonic group incorporated to the C1 and C3 positions in the imidazolium ring respectively with a fixed HSO4- anion. The synthesized ILs were characterized using NMR for structure confirmation and CHNS for elemental analysis. The thermal properties such as thermal decomposition temperature were determined using thermogravimetric analysis, and several key physical properties such as viscosity and density were measured within a temperature range of 20 C to 80 C using an Anton Paar viscometer and densitometer. The density measurement results and established equations were used to calculate the molecular volumes, standard entropies, crystal lattice energies, and thermal expansion coefficients of the synthesized ILs.
- Muhammad, Nawshad,Man, Zakaria,Elsheikh, Yasir A.,Bustam, M. Azmi,Mutalib, M.I. Abdul
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p. 579 - 584
(2014/04/03)
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- Oligomerisation of isobutene with silica supported ionic liquid catalysts
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Bronsted acidic ionic liquids, supported on silica gel, have been used effectively in oligomerisation of isobutene. The supported catalysts could be used several times without loss of activity or change in selectivity. The ratio of the products could be influenced by the proper choice of the ionic liquid component of the catalyst and the reaction temperature.
- Feher, Csaba,Krivan, Eszter,Hancsok, Jen,Skoda-Foeldes, Rita
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experimental part
p. 403 - 409
(2012/04/10)
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- Broensted acidic ionic liquids as efficient and recyclable catalysts for the carbonylation of formaldehyde
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Methyl glycolate (MG), as a precursor to ethylene glycol (EG), was synthesized by an efficient and eco-friendly procedure of one-pot, two-step, sequential reaction, including carbonylation and esterification from HCHO with Broensted acidic ionic liquids (BAILs) as catalysts. MG was obtained in high yield under mild conditions. In addition, the catalyst could be recycled eight times after separating the unreacted materials and products from the reaction system by distillation under vacuum and no significant decrease in catalytic activity was observed.
- Song, Heyuan,Li, Zhen,Chen, Jing,Xia, Chungu
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experimental part
p. 81 - 86
(2012/04/10)
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- Synthesis of 1-octanol and 1,1-dioctyl ether from biomass-derived platform chemicals
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The happy medium: A new catalytic pathway for the synthesis of the linear primary C8?alcohol products 1-octanol and dioctyl ether from furfural and acetone has been developed using retrosynthetic analysis. This opens a general strategy for the synthesis of medium-chain-length alcohols from carbohydrate feedstock.
- Julis, Jennifer,Leitner, Walter
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supporting information; experimental part
p. 8615 - 8619
(2012/09/21)
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- Intramolecular hydroalkoxylation in Bronsted acidic ionic liquids and its application to the synthesis of (±)-centrolobine
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The SO3H-tethered imidazolium and triazolium salts, nonvolatile and recyclable Bronsted acidic ionic liquids, efficiently mediate intramolecular hydroalkoxylations of alkenyl alcohols. They have been successfully employed in the synthesis of (±)-centrolobine.
- Jeong, Yunkyung,Kim, Do-Young,Choi, Yunsil,Ryu, Jae-Sang
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supporting information; experimental part
p. 374 - 378
(2011/02/28)
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- Selective and flexible transformation of biomass-derived platform chemicals by a multifunctional catalytic system
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(Figure Presented) A sustainable supply chain: The controlled transformation of the biomassderived platform compounds levulinic acid (LA) and itaconic acid (IA) into the corresponding lactones, diols, or cyclic ethers (see picture) by using a multifunctional molecular catalyst is described.
- Geilen, Frank M. A.,Engendahl, Barhel,Harwardt, Andreas,Marquardt, Wolfgang,Klankermayer, Juergen,Leitner, Walter
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supporting information; experimental part
p. 5510 - 5514
(2010/09/16)
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- Improved solubilization of pyromellitic dianhydride and 4,4′-oxydianiline in ionic liquid by the addition of zwitterion and their polycondensation
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Three different ionic liquids were prepared and examined as solvents for polyimide synthesis. The solubility of 4,4′-oxydianiline and pyromellitic dianhydride as starting materials in ionic liquids was first evaluated, and then their polycondensation was carried out. Although these starting materials were hardly soluble in 1-benzyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide (3), addition of imidazolium type zwitterion, 1-(1-butyl-3-imidazolio)butane-4-sulfonate (ZI), certainly improved their solubility. When 3 containing 40 mol % ZI was used, nothing was phase separated from this mixed solution containing both starting materials after cooling down to room temperature. After preparing prepolymer in 3 containing 40 mol % of ZI at room temperature, polycondensation was carried out in the same solution at 100, 200, and then 300 °C for every 1 h to obtain polyimide. An inherent viscosity of the obtained polyimide (0.05 g in 10 ml concentrated sulfuric acid) was 1.3 dL g-1, higher than that prepared in only 3 (0.9 dL g-1). The higher average molecular weight of the polyimide was attributed to the improved solubility of the starting materials by the addition of ZI that enabled the preparation of the prepolymer, poly(amide acid), without heating before imidation.
- Tamada, Masahiro,Hayashi, Takahiro,Ohno, Hiroyuki
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p. 1553 - 1557
(2008/02/03)
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- Design of ionic liquids for electrochemical applications
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Zwitterionic liquids composed of a tethered cation and anion were synthesized and their thermal properties and ionic conductivity were investigated as novel ionic liquids especially for electrochemical applications. We prepared nine zwitterions in this study. In addition, this paper includes 36 kinds of zwitterions already reported in order to discuss the relationship between the zwitterion structure and their properties. Most zwitterions melt above 100°C; their melting points are generally higher than that of simple ionic liquids. When an equimolar amount of equimolar amount of lithium salt (LiTFSI, LiBETI, LiCF3SO3, LiBF4, or LiClO4) was added to the zwitterion, the mixture showed only a glass transition temperature Tg. The Tg values of the zwitterionic liquid/salt mixture showed the lowest value of -37°C when with LiTFSI. This mixture also showed the highest ionic conductivity of 8.9 × 10-4 S cm-1 at 100°C. There is a good relationship between Tg and ionic conductivity of the zwitterionic liquid/lithium salt mixtures.
- Yoshizawa, Masahiro,Narita, Asako,Ohno, Hiroyuki
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p. 139 - 144
(2007/10/03)
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