4333-62-4Relevant articles and documents
Experimental and theoretical studies on imidazolium ionic liquid-promoted conversion of fructose to 5-hydroxymethylfurfural
Li, Yu-Nong,He, Liang-Nian,Yang, Zhen-Zhen,Liu, An-Hua,Yu, Bing,Luan, Chao-Ran,Wang, Jin-Quan
, p. 2752 - 2758,7 (2012)
A combined experimental and computational study on the imidazolium ionic liquid-promoted conversion of fructose to 5-hydroxymethylfurfural (HMF) was performed. In particular, 1-butyl-3-methyl-imidazolium bromide (BMImBr) was found to be unexpectedly effective for conversion of fructose into HMF without utilizing any other additive or catalyst. Under the optimized conditions, nearly 100% conversion of fructose with a 95% yield of HMF could be obtained. In addition, BMImBr could be easily recovered and reused over 6 times without significant loss of activity. This protocol represents a simple, recyclable and environmentally friendly pathway for HMF production. Furthermore, the detailed mechanism of the BMImBr-promoted conversion of fructose into HMF was also studied through an in situ FT-IR technique, NMR and density functional theory calculations, and demonstrated that the hydrogen bond interaction between BMImBr and fructose could play an important role in promoting the dehydration of fructose. This work also provides further understanding at the molecular level of the reaction process for ionic liquid-promoted conversion of fructose to HMF.
Imidazolium bromide-based ionic liquid assisted improved activity of trypsin in cationic reverse micelles
Debnath, Sisir,Das, Dibyendu,Dutta, Sounak,Das, Prasanta Kumar
, p. 4080 - 4086 (2010)
The present work reports the imidazolium-based ionic liquids (ILs) assisted enhancement in activity of water-pool solubilized enzyme trypsin in cationic reverse micelles of CTAB. A set of imidazolium ILs (1-alkyl-3-methyl imidazolium bromides) were prepared with varying lengths of their side armwhich results in the differential location of these organic salts in the reverse micelles. The different ILs offered varied activating effects on the biocatalyst. The activity of trypsin improved 30-300% in the presence of 0.1-10 mM of different ILs in reverse micelles of CTAB. Trypsin showed 300% (4-fold) increment in its activity in the presence of IL2 (1-ethyl-3-methyl imidazoliumbromide,EMIMBr) compared to that observed in the absence of IL in CTAB reverse micelles. The imidazolium moiety of the IL, resembling the histidine amino acid component of the catalytic triad of hydrolases and itsBr- counterion, presumably increases the nucleophilicity of water in the vicinity of the enzyme by forming a hydrogen bond that facilitates the enzyme-catalyzed hydrolysis of the ester.However, the ILs with increasing amphiphilic character had little to no effect on the activity of trypsin due to their increased distance from the biocatalyst, as they tend to get localized toward the interfacial region of the aggregates. Dynamic light scattering experimentationwas carried out in the presence of ILs to find a possible correlation between the trypsin activity and the size of the aggregates. In concurrencewith the observed highest activity in the presence of IL2, the circular dichroism (CD) spectrum of trypsin in CTAB reverse micelles doped with IL 2 exhibited the lowest mean residue ellipticity (MRE), which is closest to that of the native protein in aqueous buffer.
Expanding the catalytic activity of nucleophilic N-heterocyclic carbenes for transesterification reactions
Nyce, Gregory W.,Lamboy, Jorge A.,Connor, Eric F.,Waymouth, Robert M.,Hedrick, James L.
, p. 3587 - 3590 (2002)
(graph presented) Currently, there is a renewed interest in reactions that are catalyzed by organic compounds. Typical organic catalysts for acylation or transesterification reactions are based on either nucleophilic tertiary amines or phosphines. This communication discusses the use of nucleophilic N-heterocyclic carbenes as efficient transesterification catalysts. These relatively unexplored and highly versatile organic catalysts were found to be mild, selective, and more active than traditional organic nucleophiles.
Synthesis of biphenyl-4,4′-diylbis(naphthalene-1-ylmethanone) via carbonylative coupling
Song, Ju Hyun
, p. 3031 - 3034 (2015)
More recently, an interest has been developed in three component carbonylation reactions, such as the carbonylative Suzuki, carbonylative Sonogashira and carbonylative Heck reactions, which allow for a significant increase in molecular complexity. To develop a luminescent material with high colour purity, luminous efficiency and stability, we synthesized diketone by carbonylative Suzuki coupling in the presence of Pd(NHC)(NHC=N-heterocyclic carbene) complex as the catalyst. Carbonylative coupling of 4,4′-diiodobiphenyl and naphthalene-1-ylboronic acid was investigated to study the catalytic ability of Pd(NHC) complex. Reactions were carried out using both CO and metal carbonyls. bis(1,3-Dihydro-1,3-dimethyl-2H-imidazol-2-ylidene)diiodopalladium was used as the catalytic complex. Reaction products biphenyl-4,4′-diylbis(naphthalene-1-ylmethanone) 3 and (4′-iodobiphenyl-4yl)(naphthalene-1-yl)methanone 4 were obtained as a result of CO insertion into the palladium(II)-aryl bond. However, when pyridine-4-ylboronic acid was used in place of naphthalene-1-ylboronic acid as the starting reagent, synthetic reaction yielding 3 and 4 were found.
A new method for improving the ion conductivity of anion exchange membranes by using TiO2 nanoparticles coated with ionic liquid
Chu, Yuhao,Chen, Yuenan,Chen, Nanjun,Wang, Fanghui,Zhu, Hong
, p. 96768 - 96777 (2016)
Recently a new method for increasing the ion conductivity of anion exchange membranes (AEM) was developed based on the novel materials ionic liquids (ILs). We mixed the ILs into the membrane directly instead of immobilizing onto the polymer backbone as in the traditional way. Nano-TiO2 was introduced to stabilize the ILs in the membrane. The ILs were immobilized by the nano-TiO2, acting as the "active sites" in the membrane, to enhance the mobility of the hydroxyl groups so as to increase the ion conductivity. Both pure ILs composite membranes and ILs-TiO2 composite membranes were synthesized, and their properties were compared. 1H nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy were used to analyze the structures of the composite membranes. The mechanical properties, thermal stabilities, ion conductivities, water uptakes, swelling ratios, and ion exchange capacities of the membranes were investigated. The interaction between the TiO2 and ionic liquids was confirmed by X-ray diffraction. The stability of the ILs in the membrane was measured comprehensively. All these results show that this novel method is effective and promising for AEM applications.
Cleavage of Hg-C Bonds of Organomercurials Induced by ImOHSe via Two Distinct Pathways
Banerjee, Mainak,Roy, Gouriprasanna
, p. 12739 - 12750 (2017)
We show that the N-methylimidazole-based selone ImOHSe having an N-CH2CH2OH substituent has the remarkable ability to degrade methylmercury by two distinct pathways. Under basic conditions, ImOHSe converts MeHgCl into biologically inert HgSe nanoparticles and Me2Hg via the formation of an unstable intermediate (MeHg)2Se (pathway I). However, under neutral conditions, in the absence of any base, ImOHSe facilitates the cleavage of the Hg-C bond of MeHgCl at room temperature (23 °C), leading to the formation of a stable cleaved product, the tetracoordinated mononuclear mercury compound (ImOHSe)2HgCl2 and Me2Hg (pathway II). The initial rate of Hg-C bond cleavage of MeHgCl induced by ImOHSe is almost 2-fold higher than the initial rate observed by ImMeSe. Moreover, we show that ImYSe (Y = OH, Me) has an excellent ability to dealkylate Me2Hg at room temperature. Under acidic conditions, in the presence of excess ImYSe, the volatile and toxic Me2Hg further decomposes to the tetracoordinated mononuclear mercury compound [(ImYSe)4Hg]2+. In addition, the treatment of ImOHSe with MeHgCys or MeHgSG in phosphate buffer (pH 8.5) afforded water-soluble Hg(SeS) nanoparticles via unusual ligand exchange reactions, whereas its derivative ImOMeSe or ImMeSe, lacking the N-CH2CH2OH substituent, failed to produce Hg(SeS) nanoparticles under identical reaction conditions.
Steric Properties of N-Heterocyclic Carbenes affect the Performance of Electronic Probes
Barnett, Christopher,Cole, Marcus L.,Harper, Jason B.
supporting information, p. 4954 - 4958 (2021/12/02)
Electronic probes of ligands, particularly carbenes, are widely used in assessing electronic properties; the results inform the selection of a ligand for a given application. As such, it is important to ensure the data obtained is reliable and unaffected by other factors, such as the steric bulk of the ligand. The effects of such steric factors on two commonly used electronic probes (based on palladium and selenium) are investigated here, with the selenium adduct found to be particularly sensitive. It is hoped that this serves as a cautionary tale to always critically evaluate what a probe is measuring.
A Superstrong and Reversible Ionic Crystal-Based Adhesive Inspired by Ice Adhesion
Liu, Lili,Liu, Ziyang,Ren, Yongyuan,Zou, Xiuyang,Peng, Wansu,Li, Weizheng,Wu, Yiqing,Zheng, Sijie,Wang, Xiaoliang,Yan, Feng
supporting information, p. 8948 - 8959 (2021/03/16)
In this study, we developed a superstrong and reversible adhesive, which can possess a high bonding strength in the “adhesive” state and detach with the application of heating. An ionic crystal (IC) gel, in which an IC was immobilized within a soft-polymer matrix, were synthesized via in situ photo-crosslinking of a precursor solution composed of N, N-dimethyl acrylamide (DMAA) and a melted IC. The obtained IC gel is homogenous and transparent at melt point. When cooled to the phase transition temperature of the IC, the gel turns into the adhesive with the adhesion strength of 5.82 MPa (on glasses), due to the excellent wetting of melted gel and a thin layer of crystalline IC with high cohesive strength formed on the substrates. The synergistic effects between IC, polymer networks and substrates were investigated by solid state 1H NMR and molecular dynamics simulation. Such an adhesive layer is reversable and can be detached by heating and subsequent re-adhesion via cooling. This study proposed the new design of removable adhesives, which can be used in dynamic and complex environments.
Insight into the Decomposition Mechanism of Donor-Acceptor Complexes of EH2(E = Ge and Sn) and Access to Germanium Thin Films from Solution
Brown, Alex,Dai, Guoliang,Ferguson, Michael J.,Mcdonald, Robert,Rivard, Eric,Sinclair, Jocelyn
supporting information, (2020/08/12)
Electron-donating N-heterocyclic carbenes (Lewis bases, LB) and electron-accepting Lewis acids (LA) have been used in tandem to yield donor-acceptor complexes of inorganic tetrelenes LB·EH2·LA (E = Si, Ge, and Sn). Herein, we introduce the new germanium (II) dihydride adducts ImMe2·GeH2·BH3 (ImMe2 = (HCNMe)2C:) and ImiPr2Me2·GeH2·BH3 (ImiPr2Me2 = (MeCNiPr)2C:), with the former complex containing nearly 40 wt % germanium. The thermal release of bulk germanium from ImMe2·GeH2·BH3 (and its deuterated isotopologue ImMe2·GeD2·BD3) was examined in solution, and a combined kinetic and computational investigation was undertaken to probe the mechanism by which Ge is liberated. Moreover, the thermolysis of ImMe2·GeH2·BH3 in solution cleanly affords conformal nanodimensional layers of germanium as thin films of variable thicknesses (20-70 nm) on silicon wafers. We also conducted a computational investigation into potential decomposition pathways for the germanium(II)- and tin(II)-dihydride complexes NHC·EH2·BH3 (NHC = [(HCNR)2C:]; R = 2,6-iPr2C6H3 (Dipp), Me, and H; and E = Ge and Sn). Overall, this study introduces a mild and convenient solution-only protocol for the deposition of thin films of Ge, a widely used semiconductor in materials research and industry.
