Optical and Bioelectrochemical Characterization of Water‐Miscible Ionic Liquids Based Composites of Multiwalled Carbon Nanotubes

Acidic treated multiwalled carbon nanotubes (AMWNTs) were ground with water‐miscible room temperature ionic liquids, 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim]BF₄), and resulted in AMWNTs‐[bmim]BF₄ composite. Its electrical‐ionic conductivity and optical properties were compared with the other two types of carbon materials‐[bmim]BF₄ composites: pyrolytic graphite powder (PGP), pristine multiwalled carbon nanotubes (PMWNTs), through the ac impedance technology and Raman spectroscopy. The impedance data show that AMWNTs‐[bmim]BF₄ composite exhibits the highest conductivity. Raman spectra study exhibits that the [bmim]BF₄ can form gel with PMWNTs and AMWNTs but only form a viscous liquid with PGP. AMWNTs‐[bmim]BF₄ gel modified GC electrode was applied in direct electrochemistry of heme proteins (Hb and HRP) and it catalysis to the reduction of H₂O₂ was investigated.     

Iridium-catalyzed regiospecific allylation of dimethyl malonate in ionic liquids

Allylation of dimethyl malonate with 1-(4-chlorophenyl)prop-2-enyl methyl carbonate in the presence of [Pd(All)Cl]₂, [Rh(COD)Cl]₂, [Ir(COD)Cl]₂ (COD is cycloocta-1,5-diene), and a chiral ferrocenyl-containing phosphite ligand based on (R)-BINOL (BINOL is 2,2′-dihydroxy-1,1′-binaphthyl) in CH₂Cl₂ gave a mixture of linear and branched cross-coupling products, the latter having a moderate optical purity (below 51%). The rhodium-and iridium-catalyzed reactions were very highly regioselective (regiospecific in the case of Ir), giving a branched product. In ionic liquids ([bmim][BF₄] and [bdmim][BF₄]) (bmim is 1-butyl-3-methylimidazolium and bdmim is 1-butyl-2,3-dimethylimidazolium), the Ir-catalyzed reaction regiospecifically afforded a branched product as a racemate. The same result was obtained with [Ir(COD)Cl]₂ as a catalyst; this reaction easily occurred in ionic liquids even without a base. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 519–521, March, 2007.     

3-exo-tet Cyclization of 2,2-disubstituted 1,3-dihalopropanes with indium in aqueous and ionic liquid solvent system

The 3-exo-tet cyclization of 2,2-disubstituted 1,3-dihalopropanes with In powder in THF solution of 20% H₂O, dioxane solution of 20% H₂O, and ionic liquids, such as [bmim]Br, [bmim]Cl, and [bmin]BF₄, respectively, was efficiently carried out to form the corresponding 1,1-disubstituted cyclopropanes in good yields. The cyclopropanation of 2,2-disubstituted 1,3-dihalopropanes with In powder in ionic liquids, such as [bmim]Br, [bmim]Cl, and [bmin]BF₄, was markedly accelerated compared with that in a THF solution of 20% H₂O and a dioxane solution of 20% H₂O. The mechanism was proposed to involve the radical 3-exo-tet cyclization of the formed 3-halopropyl radical.     

Cationic ring-opening polymerization of 3,3-bis（chloromethyl）oxacyclobutane in ionic liquids

Cationic ring-opening polymerization of 3,3-bis(chloromethyl)oxacyclobutane catalyzed by BF_3·OEt_2 was carried out in ionic liquids [bmim]BF_4 and [bmim]PF_6.The influences of BCMO concentration and molar ratio of BCMO/BF_3·OEt_2 on the molecular weights and yield of PBCMO were investigated.The polymerization in ionic liquids proceed to high conversions,although molecular weights are limited,similar to polymerization in organic solvent such as CH_2Cl_2.Follow a viewpoint of green chemistry, we feel ionic liquid [bmim]BF_4 is superior to [bmim]PF_6.Extracting [bmim]PF_6 from the product using organic solvent as extractant limits its advantage as a green reaction media.     

Synthesis and Crystal Structures of Mixed Halophenylbismuthates(III)

Synthesis and characterisation of mixed halophenylbismuthates(III) with a general formula Bu₄N[PhBiX₂Y] where X = Cl or Br; Y = Cl, Br or I; X ≠ Y are reported. The molecular structures of Bu₄N[PhBiCl₂Br] ( 1 ) and Bu₄N[PhBiBr₂I] ( 2 ) are determined by X‐ray crystallography. In mixed halophenylbismuthates, the anion exists as a dimer with bismuth in a distorted square pyramidal coordination. In the dimer the two phenyl groups occupy anti position to each other thereby minimising the repulsion.     

Zweikernige Palladium(II)‐, Platin(II)‐ und Iridium(III)‐Komplexe von Bis[imidazol‐4‐yl]alkanen

Dinuclear Palladium(II), Platinum(II), and Iridium(III) Complexes of Bis[imidazol‐4‐yl]alkanes The reaction of bis(1,1′‐triphenylmethyl‐imidazol‐4‐yl) alkanes ((CH₂)_n bridged imidazoles L(CH₂)_nL, n = 3–6) with chloro bridged complexes [R₃P(Cl)M(μ‐Cl)M(Cl)PR₃] (M = Pd, Pt; R = Et, Pr, Bu) affords the dinuclear compounds [Cl₂(R₃P)M–L(CH₂)_nL–M(PR₃)Cl₂] 1 – 17 . The structures of [Cl₂(Et₃P)Pd–L(CH₂)₃L–Pd(PEt₃)Cl₂] ( 1 ), [Cl₂(Bu₃P)Pd–L(CH₂)₄L–Pd(PBu₃)Cl₂] ( 10 ), [Cl₂(Et₃P)Pd–L(CH₂)₅L–Pd(PEt₃)Cl₂] ( 3 ), [Cl₂(Et₃P)Pt–L(CH₂)₃L–Pt(PEt₃)Cl₂] ( 13 ) with trans Cl–M–Cl groups were determined by X‐ray diffraction. Similarly the complexes [Cl₂(Cp*)Ir–L(CH₂)_nL–Ir(Cp*)Cl₂] (n = 4–6) are obtained from [Cp*(Cl)Ir(μ‐Cl)₂Ir(Cl)Cp*] and the methylene bridged bis(imidazoles).     

An ionic liquid as reaction medium for the synthesis of halo-containing β-enaminones at room temperature

A series of twenty halomethylated β-enaminones [RC(O)CH=C(R ¹)NR ³ R ⁴, where R = CF₃,CCl₃, CHCl₂; R ¹ = H, Me, Ph; R ³ = H, Me, Bu, Et; R ⁴ = Me, Et, Bu, allyl, tert-amyl, CH₂CH₂OH, Bn, Ph] were synthesized using the ionic liquid [bmim]BF₄ at room temperature. It is demonstrated that this ionic liquid is a reaction medium suitable for the amination of β-alkoxyvinyl halomethyl ketones. The advantages of this method are the absence of solvents, short reaction times, and good yields. Correspondence: Marcos A. P. Martins, Núcleo de Química de Heterociclos – NUQUIMHE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.     

Ionothermal Synthesis of a NaCl‐type Topological Network Based on Trinuclear Cobalt(II) Clusters as Nodes

A new metal‐organic network [Co₃(tbip)₃(H₂O)₄] · 2H₂O ( 1 ) (H₂tbip = 5‐tert‐butyl‐isophthalic acid) was synthesized through the ionothermal reaction of H₂tbip, cobalt nitrate, and [bmim]Br ionic liquid ([bmim]Br = 1‐butyl‐3‐methylimidazolium bromide). It exhibits a three‐dimensional (3D) framework with NaCl topology based on trinuclear cobalt(II) clusters as nodes. The magnetic studies show that there exist antiferromagnetic interactions between the Co^II ions.     

Bisisocyanide complexes of Zn(II) halides: Synthesis,structure, and application in the catalysis of isocyanides reaction with secondary amines

Isocyanide zinc complexes [ZnX₂(CNR)₂] (X = Cl, Br, I; R = Xyl, Cy, Bu^t) have been prepared via the interaction of the corresponding zinc halides ZnX₂ and isocyanide CNR in toluene at 100°C (yield 64–77%) and characterized by the data of elemental analysis, mass spectrometry, IR and NMR spectroscopy, and X-ray diffraction analysis. The zinc complexes [ZnBr₂(CNR)₂] (R = Xyl, Сy) have been used as catalysts for the synthesis of formamidines R¹N=CHNR₂ ² [R¹ = Xyl, Сy; R₂ ² = Et₂, (CH₂)₄, (CH₂CH₂)₂NMe, Me + CH₂Ph] from isocyanides CNR¹ and secondary amines HNR₂ ² in bulk (yield 92–98%).     

Pt(II) ASSISTED DEOXYGENATION OF COORDINATED SULFOXIDES BY HYDROCHLORIC- OR HYDROBROMIC ACID

Abstract

The interaction of the complexes (Et₄ N)[Pt(R₂ SO)X₃] (R = Me, Et, CH₂ Ph, X [dbnd] C1; R [dbnd] Me, X [dbnd] Br) and cis-[Pt(Me₂ SO)₂ Cl₂] with concentrated HX (X [dbnd] Cl. Br) results in the reduction of the coordinated sulfoxides and oxidation of Pt(II) to Pt(IV). As a result [Pt(R₂ S)X₅ and [Pt(R₂S)₂ X₄] are formed. Ligands R₂ S can be removed from the complexes and isolated in a free state.     

Transfer hydrogenation of ketones catalyzed by nickel complexes bearing an NHC [CNN] pincer ligand

Four NHC [CNN] pincer nickel (II) complexes, [^iPrCNN (CH₂)₄‐Ni‐Br] ( 5a ), [^nBuCNN (CH₂)₄‐Ni‐Br] ( 5b ), [^iPrCNN (Me)₂‐Ni‐Br] ( 6a ) and [^nBuCNN (Me)₂‐Ni‐Br] ( 6b ), bearing unsymmetrical [C (carbene)N (amino)N (amine)] ligands were synthesized by the reactions of [CNN] pincer ligand precursors 4 with Ni (DME)Cl₂ in the presence of Et₃N. Complexes 5a and 5b are new and were completely characterized. The transfer hydrogenation of ketones catalyzed by the four pincer nickel complexes were explored. Complexes 5a and 6a have better catalytic activity than 5b and 6b . With a combination of NaO^tBu/ⁱPrOH/80 °C and 2% catalyst loading of 5a , 77–98% yields of aromatic alcohols could be obtained.     

Microwave‐assisted ring‐opening polymerization of trimethylene carbonate in the presence of ionic liquid

Microwave‐assisted ring‐opening polymerization (MROP) of trimethylene carbonate in the presence of 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim]BF₄) ionic liquid was investigated. In the presence of 5 wt % [bmim]BF₄, poly (trimethylene carbonate) (PTMC) with a number‐average molar mass (M_n) of 36,400 g/mol was obtained at 5 W for only 60 min. The M_n of PTMC synthesized in the presence of [bmim]BF₄ was much higher than that produced in bulk at the same reaction time. In addition, compared with those produced by conventional heating, the M_n of PTMC and monomer conversion by MROP with or without [bmim]BF₄ were both higher. Thermal properties of the resulting PTMC were characterized by differential scanning calorimetry. Under microwave irradiation in the presence of ionic liquid, the polymerization could be carried out efficiently and effectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5857–5863, 2007     

ESR Studies on a Friedel‐Crafts Alkylation Reaction in [bmim]Cl‐AlCl3 Ionic Liquid

The paramagnetic complexes formed in Friedel‐Crafts alkylation reaction systems are invistigated by electron spin resonance (ESR) spectroscopy, in room temperature ionic liquids system 1‐butyl‐3‐methyl‐limidazolium chloride‐aluminium chloride ([bmim]Cl‐AlCl₃). The results indicate that ESR spectra observed are due to polycyclic aromatic radical cations formed from their parent hydrocarbons. ESR spectrum of spin adduct is obtained in an ionic liquid system composed of [bmim]Cl‐AlCl₃. In acidic solution the ¹⁴N hyperfine coupling constant of 4‐oxo‐TEMPO, 2.15 mT, is appreciably larger due to an adduct formed with AlCl₃.     

Catalytic polymerization of phenylacetylene with dimeric [Rh(OMe)(cod)]2 complex in ionic liquids

Dimeric rhodium(I) complex [Rh(OMe)(cod)]₂ was found to be an active catalyst of phenylacetylene polymerization to poly(phenylacetylene) (PPA) in ionic liquids containing imidazolium or pyridinium cations. The highest yield of PPA (92%) was obtained in 1‐butyl‐4‐methylpyridinium tetrafluoroborate as reaction medium. The yield of PPA in imidazolium ionic liquids containing BF₄^? or PF₆^? anions increased to 83–99% when Et₃N or cycloocta‐1,5‐diene were added as co‐catalysts. In 1‐methyl‐3‐octylimidazolium chloride (MOI · Cl) polymerization rate was much lower than in other ionic liquids, although the highest M_w (72 400) was obtained. Spectroscopic studies confirmed that [Rh(OMe)(cod)]₂ reacted with MOI · Cl forming new carbene Rh(I) complex, which can participate in the polymerization process. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesen und NMR‐Untersuchungen von Salzen mit den neuen Anionen [PtXn(CF3)6‐n]2— (n = 0 ‐ 5, X = F,OH, Cl,CN) und die Kristallstrukturanalyse von K2[(CF3)2F2Pt(μ‐OH)2PtF2(CF3)2]·2H2O

Syntheses and NMR Spectroscopic Ivestigations of Salts containing the Novel Anions [PtX_n(CF₃)_6‐n]^2— (n = 0 ‐ 5, X = F, OH, Cl, CN) and Crystal Structure of K₂[(CF₃)₂F₂Pt(μ‐OH)₂PtF₂(CF₃)₂]·2H₂O The first syntheses of trifluoromethyl‐complexes of platinum through fluorination of cyanoplatinates are reported. The fluorination of tetracyanoplatinates(II), K₂[Pt(CN)₄], and hexacyanoplatinates(IV), K₂[Pt(CN)₆], with ClF in anhydrous HF leads after working up of the products to K₂[(CF₃)₂F₂Pt(μ‐OH)₂PtF₂(CF₃)₂]·2H₂O. The structure of the salt is determined by a X‐ray structure analysis, P2₁/c (Nr. 14), a = 11.391(2), b = 11.565(2), c = 13.391(3)Å, β = 90.32(3)°, Z = 4, R₁ = 0.0326 (I > 2σ(I)). The reaction of [Bu₄N]₂[Pt(CN)₄] with ClF in CH₂Cl₂ generates mainly cis‐[Bu₄N]₂[PtCl₂(CF₃)₄] and fac‐[Bu₄N]₂[PtCl₃(CF₃)₃], but in contrast that of [Bu₄N]₂[Pt(CN)₆] with ClF in CH₂Cl₂ results cis‐[Bu₄N]₂[PtX₂(CF₃)₄], [Bu₄N]₂[PtX(CF₃)₅] (X = F, Cl) and [Bu₄N]₂[Pt(CF₃)₆]. In the products [Bu₄N]₂[PtX_n(CF₃)_6‐n] (X = F, Cl, n = 0—3) it is possibel to exchange the fluoro‐ligands into chloro‐ and cyano‐ligands by treatment with (CH₃)₃SiCl und (CH₃)₃SiCN at 50 °C. With continuing warming the trifluoromethyl‐ligands are exchanged by chloro‐ and cyano‐ligands, while as intermediates CF₂Cl and CF₂CN ligands are formed. The identity of the new trifluoromethyl‐platinates is proved by ¹⁹⁵Pt‐ and ¹⁹F‐NMR‐spectroscopy.     

离子液体型表面活性剂研究

以1-甲基咪唑为原料, 制备了6个常规离子液体: 1-正丁基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[bmim][BF₄]及[bmim][PF₆])、1-正己基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[hmim][BF₄]及[hmim][PF₆])、1-正十六烷基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[C₁₆mim][BF₄]及[C₁₆mim][PF₆])和4个功能化离子液体: 1-(2-羟乙基)-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[2-hemim][BF₄]及[2-hemim][PF₆])、1-乙氧羰基甲基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[eocmmim][BF₄]及[eocmmim][PF₆]). 研究了这两类离子液体的一些物理性能, 旨在挖掘离子液体在香料香精化妆品工业中的应用价值. 分别检测了它们与一般溶剂的互溶性, 并测定了它们的表面张力和发泡性能, 实验结果表明, 仅[C₁₆mim][BF₄]和[C₁₆mim][PF₆]具有发泡性能, 发泡力分别为68和120 mm.     

Microwave‐Assisted Functionalization of Carbon Nanostructures in Ionic Liquids

The effect of microwave (MW) irradiation and ionic liquids (IL) on the cycloaddition of azomethine ylides to [60]fullerene has been investigated by screening the reaction protocol with regard to the IL medium composition, the applied MW power, and the simultaneous cooling of the system. [60]Fullerene conversion up to 98 % is achieved in 2–10 min, by using a 1:3 mixture of the IL 1‐methyl‐3‐n‐octyl imidazolium tetrafluoroborate ([omim]BF₄) and o‐dichlorobenzene, and an applied power as low as 12 W. The mono‐ versus poly‐addition selectivity to [60]fullerene can be tuned as a function of fullerene concentration. The reaction scope includes aliphatic, aromatic, and fluorous‐tagged (FT) derivatives. MW irradiation of IL‐structured bucky gels is instrumental for the functionalization of single‐walled carbon nanotubes (SWNTs), yielding group coverages of up to one functional group per 60 carbon atoms of the SWNT network. An improved performance is obtained in low viscosity bucky gels, in the order [bmim]BF₄> [omim]BF₄> [hvim]TF₂N (bmim=1‐methyl‐3‐n‐butyl imidazolium; hvim=1‐vinyl‐3‐n‐hexadecyl imidazolium). With this protocol, the introduction of fluorous‐tagged pyrrolidine moieties onto the SWNT surface (1/108 functional coverage) yields novel FT‐CNS (carbon nanostructures) with high affinity for fluorinated phases.     

Effect of Different Ionic Liquids on 5-Hydroxymethylfurfural Preparation from Glucose in DMA over AlCl3: Experimental and Theoretical Study

In this work, effect of different ionic liquids (ILs) on 5‐hydroxymethylfurfural (HMF) preparation from glucose in N,N‐dimethylacetamide (DMA) over AlCl₃ was revealed by a combined experimental and computational study. ILs used as cocatalysts in this work included N‐methyl‐2‐pyrrolidone hydrogen sulfate ([NMP]HSO₄), N‐methyl‐2‐pyrrolidone methyl sulfate ([NMP]CH₃SO₃), N‐methyl‐2‐pyrrolidone chlorine ([NMP]Cl) and N‐methyl‐2‐pyrrolidone bromide ([NMP]Br) which were endowed with the same cation but different anions. According to the conclusion that fructose was intermediate product from glucose to HMF, we found fructose was transformed to more by‐products by [NMP]HSO₄, making HMF yield decline significantly when glucose was treated as substrate. Neither glucose nor fructose could be converted by [NMP]CH₃SO₃ efficiently, leading to its no influence on glucose conversion to HMF. [NMP]Br had a higher selectivity for HMF from fructose than [NMP]Cl and AlCl₃. Besides, Al³⁺ preferred to combine with Br^?, slightly decreasing both the overall free energy barrier for glucose isomerization and activation barrier for H‐shift at 393.15 K. So a high HMF yield of 57% was obtained from glucose catalyzed by AlCl₃ together with [NMP]Br under mild conditions.     

Zur Reaktion von Trifluorhalomethanen mit Phosphanen

On the Reaction of Trifluorohalomethanes with Phosphanes The reactions of trifluorohalomethanes CF₃X (X = Cl, Br, I) with Ph₃P, Bu₃P, (Me₂N)₃P, and (Et₂N)₃P were investigated. CClF₃ does not react. In the reactions of CBrF₃ and CF₃I with Bu₃P in acetonitrile trifluorophosphonium salts, [Bu₃PCF₃]X (X = Br, I), are formed, whereas gaseous CF₃I and Bu₃P yield Bu₂PCF₃. Depending on the reaction conditions the aminophosphanes form either [(R₂N)₃PX]X (R = Me, Et; X = Br, I) and CF₃H or [(R₂N)₃PCF₃]X.     

Room Temperature Ionic Liquids (RTILs) and Multiwalled Carbon Nanotubes (MWCNTs) as Modifiers for Improvement of Carbon Paste Ion Selective Electrode Response; A Comparison Study with PVC Membrane

Room temperature ionic liquids (RTILs), 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate, [bmim]BF₄, and multiwalled carbon nanotubes (MWCNTs) were used for improvement of a praseodymium carbon paste ion selective sensor response. [bmim]BF₄ can be a better binder than mineral oils. MWCNTs have a good conductivity which helps the transduction of the signal in carbon paste electrode. The characteristics of these electrodes as potentiometric sensors were evaluated and compared with PVC membrane sensor. The results indicate that potentiometric sensor constructed with ionic liquid shows an increase in performance in terms of Nernstian slope, selectivity, response time, and response stability compared to Pr(III) PVC membrane sensor.