Catalytic transformations of 1-octanol and 2-ethyl-1-hexanol over oxide catalysts, part II. Promoted zinc oxide as a catalyst

Silica supported ZnO was modified with alkaline promoters to reduce its dehydrating activity towards 1-octanol and 2-ethyl-1-hexanol. Neutralization of zinca acidic centers led to the significant decrease of the yields of alkenes formed during dehydration. Simultaneously, the enhancement of ZnO dehydrogenating activity was observed. The effect of modifier diminished in the sequence: K₂CO₃>KOH>Na₂CO₃.     

Determination of alternative and conventional chelating agents as copper(II) complexes by capillary zone electrophoresis--the first use of didecyldimethylammonium bromide as a flow reversal reagent

A capillary zone electrophoresis (CZE) method for analyzing 11 chelating agents [β-alaninediacetic acid (β-ADA), trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediamine-N,N′,N′-triacetic acid (HEDTA), N-(2-hydroxyethyl)iminodiacetic acid (HEIDA), iminodiacetic acid (IDA), methylglycinediacetic acid (MGDA), nitrilotriacetic acid (NTA), 1,3-diaminopropane-N,N,N′,N′-tetraacetic acid (PDTA) and triethylenetetraaminehexaacetic acid (TTHA)] as negatively charged copper(II) complexes has been established. Both conventional and alternative chelating agents were included in this study, because they are used side by side in industrial applications. In this study, didecyldimethylammonium bromide (DMDDAB) was successfully used as a flow reversal reagent for the first time in an aqueous CZE method based on phosphate BGE with UV spectrophotometric detection. In addition this new flow modifier was compared to common TTAB. Method development was done using a fused silica capillary (61 cm × 50 μm i.d.). The optimized BGE was a 105 mmol L⁻¹ phosphate buffer with TTAB or DMDDAB in the concentration 0.5 mmol L⁻¹ at pH 7.1. The measurements were done with −20 kV voltage using direct UV detection at 254 nm. In both CZE methods all 11 analyte zones were properly separated (resolutions ≥2.4), and the calibrations gave excellent correlation coefficients (≥0.998; linear range tested 0.5-2.0 mmol L⁻¹). The limits of detection were ≤34 and ≤49 μmol L⁻¹ with the method of DMDDAB and TTAB, respectively. A clear benefit of both methods was the short analysis time; all 11 complexes were detected in less than 6 and 5.5 min with the methods of TTAB and DMDDAB, respectively. The two methods were tested with dishwashing detergents and paper mill wastewater samples and proved to be suitable for practical use.     

Bromodimethylsulfonium bromide (BDMS) in ionic liquid: a mild and efficient catalyst for Beckmann rearrangement

Bromodimethylsulfonium bromide (BDMS)-catalyzed Beckmann rearrangement of a variety of ketoximes has been carried out in the imidazolium-based ionic liquid [bmim]PF₆ under mild conditions without using any additional cocatalyst or solvent to afford excellent conversion and selectivity. The ionic liquid is recovered and reused for up to three runs without any loss of efficiency.     

Convenient preparation of highly active phase-transfer catalyst for catalytic asymmetric synthesis of α-alkyl- and α,α-dialkyl-α-amino acids: application to the short asymmetric synthesis of BIRT-377

A highly active phase-transfer catalyst was conveniently prepared from the known, easily available (S)-4,5,6,4′,5′,6′-hexamethoxybiphenyldicarboxylic acid. This catalyst exhibited the high catalytic performance (0.01-1 mol %) in the asymmetric alkylation of N-(diphenylmethylene)glycine tert-butyl ester and N-(p-chlorophenylmethylene)alanine tert-butyl ester compared to the existing chiral phase-transfer catalysts, thereby allowing to realize a general and useful procedure for highly practical enantioselective synthesis of structurally diverse natural and unnatural α-alkyl-α-amino acids as well as α,α-dialkyl-α-amino acids.     

Water soluble gold-polyaniline nanocomposite: A substrate for surface enhanced Raman scattering and catalyst for dye degradation

In this work, a water-soluble gold nanoparticle-encapsulated polyaniline nanocomposite (AuNP-PANI) was prepared in the presence of an ionic surfactant such as cetyltrimethylammonium bromide (CTAB) using versatile two steps method. The prepared nanoparticles (AuNPs) were characterized by UV–Visible spectroscopy, Transmission Electron Microscope (TEM) and Dynamic Light Scattering (DLS). The nanocomposite (AuNP-PANI) were initially characterized using UV–Visible spectroscopy, Transmission Electron Microscope (TEM), Scanning Transmission Electron Microscope (STEM) and DLS. The structure and composition of AuNP-PANI further characterized using Fourier Transmission Infrared Spectroscopy (FTIR), X-ray diffraction study (XRD), Energy Dispersive X-ray Spectroscopy (EDS) and Thermogravimetric analysis (TGA). Electrochemical properties of AuNP-PANI were studied using Cyclic Voltammetry (CV). The prepared nanocomposite exhibited good surface enhanced Raman scattering (SERS) of 4-amino thiophenol (4-ATP) and 4- (dimethyl amino) pyridine (4-DMAP) for which the enhancement factor (EF) were found to be1.95 × 10⁵ and 2.016 × 10⁵, respectively. The nanocomposite also showed excellent catalytic activity for the chemical degradation of Congo red (CR) and methylene blue (MB) as evidenced from the calculated rate constants which were determined to be 0.30 s⁻¹ and 0.33 s⁻¹, respectively.     

Bismuth(III) bromide in organic synthesis. A catalytic method for the allylation of tetrahydrofuranyl and tetrahydropyranyl ethers

A bismuth bromide-catalyzed (10.0 mol %) multicomponent reaction involving the allylation of THF- and THP-ethers, followed by in situ derivatization with acetic anhydride to generate highly functionalized esters has been developed under solvent-free conditions. To the best of our knowledge, this is the first report of a catalytic procedure for the allylation of THF- and THP-ethers to yield ring-opened products.     

Immobilization of the Grubbs second-generation ruthenium-carbene complex on poly(ethylene glycol): a highly reactive and recyclable catalyst for ring-closing and cross-metathesis

A poly(ethylene glycol)-bound Hoveyda-Grubbs Ru catalyst derived from the Grubbs second-generation Ru carbene complex was synthesized and shown to be highly reactive in the ring-closing metathesis of a wide variety of diene substrates, yielding di-, tri-, and tetra-substituted carbocyclic and heterocyclic olefins. The immobilized catalyst also proved to be highly reactive and recyclable in cross-metathesis and ring-opening/cross-metathesis. In all cases tested, the catalyst exhibited a high level of recyclability and reusability.     

Pd(OH)2/C (Pearlman's catalyst): a highly active catalyst for Fukuyama,Sonogashira, and Suzuki coupling reactions

Treatment of thiol esters 1 with zinc reagent 2 in the presence of a small amount (相似文献   

Bromodimethylsulfonium bromide (BDMS): a useful reagent for conversion of aldoximes and primary amides to nitriles

An operationally simple and high yielding procedure has been developed for the preparation of nitriles from aldoximes and primary amides using bromodimethylsulfonium bromide (BDMS) as a novel and efficient reagent in the absence of any added base or catalyst. The optimal protocol is applicable to access a wide range of cyano compounds including aromatic, heterocyclic, and aliphatic species. The conversion of aldoximes to nitriles takes place at room temperature in acetonitrile, whereas acetonitrile at reflux temperature is required for rapid conversion in the case of primary amides.     

Chromium(III) octaethylporphyrinato tetracarbonylcobaltate: a highly active, selective, and versatile catalyst for epoxide carbonylation

The development of a highly active and selective porphyrin-based epoxide carbonylation catalyst, [(OEP)Cr(THF)2][Co(CO)4] (1; OEP = octaethylporphyrinato; THF = tetrahydrofuran), is detailed. Complex 1 is a separated ion pair composed of a tetracarbonylcobaltate anion and an octahedral chromium porphyrin complex axially ligated by two THF ligands. Regarding the carbonylation of epoxides to beta-lactones, catalyst 1 exhibits excellent turnover numbers (up to 10,000) and turnover frequencies (up to 1670 h(-1)), with regioselective carbonyl insertion occurring between the oxygen and the sterically less hindered carbon of the epoxide substrate. Complex 1 is highly tolerant of nonprotic functional groups, carbonylating an array of aliphatic and cycloaliphatic epoxides, as well as epoxides with pendant ethers, esters, and amides. With careful control of reaction conditions in the carbonylation of glycidyl esters, the exclusive production of either the beta- or gamma-lactone isomer was achieved. Through analysis of reaction stereochemistry, a mechanism for the formation of gamma-lactone products was proposed. Overall, a broad array of synthetically useful lactones has been synthesized in a rapid and selective fashion by catalytic carbonylation using [(OEP)Cr(THF)2][Co(CO)4].     

Polystyrene-bound electron-deficient tin(IV) porphyrin: A new, highly efficient, robust and reusable catalyst for acetylation of alcohols and phenols with acetic anhydride

In the present work, tetrakis(p-aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [Sn^IV(TNH₂PP)(OTf)₂], supported on chloromethylated polystyrene was prepared and characterized by elemental analysis, FT IR and diffuse reflectance UV-Vis spectroscopic methods. This new heterogenized catalyst was used for acetylation of alcohols and phenols with acetic anhydride in short reaction times and high yields. The catalyst is of high reusability and stability in the acetylation reactions and was recovered several times without loss of its initial activity and catalyst leaching.     

Bifunctional cobalt Salen complex: a highly selective catalyst for the coupling of CO2 and epoxides under mild conditions

A bifunctional cobalt Salen complex containing a Lewis acid metal center and two covalent bonded Lewis bases on the ligand was designed and used for the coupling of CO₂ and epoxides under mild conditions. The complex exhibited excellent activity (turnover frequency = 673/h) and selectivity (no less than 97%) for polymer formation in the copolymerization of propylene oxide (PO) and CO₂ at an appropriate combination of all variables. High molecular weight of 110 200 and yield 99% were achieved at a higher [PO]/[complex] ratio of 6000:1. The complex also worked satisfactorily for the terpolymerization of CO₂, PO and cyclohexene oxide (CHO), without formation of cyclic carbonate or ether linkages to give the polycarbonate. High cyclohexene carbonate unit content in the CO₂/PO/CHO terpolymers resulted in enhanced thermal stability. Copyright © 2011 John Wiley & Sons, Ltd.     

Polymer-supported ytterbium perfluorooctanesulfonate [Yb(OPf)3]: A recyclable catalyst for organic reactions

Amberlyst A-21, a kind of well-known and cheap polymeric material, was treated with ytterbium perfluorooctanesulfonate [Yb(OPf)₃] giving a reagent with a ytterbium loading of 1.34 (wt%). The polymer-supported fluorous ytterbium catalyses the highly efficient nitration, esterification, Fridel-Crafts acylation, and aldol condensation. The catalyst can be recovered by simple filtration and used again without a significant loss of catalytic activity. The protocol avoids the use of fluorous solvents during the reaction or workup, which are expensive and can leach in small amounts.     

Synthesis, characterization, physical properties, and applications of highly fluorescent pyrene-functionalized 9,9-bis(4-diarylaminophenyl)fluorene in organic light-emitting diodes

A new, highly fluorescent pyrene-functionalized 9,9-bis(4-diarylaminophenyl)fluorene, namely PTF, was synthesized and characterized. This material is an amorphous molecular glass with notably high T_g, is electrochemically stable, and exhibits strong blue emission both in solution and solid state. It shows promising ability as a solution processed blue emitter and hole-transporter for OLEDs. High-efficiency sky-blue and Alq3-based green devices with luminance efficiencies of 1.13 and 4.08 cd/A are achieved, respectively.     

Polyurea-encapsulated palladium(II) acetate: a robust and recyclable catalyst for use in conventional and supercritical media

Palladium(II) acetate microencapsulated in polyurea (MC-[Pd]) is an economical and versatile heterogeneous catalyst for a range of phosphine-free cross-coupling reactions in both conventional solvents and supercritical carbon dioxide (scCO2); the catalyst can be recovered by a simple filtration and recycled up to four times.     

Dichlororuthenium(IV) complex of meso-tetrakis(2,6-dichlorophenyl)porphyrin: active and robust catalyst for highly selective oxidation of arenes, unsaturated steroids, and electron-deficient alkenes by using 2,6-dichloropyridine N-oxide

[Ru(IV)(2,6-Cl2tpp)Cl2], prepared in 90 % yield from the reaction of [Ru(VI)(2,6-Cl2tpp)O2] with Me3SiCl and structurally characterized by X-ray crystallography, is markedly superior to [Ru(IV)(tmp)Cl2], [Ru(IV)(ttp)Cl2], and [Ru(II)(por)(CO)] (por=2,6-Cl2tpp, F20-tpp, F28-tpp) as a catalyst for alkene epoxidation with 2,6-Cl2pyNO (2,6-Cl2tpp=meso-tetrakis(2,6-dichlorophenyl)porphyrinato dianion; tmp=meso-tetramesitylporphyrinato dianion; ttp=meso-tetrakis(p-tolyl)porphyrinato dianion; F20-tpp=meso-tetrakis(pentafluorophenyl)porphyrinato dianion; F28-tpp=2,3,7,8,12,13,17,18-octafluoro-5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato dianion). The "[Ru(IV)(2,6-Cl2tpp)Cl2]+2,6-Cl2pyNO" protocol oxidized, under acid-free conditions, a wide variety of hydrocarbons including 1) cycloalkenes, conjugated enynes, electron-deficient alkenes (to afford epoxides), 2) arenes (to afford quinones), and 3) Delta5-unsaturated steroids, Delta4-3-ketosteroids, and estratetraene derivatives (to afford epoxide/ketone derivatives of steroids) in up to 99 % product yield within several hours with up to 100 % substrate conversion and excellent regio- or diastereoselectivity. Catalyst [Ru(IV)(2,6-Cl2tpp)Cl2] is remarkably active and robust toward the above oxidation reactions, and turnover numbers of up to 6.4x10(3), 2.0x10(4), and 1.6x10(4) were obtained for the oxidation of alpha,beta-unsaturated ketones, arenes, and Delta5-unsaturated steroids, respectively.     

Quantitative analysis of a quaternary ammonium drug: ipratropium bromide by LC/ESI-MS(n) in horse plasma and urine

A quantitative method, using LC/ESI-MS(n) with a quadrupole linear ion trap mass analyzer, has been developed for the analysis of ipratropium cation in horse plasma and urine. The method applies solid-phase extraction with WCX cartridges for plasma and MM2 cartridges for urine, prior to analysis by LC/ESI-MS(n). The efficiency of extraction combined with the sensitivity and the selectivity of MS(n) allows for the quantification of ipratropium cation at picogram per milliliter levels. The analytical capabilities of the method have been successfully checked by the quantitative analysis of ipratropium cation in post-administration samples collected from horses treated by nebulization.     

Double metal cyanide complex based on Zn3[Co(CN)6]2 as highly active catalyst for copolymerization of carbon dioxide and cyclohexene oxide

Double metal cyanide complexes based on Zn₃[Co(CN)₆]₂ were prepared in the presence of different complexing agents and used in the copolymerization of carbon dioxide and cyclohexene oxide. The FTIR and ¹H NMR spectra of the products verified the formation of polycarbonate. Compared with zinc carboxylate, zinc phenoxide, and so forth, these catalysts demonstrated great enhancement of catalytic activity. Their highest turnover number and turnover frequency reached 3300 and 1650 h^?1, respectively, at 90 °C. The molar fraction of CO₂ (F_CO2) for the copolymers was about 0.44–0.47, and it varied slightly with different catalysts under a temperature of 90 °C and a pressure of 3.8 MPa. The study showed that the F_CO2 can reach 0.40 even at 0.6 MPa, and it changed slightly above 3.8 MPa. The reaction rate had little influence on the F_CO2 under our experimental conditions. A relatively low temperature was favorable for the incorporation of CO₂. The monitoring of copolymerization revealed the molecular weight was proportional to the reaction conversion. The molecular weight distribution was in the range of 4.5–6, and the reaction rate was proportional to the amount of catalyst that was used. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5284–5291, 2004