Solvent‐free Synthesis of Novel and Known Octahydroquinazolinones/thiones by the Use of ZrOCl2.8H2O as a Highly Efficient and Reusable Catalyst

A solvent‐free reaction between urea/thiourea, dimedone and aromatic aldehydes in the presence of catalytic amounts of zirconium (IV) oxychloride octahydrate (ZrOCl₂.8H₂O) as a powerfull Lewis acid leads to octahydroquinazolinone/thione derivatives in good yields. This method has advantages such as avoidance of the organic solvents, production of pure products without any by‐product, short reaction times and simple operation.     

Effect of Fluoride or Chloride Ions on the Morphology of ZrO2 Thin Film Grown in Ethylene Glycol Electrolyte by Anodization

0.3 wt % ammonium fluoride (NH₄F) or ammonium chloride (NH₄Cl) was added to ethylene glycol (EG) as an active ingredient for the formation of anodic oxide comprising of ZrO₂ nanotubes (ZNTs) by anodic oxidation of zirconium (Zr) at 20 V for 10 min. It was observed that nanotubes were successfully grown in EG/NH₄F/H₂O with aspect ratio of 144.3. Shorter tubes were formed in EG/NH₄F/H₂O₂. This could be due to higher excessive chemical etching at the tip of the tubes. When fluoride was replaced by chloride in both electrolytes, multilayered oxide resembling pyramids was observed. The pyramids have width at the bottom of 3-4 μm and the top is 1-2 μm with 10.7 μm height. Oxidation of Zr in EG/NH₄Cl/H₂O₂ was rater rapid. The multilayered structure is thought to have formed due to the re-deposition of ZrO₂ or hydrated ZrO₂ on the foil inside pores formed within the oxide layer. XRD result revealed an amorphous structure for as-anodized samples regardless of the electrolytes used for this work.     

Preparation of Crack-free 3Y-TZP/Al2O3 Composite Ceramic Fiber by Electrolysis-sol-gel Method

Polycrystalline 3Y-TZP/Al2O3 tetragonal zirconia fiber was obtained by the pyrolysis of gel fibers using zirconium oxychloride octahydrate(ZOC)as the raw material.The spinnable zirconia sol was prepared by electrolyzing the zirconium oxychloride octahydrate(ZOC)solution in the presence of acetic acid and sugar(sucrose,glucrose or fructose),in which the molar ratios of CH3COOH/ZOC and sugar/ZOC were 1.0-4.0 and 0.2-0.4,respectively.The prepared tetragonal zirconia fibers sintered at different temperatures showed smooth and crack-free surfaces with diameters of 5-10 μm.The addition of Al2O3 enhanced the sintering process and prevented the crystals from growing.Thermogravimetric analysis(TG),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron microscope(SEM)techniques were used to characterize the prepared fibers.     

Highly active copolymerization of ethylene with 10‐undecen‐1‐ol using phenoxy‐based zirconium/methylaluminoxane catalysts

Activated with methylaluminoxane (MAO), phenoxy‐based zirconium complexes bis[(3‐^tBu‐C₆H₃‐2‐O)‐CH?NC₆H₅]ZrCl₂, bis[(3,5‐di‐^tBu‐C₆H₂‐2‐O)‐PhC?NC₆H₅] ZrCl₂, and bis[(3,5‐di‐^tBu‐C₆H₂‐2‐O)‐PhC?N(2‐F‐C₆H₄)]ZrCl₂ for the first time have been used for the copolymerization of ethylene with 10‐undecen‐1‐ol. In comparison with the conventional metallocene, the phenoxy‐based zirconium complexes exhibit much higher catalytic activities [>10⁷ g of polymer (mol of catalyst)^?1 h^?1]. The incorporation of 10‐undecen‐1‐ol into the copolymers and the properties of the copolymers are strongly affected by the catalyst structure. Among the three catalysts, complex c is the most favorable for preparing higher molecular weight functionalized polyethylene containing a higher content of hydroxyl groups. Studies on the polymerization conditions indicate that the incorporated commoner content in the copolymers mainly depends on the comonomer concentration in the feed. The catalytic activity is slightly affected by the Al_(MAO)/Zr molar ratio but decreases greatly with an increase in the polymerization temperature. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5944–5952, 2005     

Sol-Gel Preparation of Highly Active Sulfated Zirconia Supported by Alumina Catalysts

A series of sulfated mixed oxides of alumina and zirconia having a relative composition of 5% and 10% of ZrO₂ was prepared by means of sol-gel methods using zirconium propoxide or zirconium acetylacetone as precursor. The characterization of the physicochemical properties was carried out using ²⁷Al NMR, XRD, N₂ adsorption at 77 K, thermogravimetry, FTIR analysis of adsorbed pyridine, ²⁷Al NMR-MAS and XPS. The catalytic properties were studied by means of isomerization of n-hexane at 250°C. Results obtained allowed to propose that the use of Zr(acac)₄ as a zirconium precursor leads to a better retention of sulfate species which seems to form polymeric superficial sites. The symmetry of aluminium undergo an increase from tetrahedral to octahedral coordination and Zirconium atoms seems to be located in the second coordination sphere of Al. XRD analysis indicated an amorphous structure of obtained solids calcined at 650°C. The sulfated solids presented both Lewis and Brönsted acidic sites. Catalytic results showed that both activity and selectivity towards isomerization products were better using Zr (acac)₄ as precursor. Furthermore, the increase of the Zr loading affected considerably the catalytic properties of sulfated zirconia supported by alumina.     

Reactivity of titanium isopropoxide,zirconium propoxide and niobium ethoxide in the system of 2-methoxyethanol, 2,4-pentanedione and water

Titanium isopropoxide, zirconium propoxide and niobium ethoxide have been studied in reaction with 2-methoxyethanol (moe), acetylacetone (acac) and water. Structural information has been obtained using FTIR and ¹H, ¹³C FT NMR spectroscopies. The number of interchanged alkoxy groups increased with increasing excess of 2-methoxyethanol and reaction temperature. The exchange reaction between Nb(OEt)₅ and 2-methoxyethanol was the least effective. Reaction with acetylacetone proved to be very efficient, but dilution with an excess of solvent quenched this reaction. A solid phase of Zr(acac)₄ was formed for more than 2 modes of acac added. The appearance of multiplets in NMR spectra due to CH, CO centers of acac ring in Zr monoacetylacetonate indicated non-symmetric bonding of the bidentate acac group and more than one magnetically non-equivalent species. Conversely, a modified Nb(OEt)₄ (acac) precursor proved to be monomeric with a symmetrically bound acac group. During the interchange reaction the symmetry of the Nb(OEt) _x (Omoe)_4−x (acac) species was reduced. Alkoxy groups were first hydrolyzed followed by very slow removal of the acac ring. Zirconium and niobium modified precursors, respectively, were the least and the most susceptible to gelation. Addition of strong acid further increased the stability of acetylacetonates against condensation.     

Gold Surface Functionalization with S‐containing Organic Compounds and Gold Nanoparticles for Ethylene Glycol Electrooxidation

In this work a gold electrode modified with self‐assembled layers (SAMs) composed with organic S‐containing compound and gold nanoparticles was prepared. The electrode with SAMs endowed with gold nanoparticles gave the high catalytic effect for ethylene glycol (EG) electrooxidation in solution at pH 7. For this novel sensor a linear relationship between the current response of EG at the potential of peak maximum (j_p) and the concentration of this compound in solution (c_EG) was found over the range 0.1 µM to 0.7 M with the detection sensitivity j_p/c_EG equal to about 5 A cm^?2 mol^?1 dm³ (at v=0.1 V s^?1) and the detection limit of 0.046 µM.     

Synthesis and mechanism research of an ethylene glycol-based sol-gel method for preparing PZT nanopowders

Lead zirconate titanate nanopowders Pb(Zr_0.52Ti_0.48)O₃ (PZT) were prepared by modified sol-gel process in ethylene glycol system with zirconium nitrate as the zirconium source. The research showed that it was critical to add lead acetate after the reaction of zirconium nitrate and tetrabutyl titanate in ethylene glycol system for preparing PZT of exact titanium content. The reaction mechanisms of the sol synthesis, preparation of xerogel and agglutinating process were characterized through using FT-IR, NMR, TG-FTIR, and GC-MS. The experiment proved that ethylene glycol system did not rely on hydrolysis and condensation reactions in the process of the sol formation, but on the formation of chain or network large molecules from complexation of ethylene glycol and all Ti and minor Pd, Zr. In the preparation of xerogel, the complexation reaction was so completed that it formed large molecules network composed of metal and dioxyethyl. Bulk weight loss happened before 350°C in the process of sintering xerogel to prepare PZT nanopowders. Volatile matters and vapor phase decomposition resultants were primarily oxy-compounds including ethylene glycol, aldehyde-ketone compounds, carbon dioxide and nitrate radical conversion matters. After 350°C, primary vapor phase decomposition resultants were carbon dioxide and minor carbonyl compound.     

Heteroleptic Complexes of Zirconium Acetylacetonates: Better Precursors for the Preparation of Zirconia. Structural Characterization of [(acac)2Zr{ONC(Me)py‐2}2]

The reactions of the heteroleptic zirconium diisopropoxide bis(acetylacetonate) in benzene solution with two equivalents of oximes, alkoxyalkanols, triphenylsilanol and trimethylsilyl acetate yield products with the formula [{MeC(O)CHC(O)Me}₂ZrL₂] with L = —ONC(Me)C₅H₄N‐2, —ONC(Me)C₄H₃O‐2, —OCH₂CH₂OR (R = Me, Et, Buⁿ; py = pyridine, fu = furan), —OSiPh₃ and —OSiMe₃. Most of these derivatives are solids, but the [(acac)₂Zr(OSiMe₃)₂] is a viscous oil. They could be purified either by recrystallization or by vacuum distillation; all of these are monomeric in boiling benzene. Their elemental analyses, molecular weight measurements and IR as well as NMR spectra were measured. The oximato complex [(acac)₂Zr{ONC(Me)py‐2}₂] has been shown by single crystal X‐ray crystallography to be monoclinic and mononuclear in the solid state, where zirconium has the coordination number 8; all the ligands are situated in cis‐ position and the oximato ligand binds via N and O in a dihapto (η²‐N, O) manner.     

Studies on the syntheses of polymetalloxanes and their properties as a precursor for amorphous oxide. VII. Preparation and properties of polyzirconoxanes as a precursor for zirconia fibers by the hydrolysis of bis (ethyl acetoacetato) zirconium dialkoxide

Acid-catalyzed hydolysis of bis(ethyl acetoacetato) zirconium dialkoxide in methanol or THF was investigated. The hydrolysis of the chelates in the molar ratios of H₂O/ chelate = 1.0–2.0 and HCl/chelate = 0.1–0.2 provided concentrated solutions (ca. 83 wt %) of polyzirconoxanes (PZO) which showed excellent spinnability and stability to self-condensation. Continuous gel fibers were prepared by dry spinning the solutions. Polyzirconoxanes were isolated as powders when the concentrated solution was precipitated with hexane. Silylation allowed the investigation of the structure of PZO. It was confirmed to be the polymers of a low degree of polymerization with the ligand and hydroxy group as pendants. © 1992 John Wiley & Sons, Inc.     

The molecular composition of non-modified and acac-modified propoxide and butoxide precursors of zirconium and hafnium dioxides

Long-term storage at 0 °C of a paraffin-sealed flask with commercial 70 wt% solution of zirconium n-propoxide in n-propanol resulted in crystallization of an individual oxoalkoxide complex Zr₄O(OⁿPr)₁₄(ⁿPrOH)₂ in over 20% yield. The structure of this molecule can be described as a triangular Zr₃(μ₃-O)(OR)₁₀(ROH) core of 3 edge-sharing octahedrons with an additional Zr(OR)₄(ROH) unit attached through a pair of (μ-OR) bridges. Mass spectrometric and ¹H NMR investigation of the commercial samples of the most broadly applied zirconium and hafnium n-propoxides and n-butoxides indicate the presence of analogous species in the commercial alkoxide precursors. The content of oxo-alkoxide species in the commercial precursors has been estimated to be ~20% for n-propoxide and ~35% for zirconium n-butoxide. A new route has been presented for synthesis of the individual crystalline mixed ligand precursor [Zr(OⁿPr)(OⁱPr)₃(ⁱPrOH)]₂, from zirconium n-propoxide. A high yield has been observed (~90%), indicative of an almost complete precursor transformation. Mass spectrometry has shown that the synthesized mixed ligand precursor is dimeric, which makes it an attractive alternative to zirconium n-propoxide. Addition of 1 eq of Acetylacetone to zirconium or hafnium alkoxide precursors results in formation of dimeric [M(OR)₃(acac)]₂ in high yields. These species have limited stability (much higher for Hf than for Zr) and transform in solution into hydrolysis-insensitive M(acac)₄ through very unstable M(acac)₃(OR) intermediates containing 7-coordinated metal centers. This transformation can be followed kinetically in hydrocarbon solvents by ¹H NMR and is noticeably accelerated by addition of parent alcohols. The obtained results clearly reveal limited applicability of EXAFS and XANES techniques for the study of such systems, especially in the context of structure prediction. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The effect of crosslinked networks with poly(ethylene glycol) on sulfonated polyimide for polymer electrolyte membrane fuel cell

To investigate the effect of crosslinking by a hydrophilic group on a sulfonated polyimide electrolyte membrane, sulfonated polyimide end‐capped with maleic anhydride was synthesized using 1,4,5,8‐naphthalenetetracarboxylic dianhydride, 4,4′‐diaminobiphenyl, 2,2′‐disulfonic acid, 2‐bis [4‐(4‐aminophenoxy)phenyl] hexafluropropane and maleic anhydride. The sulfonated polyimides end‐capped with maleic anhydride were self‐crosslinked or crosslinked with poly(ethylene glycol) diacrylate. A series of the crosslinked sulfonated polyimides having various ratios of sulfonated polyimide and poly(ethylene glycol) diacrylate were prepared and compared with uncrosslinked and self‐crosslinked sulfonated polyimides. The synthesized sulfonated polyimide films were characterized for FTIR spectrum, thermal stability, ion exchange capacity, water uptake, hydrolytic stability, morphological structure, and proton conductivity. The formation of sulfonated polyimide was confirmed in FTIR spectrum. Thermal stability was good for all the sulfonated polyimides that exhibited a three‐step degradation pattern. Ion exchange capacity was the same for both the uncrosslinked and the self‐crosslinked sulfonated polyimides (1.30 mEq/g). When the crosslinked sulfonated polyimides with poly(ethylene glycol) were compared, the ion exchange capacity was decreased as 1.27 > 1.25 > 1.23 mEq/g and water uptake was increased as 23.8 < 24.0 < 24.3% with the increase in poly(ethylene glycol) diacrylate content. All the crosslinked sulfonated polyimides with poly(ethylene glycol) diacrylate were stable for over 200 h at 80 °C in deionized water. Morphological structure and mean intermolecular distance were obtained by WAXD. Proton conductivities were measured at 30, 50, 70, and 90 °C. The proton conductivity of the crosslinked sulfonated polyimides with poly(ethylene glycol) diacrylate increased with the increase in poly(ethylene glycol) diacrylate content despite the fact that the ion exchange capacity was decreased. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1455–1464, 2005     

Carbothermal synthesis of ultra-fine zirconium carbide powders using inorganic precursors via sol–gel method

Ultra-fine zirconium carbide (ZrC) powders have been synthesized by carbothermal reduction reactions using inorganic precursors zirconium oxychloride (ZrOCl₂ · 8H₂O) as sources of zirconium and phenolic resin as the carbon source. The reactions were substantially completed at relatively lower temperatures (∼1400 °C/1 h) and the synthesized powders had a small average crystallite size (<200 nm) and a large specific area (54 m²/g). The oxygen content of the powder synthesized at 1400 °C/1 h was less than 1.0 wt%. The thermodynamic change process in the ZrO₂–C system and the synthesis mechanism were studied.     

Preparation of linear low‐density polyethylene by the in situ copolymerization of ethylene with an iron oligomerization catalyst and rac‐ethylene bis(indenyl) zirconium (IV) dichloride

An iron oligomerization catalyst, [(2‐ArN?C(Me))₂C₅H₃N]FeCl₂ [Ar = 2,6‐C₆H₃(F)₂], was combined with rac‐ethylene bis(indenyl)zirconium (IV) dichloride [rac‐Et(Ind)₂ZrCl₂] to prepare linear low‐density polyethylene (LLDPE) by the in situ copolymerization of ethylene. A series of LLDPEs with different properties were prepared by the alteration of the reaction temperature, Fe/Zr molar ratio, Al/(Fe + Zr) molar ratio, and reaction time. The structures of the polymers were characterized with differential scanning calorimetry, ¹³C NMR, gel permeation chromatography (GPC), and so forth. The melting points, crystallizations, and densities of the resulting products increased, and the average branching degree decreased, as the reaction temperature, Al/(Fe + Zr) ratio, and reaction time increased. The melting points, crystallizations, and densities of the polymers decreased, and the average branching degree increased, when the Fe/Zr ratio increased. The ¹³C NMR and GPC results showed that there were no unreacted α‐olefins remaining in the resulting polymers because the percentage of low‐molar‐mass sections (C₄–C₁₀) of the oligomers obtained with this catalyst was very high (>70%). In addition, the formation of polymers with two melting points under different reaction conditions was examined in detail, and the results indicated that the two melting points of the polymers could be attributed to polyethylene with different branches. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 984–993, 2005     

Layer‐by‐layer deposition of nitrilotris(methylene)triphosphonic acid and Zr(IV): an XPS,ToF‐SIMS,ellipsometry, and AFM study

Layer‐by‐layer assemblies consisting of alternating layers of nitrilotris(methylene)triphosphonic acid (NTMP), a polyfunctional corrosion inhibitor, and zirconium(IV) were prepared on alumina. In particular, a nine‐layer (NTMP/Zr(IV))₄NTMP stack could be constructed at room temperature, which showed a steady increase in film thickness throughout its growth by spectroscopic ellipsometry up to a final thickness of 1.79 ± 0.04 nm. At higher temperature (70 °C), even a two‐layer NTMP/Zr(IV) assembly could not be prepared because of etching of the alumina substrate by the heated Zr(IV) solution. XPS characterization of the layer‐by‐layer assembly showed a saw tooth pattern in the nitrogen, phosphorus, and zirconium signals, where the modest increases and decreases in these signals corresponded to the expected deposition and perhaps removal of NTMP and Zr(IV). Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) confirmed the attachment of the NTMP molecule to the surface through PO^?, PO₂^?, PO₃^?, and CN^? signals. Increasing attenuation of the Al signal from the substrate after deposition of each layer was observed by both XPS and ToF‐SIMS. Essentially complete etching of the alumina by the heated Zr(IV) solution was confirmed by spectroscopic ellipsometry, XPS, and ToF‐SIMS. Atomic force microscopy revealed that all the films were smooth with R_q roughness values less than 0.5 nm. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of Synthesis Parameters on Sol–Gel Silica Modified by Zirconia

An experimental strategy was developed to obtain mesoporous SiO₂-ZrO₂ mixed oxides via a sol–gel process, which involved the use of tetraethylorthosilicate (TEOS) and an inorganic Zr-containing salt. The effects of key process parameters on the properties of the materials were investigated, including the choice of Zr(IV) source (zirconium oxychloride or nitrate), the ZrO₂ content and the synthesis pressure (i.e. ambient pressure or hydrothermal conditions). The resulting solids were dried, calcined at 500 °C, and characterized by nitrogen physisorption, pyridine chemisorption, ²⁹Si Nuclear Magnetic Resonance and X-ray diffraction. The data revealed that mesoporous materials with very narrow pore diameter distribution were obtained when using the autoclave procedure from both zirconium nitrate and oxychloride salts. The surface areas and pore size distributions were a function of ZrO₂ content. Differences in acidity, as determined by pyridine adsorption, were observed depending on the synthesis parameters.     

Thermal behavior of the composite xerogels of zirconium oxyhydroxide and silicic acid

Gels were prepared via sol?Cgel method by addition of zirconium oxychloride solution into sodium metasilicate (SZ) and sodium metasilicate solution into zirconium oxychloride (ZS) at varying final pH. Si/Zr molar ratio equaled 1/1. Synthesized gels were dried with calcium chloride until they reached a constant mass. SEM and nitrogen adsorption analysis have shown that SZ gels have surface area 175?C200?m^2?g^?1, consist of 20?C30?nm grains. ZS samples have surface area about 1?m^2?g^?1, consist of grains smaller than 10?nm. Thermal and X-ray phase analysis have shown that transition of amorphous ZrO₂ to crystalline form shifts from 430 to 850?C870?°C for SZ gels. Unlike zirconia gels phase transitions that proceed in order: ??amorphous (430?°C)??tetragonal (800?°C)??monoclinic (1,000?°C) phases??, the monoclinic phase in ZS gels appears immediately after transition from amorphous to crystalline state; the tetragonal phase in SZ samples is stable until 1,000?°C.     

Dispersion of carbon nanotubes by the branched block copolymer Tetronic 1107 in an alcohol–water solution

The dispersion of carbon nanotubes (CNTs) by the branched block copolymer Tetronic 1107 was investigated in mixed solvents consisting of water and one of the following alcohols: ethanol, n-propanol, ethylene glycol (EG), or glycerol (GLY). The maximum concentration of dispersed CNTs (C _limit) and the optimum T1107 concentration (C _opt) to disperse the maximum amount of CNTs in different solvents were obtained from UV–vis–NIR absorbance spectra. The addition of ethanol or n-propanol to water dramatically increases the C _limit. The value of C _opt follows the order: n-propanol–water?>?ethanol–water?>?EG–water?≈?GLY–water mixtures. I _D/I _G was used to characterize the defect density of CNTs dispersed in the mixed solvents, which was investigated by Raman spectroscopy. The I _D/I _G values in n-propanol–water and ethanol–water mixtures are higher than those in EG–water and GLY–water mixtures. High-resolution transmission electron microscopy is used to confirm a favorable dispersion in the presence of different alcohols.     

Initiation process of L‐lactide polymerization carried out with zirconium(IV) acetylacetonate

Lactide polymerization using zirconium(IV) acetylacetonate [Zr(acac)₄] as an initiator was investigated. In the reaction between Zr(acac)₄ and the monomer molecule, lactide deprotonation and the release of acetylacetone occurred. The structures of the obtained complexes were analyzed with high‐resolution NMR spectroscopy. A computational method was used to calculate the hypothetical structures. The role of the obtained complexes in the initiation of polymerization and the reaction of chain growth was proposed. The influence of the reaction temperature on the structures of the complexes was investigated. Polylactide chain growth proceeded by an insertion‐coordination mechanism. The polymer chain grew on one ligand, which was formed in advance from a deprotonated lactide. The molecular masses of the obtained polymers were the same as the theoretical masses and were directly proportional to the reaction conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1886–1900, 2004     

Effects of additives and post‐treatment on the thermoelectric performance of vapor‐phase polymerized PEDOT films

Vapor‐phase polymerization (VPP) is an important method for the fabrication of high‐quality conducting polymers, especially poly(3,4‐ethylenedioxythiophene) (PEDOT). In this work, the effects of additives and post‐treatment solvents on the thermoelectric (TE) performance of VPP‐PEDOT films were systematically investigated. The use of 1‐butyl‐3‐menthylinidazolium tetrafluoroborate ([BMIm][BF₄], an ionic liquid) was shown to significantly enhance the electrical conductivity of VPP‐PEDOT films compared with other additives. The VPP‐PEDOT film post‐treated with mixed ethylene glycol (EG)/[BMIm][BF₄] solvent displayed the high power factor of 45.3 μW m^?1 K^?2 which is 122% higher than that prepared without any additive or post‐treatment solvent, along with enhanced electrical conductivity and Seebeck coefficient. This work highlighted the superior effect of the [BMIm][BF₄] additive and the EG/[BMIm][BF₄] solvent post‐treatment on the TE performance of the VPP‐PEDOT film. These results should help with developing the VPP method to fabricate high‐performance PEDOT films. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1738–1744