Zirconium tetra-n-butylate modified with different organic acids: Hydrolysis and polymerization of the products

In this work; (a) complexation reaction of zirconium tetra-n-butylate, Zr(OBu ⁿ )₄, with MAc and different organic acids. (b) the hydrolysis reaction of modified Zr species, and (c) the polymerization reaction of complex products are studied. Zr(OBu ⁿ )₄ was reacted with different mole ratios of methacrylic acid (MAc) at room temperature and the maximum combination ratio was found to be 1∶2 [Zr(OBu ⁿ )₄∶MAc] by FT IR. The modification of zirconium tetra-n-butylate with the acid mixtures [methacrylic acid-acetic acid (MeCOOH), methacrylic acid-propionic acid (EtCOOH), methacrylic acidbutyric acid (PrCOOH)] was made for a combination ratio of 1∶1∶1 [MAc∶RCOOH∶Zr(OBu ⁿ )₄∶R∶Me. Et, Pr] and the products were characterized by¹H-NMR, FT-IR, and UV-spectroscopies. Following their synthesis, hydrolysis of the complexes with various amounts of water and polymerization with benzoyl peroxide were realized. The hydrolysis and polymerization products of the complexes were studied by Karl-Fischer Coulometric titration and thermal analysis respectively. Methyl-ethyl-ketone (MEK) and chloroform were chosen as solvents.     

Zirconium tetra-n-butylate modified with different organic acids: Hydrolysis and polymerization of the products

In this work, (a) complexation reaction of zirconium tetra-n-butylate, Zr(OBu ⁿ )₄, with MAc and different organic acids, (b) the hydrolysis reaction of modified Zr species, and (c) the polymerization reaction of complex products are studied. Zr(OBu ⁿ )₄ was reacted with different mole ratios of methacrylic acid (MAc) at room temperature and the maximum combination ratio was found to be 1:2 [Zr(OBu ⁿ )₄:MAc] by FT-IR. The modification of zirconium tetra-n-butylate with the acid mixtures [methacrylic acid-acetic acid (MeCOOH), methacrylic acid-propionic acid (EtCOOH), methacrylic acid-butyric acid (PrCOOH)] was made for a combination ratio of 1:1:1 [MAc:RCOOH:Zr(OBu ⁿ )₄; R: Me, Et, Pr] and the products were characterized by¹H-NMR, FT-IR, and UV spectroscopies. Following their synthesis, hydrolysis of the complexes with various amounts of water and polymerization with benzoyl peroxide were realized. The hydrolysis and polymerization products of the complexes were studied by Karl-Fischer coulometric titration and thermal analysis, respectively. Methyl ethyl ketone(MEK) and chloroform were chosen as solvents.     

Inorganic–Organic Hybrid Materials of Zirconium and Aluminum and Their Usage in the Removal of Methylene Blue

Two novel inorganic–organic hybrid materials, Al-Pydca-3-APDEMS-H and Zr-Pydca-3-APDEMS-H, were prepared by the sol gel method in two steps. In the first step, Al(O^sBu)₂-Pydca and Zr(OPrⁿ)₃-Pydca complexes were prepared from the reactions of aluminum sec-butoxide Al(O^sBu)₃ and zirconium n-propoxide Zr(OPrⁿ)₄ with 2,6-pyridinedicarboxylic acid, respectively. After 3 h of stirring, 3-aminopropyldiethoxymethyl silane (3-APDEMS) and dilute hydrochloric acid were added to the Al(O^sBu)₂-Pydca and Zr(OPrⁿ)₃-Pydca mixtures to hydrolyze the reactions and to form condensation products. These hybrid products were characterized by a combination of Fourier-transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray (EDX) spectroscopy, Brunauer–Emmett–Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) and other analysis methods. These hybrid materials were used for the removal of methylene blue (MB), a cationic organic dye. The removal efficiency of hybrid materials was measured by UV–Vis spectroscopy.

     

Inorganic–organic hybrid materials prepared from zirconium oxo‐clusters and 2‐hydroxyethyl methacrylate

This article describes the preparation and characterization of hybrid materials obtained from the polymerization of vinyl‐substituted zirconium oxo‐clusters [Zr₆O₄(OH)₄(OOCCH₂CHCH₂)₁₂(n‐PrOH)]₂·4(CH₂CHCH₂COOH) (Zr12) and 2‐hydroxyethyl methacrylate (HEMA). The zirconium oxo‐clusters serve as cross‐linking agents, forming a 3D network by means of the copolymerization of their vinylic ligands with HEMA. To optimize the conditions for cross‐linking, the polymerization was monitored with a differential scanning calorimeter. The resulting hybrid materials were also characterized using thermo‐mechanical techniques. There was evidence not only of a greater rigidity above T_g, but also of a better thermal stability for several hybrid formulations than for simple poly‐2‐hydroxyethyl methacrylate. After immersion in water, the hybrids containing 20 or 60% w/w zirconium oxo‐clusters also showed a stable behavior with an equilibrium swelling at about 27 and 18% w/w of water, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41568.     

Zirconium tetra-n-butylate modified with different organic acids: Hydrolysis and polymerization of the products

In this work, (a) complexation reaction of zirconium tetra-n-butylate, Zr(OBu ⁿ )₄, with MAc and different organic acids, (b) the hydrolysis reaction of modified Zr species, and (c) the polymerization reaction of complex products are studied. Zr(OBu ⁿ )₄ was reacted with different mole ratios of methacrylic acid (MAc) at room temperature and the maximum combination ratio was found to be 1:2 [Zr(OBu ⁿ )₄:MAc] by FT-IR. The modification of zirconium tetra-n-butylate with the acid mixtures [methacrylic acid-acetic acid (MeCOOH), methacrylic acid-propionic acid (EtCOOH), methacrylic acid-butyric acid (PrCOOH)] was made for a combination ratio of 1:1:1 [MAc:RCOOH:Zr(OBu ⁿ )₄; R: Me, Et, Pr] and the products were characterized by¹H-NMR, FT-IR, and UV spectroscopies. Following their synthesis, hydrolysis of the complexes with various amounts of water and polymerization with benzoyl peroxide were realized. The hydrolysis and polymerization products of the complexes were studied by Karl-Fischer coulometric titration and thermal analysis, respectively. Methyl ethyl ketone(MEK) and chloroform were chosen as solvents.     

Modification of Different Zirconium Propoxide Precursors by Diethanolamine. Is There a Shelf Stability Issue for Sol-Gel Applications?

Modification of different zirconium propoxide precursors with H₂dea was investigated by characterization of the isolated modified species. Upon modification of zirconium n-propoxide and [Zr(OⁿPr)(OⁱPr)₃(ⁱPrOH)]₂ with ½ a mol equivalent of H₂dea the complexes [Zr₂(OⁿPr)₆(OCH₂CH₂)₂NH]₂ (1) and [Zr₂(OⁿPr)₂(OⁱPr)₄(OCH₂CH₂)₂NH]₂ (2) were obtained. However, ¹H-NMR studies of these tetranuclear compounds showed that these are not time-stable either in solution or solid form. The effect of this time instability on material properties is demonstrated by light scattering and TEM experiments. Modification of zirconium isopropoxide with either ½ or 1 equivalent mol of H₂dea results in formation of the trinuclear complex, Zr{η³μ₂-NH(C₂H₄O)₂}₃[Zr(OⁱPr)₃]₂(iPrOH)₂ (3) countering a unique nona-coordinated central zirconium atom. This complex 3 is one of the first modified zirconium propoxide precursors shown to be stable in solution for long periods of time. The particle size and morphology of the products of sol-gel synthesis are strongly dependent on the time factor and eventual heat treatment of the precursor solution. Reproducible sol-gel synthesis requires the use of solution stable precursors.     

Synthesis,Characterization, and Application of Hybrid Inorganic–Organic Composites (K/Na)ZrSi(R)O<Subscript>x</Subscript>

Hybrid inorganic–organic composites, (K/Na)ZrSi(R)O_x, were synthesized from the hydrolysis of the mixture of zirconium n-propoxide (Zr(OPrⁿ)₄) and 3-glycidyloxypropyltrimethoxy silane (GPTS) in 1:1 mol ratio. The hydrolysis reaction was carried out with 0.1 molar HCl in 150 ml of butanol. Then, the synthesized Zr(OPrⁿ)₄-GPTS-hydrolyzate reacted with KOBu^t and NaOSiMe₃ in 1:1 mol ratio at 40 and 50 °C for 24 h, respectively. After these stages, composites were washed and dried under vacuum. Composites and their oxide prepared at 1250 °C by calcinations were characterized by a combination of powder X-ray diffraction, scanning electron microscope, energy dispersive X-ray, Brunauer–Emmett–Teller analysis, Barrett–Joyner–Halenda analysis, and Fourier transform infrared spectroscopies. These hybrid inorganic–organic composites except oxides were used as catalysts in order to see their activities in the polymerization of ε-caprolactone (ε-CL). This study showed that new composite materials except their oxides were effective catalyst in ε-CL polymerization.     

Hybrid inorganic-organic polymer electrolytes: synthesis, FT-Raman studies and conductivity of {Zr[(CH2CH2O)8.7]ρ/(LiClO4)z}n network complexes

This paper describes the synthesis and characterization of three-dimensional hybrid inorganic-organic networks prepared by a polycondensation reaction between Zr(O(CH₂)₃CH₃)₄ and polyethylene glycol 400 (PEG400). Eleven hybrid networks doped with varying concentrations of LiClO₄ salt were prepared. On the basis of analytical data and FT-Raman studies it was concluded that these polymer electrolytes consist of inorganic-organic networks with zirconium atoms bonded together by PEG400 bridges. These polymers are transparent with a solid rubber consistency and are very stable under inert atmosphere. Scanning electron microscopy revealed a smooth glassy surface. X-ray fluorescence microanalysis with energy dispersive spectroscopy demonstrated that all the constituent elements are homogeneously distributed in the materials. Thermogravimetric measurements revealed that these materials are thermally stable up to 262 °C. Differential Scanning Calorimetry measurements indicated that the glass transition temperature T_g of these inorganic-organic hybrids varies from −43 to −15 °C with increasing LiClO₄ concentration. FT-Raman investigations revealed the TGT (T=trans, G=gauche) conformation of polyether chains and allowed characterization of the types of ion-ion and ion-polymer host interactions in the bulk materials. The conductivity of the materials at different temperatures was determined by impedance spectroscopy over the 20 Hz-1 MHz frequency range. Results indicated that the materials conduct ionically and that their ionic conductivity is strongly influenced by the segmental motion of the polymer network and the type of ionic species distributed in the bulk material. Finally, it is to be highlighted that the hybrid network with a n_Li/n_O molar ratio of 0.0223 shows a conductivity of ca. 1×10⁻⁵ S cm⁻¹ at 40 °C.     

Isolation and structural characterization of the first homoleptic lanthanide–zirconium oxoisopropoxide,La2Zr3O(OPri)16. Combination of an [M4O] tetrahedron with an [MO6] octahedron – A new structure type for pentanuclear alkoxide complexes

The amorphous bimetallic isopropoxides of variable composition LaZr_nO_x(OPrⁱ)_3+4n−2x, where n = 0.5–3 formed on interaction of the two homometallic isopropoxides, La₅O(OⁱPr)₁₃ and Zr(OⁱPr)₄(ⁱPrOH), in solutions in parent alcohol crystallize slowly yielding a bimetallic oxoalkoxide La₂Zr₃O(OPrⁱ)₁₆ (1). In its molecule an octahedrally coordinated zirconium atom is connected via two μ₃-OR and two μ-OR-groups with two lanthanum atoms of a tetrahedral [La₂Zr₂(μ₄-O)] aggregate. This structure type has not been previously observed in the structures of pentanuclear alkoxide aggregates. The conditions leading to formation of 1 from solutions containing the homometallic alkoxides are outlined.     

Investigation of the tetracarbonatozirconate ion by electrospray mass spectrometry in aqueous media

Reported here is the study of zirconium (IV) aqueous solutions in carbonate media by electrospray ionisation mass spectrometry (ESI–MS). Spectra analysis lead to consider the existence in the spray of the initial pseudomolecular labile species [Zr(CO₃)₄(HCO₃)]⁵⁻, xH⁺, (6−x) K⁺ (or Na⁺). The existence of this species confirms the associative exchange mechanism of carbonate ions with [Zr(CO₃)₄]⁴⁻ ion.     

Zirconium tetra-n-butylate modified with different organic acids: Hydrolysis and polymerization of the products

In this work; (a) complexation reaction of zirconium tetra-n-butylate, Zr(OBu ⁿ )₄, with MAc and different organic acids. (b) the hydrolysis reaction of modified Zr species, and (c) the polymerization reaction of complex products are studied. Zr(OBu ⁿ )₄ was reacted with different mole ratios of methacrylic acid (MAc) at room temperature and the maximum combination ratio was found to be 12 [Zr(OBu ⁿ )₄MAc] by FT IR. The modification of zirconium tetra-n-butylate with the acid mixtures [methacrylic acid-acetic acid (MeCOOH), methacrylic acid-propionic acid (EtCOOH), methacrylic acidbutyric acid (PrCOOH)] was made for a combination ratio of 111 [MAcRCOOHZr(OBu ⁿ )₄RMe. Et, Pr] and the products were characterized by¹H-NMR, FT-IR, and UV-spectroscopies. Following their synthesis, hydrolysis of the complexes with various amounts of water and polymerization with benzoyl peroxide were realized. The hydrolysis and polymerization products of the complexes were studied by Karl-Fischer Coulometric titration and thermal analysis respectively. Methyl-ethyl-ketone (MEK) and chloroform were chosen as solvents.     

Straightforward synthesis and structural characterization of the first alkoxy-zircono-silsesquioxanes — Potential models for zirconia–silica epoxidation catalysts: Molecular hybrid materials mimicking solution exchange in MOFs

The first representatives of alkoxy-zircono-silsesquioxane compounds, dinuclear [Cy₇Si₇O₁₂]Zr(ROH)(μ-OR)₂Zr(ROH)[O₁₂Si₇Cy₇], where R = ⁿPr, ⁿBu, ^tBu; Cy = c-C₆H₁₁, and [Cy*₇Si₇O₁₂]Zr(μ-ROH)(μ-OR)₂Zr[O₁₂Si₇Cy*₇], R = ^tBu; Cy* = c-C₅H₉, have been prepared with quantitative yield by interaction of the corresponding zirconium alkoxides with the cycloalkyl-substituted cage silsesquioxanes in hexane. The X-ray single crystal study of the n-butoxide derivative revealed that zirconium atoms are hexacoordinated with the 3 oxygen atoms of the cage ligand, 2 — from the bridging alkoxide groups and one — from the solvating alcohol molecule in the coordination sphere. The molecule is additionally supported by a hydrogen bond between the solvating alcohol and an oxygen atom belonging to the cage ligand coordinated by the other zirconium atom. The structures of produced silsesquioxanes display behavior typical for metal–organic frameworks as they crystallize initially as hexane clathrates, but lose the solvent on storage in inert atmosphere. This results in formation of empty channels situated along the c-axis.     

Zirconium complexes of amino(polyphenolic) ligands and their hydrolytic stability

Three amino(polyphenolic) ligands, N,N′-bis(5-tert-butyl-2-hydroxybenzyl)-1,2-diaminoethane 1, tris(5-tert-butyl-2-hydroxy-3-methylbenzyl)amine 3, its 3-chloro analogue 4 and their Zr^IV complexes have been synthesised. The crystal structure of the Zr^IV complex of tris(5-tert-butyl-3-chloro-2-hydroxybenzyl)amine, shows this to be [Zr(4-2H)₂] in which both ligands exists in a zwitterionic form with one alkylammonium and three phenolate groups. The complexes are stable in a two phase, chloroform/water, system at high pH, but the zirconium is stripped at pH < 2.5. The pH value needed to strip 50% of the Zr^IV from the complex [Zr(1-4H)] of the tetraphenolic ligand is ∼2.0 whilst the complexes [Zr(3-2H)₂] and [Zr(4-2H)₂] of the triphenolic ligands are slightly more stable with pH_1/2 values of ∼1.4. We were unable to use the ligands to extract zirconium from low pH aqueous zirconium oxychloride solutions into an organic phase under a variety of conditions.     

Complexation of Zirconium Alkoxides with 3-Pentenoic Acid and Hydrolytic Stability of Their Products

Reactions of Zr(OPr ⁿ )₄ and Zr(OBu ⁿ )₄ with 3-pentenoic acid (PA) in 1:1 molar ratio were studied in propanol and butanol solution at room temperature by the sol–gel process. The complexations were investigated by ¹³C{¹H}, ¹H-NMR and FTIR spectroscopy. The ¹³C{¹H}, ¹H-NMR and FTIR spectra showed that PA completely reacted with Zr(OPr ⁿ )₄ and Zr(OBu ⁿ )₄. The new products were hydrolyzed by water in a ratio of 1:4 (Zr(OR ⁿ )₄/ H₂O, R = propyl, butyl). The stability of hydrolyzed products was investigated spectroscopically. After hydrolysis, it was observed that no PA was released from the complexes, [Zr(OPr ⁿ )₃(PA)] and [Zr(OBu ⁿ )₃(PA)], under the reaction conditions.     

Silica‐Supported Zirconium Complexes and their Polyoligosilsesquioxane Analogues in the Transesterification of Acrylates: Part 2. Activity,Recycling and Regeneration

The catalytic activity of both supported and soluble molecular zirconium complexes was studied in the transesterification reaction of ethyl acrylate by butanol. Two series of catalysts were employed: three well defined silica‐supported acetylacetonate and n‐butoxy zirconium(IV) complexes linked to the surface by one or three siloxane bonds, (SiO)Zr(acac)₃ ( 1 ) (SiO)₃Zr(acac) ( 2 ) and (SiO)₃Zr(O‐n‐Bu) ( 3 ), and their soluble polyoligosilsesquioxy analogues (c‐C₅H₉)₇Si₈O₁₂(CH₃)₂Zr(acac)₃ ( 1′ ), (c‐C₅H₉)₇Si₇O₁₂Zr(acac) ( 2′ ), and (c‐C₅H₉)₇Si₇O₁₂Zr(O‐n‐Bu) (3′ ). The reactivity of these complexes were compared to relevant molecular catalysts [zirconium tetraacetylacetonate, Zr(acac)₄ and zirconium tetra‐n‐butoxide, Zr(O‐n‐Bu)₄]. Strong activity relationships between the silica‐supported complexes and their polyoligosilsesquioxane analogues were established. Acetylacetonate complexes were found to be far superior to alkoxide complexes. The monopodal complexes 1 and 1′ were found to be the most active in their respective series. Studies on the recycling of the heterogeneous catalysts showed significant degradation of activity for the acetylacetonate complexes ( 1 and 2 ) but not for the less active tripodal alkoxide catalyst, 3 . Two factors are thought to contribute to the deactivation of catalyst: the lixivation of zirconium by cleavage of surface siloxide bonds and exchange reactions between acetylacetonate ligands and alcohols in the substrate/product solution. It was shown that the addition of acetylacetone to the low activity catalyst Zr(O‐n‐Bu)₄ produced a system that was as active as Zr(acac)₄. The applicability of ligand addition to heterogeneous systems was then studied. The addition of acetylacetone to the low activity solid catalyst 3 produced a highly active catalyst and the addition of a stoichiometric quantity of acetylacetone at each successive batch catalytic run greatly reduced catalyst deactivation for the highly active catalyst 1 .     

Preparation and Characterization of Pillared Zirconium Phosphite-Diphosphonates with Tuneable Inter-Crystal Mesoporosity

A series of -pillared zirconium phosphite-diphosphonates of general formula Zr(O₃PH)_x(O₃P-C₆ H₄-PO₃)_y was prepared in water, dimethylsulfoxide-water andn -propanol-water, by changing the ratios and the concentrations of the reagents. Pure mesoporous solids with a large surface area (230 to 400 m² g^-2) and a great pore volume (0.3 to 0.7 cm³ g^-2) were obtained. These materials showed a narrow distribution of pores that was tuneable over the range 4–14 nm diameter by simply varying the conditions of preparation, especially the concentration of the reagents. The formation of interparticle mesoporosity has been attributed to edge-edge interactions between rigid packets of a few pillared -layers giving rise to stable aggregates with a house of cards structure.     

Complexation of Titanium Alkoxides with Cis-2-butene-1,4-diol and Hydrolysis of Their Products

Reaction of Ti(OEt)₄ and Ti(OBu ⁿ )₄ with cis-2-butene-1,4-diol (B.diol-2H) in 1:1 molar ratio was studied at room temperature using the sol-gel process. ¹³C{¹H}- and ¹H-NMR data showed that all the B.diol-2H completely reacted with both titanium alkoxides. Each of the products was hydrolyzed by water. The new hydrolyzed products were characterized by ¹³C- and ¹H-NMR spectroscopy and Karl–Fischer Titration. Thermogravimetric and differential thermal analyses (TGA-DTA) of the hydrolyzed-products were also studied.     

Microstructural investigations on zirconium oxide-carbon nanotube composites synthesized by hydrothermal crystallization

Zirconium oxide (ZrO₂)/carbon nanotube composites were prepared by hydrothermal crystallization at 200 °C for 8 h of zirconium hydroxide [(Zr(OH)₄nH₂O; n=8-16] in the presence of carbon nanotubes. The hydrothermal crystallization of zirconium oxide, under autoclave conditions, occurred on the walls of the tubes. The process yielded a homogeneous composite powder consisting of microcrystalline ZrO₂ and multi-walled nanotubes, hence representing an alternative route for the synthesis of ceramic-nanotube composites. Microstructural and qualitative characterizations were performed using different electron microscopy techniques.     

Up-scalable preparation of nano zirconium carbide powder in liquid polymeric precursor and its pyrolysis mechanism

Nano size ZrC powder was prepared by liquid polymeric precursor method. Zirconium n-butoxide (Zr(OⁿBu)₄) and benzoylacetone (BA) were mixed directly with different molar ratios to synthesize transparent liquid zirconium carbide single-source precursors. The carbon content in the precursor could be changed by adding different amount of BA. X-ray pure ZrC was obtained when the molar ratio of BA/Zr(OⁿBu)₄ was 4.6:1. The viscosity of the precursor was very low (<8 mPa s) without the addition of solvents. Zirconium carbide powders were fabricated by the pyrolysis at 800 °C in argon and subsequent heating at various temperatures in vacuum for carbothermal reduction reaction. The pyrolysis behavior, phase composition and transformation, and microstructure of the as-fabricated ZrC powders were analyzed. The gases of CH₄, CO and CO₂ released due to decomposition and evaporation of the organic component and transformation from ZrO₂ to ZrC during pyrolysis resulted in total 60–70% mass loss. The average grain size of the synthesized X-ray pure ZrC powders was less than 30 nm. Meanwhile, the pyrolysis mechanism of nano zirconium carbide powder was deduced.     

The influence of iron content on the promotion of the zircon structure and the optical properties of pink coral pigments

A sol–gel reaction starting from Si and Zr alkoxides, in water-ethanol mixtures, was employed to obtain iron doped zirconium silicate powders (zircon). The starting amount of the ferric salt in the sol–gel reacting mixture was varied in order to obtain Fe₂O₃/Zr molar ratios in the range 0.7–10%. The products of the sol–gel reaction were calcined in the range 800–1300 °C. X-ray diffractograms, EDX analyses and diffuse reflectance spectra were obtained and analysed for all the calcined powders; the colour of the pigments was characterised on the grounds of the CIE (Commission Internationale de l’Eclairage) standard procedure (CIE L¹a¹b¹ measurements). Results from the structural and spectral characterisations are examined and cross-compared to produce a consistent picture of the role played by iron on the promotion of the zircon lattice and on the optical properties of the reaction products.