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Titanium Compounds (titanium + compound)
Selected AbstractsReduction of Carbonyl Compounds with Polyethylsiloxane in the Presence of Titanium Compounds.CHEMINFORM, Issue 8 2005V. V. Kozhukhova Abstract For Abstract see ChemInform Abstract in Full Text. [source] Use of Titanates to Achieve a Temperature-Stable Low-Temperature Cofired Ceramic Dielectric for Wireless ApplicationsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2002Steve Xunhu Dai A low-loss and near-zero temperature coefficient of resonant frequency (Tf) low-temperature cofired ceramic (LTCC) host dielectric was developed for portable consumer wireless device applications. The low Tf was realized by compensating the Al2O3 -filled-glass dielectric with admixtures of TiO2 (negative temperature coefficient of dielectric constant (T,)) in the starting formulation. XRD data indicated a portion of the TiO2 in the starting formulation dissolved into the glass, and extensive formation of crystalline titanium compounds was observed via a nucleation and growth mechanism. The dissolution of TiO2 in the glass and subsequent formation of titanium compounds was believed to result in the relatively small amount of TiO2 required to achieve a near-zero Tf in the final sintered structure. [source] Screening of Different Titanium (IV) Catalysts in the Synthesis of Poly(ethylene terephthalate)MACROMOLECULAR REACTION ENGINEERING, Issue 6 2008Fatemeh Ahmadnian Abstract The polycondensation of bis(hydroxyethylene) terephthalate and its oligomers to PET catalyzed by different chelated and non-chelated titanium catalysts in a lab-scale stirred-tank reactor and differential scanning calorimeter were investigated. Different titanium compounds showed different activity and selectivity. The nature of catalyst ligands plays an important role in catalyst efficiency. Non-chelated titanium derivatives were more active and less selective. Reaction progress is characterized by an initial inhibition period depending on the type of catalyst. The original titanium compounds used are precursors and are probably activated by a ligand exchange reaction. [source] Titanium-Based Molecular Squares and Rectangles: Syntheses by Self-Assembly Reactions of Titanocene Fragments and Aromatic N-HeterocyclesCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2005Susanne Kraft Dr. Abstract This paper reports on the potential of titanium compounds as building blocks for supramolecular polygons. Self-assembly reactions of low-valent titanocene units and N-heterocyclic bridging ligands lead to novel titanium-based supramolecular squares. Pyrazine (3), 4,4,-bipyridine (4), and tetrazine (5) were used as bridging ligands, and the acetylene complexes [Cp2Ti{,2 -C2(SiMe3)2}] (1) and [(tBuCp)2Ti{,2 -C2(SiMe3)2}] (2) as sources of titanocene fragments. Molecular rectangles can be synthesized by stepwise reduction of the titanocene dichlorides [Cp2TiCl2] and [(tBuCp)2TiCl2] and consecutive coordination of two different bridging ligands. The resulting complexes are the first examples of molecular rectangles containing bent metallocene corner units. Single-crystal X-ray analyses of the tetranuclear compounds revealed the geometric properties of the molecular polygons in the solid state. Comparison of bond lengths and angles in coordinated and free ligands reveals the reduced state of the bridging ligand in the low-valent titanium compounds. The syntheses and properties of these novel, highly air- and moisture-sensitive compounds are discussed. [source] | |||||||||||||