Titanium tetra-alkoxides preparation

The addition of a base, typically ammonia, to mixtnres of metal(loid) halides and alcohols allows the synthesis of homoleptic alkoxides for a wide range of metals and metalloids. Anhydrous ammonia appears to have been employed for the first time by Nelles " in 1939 for the preparation of titanium tetra-alkoxides (Eq. 2.33) ... 

Powders from Alkoxides and Salts. Two solutions were prepared individually for the synthesis of lead titanate (PbTiOs) particles by Tartaj et al. (2001) (i) titanium tetra-butoxide in 2-propanol, and (ii) lead acetate in glacial acetic acid. The solutions were mixed under stirring, and a water-2-propanol mixture added to this for the initiation of hydrolysis. As in some other cases, crystalline seeds of the target compound, suspended in 2-propanol, were added (10 wt%) to the transparent sol already obtained. The gels obtained through this process were dried and ground to small particles and calcined at 400°C for 20 h for use in the preparation of sintered bodies. X-ray diffractometry of the calcined sample showed it to be fully crystallized to phase-pure PbTiOs, while an unseeded sample did not crystallize under the same conditions. 

Higher alkoxides, such as tetra(2-ethylhexyl) titanate, TYZOR TOT [1070-10-6], can be prepared by alcohol interchange (transestenfication) in a solvent, such as benzene or cyclohexane, to form a volatile a2eotrope with the displaced alcohol, or by a solvent-free process involving vacuum removal of the more volatile displaced alcohol. The affinity of an alcohol for titanium decreases in the order primary > secondary > tertiary, and... 

Tetra-alkoxy titanates are the most commonly used catalysts for PBT pol)mierization [15, 20]. As opposed to the PET process, where a different catalyst is used in each of the two polymerization phases, in the PBT process, a single catalyst is typically used for both reaction steps. The most frequently used titanates are tet-rabutoxy titanate (Ti(OBu) ) [26, 27, 29, 30] and tetraisopropoxy titanate (Ti(OiPr) ) [31]. Ti(OBu), and Ti(OiPr) are very efficient catalysts which do not generate side effects, especially discoloration. Titanium and zirconium alkoxides are sometimes involved in the same preparation [23]. Other compounds have also been also proposed CHgCOONa [28] Ti(OBu), (95%) + CHjCOONa (5%) [29] Ti(OBu), (50%) + Sn(OBu), (50%) [26] Ti(OBu) + Ca(OAc)2 [32] Ti(OBu) + Mg(OAc)2 [30] TiOj-xH O [25], etc. These catalytic... 

Numerous titanium alkoxides are used in sol-gel chemistry, in order to prepare inorganic titanium oxides. They are, for instance, Ti tetra-iso-propoxide (TIPT) and Ti tetra-n-butoxide (TBOT). The sol-gel transformation mechanisms of TIPT-derived coatings have been qualitatively studied by FUR spectroscopy (Burgos and Langlet, 1999), allowing a good knowledge of the hydrolysis and condensation reactions of the aUcoxide. 

Further studies of equilibration reactions of aliphatic polyesters in solution catalyzed by titanium alkoxides were contributed by BiUmeyer et al. [16-18]. Semiyen et al. [19] used a dibutyltin salt for the preparation of cyclic oligomers by depolymerization of poly(tetraethyleneglycol succinate). Extraction and characterization of cyclic oligo(alkylene isophthalate)s and oligo(alkylene terephthalate)s [20-24] beg an in 1954 with the work of Ross et al. [20], who isolated the cyclic trimer from PET. A detailed study of 13 different polyesters was reported by Wick and Zeigler [25]. Semiyen et al. [26] were particularly interested in the depolymerisation of polyesters derived from tetra(ethyleneglycol) and phthalic, isophthalic and terephthalic acidacid, whereas Montaudo et al. [27] studied other polyesters of terephthalic acid. 

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