Titanium ethoxide

MOCVD of Titania. Ti02 is often produced by the pyrolysis of a titanium alkoxide, such as titanium ethoxide, Ti(OC2H5)4, in an oxygen and helium atmosphere at 450°C. Another reaction is based on titanium tetraisopropoxide, Ti(OC3H-7)4, with oxygen at 300°C and at low pressure (< 1 Torr).P ]P ] These precursors have low boiling point (ca. 120°C). 

Tetraethyl orthotitanate (Fluka Chemical Corporation), Titanium ethoxide (Aldrich Chemical Company, Inc.) Ethyl alcohol, titanium(4+) salt (8) Ethanol, titanium(4+) salt (9) (3087-36-3)... 

Evaporative decomposition erf solutions and spary pyrolysis have been found to be useful in the preparation of submicrometer oxide and non-oxide particles, including high temperature superconducting ceramics [819, 820], Allowing uniform aerosol droplets (titanium ethoxide in ethanol, for example) to react with a vapor (water, for example) to produce spherical colloidal particles with controllable sizes and size distributions [821-825] is an alternative vapor phase approach. Chemical vapor deposition techniques (CVD) have also been extended to the formation of ceramic particles [825]. 

Alkoxides (titanium ethoxide, titanium n-propoxide, titanium n-butoxide, titanium sec-butoxide, titanium ethylhexoxide, aluminum sec-butoxide, zirconium n-propoxide, and their mixtures), typically 3 ml, sonicated with propylene carbonate, typically 17 ml, for 20-30 to form uniformly turbid emulsions. Immediate addition of water (10 mol excess) hydrolyzed the alkoxides. Precipitated oxide powders washed (in a Soxhlet extractor) with THF or 2-propanol for 21-30 h, dried, calcinated... 

The Al-containing Ti-beta sample, TB-1, was synthesized according to the methods proposed by Camblor et al. [4], Aerosil 200 (Degussa), titanium ethoxide. tetraethylammonium (TEAOH 40 wt%, Alfa), and aluminum nitrate nonahydrate were used as reagents. The ratios Si/Ti and Si/Al were adjusted as needed. 

One approach to making such powders is the sol-gel method, in which a metal oxide powder is synthesized from a metal alkoxide, a compound derived from a metal and an alcohol. In the synthesis of titania (Ti02) from titanium ethoxide, Ti(OCH2CH3)4, for example, the Ti(OCH2CH3)4 starting material is made by the reaction of titanium(IV) chloride with ethanol and ammonia in a benzene solution ... 

Hydrolysis of Ti(OPr )4 does not allow the obtaining of ideal Ti02 powders [1394], In contrast to oligomeric titanium ethoxide and butoxide, titanium isopropoxide is a monomeric molecule condensation of its hydrolysis product occurs very quickly and results in quick nonuniform particle growth and minute particles quickly agglomerate into polydisperse species. 

A particularly effective method for the asymmetric synthesis of both aldehyde-and ketone-derived sulfinimines recently introduced by Davis and co-workers is the condensation of (5)-(+)-p-toluenesulfinamide (63) with aldehydes and ketones using activated 4-A molecular sieves or titanium ethoxide [Ti(OEt)4].46 This procedure avoids the problem of removing the menthol by-product of the one-pot procedure (see Section II.D) which is sometimes problematic.23 Importantly, this methodology affords ketone derived sulfinimines 66 which are difficult to prepare by other means. 

A different method was used by Parkhurst et al. (36) to incorporate titanium ethoxide into TEOS-based silica gels. In their procedure, the TEOS species is allowed to hydrolyze partially and condense in the presence of an acid catalyst and water before the fast-reacting titanium ethoxide is added. Once introduced, the titanium ethoxide quickly hydrolyzes and condenses into the preexisting immature TEOS-based network rather than precipitating as titanium dioxide. 

We have studied the phase transformation from nanometer-sized amorphous titania (Ti02) to nanocrystalline anatase at 300 - 400° C (unpublished). Amorphous titania samples were prepared by fast hydrolysis of titanium ethoxide in water at 0° C (Zhang et al. 2001). The extent of transformation was monitored using XRD determination of the phase mixture as a function of time. We also found that the transformation kinetics do not follow the widely employed JMAK equation. 

Spherical particles of Ti02 are prepared by condensing vapors of TiCU or titanium ethoxide as uniform-sized aerosol droplets on AgCl nuclei. The aerosol is subsequently hydrolyzed to give Ti02 spherical particles of narrow size distribution with model diameters ranging from 0.06 to 0.6 pm. 

This reaction occurs between 400 and 1000°C . Alkoxides such as titanium isopropoxide and titanium ethoxide have also been used to obtain deposition at temperatures as low as SOO C "". Most recently, IBCVD has been applied in the room temperature deposition of Ti02 films using titanium alkoxides and O2 ions. ... 

J. Valverde, P. Sanchez, F. Dorado, C. Molina, and A. Romero, Influence of the Synthesis Conditions on the Preparation of Titanium-pillared Clays Using Hydrolyzed Titanium Ethoxide as the Pillared Agent. Microporous Mesoporous Mater., 2002, 54, 155-165. 

Recipe from [2125] 0.5 M solution of titanium ethoxide, isopropoxide or tert-butoxide in corresponding alcohol was added dropwise to alcohol-water mixture. The precipitate was washed with water, redispersed in 0.075 M HNO3, and refluxed for 8 h at 80 C. Reference [2013] was also cited for the recipe, but no specific recipe (based on hydrolysis of alkoxide) is reported there. 

The reduction of sullinyl imines is well precedented. Recently, Ellman demonstrated that the tcrt-butyl derivative is a highly selective reagent for this transformation that can also be removed under very mild conditions. Formation of the imine using titanium ethoxide followed by reduction under standard conditions (sodium borohydride in methanol) provided the desired product as a 5 1 mixture of diastereomers (Scheme 5.14). 

The final optimized protocol involved the formation of the imine in toluene using titanium ethoxide as the Lewis acid, followed by quenching with water and filtering off the titanium oxide products. The resulting imine solution was then reduced to provide 10 1 diastereoselectivity. This... 

Fig. 3a-c. SEM images of macroporous titania samples synthesized from alkoxides at various dilution levels. The fractions of titanium ethoxide (TET) in ethanol are a 100% TET b 43% TET c 14% TET. The scale bar shown corresponds to all of the images. Reprinted in part with permission from [21], Copyright 1999 American Chemical Society... 

Powders of metal oxides, sulfides, chlorides, etc., containing uniform particles can be prepared by chemical reactions in aerosols. For example, uniform powders of titanium dioxide are obtained when the aerosol droplets of titanium ethoxide, Ti(OC2H5)4 or titanium... 

Bulky secondary or tertiary alkoxy groups tend to prevent oligomerization, and the steric hindrance of alkoxy ligands appears to be a major parameter. Oligomeric species [Ti(OEt)4]n (n = 2 or 3) have been evidenced for titanium ethoxide whereas Ti(OiPr)4 and Ti(OtAm)4 remain monomeric (Fig. 1). 

Their structure appears to be closely related to that of the corresponding polyanions formed in aqueous solutions. The first hydrolysis product (h = 0.6) of titanium ethoxide, for instance Ti7O4(OEt)20, contains [TivOaa] units isostructural with [29]. Larger species, such as Tiio08(OEt)24 (h =... 

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