Titanium isopropoxide

Titanium Alkoxides. Titanium alkoxides are made from titanium tetrachloride and the corresponding alcohols in the presence of ammonia. Higher titanium alkoxides are manufactured from lower alkoxides by alcoholysis. Titanium isopropoxide and -butoxide are commercially available in barrels. Annual production of titanium alkoxides is estimated at 3000—4000 metric tons at an average price of about 4/kg. 

The Sharpless-Katsuki asymmetric epoxidation reaction (most commonly referred by the discovering scientists as the AE reaction) is an efficient and highly selective method for the preparation of a wide variety of chiral epoxy alcohols. The AE reaction is comprised of four key components the substrate allylic alcohol, the titanium isopropoxide precatalyst, the chiral ligand diethyl tartrate, and the terminal oxidant tert-butyl hydroperoxide. The reaction protocol is straightforward and does not require any special handling techniques. The only requirement is that the reacting olefin contains an allylic alcohol. 

Bismuth titanate (Bi4Ti30i2) by reacting triphenyl bismuth, Bi(C5H5)3 and titanium isopropoxide at 600-800°C and 5 Torr. 

Strontium titanate (SrXi03) by reacting titanium isopropoxide and a strontium beta-diketonate complex at 600-850°C and 5 Xorr. 

Another ferroelectric material is bismuth titanate, (Bi4Ti30i2), which is deposited from triphenyl bismuth, Bi(C5H5)3, and titanium isopropoxide at low pressure (5 Torr) and at temperatures of 600-800°C.[43]... 

Strontium titanate (SrTi03) has a large dielectric constant of 12, and a high refractive index with potential opto-electronic applications. It is deposited by MOCVD from titanium isopropoxide and a strontium beta-diketonate complex at 600-850°C and 5 Torr.t" " ... 

Nanoparticles of the semicondnctor titanium dioxide have also been spread as mono-layers [164]. Nanoparticles of TiOi were formed by the arrested hydrolysis of titanium iso-propoxide. A very small amount of water was mixed with a chloroform/isopropanol solution of titanium isopropoxide with the surfactant hexadecyltrimethylammonium bromide (CTAB) and a catalyst. The particles produced were 1.8-2.2 nm in diameter. The stabilized particles were spread as monolayers. Successive cycles of II-A isotherms exhibited smaller areas for the initial pressnre rise, attributed to dissolution of excess surfactant into the subphase. And BAM observation showed the solid state of the films at 50 mN m was featureless and bright collapse then appeared as a series of stripes across the image. The area per particle determined from the isotherms decreased when sols were subjected to a heat treatment prior to spreading. This effect was believed to arise from a modification to the particle surface that made surfactant adsorption less favorable. 

This method has proven to be an extremely useful means of synthesizing enantiomeri-cally enriched compounds. Various improvements in the methods for carrying out the Sharpless oxidation have been developed.56 The reaction can be done with catalytic amounts of titanium isopropoxide and the tartrate ligand.57 This procedure uses molecular sieves to sequester water, which has a deleterious effect on both the rate and enantioselectivity of the reaction. 

Interaction of anhydrous hydrazine and titanium isopropoxide is explosive at 130° C in absence of solvent. Evaporation of solvent ether from the reaction product of tetrakis(dimethylamino)titanium and anhydrous hydrazine caused an explosion, attributed to formation and ignition of dimethylamine. /V-Metal derivatives may also have been formed. 

The original epoxidation with titanium-tartrate is homogeneous, but it can be carried out heterogeneously without diminishing enantioselectivity by using titanium-pillared montmorillonite catalyst (Ti-PILC) prepared from titanium isopropoxide, (+)-DAT, and Na+-montmorillonite.38 Due to the limited spacing of Ti-PILC, the epoxidation becomes slower as the allylic alcohol gets bulkier. 

Gagliardi, C. D. Dunuwila, D. Van Vlierberge-Torgerson, B. A. Berglund, K. A. 1992. Reaction kinetics for the hydrolysis of titanium isopropoxide carboxylate complexes. In Better Ceramics Through Chemistry V, edited by Hampden-Smith, M. J. Klemperer, W. G. Brinker, C. J. Mat. Res. Soc. Symp. Proc. 271 257-262. 

Mikami and co-workers16-19 have done extensive work for developing catalysts for the asymmetric carbonyl-ene reaction. Excellent enantioselectivites are accessible with the binol-titanium catalyst 17 (Equation (10)) for the condensation of 2-methyl butadiene (R1 = vinyl) and glyoxalates (binol = l,T-binaphthalene-2,2 -diol).16 The products were further manipulated toward the total synthesis of (i )-(-)-ipsdienol. The oxo-titanium species 18 also provides excellent enantioselectivity in the coupling of a-methyl styrene with methyl glyoxalate.17 Reasonable yields and good enantioselectivites are also obtained when the catalyst 19 is formed in situ from titanium isopropoxide and the binol and biphenol derivatives.18... 

Since its discovery in 1980,7 the Sharpless expoxidation of allylic alcohols has become a benchmark classic method in asymmetric synthesis. A wide variety of primary allylic alcohols have been epoxidized with over 90% optical yield and 70-90% chemical yield using TBHP (r-BuOOH) as the oxygen donor and titanium isopropoxide-diethyl tartrate (DET, the most frequently used dialkyl tartrate) as the catalyst. One factor that simplifies the standard epoxidation reaction is that the active chiral catalyst is generated in situ, which means that the pre-preparation of the active catalyst is not required. 

Direct hydrothermal synthesis. Prepared using titanium isopropoxide (triethanolaminato) and TEOS as the sources of Ti and Si, respectively, and the Gemini-type surfactant 18-12-18 or cetyl-benzyl dimethylammonium chloride (CBDAC) as a template. In the grafting method, silicious MCM-48 first prepared and then the dry surface grafted with titanium isopropoxide... 

Ti-SBA-15 Grafting method. SBA-15 prepared first using the amphiphilic triblock copolymer poly(ethyleneox-ide) -poly (propyleneoxide) -poly (ethyleneoxide) (EO-PO-EO) as template and TEOS as Si source. The composition was 2 g copolymer 0.021 mol TEOS 0.12 mol HC1 3.33 mol H20. The solid was calcined at 600 K for 4 h to remove the copolymer. Ti in the form of titanium isopropoxide was grafted onto the dehydrated surface of SBA-15 Pore diameter = 6.3 nm, surface area = 518 m2/g, pore volume = 0.68 (25)... 

Incipient wetness method. For every 1 g of SBA-15, varying amounts of titanium isopropoxide in 10 g of ethanol were used for impregnation. The titanium concentration in the solution varies from 0.05 to 5 M, depending on the desired titanium loading. The impregnated material was dried and calcined at 723 K for 5 h. 0.6-36 (XPS) Pore size = 4.2-5.1 nm, specific surface area = 690-997 m2/g, volume = 0.81-1.17 cm3/g (27)... 

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