Isopropoxides isopropanolate

Bao and co-workers also reported enantioselective ring-opening ami-nolysis of epoxide, 93, with benzylamine, 94, catalyzed by the titanium isopropoxide-BINOL-water system (BlNOL=l,l -bi-2-naphthol-96) in toluene (reaction 7.16) [66]. Titanium isopropoxide-isopropanol, 96, system also used by Kim et al. for asymmetric methallylation of ketones (reaction 7.17) with high yield and enantioselectivity [67]. 

The differences in solubility of metal isopropoxides and their alcoholates have led to the crystallization of pure isopropoxide isopropanolates of some tetravalent elements. For example, zirconium tetraisopropoxide is a viscous supercooled liquid which dissolves in excess of isopropyl alcohol and crystallizes out in the form of pure white crystals which were characterized as Zr(OPr )4.Pr OH. Similarly tin tetraisopropoxide and cerium tetraisopropoxide have been obtained as crystalline alcoholates, Sn(OPr )4.Pr OH ° and Ce(OPP)4.Pr OH which were used as the starting materials for the synthesis of a number of new alkoxides. 

Relatively few structures of alkoxo zirconium compounds have been reported. Although a dimeric structme [Zr2(/z-OlV)2(OlV)6(l OH)2] had been proposed for the crystalhne zirconium isopropoxide isopropanolate many years ago the edge-shared bi-octahedral structure was not properly determined by X-ray crystallography until 1990. An interesting feature of this structme is the location of the coordinated isopropanol molecules which are each linked by a hydrogen bond to the terminal... 

In potassium aluminium isopropoxide isopropanolate [(Pr OH)2K(/r-OlV)4Al] the alternating K and A1 atoms are joined by double isopropoxo bridges in a zig-zag linear chain. The two coordinated isopropanols give the potassium a distorted octahedral configuration whilst the A1 is distorted tetrahedral." ... 

S. B. Tyagi, B. Singh, R. N. Kapoor, Reactions of Hafriium(IV) Isopropoxide Isopropanolate with 1,5-Diarylthiocarbazones, Acta Chim. Hungarica, 1986, 722, 229-234. 

NiFe204 Nickel ethylhexano-isopropoxide Isopropanol Acetic acid PVP Li et al. (2003a)... 

Priebsch W., Rehder D. Oxovanadium alkoxides structure, reactivity and vanadium-51 NMR characteristics. Crystal and molecular structures of tris(2-chloroethoxo)oxovanadium and aquadichlorooxobis(tetrahydrofuran) vanadium. Inorg. Chem. 1990 29 3013 Razuvaev GA., Drobotmko V.V. Synthesis and properties of alkoxy derivatives of vanadium R2V(0R )2, J. Organometal. Chem. 1977 131 43 Reuter H., Kremser M. Investigations into tin(IV) alkoxides 1. Crystal and molecular structure of tin(IV) isopropoxide-isopropanol solvate, Sn(0 Pr)4 PrOH. Z. Anorg. AUg. Chem. 1991 598 259... 

In the following preparation to illustrate the Meen.vein-Pormdorf-Verley reduc tion, a solution of benzophenone in isopropanol is rapidly reduced in the presence of aluminium isopropoxide to benzhydrol (CaHs)2CO (C Hj)jCH OH. It is clear that the aluminium isopropoxide must take some essential part in this reaction, for benzophenone when dissolved even in cold isopropanol with a trace of acetic acid is reduced to tetraphenylethyleneglycol (p. 150). 

It is advisable in any case before an experiment to place the weighed aluminium isopropoxide overnight in a shallow dish in a vacuum desiccator over sodium hydroxide. The isopropanol should be dried over anhydrous sodium sulphate, and the clear liquid decanted off before use. 

The powdered isopropoxide and the isopropanol must be dried as described above. 

Place in the flask 2 g. of benzophenone, 15 ml. of isopropanol and 2 5 g. of aluminium isopropoxide. This mixture has now to be heated gently under reflux so that the temperature registered by the thermometer in the column does not exceed 80°, i.e., so that only acetone distils. For this purpose, the flask should preferably be heated in an oil-bath direct heating, even over an asbestos sheet, may cause local overheating and decomposition the use of a water-bath on the other hand may make the column undesirably damp. 

The reduction of thiazole carboxaldehydes with isopropanol and aluminium isopropoxide gives the corresponding alcohols (37, 107, 108). 

Hydrolysis of metal-organic solutions Example. Ba(OC3H7)2 + Ti(OC5Hu)4 + H2O — BaTiOs (Barium isopropoxide and Titanium tertiary amyloxide are refluxed in isopropanol and then hydrolyzed with de-ionized water to produce a sol-gel. ... 

Meerwein-Pondorff reduction is the synthesis of alcohols by heating carbonyl compounds with aluminium isopropoxide in isopropanol and distilling off acetone by-product... 

Deuterium oxide (7.5 ml) is added dropwise to aluminum isopropoxide (25 g.) The mixture is shaken for about 5 min and then warmed to 70° for 10 min to complete the reaction. The resulting deuterioisopropanol is distilled at room temperature and 1 mm pressure into a liquid nitrogen-cooled trap. Redistillation at atmospheric pressure yields pure isopropanol-OD (9.5 g bp 82-83°). All operations must be protected from moisture. 

A mixture of 37.6 g of N-acetyl-L-glutamine and 1.000 ml of water is heated to 40°C, and 900 ml of an isopropanol solution containing 40 g of aluminum isopropoxide isadded to the warm mixture with stirring. The stirring is continued for 10 minutes. The reaction mixture is filtered and the filtrate is concentrated under reduced pressure. Isopropanol is added to the aqueous solution and the salt precipitates in the solution. The precipitates are collected by filtration and upon drying, 48.5 g of the crystalline-like aluminum salt of N-acetyl-L-glutamine are obtained. 

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. 

Dining distillation of 2-propanol recovered from the reduction of crotonaldehyde with isopropanol/aluminium isopropoxide, a violent explosion occurred. This was attributed to peroxidised diisopropyl ether (a possible by-product) or to peroxidised crotonaldehyde. An alternative or additional possibility is that the isopropanol may have contained traces of a higher secondary alcohol (e.g. 2-butanol) which would be oxidised during the Meerwein-Ponndorf reduction procedure to 2-butanone. The latter would then effectively sensitise the isopropanol or other peroxidisable species to peroxidation. 

The catalysts are best prepared in situ by mixing a half-equivalent of the di-chloro-metal aromatic dimer with an equivalent of the ligand in a suitable solvent such as acetonitrile, dichloromethane or isopropanol. A base is used to remove the hydrochloric acid formed (Fig. 35.3). If 1 equiv. of base is used, the inactive pre-catalyst is prepared, and further addition of base activates the catalyst to the 16-electron species. In the IPA system the base is conveniently aqueous sodium hydroxide or sodium isopropoxide in isopropanol, whereas in the TEAF system, triethylamine activates the catalyst. In practice, since the amount of catalyst is tiny, any residual acid in the solvent can neutralize the added base, so a small excess is often used. To prevent the active 16-electron species sitting around, the catalyst is often activated in the presence of the hydrogen donor. The amount of catalyst required for a transformation depends on the desired reaction rate. Typically, it is desirable to achieve complete conversion of the substrate within several hours, and to this extent the catalyst is often used at 0.1 mol.% (with SCR 1000 1). Some substrate-catalyst combinations are less active, requiring more catalyst (e.g., up to 1 mol.% SCR 100 1), in other reactions catalyst TONs of 10000 (SCR 10000 1) have been realized. 

A wide range of aluminum alkoxides can easily be synthesized by the reaction of alcohols with triethylaluminum. These alcohols can even be substituted by compatible functional groups such as bromides, olefins, and tertiary amines (Fig. 10) [20, 21]. An alternative route towards aluminum alkoxides relies on the reaction of the alcohols with aluminum isopropoxide in toluene. Isopropanol (iPr) formed during this reaction is withdrawn by the distillation of the azeotrope made up of toluene and isopropanol [20, 21]. 

Methylethylketone (5 g) solutions of the polymer (10 wt%) was added to isopropanol (0.2732 g) solutions of titanium isopropoxide (0.106 g, 0.3687 mmol) and barium bis-isopropoxide (0.367 g, 0.3687 mmol) the solution was cast onto microscope slides. The polymer film was dried, removed, and hydrolyzed in boiling barium hydroxide solution... 

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