Titanium tetrakis

The first practical method for asymmetric epoxidation of primary and secondary allylic alcohols was developed by K.B. Sharpless in 1980 (T. Katsuki, 1980 K.B. Sharpless, 1983 A, B, 1986 see also D. Hoppe, 1982). Tartaric esters, e.g., DET and DIPT" ( = diethyl and diisopropyl ( + )- or (— )-tartrates), are applied as chiral auxiliaries, titanium tetrakis(2-pro-panolate) as a catalyst and tert-butyl hydroperoxide (= TBHP, Bu OOH) as the oxidant. If the reaction mixture is kept absolutely dry, catalytic amounts of the dialkyl tartrate-titanium(IV) complex are suflicient, which largely facilitates work-up procedures (Y. Gao, 1987). Depending on the tartrate enantiomer used, either one of the 2,3-epoxy alcohols may be obtained with high enantioselectivity. The titanium probably binds to the diol grouping of one tartrate molecule and to the hydroxy groups of the bulky hydroperoxide and of the allylic alcohol... 

Organic titanates can be used to cross-link sUicones on leather (49). Tetrabutyltitanate and tetrakis( P-aminoethoxy)titanium cross-link sUicones, eg, poly(dimethyl sUoxane), to iacrease both water repeUency and durabUity. For example, good repeUency results from the impregnation of leather with a solution of 10 wt % tetrabutyltitanate ia butyl acetate, foUowed by impregnation with a 9 1 mixture of sUicones and tetrabutyltitanate (50). 

Titanium tetrakis(diethylamide) selectively adds to aldehydes in the presence of ketones and to the least hindered ketone in compounds containing more than one ketone. The protection is in situ, which thus avoids the usual protection-deprotec-tion sequence. Selective aldol and Grignard additions are readily performed employing this protection methodology. ... 

Tetrakis(diethylamino) titanium [(titanium tetrakis(diethylamide)] [4419-47-0] M 336.4, b 85-90"/0.1mm, 112"/0.1mm, d 0.93, n p 1.54. Dissolve in C6H6, filter if a solid separates, evaporate under reduced pressure and distil. Orange liquid which reacts violently with alcohols. [7 Chem Soc 3857 I 960.]... 

A reagent more reactive than tris(dimethylamino)arsine employed by Weingarten and White 39) was tetrakis(dimethylamino)titanium (145). With this compound it was possible to prepare N,N-dimethyl(l-isopropyl-2-methylpropcnyl)amine (147) from diisopropyl ketone. Weingarten and White 39) have suggested a possible mechanism for this reaction (see p. 88). If benzaldehyde 39,111), formaldehyde 111), or acetaldehyde 39) is used, the corresponding gem diamine or aminal (143) is formed. 

Since tetrakis(dialkylamino)titanium compounds must be synthesized, White and Weingarten 43) sought a more versatile synthetie pathway. 

Chlorotris(diethylamino)titanium24 is prepared directly from diethylamine, lithium and tilani-um(IV) chloride in the presence of styrene as reducing agent25. However, a metathesis reaction between tetrakis(diethylamino)titanium26 28 and titanium(lV) chloride gives a cleaner product and is thus preferred. Bromotris(diethylamino)titanium is prepared similarly7,29. 

All manipulations are carried out with exclusion of moisture under argon. In a two-necked 250-mL flask under argon, 15.2 g (68 mmol) of tetrakis(dimethylamino)titanium in 20 mL of hexane arc chilled to — 30 nC and a solution of 4.31 g (22.7 mmol) of titanium(IV) chloride in 40 mL of hexane is added dropwise with stirring. After heating the red solution to reflux for 2.5 h. distillation affords an oil which solidifies on standing yield 17.0 g (87%) bp 106-108 °C (0.5Torr). 

Chlorotris(dimethylamino)titanium has the advantage that the starting material, tetrakis(di-methylamino)titanium, is commercially available24. 

Titanium, tetrakis(trimethysilyl)oxy-, 3, 334 Titanium, tetranitrato-stereochemistry, 1,94 Titanium, triaquabis(oxalato)-structure, I, 78 Titanium, tris(acetylacetone)-structurc, 1,65 Titanium alkoxides oligomeric structure, 2,346 synthesis ammonia, 2, 338 Titanium chloride photographic developer, 6,99 Titanium complexes acetylacetone dinuclear, 2, 372 alkyl... 

Reaction of tetrakis-diethylamino titanium (TDEAT) or tetrakis-dimethylamino titanium (TDMAT) with ammonia (NH3) at 300°C in a flow of helium. Possible carbon retention. 

Pyrolysis of tetrakis(dimethylamido)titanium (TDMAT) in nitrogen at 300°C. 

MOCVD Reactions. A great deal of interest has been generated by the availability of two metallo-organic titanium compounds, tetrakis-diethylamino titanium (TDEAT) andtetrakis-dimethylamino titanium (TDMAT). These precursors make possible the deposition of TiN at lower temperature.[ " k l These compounds are liquid at room temperature. A flow of helium bubbling through the warm precursor entrains the vapor into the deposition chamber. Deposition temperature is approximately 320°C. The following reactions occur ... 

Deposition of TiN by the thermal decomposition of tetrakis(dimethylamido)titanium (TDMAT) in a nitrogen atmosphere (as opposed to ammonia) was characterized by a simple Arrhenius rate expression. Adequate deposition rates and good step coverage were achieved for 3/1 aspect ratio holes, 0.40 micron in size. A reactor model was designed,... 

General Considerations. The following chemicals were commercially available and used as received 3,3,3-Triphenylpropionic acid (Acros), 1.0 M LiAlH4 in tetrahydrofuran (THF) (Aldrich), pyridinium dichromate (Acros), 2,6 di-tert-butylpyridine (Acros), dichlorodimethylsilane (Acros), tetraethyl orthosilicate (Aldrich), 3-aminopropyltrimethoxy silane (Aldrich), hexamethyldisilazane (Aldrich), tetrakis (diethylamino) titanium (Aldrich), trimethyl silyl chloride (Aldrich), terephthaloyl chloride (Acros), anhydrous toluene (Acros), and n-butyllithium in hexanes (Aldrich). Anhydrous ether, anhydrous THF, anhydrous dichloromethane, and anhydrous hexanes were obtained from a packed bed solvent purification system utilizing columns of copper oxide catalyst and alumina (ether, hexanes) or dual alumina columns (tetrahydrofuran, dichloromethane) (9). Tetramethylcyclopentadiene (Aldrich) was distilled over sodium metal prior to use. p-Aminophenyltrimethoxysilane (Gelest) was purified by recrystallization from methanol. Anhydrous methanol (Acros) was... 

Metallation of cyclopentadienyl-functionalized silica materials with tetrakis (diethylamino) titanium. 

The cyclopentadienyl-functionalized solid was added to a flask with excess tetrakis (diethylamino) titanium in toluene. The mixture was stirred under reflux for 24 hours. The resulting solid was filtered, washed with toluene, and dried under vacuum at room temperature overnight, and then stored in a drybox. 

See related a-PHENYLAZO HYDROPEROXIDES, ORGANIC PEROXIDES 3842. Tetrakis(pentafluorophenyl)titanium... 

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. 

Chlorophenyllithium, 2139 4-Fluorophenyllithium, 2166 Pentafluorophenylaluminium dibromide, 2053 Pentafluorophenyllithium, 2059 Tetrakis(pentafluorophenyl)titanium, 3842... 

Tetrakis(ethylthio)uranium, 3096 Titanium butoxide, 3730 Titanium(III) methoxide, 1317 Titanium tetraisopropoxide, 3579 Tungsten hexamethoxide, 2604 Zinc ethoxide, 1704... 

S-Donor Ligands. The full account of the crystal and molecular structure of tetrakis-(AfJV-diethyldithiocarbamato)titanium(iv), [Ti(S2CNEt2)4], has been published. The difference in the Ti—= 260.6(8) and Ti—Sg = 252.2(8) pm bond lengths in the trigonal-dodecahedral structure could be due to 7r-donation... 

MCM-41 (1060 30m g ) with a narrow distribution of pore diameters, centered around 3.2 nm, was chosen as support. Tetrakis(neopentyl)titanium, TiNp4 (1), reacts with this support to form =SiO-TiNp3 (2a) and (=SiO)2TiNp2 (2b). The reaction leads to a more important proportion of bis-siloxy surface species, 2b, than on non-porous Aerosil silica (Scheme 2.8). 

Propano1, titanium (4+) salt (546-68-9), 65, 230 Tetrakis(acetonitrile)palladium tetrafluoroborate (21797-13-7),... 

Reaction of tris(dimethylamino)arsine or tetrakis(dimethylamino)-titanium with aldehydes or ketones to give enamines [164, 165]. 

Titanium tetrakis(diethylamide) see tetrakis(diethylamino) titanium. 

DIENES Bcn/.yldtlotobis(Iriphenyl-phosphine)palladium(ll). Copper(I) bromide-Dimethyl sulfide. Palladium(Il) chloride. Tetrakis(triphenyEphosphine)-palladium. Titanium IVichloride-Lithium aluminum hydride. 

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