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Titanium reactions

Among the appHcations of lower valent titanium, the McMurry reaction, which involves the reductive coupling of carbonyl compounds to produce alkenes, is the most weU known. An excellent review of lower valent titanium reactions is available (195). Titanium(II)-based technology is less well known. A titanium(II)-based complex has been used to mediate a stetio- and regio-specific reduction of isolated conjugated triple bonds to the corresponding polyenes (196). [Pg.153]

A more effective control of both simple diastereoselectivity and induced stereoselectivity is provided by the titanium enolate generated in situ by transmetalation of deprotonated 2,6-dimethylphenyl propanoate with chloro(cyclopentadienyl)bis(l,2 5,6-di-0-isopropylidene-a-D-glucofuranos-3-0-yl)titanium. Reaction of this titanium enolate with aldehydes yields predominantly the. yyw-adducts (syn/anti 89 11 to 97 3). The chemical yields of the adducts are 24 87% while the n-u-products have 93 to 98% ee62. [Pg.475]

Conditions. Table II provides temperature, pressure, and other conditions for the experiments. The surface area/volume ratio for all experiments was 2.7 x 103 cm 1. The hydrothermal apparatus was a Dickson-type sampling autoclave with a gold-titanium reaction cell, a gold-lined sampling tube, and a titanium sampling valve block (11). Samples of the reacting fluid could be taken over time without disturbing the pressure-temperature conditions of a run. The autoclaves were rocked 180 at about 4 cycles/min. [Pg.181]

Asymmetric aldol reactions5 (11, 379-380). The lithium enolate of the N-propionyloxazolidinone (1) derived from L-valine reacts with aldehydes with low syn vs. anti-selectivity, but with fair diastereofacial selectivity attributable to chelation. Transmetallation of the lithium enolate with ClTi(0-i-Pr)3 (excess) provides a titanium enolate, which reacts with aldehydes to form mainly the syn-aldol resulting from chelation, the diastereomer of the aldol obtained from reactions of the boron enolate (11, 379-380). The reversal of stereocontrol is a result of chelation in the titanium reaction, which is not possible with boron enolates. This difference is of practical value, since it can result in products of different configuration from the same chiral auxiliary. [Pg.257]

Essentially this method solves the problems of the bomb lining, in this case calcium fluoride and of titanium reaction with the iron wall. This compoimd, because of its low melting point (1300° C.), which is many hundred degrees below that of either titanium or zirconium, would melt if it had to contain the pure fused metals. However, the zinc alloys with 20 to 30% zinc melt below 1300° C., thus making possible the use of calcium fluoride as a liner for the bombs. [Pg.148]

Carlson, O.N., D.W. Bare, E.D. Gibson, and F.A. Schmidt, 1959, Survey of the Mechanical Properties of Yttrium and Yttrium Alloys, in Symposium on Newer Metals, A.S.T.M. Special Technical Publication No. 272 (American Society for Testing Materials, Philadelphia), pp. 144-159. Yttrium prepared by reduction of YF3 with calcium in the presence of magnesium (intermediate alloy process) in a titanium reaction vessel. [Pg.598]

The reaction uses a fixed-bed vanadium pentoxide-titanium dioxide catalyst which gives good selectivity for phthalic anhydride, providing temperature is controlled within relatively narrow limits. The reaction is carried out in the vapor phase with reactor temperatures typically in the range 380 to 400°C. [Pg.332]

Besides stmctural variety, chemical diversity has also increased. Pure silicon fonns of zeolite ZSM-5 and ZSM-11, designated silicalite-l [19] and silicahte-2 [20], have been synthesised. A number of other pure silicon analogues of zeolites, called porosils, are known [21]. Various chemical elements other than silicon or aluminium have been incoriDorated into zeolite lattice stmctures [22, 23]. Most important among those from an applications point of view are the incoriDoration of titanium, cobalt, and iron for oxidation catalysts, boron for acid strength variation, and gallium for dehydrogenation/aromatization reactions. In some cases it remains questionable, however, whether incoriDoration into the zeolite lattice stmcture has really occurred. [Pg.2782]

Stereoselectivities of 99% are also obtained by Mukaiyama type aldol reactions (cf. p. 58) of the titanium enolate of Masamune s chired a-silyloxy ketone with aldehydes. An excess of titanium reagent (s 2 mol) must be used to prevent interference by the lithium salt formed, when the titanium enolate is generated via the lithium enolate (C. Siegel, 1989). The mechanism and the stereochemistry are the same as with the boron enolate. [Pg.62]

Conventional synthetic schemes to produce 1,6-disubstituted products, e.g. reaction of a - with d -synthons, are largely unsuccessful. An exception is the following reaction, which provides a useful alternative when Michael type additions fail, e. g., at angular or other tertiary carbon atoms. In such cases the addition of allylsilanes catalyzed by titanium tetrachloride, the Sakurai reaction, is most appropriate (A. Hosomi, 1977). Isomerization of the double bond with bis(benzonitrile-N)dichloropalladium gives the y-double bond in excellent yield. Subsequent ozonolysis provides a pathway to 1,4-dicarbonyl compounds. Thus 1,6-, 1,5- and 1,4-difunctional compounds are accessible by this reaction. [Pg.90]

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... [Pg.124]

Several structures of the transition state have been proposed (I. D. Williams, 1984 K. A. Jorgensen, 1987 E.J. Corey, 1990 C S. Takano, 1991). They are compatible with most data, such as the observed stereoselectivity, NMR measuiements (M.O. Finn, 1983), and X-ray structures of titanium complexes with tartaric acid derivatives (I.D. Williams, 1984). The models, e. g., Jorgensen s and Corey s, are, however, not compatible with each other. One may predict that there is no single dominant Sharpless transition state (as has been found in the similar case of the Wittig reaction see p. 29f.). [Pg.124]

The bimetallic mechanism is illustrated in Fig. 7.13b the bimetallic active center is the distinguishing feature of this mechanism. The precise distribution of halides and alkyls is not spelled out because of the exchanges described by reaction (7.Q). An alkyl bridge is assumed based on observations of other organometallic compounds. The pi coordination of the olefin with the titanium is followed by insertion of the monomer into the bridge to propagate the reaction. [Pg.493]

Polypropylene polymerized with triethyl aluminum and titanium trichloride has been found to contain various kinds of chain ends. Both terminal vinylidene unsaturation and aluminum-bound chain ends have been identified. Propose two termination reactions which can account for these observations. Do the termination reactions allow any discrimination between the monometallic and bimetallic propagation mechanisms ... [Pg.493]

These reactions appear equally feasible for titanium in either the monometallic or bimetallic intermediate. Thus they account for the different types of end groups in the polymer, but do not differentiate between propagation intermediates. [Pg.495]

Dialkylaminoethyl acryhc esters are readily prepared by transesterification of the corresponding dialkylaminoethanol (102,103). Catalysts include strong acids and tetraalkyl titanates for higher alkyl esters and titanates, sodium phenoxides, magnesium alkoxides, and dialkyitin oxides, as well as titanium and zirconium chelates, for the preparation of functional esters. Because of loss of catalyst activity during the reaction, incremental or continuous additions may be required to maintain an adequate reaction rate. [Pg.156]

Long-chain esters of pentaerythritol have been prepared by a variety of methods. The tetranonanoate is made by treatment of methyl nonanoate [7289-51-2] and pentaerythritol at elevated temperatures using sodium phenoxide alone, or titanium tetrapropoxide in xylene (12). PhenoHc esters having good antioxidant activity have been synthesized by reaction of phenols or long-chain aUphatic acids and pentaerythritol or trimethyl olpropane (13). [Pg.464]

Tin reacts completely with fluorine above 190°C to form tin tetrafluoride [7783-62-2] SnF. Titanium reacts appreciably above 150°C at a rate dependent on the size of the particles the conversion to titanium tetrafluoride [7783-63-3] TiF, is complete above 200°C. Fluorine reacts with zirconium metal above 190°C. However, the formation of a coating of zirconium tetrafluoride [7783-64 ] ZrF, prevents complete conversion, the reaction reaching... [Pg.123]


See other pages where Titanium reactions is mentioned: [Pg.339]    [Pg.267]    [Pg.4913]    [Pg.637]    [Pg.4912]    [Pg.162]    [Pg.411]    [Pg.208]    [Pg.220]    [Pg.778]    [Pg.339]    [Pg.267]    [Pg.4913]    [Pg.637]    [Pg.4912]    [Pg.162]    [Pg.411]    [Pg.208]    [Pg.220]    [Pg.778]    [Pg.283]    [Pg.1942]    [Pg.2902]    [Pg.424]    [Pg.44]    [Pg.94]    [Pg.134]    [Pg.191]    [Pg.53]    [Pg.261]    [Pg.51]    [Pg.78]    [Pg.488]    [Pg.504]    [Pg.140]   
See also in sourсe #XX -- [ Pg.107 ]

See also in sourсe #XX -- [ Pg.25 , Pg.275 ]

See also in sourсe #XX -- [ Pg.451 ]

See also in sourсe #XX -- [ Pg.691 ]




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Acrylate titanium tetrachloride reaction

Addition reactions titanium enolates

Aldol reactions Titanium chloride

Aldol reactions With titanium enolates

Aldol reactions chloro ] titanium

Aldol reactions titanium enolates

Aldol-type reactions Titanium chloride

Allyl titanium complexes, reaction with

Ammonium titanium fluoride reaction with

Ammonium titanium fluoride reaction with zeolites

Boron titanium carbide, reaction

Carbonyl coupling reaction titanium induced

Carboxylic acids, syn-a-methyl-p-hydroxyaldol reaction titanium enolates, chiral auxiliary

Chiral titanium catalyst, Diels-Alder reaction

Conjugate addition reactions Titanium chloride

Cyclopentadienyl-titanium reaction

Diels-Alder reactions titanium

Furan, 2,5-bis reaction with carbonyl compounds titanium tetrachloride catalyst

Gold on titanium dioxide—the hydrogen-oxygen reaction

Imines reactions with allenic titanium reagents

Intramolecular addition reactions Titanium chloride

Iron—titanium bonds reactions with

Ketones syn selective aldol reaction, titanium enolates

Lewis acids titanium enolate aldol reactions

Mannich reaction titanium tetrachloride mediated

Mesoporous titanium silicates epoxidation reactions

Mukaiyama aldol reaction Titanium chloride

Natural Product Synthesis via Titanium Enolate Aldol Reactions

Oxidation reactions titanium tetrachloride

Oxidation reactions titanium-catalysed

Oxidation reactions, transition-metal Sharpless titanium

Reactions Catalyzed by Titanium and Zirconium(IV) Complexes

Reactions of niobium-containing met-cars and titanium carbide clusters with acetone

Reactions with allenic titanium reagents

Reactions with allenylsilanes titanium tetrachloride

Reduction reactions Titanium chloride

Reduction reactions titanium-catalysed

Sakurai reaction Titanium chloride

Tebbe reaction titanium-stabilized methylenation

Tetrakis titanium, reactions

Tetrakis titanium, reactions with amides

Titania titanium compound reaction

Titanium Lewis Acids in Radical Reactions

Titanium Strecker reaction

Titanium Tebbe reaction

Titanium Tetraisopropoxide asymmetric epoxidation reactions

Titanium aldol type reactions

Titanium alkoxides alcoholysis reactions

Titanium atoms, reactions

Titanium catalysts aldol reactions

Titanium catalysts reactions

Titanium catalysts sulfoxidation reactions

Titanium chloride reaction with, phosgene

Titanium chlorides, Reformatsky reactions

Titanium complexes hydrolysis reactions

Titanium complexes ligand metathesis reactions

Titanium complexes metathesis reactions

Titanium complexes organic reactions

Titanium complexes reaction with dioxygen

Titanium complexes reactions

Titanium complexes reactions with carbonyl compounds

Titanium complexes reduction reactions

Titanium complexes water exchange reaction

Titanium complexes, electron-transfer reactions

Titanium complexes, electron-transfer reactions alkyls

Titanium complexes, reaction with

Titanium complexes, reaction with carbon

Titanium complexes, reaction with carbon alkyls

Titanium complexes, reaction with carbon allyl

Titanium complexes, reaction with carbon dioxide

Titanium complexes, reaction with pyridines

Titanium compounds intermolecular reactions

Titanium compounds use in intermolecular pinacol coupling reactions

Titanium compounds use in intramolecular pinacol coupling reactions

Titanium compounds use in pinacol coupling reactions

Titanium dioxide nickel reaction

Titanium dioxide reactions

Titanium homoenolates reactions

Titanium imido complexes, reaction with

Titanium inflammatory reactions

Titanium insertion reactions

Titanium ions, reactions

Titanium nitric acid, fuming, reaction with

Titanium oxidation reactions

Titanium oxide reaction with

Titanium oxygen abstraction reactions

Titanium photo-oxidation reactions

Titanium reaction layer from

Titanium reaction with, phosgene

Titanium reactions with

Titanium reductive coupling reactions

Titanium silicalite reactions

Titanium silicalite selective oxidation reactions

Titanium silicate molecular sieves oxidation reactions

Titanium silicates catalytic reactions

Titanium silicates reactions

Titanium tartrate asymmetric epoxidation, reaction variables

Titanium tetrabromide, reaction

Titanium tetrachloride Diels-Alder reaction

Titanium tetrachloride Diels-Alder reaction catalysts

Titanium tetrachloride Knoevenagel reaction

Titanium tetrachloride Mukaiyama reaction

Titanium tetrachloride allylsilane reactions

Titanium tetrachloride allylsilane reactions with acetals

Titanium tetrachloride allylsilane reactions, diastereoselectivity

Titanium tetrachloride allylstannane reactions with carbonyl compounds

Titanium tetrachloride catalyzed reaction

Titanium tetrachloride exchange reactions

Titanium tetrachloride glycolacetal reactions with allylsilanes

Titanium tetrachloride reactions with carbonyl compounds

Titanium tetrachloride, reaction

Titanium tetrachloride, reaction allyl silanes

Titanium tetrachloride, reaction with

Titanium tetrachloride, reaction with orthoacetate

Titanium tetrachloride, reaction with orthoesters

Titanium tetrachloride, reaction with rearrangement of orthoesters

Titanium tetraisopropoxide enantioselective reactions

Titanium tetraisopropoxide methanol reaction

Titanium tetraisopropoxide reaction with aldehydes

Titanium trichloride Wurtz reaction

Titanium vapours, reaction with

Titanium, ally 1heterosubstituted reactions with carbonyl compounds

Titanium, allylheterosubstituted reactions with carbonyl compounds

Titanium, chlorotris reaction with aldehydes

Titanium, chlorotris reaction with aldehydes diastereoselectivity

Titanium, cyclopentadienyldialkoxyenolates enantioselective aldol reaction

Titanium, methyl reactions with carbonyl compounds

Titanium, methylchiral ligands reactions with aromatic aldehydes

Titanium, phenylchiral ligands reactions with aromatic aldehydes

Titanium, trialkoxyenolates aldol reaction, syn stereoselectivity

Titanium, trichloroenolates stereochemistry of reaction

Titanium, trichloromethylproperties reaction with 2-benzyloxy-3-pentanone

Titanium, trichloromethylproperties reaction with carbonyl compounds

Titanium, triisopropoxyenolates aldol reaction, syn.anti selectivity

Titanium, tris enolates aldol reaction, syn stereoselectivity

Titanium, tris enolates aldol reaction, syn.anti selectivity

Titanium, tris methylproperties reaction with alkoxy ketones

Titanium, tris methylproperties reaction with carbonyl compounds

Titanium-Binol catalyst Keck allylation reaction

Titanium-Binol catalyst asymmetric reactions

Titanium-catalysed Miscellaneous Reactions

Titanium-catalysed reactions

Titanium-catalysed reactions alkene metallation

Titanium-catalysed reactions reagent

Titanium-catalyzed Grignard exchange reaction

Titanium-catalyzed reactions

Titanium-induced intramolecular carbonyl coupling reactions

Titanium-induced reactions

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