Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Trimethylsilylmethyl compounds

Methyl, butyl, or trimethylsilylmethyl compounds of Na, K, Rb, or Cs can be used to generate other organometallic compounds by alkyl group exchange. [Pg.270]

G. Yagupsky, W. Mowat, A. Shortland, and G. Wilkinson, Trimethylsilylmethyl Compounds of Transition Metals, Chem. Comm. 1970, 1369-1370. [Pg.327]

K. Mertis, D. H. Williamson, and G. Wilkinson, Synthesis and Properties of Oxorhe-nium(VI) Methyl and Trimethylsilylmethyl Compounds, J. Chem. Soc., Dalton Trans. 1975, 607-611. [Pg.330]

For example, data representing the kinetics of polymerization with the Cr(II) trimethylsilylmethyl compound are shown in Figure 183. The alumina support was first treated with fluoride and calcined at 600 °C, and then it was impregnated with three different loadings of the chromium compound, which actually exists as a tetramer, Cr4(TMSM)8 [660]. These catalysts were then tested for ethylene polymerization, and the observed activity was found to be roughly proportional to the chromium coverage. [Pg.456]

Ionic systems - less susceptible to deleterious dimerization - are accessible with a Judicious choice of ancillary ligand. The /3-diketoiminate scandium dimethyl complex (7) (Figure 11 Ar = 2,6-diisopropylphenyl), activated by B(C6Fs)3 leads to a structurally characterizable ionic complex which polymerizes ethylene. The neutral 1,4,7-triazocyclononane ligand was used to prepare a scandium trimethyl complex (8), which polymerizes ethylene when B(CeF5)3 is used as a cocatalyst. A derivative pendant amide arm leads to the yttrium bis (trimethylsilylmethyl) compound (9), which exhibits modest activity in the presence of [HNMe2Ph][B(C6F5)4l.= ... [Pg.3208]

The mechanism involves initial nucleophilic attack by the trimethylsilyl compound on the electrophilic sulfur atom of trimethylsilyl chlorosulfonate 459 with loss of trimethylsilyl chloride. In the second step, the initially formed trimethylsilyl sulfonate is hydrolysed to the corresponding sulfonic acid (Scheme 14). Chlorosulfonic acid reacts as a nucleophile with certain trimethylsilylmethyl compounds with regioselective cleavage of the silicon-carbon (sp hybridized) bond. For instance, trimethylsilylmethyl chloride 461 with chlorosulfonic acid afforded the compound 462, which on heating gave the compounds 463-465 (Scheme 15). °... [Pg.124]

Dialkyl zinc compounds form phosphine complexes of formula RZnP(SiMe3)2 on addition of one equivalent of bis(trimethylsilyl)phosphine. Solution and solid-state studies showed that the complexes are dimeric or trimeric in solution or the solid state. Bis(trimethylsilyl)phosphido-methylzinc crystallizes as a trimeric molecule with a Zn3P3 core in the twist-boat conformation. Bis(trimethylsilyl)phosphido- -butylzinc, shows a similar central Zn3P3 fragment. The sterically more demanding trimethylsilylmethyl substituent forms a dimeric species of bis(trimethylsilyl) phosphido-trimethylsilylmethylzinc. Solution studies of bis(trimethylsilyl)phosphido- .vo-propyl-zinc demonstrate a temperature-dependent equilibrium of the dimeric and trimeric species and the crystalline state contains a 1 1 mixture of these two oligomers. A monomeric bis(trimethyl-silyl)phosphido-tris(trimethylsilyl)methylzinc has also been synthesized.313... [Pg.1170]

Synthesis and Characterization. Tris(trimethylsilylpropyl)tin fluoride (PTF) and tris(trimethylsilylmethyl)tin fluoride (MTF) were synthesized according to scheme A (Figure 1) while scheme B (Figure 1) was followed in the synthesis of dibutyl-(trimethylsilylpropyl)tin fluoride (BTF). MTF has been reported in the literature (6) however, it was synthesized to compare its solution properties with the other two novel compounds. The steps involved in these syntheses were straight-forward and thus need no elaboration. In the synthesis of BTF, the unsymmetrical triorganotin fluoride, bromination of tetraorganotin compound resulted... [Pg.531]

Addition reactions such as A-alkylation do not occur readily, and trimethylsilylmethylation of 3,4-diphenyl-l,2,5-thiadiazole 8 with trimethylsilylmethyl trifluoromethanesulfonate at 80°C occurred at N-2 < 1999J(P1) 1709>. The electron-rich 3-hydroxy-l,2,5-thiadiazole can be preferentially methylated on N-2 using trimethyl orthoacetate in toluene to afford the 2-methyl-l,2,5-thiadiazol-3-one in 69% yield <2002EJ01763>, although a mixture of 3-hydroxythiadiazole and neat trimethyl orthoacetate showed a 20 80 ratio of N- versus 0-alkylation products by H NMR. Treatment of 3-hydroxy-l,2,5-thiadiazole with /-butyl acetate under acid catalysis (Amberlyst 15) gave almost exclusively the A-alkylated compound <2002BMC2259>. [Pg.528]

Similarly, Hosomi and co-workers (15) reported isothioureas as azomethine ylide equivalents. Both A-substituted and A-unsubstituted A-(trimethylsilylmethyl)-isothiourea precursors underwent cycloaddition reactions with carbonyl compounds, when treated with stoichiometric CsF to deliver a range of 2-iminooxazolidine derivatives. Typically, 63 (R = CN, R = H) furnished adduct... [Pg.179]

For A-(trimethylsilylmethyl)-5-methylisothioureas 262, cycloaddition with carbonyl compounds results in 2-aminooxazolines 263. ° Aliphatic and aromatic aldehydes and ketones can be employed successfully. However, reaction with ketones appears to be poor. Ylide generation with CsF is the method of choice although TBAF and KF have also been used but with lower yields. A polar solvent such as MeCN, DMF, or hexamethylphosphoric triamide (HMPA) is required for a succesful reaction (Scheme 8.73). [Pg.408]

Stabilized compounds are inherently more stable then those compounds, which contain /1-hydrogens. Therefore, catalysts where the -positions are blocked, are preferred (8). Examples are zirconium tetrakis(trimethylsilylmethyl) or hafnium tetrakis(trimethylsil-ylmethyl). Catalyst supports are porous alumina with an amount of 0.5% of silica. [Pg.78]

This route has, for example, been used to make the butyl compounds.15 The trimethylsilylmethyl derivatives have also been made1617 they can be precipitated from cyclohexane, washed free from organomercury starting materials, and obtained without organometal-alkoxide contaminants. Alternatively, KCH2SiMe3 may be used in situ, e.g., for metallation of alkenes.18... [Pg.270]

Trimethylsilylmethyl derivatives of the heavier alkali metals have been used in the synthesis of other organometallic compounds.61617,45 but so far there do not appear to be any reports of structure determinations. [Pg.280]

Many other organochromium compounds have since been synthesized and found to be active, including those with chromium exhibiting every valence up to Cr (IV). Chromocene is a well-studied example of an active divalent compound (52-55). Pentadiene-Cr(II) (56) is another, along with allyl-Cr(II) (52, 57). Allyl-Cr(III) is also active (52, 57-61). -Stabilized alkyls of Cr(II) and Cr(IV) such as trimethylsilylmethyl-Cr(IV), which also polymerizes ethylene when supported on an oxide carrier, have been synthesized and tested in this laboratory (57,62). All these organochromium catalysts are comparable in activity to the Cr(VI)/silica standard. [Pg.58]


See other pages where Trimethylsilylmethyl compounds is mentioned: [Pg.328]    [Pg.82]    [Pg.299]    [Pg.301]    [Pg.328]    [Pg.82]    [Pg.299]    [Pg.301]    [Pg.227]    [Pg.311]    [Pg.999]    [Pg.300]    [Pg.791]    [Pg.315]    [Pg.315]    [Pg.316]    [Pg.316]    [Pg.319]    [Pg.322]    [Pg.452]    [Pg.119]    [Pg.490]    [Pg.68]    [Pg.136]    [Pg.945]    [Pg.93]    [Pg.195]    [Pg.247]    [Pg.401]    [Pg.443]    [Pg.388]    [Pg.55]    [Pg.153]    [Pg.623]    [Pg.388]    [Pg.270]    [Pg.412]   
See also in sourсe #XX -- [ Pg.3 , Pg.12 , Pg.219 ]




SEARCH



Trimethylsilylmethyl

Trimethylsilylmethylation

© 2024 chempedia.info