Examinando por Autor "Royo, Beatriz"

Mostrando 1 - 3 de 3

Cyclopentadienyl–Silsesquioxane Titanium Catalysts: Factors Affecting Their Formation and Activity in Olefin Epoxidation with Aqueous Hydrogen Peroxide
(Wiley, 2016-04-20) Ventura, Maria; Tabernero, Vanessa; Cuenca, Tomas; Royo, Beatriz; Jimenez, Gerardo
The reaction of titanium chlorosilyl-substituted cyclopentadienyl (Cp) complexes, Ti(eta(5)-C5H3R'SiMe2Cl)Cl-3 (R' = H, 1b; SiMe3, 1c), with 1 equiv. of various silsesquioxane trisilanols, R7Si7O9(OH)(3) (R = iBu, 2a; Ph, 2b), affords either corner-capped Cp derivatives, Ti(eta(5)-C5H3R'SiMe2Cl)(R7Si7O12-kappa O-3(3)) (R' = H, R = iBu, 5a, Ph, 5b; R' = SiMe3, R = iBu, 7a, Ph, 7b), or cyclopentadienyl-silsesquioxane complexes, Ti(eta(5)-C5H4SiMe2OR7Si7O11 kappa O-2(2)) Cl (R' = H, R = iBu, 6a, Ph, 6b; R' = SiMe3, R = iBu, 8a, Ph, 8b), depending on the reaction conditions. In any case, upon heating, kinetic products 5 and 7 are transformed into the corresponding thermodynamic products 6 and 8, respectively. The electron-donating ability of the Cp ring is a relevant controlling parameter: a strong p-donor character facilitates the isomerization process. In addition, the nature of the silicon substituents in the silsesquioxane framework, the type of solvent, and the reaction temperature are also factors that significantly affect this process. Cyclopentadienyl-silsesquioxane complexes 6b and 8b are efficient and selective catalysts for epoxidation with aqueous hydrogen peroxide under mild conditions. Such a catalytic efficiency is attributed to the hydrophobic environment generated about the titanium atom by the Cp ring incorporated into the cyclopentadienyl-silsesquioxane ligand
Cyclopentadienyl-silsesquioxane titanium complexes: Highly active catalysts for epoxidation of alkenes with aqueous hydrogen peroxide
(American Chemical Society, 2012-05-17) Ventura, Maria; Gonzalez Mosquera, Marta Elena; Cuenca, Tomas; Royo, Beatriz; Jimenez, Gerardo
Titanium complexes bearing an unprecedented tridentate cyclopentadienyl−silsesquioxanate ligand provide a new class of efficient and selective catalysts for epoxidation of olefins with aqueous hydrogen peroxide under homogeneous conditions.
Selective sulfoxidation with hydrogen peroxide catalysed by a titanium catalyst
(Royal Society of Chemistry, 2014-08-21) Postigo, Lorena; Ventura, Maria; Cuenca, Tomás; Jimenez, Gerardo; Royo, Beatriz
A moisture-tolerant cyclopentadienyl-silsesquioxane titanium complex efficiently catalyses the selective oxidation of various types of sulfides to either sulfoxides (TOFs up to 32 530 h(-1)) or sulfones with H2O2 (30% in water) under mild conditions.