Strategies for copper bis(oxazoline) immobilization onto porous silica based materials
authors Silva, AR; Albuquerque, H; Borges, S; Siegel, R; Mafra, L; Carvalho, AP; Pires, J
nationality International
journal MICROPOROUS AND MESOPOROUS MATERIALS
author keywords Anchoring; Mesoporous silicas; Cyclopropanation; Heterogeneous catalysis; Asymmetric catalysis
keywords ENANTIOSELECTIVE CATALYSIS; ASYMMETRIC CYCLOPROPANATION; MESOPOROUS MATERIALS; CHIRAL CATALYSTS; COMPLEXES; EPOXIDATION; AZIRIDINATION; BISOXAZOLINES; CONFINEMENT; STYRENE
abstract A copper(II) chiral bis(oxazoline) homogeneous catalyst (CuBox) was anchored onto mesoporous materials using three procedures: method 1, first anchoring of the bis(oxazoline) functionalized with 3-iodopropyltrimethoxysilane onto hexagonal mesoporous silica, SBA-15 and silica gel and then copper(II) coordination; method 2, anchoring of the CuBox functionalized with 3-iodopropyltrimethoxysilane onto hexagonal mesoporous silica. SBA-15 and silica gel; and method 3, first anchoring onto silica gel of 3-iodopropyltrimethoxysilane and then anchoring of the CuBox. In methods 1 and 3, the remaining free silanol groups of the silica materials were also capped using trimethylsilane groups. The bis(oxazoline) ligand was also encapsulated onto copper(II) exchanged zeolites NaY and NaUSY as a simpler strategy for the homogeneous catalyst immobilization, method 4. The materials were characterized by ICP-AES, elemental analyzes, C-13 and Si-29 MAS NMR, FTIR, thermogravimetry and nitrogen adsorption at -196 degrees C. The materials were tested as heterogeneous catalysts in the benchmark reaction of cyclopropanation of styrene to check the effect of the immobilization strategy on the catalytic parameters as well as on their reutilization in several catalytic cycles. (C) 2012 Elsevier Inc. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 1387-1811
year published 2012
volume 158
beginning page 26
ending page 38
digital object identifier (doi) 10.1016/j.micromeso.2012.02.044
web of science category Chemistry, Applied; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary
subject category Chemistry; Science & Technology - Other Topics; Materials Science
unique article identifier WOS:000305714200005
  ciceco authors
  impact metrics
journal analysis (jcr 2019):
journal impact factor 4.551
5 year journal impact factor 4.157
category normalized journal impact factor percentile 71.108
dimensions (citation analysis):
altmetrics (social interaction):



 


Apoio

1suponsers_list_ciceco.jpg