Siliceous mesoporous foam

Further examples of supported catalysts used for ATH of imines include those based on recyclable silica [84], functionalized MCM-41 [85], siliceous mesocellular foam [86] and magnetic mesoporous silica. In the latter case, the reusable immobilized catalyst exhibited high activity and enantioselectivities in the ATH of imines in FA/TEA. It was able to be separated mechanically using an external magnet to facilitate ready recycling [87],... 

A Cu-Box complex supported on monolith (51) was developed for the enantio-selective cydopropanation of ethyl diazoacetate. The flow reactions using (51) provided an increase in enantioselectivities of about 20% relative to those for the homogenous batch process (Scheme 7.38) [142]. Pyridine-oxazolidine based monoliths (52) and (53), whose central metals were Ru and Cu, respectively, were also developed [143,144]. Mesoporous silica was utilized as a support for the Cu-Box complex for asymmetric cydopropanation in a flow reador. Aza(bisoxazoline) was easily immobilized on siliceous mesocellular foam MCF) microparticles, which are... 

Immobilized CPO in the mesoporous silicate material, mesocellular foam The optimal pH at which the maximum amount of enzyme is immobilized was determined to be pH 3.4, slightly below the isoelectric point of the enzyme [12]... 

P. Schmidt-Winkel, W.W. Lukens, P.D. Yang, D.I. Margolese, J.S. Lettow, J.Y. Ying, and G.D. Stucky, Microemulsion Templating of Siliceous Mesostructured Cellular Foams with Well-defined Ultralarge Mesopores. Chem. Mater., 2000, 12, 686-696. 

There have been multiple efforts toward supported catalysts for asymmetric transfer hydrogenation, and the 4 position on the aryl sulfonate group of 26 has proven a convenient site for functionalization. Thus far, this ligand has been supported on dendrimers [181,182], polystyrenes [183], silica gel [184], mesoporous siliceous foam [185], and mesoporous siliceous foam modified with magnetic particles [186]. The resulting modified ligands have been used in combination with ruthenium, rhodium, and iridium to catalyze the asymmetric transfer of imines and, more commonly, ketones. 

Making use of constrained polymerisation of divinylbenzene on surfactant-modified colloid silica, Jang and Lim prepared carbon nanocapsules and mesocellular foams. Later, they reported that mesoporous carbons with highly uniform and tunable mesopores were fabricated by one-step vapour deposition polymerisation using colloidal silica nanoparticles as template and polyacrylonitrile as carbon precursor. Hampsey et al. recently reported the synthesis of spherical mesoporous carbons via an aerosol-based, one-step approach using colloidal silica particles and/or silicate clusters as template. ... 

The first mesoporous silicate materials were developed in 1970 [134] but received little attention. Mesoporous silicas finally came to prominence when Mobil Research produced a family of hexagonally-pored silicas, MCM-41, in the early 90s [135]. Since then, many subsequent varieties have been prepared, including SBA, MSU, KIT, HMS and FSM. These materials differ in the morphology and size of their pores, e.g. SBA-15 has a hexagonal structure while MSUs have a foam-like structure. 

Schmidt-Winkel, P. Lukens Wayne, W. Yang, P. Margolese, D. I. Lettow, J. S. Ying, J. Y. Stucky, G. D., Microemulsion Templating of Siliceous Mesostruc-tured Cellular Foams with Well-Defined Ultralarge Mesopores. Chem. Mater. 2000,12, 686-696. 

Fig. 8.3 Titanium oxide entrapped in the cage-Uke mesopores of hydrophobically modified mesocellular siliceous foam (MCE) for the hydroxylatirui of benzene (Reprinted with permission [51], Copyright 2011 Elsevier)...

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