Heterogeneous enantioselective epoxidation catalyzed by Mn(salen) complexes grafted onto mesoporous materials by phenoxy group

Enantioselective Epoxidation of Alkenes by Jacobsen Catalyst Anchored onto Aminopropyl-functionalised Laponite, MCM-41 and FSM-16

“…materials started to be used, being the first reports on the Mn(III) salen encapsulation into zeolites [13][14][15][16]. With the development of ordered mesoporous materials, several reports were published on the covalent attachment of Mn(III) salen catalysts mainly on MCM-41 [17][18][19][20][21][22][23][24][25][26]. The covalent attachment through the ligand has generally led to reduce activity and enantioselectivity compared to the homogeneous counterparts [17][18][19], probably due to the structural/electronic modifications introduced in the salen ligand to allow for its covalent attachment [27].…”

“…Recently, the anchoring of [M (salen)] catalysts [M = transition cation] into mesoporous materials through axial coordination to the metal center have been published, with specific emphasis on the improved enantioselectivity in comparison to their homogeneous counterparts [20][21][22][23][24][25][26][28][29][30][31][32][33]. Despite the efficiency of some of immobilization strategies, they usually involve multi-step procedures which often require time-consuming synthetic manipulations, thus limiting their application; therefore, the demand for simpler and effective procedures to prepare heterogenized Mn(III) salen catalysts is still a topic of major importance.…”

An Overview of Zeolite, Zeotype and Mesoporous Solids Chemistry: Design, Synthesis and Catalytic Properties

“…The most recent development of this type of catalyst (with respect to immobilization onto a solid mesoporous support) was the use of a phenoxy group, which coordinates with a Mn(salen) complex by displacing a chloride moiety with oxygen. [117] The inorganic host material is functionalized with (para-HOPh)Si(OEt) 3 in the epoxidation of a-methylstyrene and cis-b-methylstyrene compared with the 'free' complex, however, yields were generally poorer. The first paper to illustrate the beneficial effect of confining a chiral catalyst inside a periodic mesoporous host regarding the regioselectivity and ee of the products was published by Johnson et al in 1999.…”

A New Chiral Catalytic Ceramic Membrane Reactor and Its Use in Catalyzing Epoxidation of Styrene

“…Inorganic matrixes had received much attention [6] [7] in recent years due to their high chemical stability. The mostly used inorganic supports for immobilizing salen catalysts are clay [8], activated silica [9], molecular sieve [10] and so on. But the separation of immobilized-catalysts in suspension is also a challenge in industry field applications, especially for ultrafine particles [11].…”