Epoxidation of olefins catalyzed by manganese(III) salen complexes grafted to porous heterostructured clays

The enantioselectivity of the manganese-salen complex in the epoxidation of unfunctionalized olefins and the influence of grafting

“…The conversion is significantly lower compared to the commercial Jacobsen complex in homogeneous conditions, which yielded a conversion of approximately 85%. The selectivity is also lower; which has been observed in similar grafting procedures on other carrier materials [28,29,33,52,53]. Some alternative immobilization procedures such as electrostatic grafting and encapsulation have shown to maintain the original selectivity as we have shown in earlier reports [30,35].…”

Porous clay heterostructures: A new inorganic host for 5-fluorouracil encapsulation

“…27 Like in case of synthetic clays (pillared clays, mesoporous silica), 28 the PCH properties (pores dimension, BET surface area, adsorption 29 capacity) depend on the synthesis conditions (surfactant type, 30 surfactant concentration, co-surfactant type, ratio between start-31 ing layered silicate: silica precursor: co-surfactant) (Santos et al,32 2010; Zapata et al, 2013;Nunes et al, 2008;Chmielarz et al, 33 2009a,b,c;Betega de Paiva et al, 2008;Capková et al, 2006;Hedley 34 et al, 2007;Zhou et al, 2004). 35 The advantageous properties of natural and synthetic clays 36 recommend these materials in a wide range of applications, like 37 heterogeneous catalysts, molecular sieves, adsorbents, decontam-38 ination agents and drug delivery systems (Qu et al, 2009;39 Chmielarz et al, 2009a,b,c;Arellano-Cárdenas et al, 2010;Pires 40 et al, 2008;Ku zniarska-Biernacka et al, 2011;Nguyen-Thanh et al, 41 2006; Apps et al, 2014).…”

Covalent immobilization of the Jacobsen catalyst on mesoporous phenolic polymer: A highly enantioselective and stable asymmetric epoxidation catalyst

“…The majority of the reports on the heterogenization of Mn (III) salen catalysts have mostly been centered on encapsulation, adsorption or covalent attachment to porous inorganic supports, such as zeolites, MCM-41, Al-MCM-41, mesoporous silicagel, SBA-15 and clays [1,[12][13][14][15][16][17][18][19] . These strategies have proven to be efficient, yet for covalent immobilization the original structure of the manganese complex is modified or multiple synthetic steps and structural changes to the parent catalyst structure and support are required.…”