Iron(III) Versatile Catalysts for Cycloaddition of CO₂ to Epoxides and Epoxidation of Alkenes

Abstract

Fe(III) complexes with tridentate pyridine-imine-phenolato ligands differing in the chain length between the imine and pyridine groups (2-methylpyridine L1 and 2-ethylpyridine L2) have been synthesized. New complex [Fe(L2) 2 ]ClO 4 (2) was characterized by X-ray diffraction and spectroscopic techniques.[Fe(L1) 2 ]ClO 4 (1) and 2 form active catalysts for the cycloaddition of CO 2 to epoxides and for the epoxidation of alkenes. Catalytic systems with the more flexible skeleton (2) in combination with tetrabutylammonium bromide (TBAB) were more active than 1/TBAB in the cycloaddition of CO 2 to epoxides. TOFs up to 900 h À1 for the selective synthesis of styrene carbonate and 3640 h À1 for the synthesis of glycidol carbonate were obtained using 2/TBAB at low catalyst loadings (0.025 mol %). Additionally, 2 was also active in the epoxidation of styrene derivatives such as trans-stilbene (conversion 88 %) and trans-bmethylstyrene (conversion 100 %) using tert-butylhydroperoxide as oxidant at 60 8C in acetonitrile. Epoxidation of styrene and cyclohexene proceed at low conversions.[a] Dr.

Syntheses, crystal structures, photo-physical properties, antioxidant and antifungal activities of Mg(II) 4,4′-bipyridine and Mg(II) pyrazine complexes of the 5,10,15,20 tetrakis(4–bromophenyl)porphyrin

“…Porphyrins and their metal complexes were considered as active materials used in polyme rization [1][2][3] and they also exhibited important function as catalysts, in medicinal and pharmaceutical fields [4][5][6], and functional dyes and pigments [7]. For example, iron and manganese porphyrinic complexes were used as efficient catalysts for hydroxylation of alkanes and epoxidation of alkenes [8][9][10][11][12][13][14]. Having conjugated configuration, porphyrins and metalloporphyrins are remarkable precursors in supramolecular chemistry [15,16] and are considered as excellent components in the design of functional molecular materials with improved electrochemical and physical-chemical properties [16].…”

Homogeneous Iron Catalysts in the Reaction of Epoxides with Carbon Dioxide

“…In 2016, the synthesis and characterisation of Fe(III) complexes supported by tridentate phenoxy‐iminopyridinic ligands were described by Masdeu‐Bultò et al. (Figure ) . The selective formation of SC was performed using 0.05 mol% of the complexes 16a and 16b , in the presence of five equivalents of TBAB, at 80 °C and 50 bar of CO 2 .…”

Hybrid Metalloporphyrin Magnetic Nanoparticles as Catalysts for Sequential Transformation of Alkenes and CO2 into Cyclic Carbonates

“…[32][33][34][35][36][37][38][39][40][41][42][43] However,t he previous synthesis of epoxides often in-volve the use of toxic and expensiver eagents, andr equire hard separation/purification procedures. [49][50][51][52][53][54][55][56][57][58][59][60][61][62] Despite such advances, the designo fe fficient catalytic systems able to sequentially promote olefin epoxidation followed by CO 2 addition to epoxides is ag reat challenge [63,64] and further studies are still required to overcomes everal issues related to the instabilityo fh omogeneousc atalysts and the selectiono fa ppropriate oxidants. [49][50][51][52][53][54][55][56][57][58][59][60][61][62] Despite such advances, the designo fe fficient catalytic systems able to sequentially promote olefin epoxidation followed by CO 2 addition to epoxides is ag reat challenge [63,64] and further studies are still required to overcomes everal issues related to the instabilityo fh om...…”

“…[44][45][46][47][48] Alternatively, synthetic metalloporphyrins have been described as excellent cytochrome P450 biomimeticc atalysts to selectivelyp romote olefin epoxidation in as ustainable fashion. [49][50][51][52][53][54][55][56][57][58][59][60][61][62] Despite such advances, the designo fe fficient catalytic systems able to sequentially promote olefin epoxidation followed by CO 2 addition to epoxides is ag reat challenge [63,64] and further studies are still required to overcomes everal issues related to the instabilityo fh omogeneousc atalysts and the selectiono fa ppropriate oxidants. [65][66][67][68][69][70] Therefore,m ore robustc atalysts such as heterogeneous and/orb iphasic systems have been lately developed,n amely those based on metal oxides, [71,72] supported gold catalysts, [73][74][75] sodium phosphotungstate, [76] and ionic liquids, [77] most of them using alkyl hydroperoxides as oxygen donors.…”