Immobilized metalloporphyrins on 3-aminopropyl-functionalized silica support as heterogeneous catalysts for selective oxidation of primary and secondary alcohols

Abstract

Iron(III), manganese(III), and cobalt(II) complexes of meso-tetrakis(p-chlorophenyl)porphyrin (Fe(TCl-PP)X, Mn(TClPP)X, and Co(TClPP)X, X = Cl or OAc) were immobilized onto 3-aminopropyl-functionalized silica (SF-3-APTS). SF-3-APTS acts as both axial base and support for immobilization of these metalloporphyrins. The obtained heterogeneous catalysts were characterized by Fourier transform infrared (FT-IR), UV-Vis, and inductively coupled plasma (ICP) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and thermogravimetric analysis (TGA) techniques. Their catalytic activity as biomimetic catalysts was investigated for the selective oxidation of primary and secondary benzylic alcohols to the corresponding carbonyl compounds with t-butylhydroperoxide as oxidant. SF-3-APTS-Fe(TClPP)Cl demonstrated higher catalytic activity than SF-3-APTS-Mn(TClPP)Cl and SF-3-APTS-Co(TClPP)OAc. The presence of electronwithdrawing substituents on benzylic alcohols enhances the rate of catalytic oxidation. SF-3-APTS-Fe(TClPP)Cl could be reused at least four times without significant loss of its catalytic activity.

Magnetic HMS silica as a Support to Immobilization of Catalysts Based on Cationic Manganese Porphyrins

“…According to IUPAC classification, HMS , HMS‐Mag and MnP‐HMS‐Mag showed type I isotherm with H4 hysteresis (Figure a), characteristic of microporous materials with narrow slit‐like pores being less uniform when compared with solid that exhibits H1 hysteresis, such as SBA‐15 silica . It is worth noting that the form of the adsorption isotherms is not affected by Mag , suggesting that the pores of the HMS layer of HMS‐Mag were not blocked upon coating of Mag.…”

“…When the catalytic efficiency of the different cationic MnP are compared, the ortho isomer (MnP1- Table 5, Entries14 and 15) presented better results in comparison to the meta and para isomers (MnP2 and MnP3 - Table 5, Entries [16][17][18][19] suggesting that charge position in the macrocycle ligand can influence the catalytic yield. This difference may be ascribed to the combined steric hindrance and electronic effects of the ortho isomer, since it has positively charged groups in close vicinity to the metal site in relation to others isomers, facilitating the approach of the substrate to the Mn n + center, thus affording higher catalytic performances.…”

“…Among the supports regularly explored for MP immobilization, silica is often used for their mechanical and thermal stability, chemical inertness in oxidation reactions and easy functionalization due to the presence of reactive silanol groups. [16][17][18][19] Addition of different template molecules during the process of silica formation (e. g. sol gel process by hydrolysis and condensation) can direct the formation of porous silica (according to IUPAC, pores with widths exceeding about 50 nm are called macroporous and not exceeding about 2 nm are called microporous), [20] which makes them promising materials as catalyst supports. The presence of the pores in these materials can comprise an additional advantage for catalysis by facilitating mass transfer and high surface area, which allow a high concentration of active sites per mass of material and improvement of the catalytic activity.…”

Porphyrins functionalized by quaternary pyridinium units

“…Many reports concern porphyrins with various central metal ions [92][93][94][95]; among them one example is mentioned [96]. Moreover, in view of a growing attention paid today to porphyrin metal-organic frameworks (MOFs) [97,98] and porphyrin metal-organic materials (MOMs) [99,100], two such examples are described.…”

An efficient selective oxidation of alcohols with iron zirconium phosphate under solvent-free conditions

“…As a typical product of alcohol oxidation and a starting material, benzaldehyde (BzH) is an important chemical for the preparation of intermediates in the industry of dyestuff, agrochemicals, perfumery, and pharmaceuticals [27][28][29]. Thus, from economic and environmental viewpoints, there have been many recent publications emphasizing environmentally benign methods for the oxidation of alcohols, using molecular O 2 or aqueous H 2 O 2 as the oxidant, in the presence and/or absence of the solvent such as CuSO 4 [25], CuBr 2 [26], AMPA [28], MPA/V 2 O 5 /Al 2 O 3 [29], TEMPO-IL/CuCl [30], Ni 3 [Fe(CN) 6 ] 2 [31], Pd/Fe@C [32], silicagel-TEMPO-NO x [33], CoTM4PyP-MT [34], PdO/ SBA-15 [35] (TEAH)H 2 PW 12 O 40 [36], Zn-Co-LDH [37], RuCl 3 Á3H 2 O [38], VPO/HMS [39], AuRu/AC [40], oxidovanadium(V) complexes [41], Ag/SBA-15 [42], DHPDMDO [43], [45], NaBrO 3 /[bmim]Br [46], DCMBF [47], WO 4 @PMO-IL [48], Cu-NHC-TEMPO complexes [49], Cu/AlO(OH) [50], SSA-SiO 2 /KMnO 4 [51], copper/ imidazolium/TEMPO [52], Ca(ClO) 2 /Al 2 O 3 [53], PVPTB [54], Au/UiO-66 [55], PSFC [56], Au/Al 2 O 3 [57], PMo11 M (M = Co, Mn, Ni) [58], Mn(salen)OAc [59], BPFC [60], KMnO 4 -aluminum silicate [61], KBr/oxone [62], PVP-H 2 O 2 [63], TMP/KMnO 4 …”