Catalytic activity in oxidation reactions of anionic iron(III) porphyrins immobilized on raw and grafted chrysotile

Abstract

Crisotila natural e quimicamente modificada foi usada como matrizes para imobilização de ferroporfirinas de segunda geração. As atividades catalíticas dos sólidos obtidos foram avaliadas em reações de oxidação de cicloexano, usando iodosilbenzeno como oxidante. Os resultados de catálise foram analisados e comparados aos obtidos pela imobilização das mesmas ferroporfirinas em sílica funcionalizada com 3-APTS, derivadas do tratamento ácido da crisotila. Os resultados preliminares mostraram que os catalisadores são eficientes e seletivos para a obtenção de álcool.Natural and grafted chrysotile were used as matrices for the immobilization of second generation iron porphyrins. The catalysts obtained were evaluated in the oxidation reaction of cyclohexane, using iodosylbenzene as oxidant agent. The catalyst activity for different conditions was compared with results for the same porphyrins immobilized with 3-APTS grafted disordered silica, obtained from acid-leached chrysotile. Preliminary results have shown that high activity can be obtained with short reaction times, and that the reaction is specific for alcohol.

Anionic Iron(III) Porphyrin Immobilized on/into Exfoliated Macroporous Layered Double Hydroxides as Catalyst for Oxidation Reactions

“…The use of FePs as catalysts promotes C-H bond activation by oxidation under biomimetic mild conditions and in the presence of a number of oxygen atom donors such as iodosylbenzene, 8,11,14,16,28,70 hydrogen peroxide, 71 and dioxygen, 72,73 among others. Here, we decided to employ PhIO as oxygen donor because MP/PhIO is a classical biomimetic system that can produce the same intermediate catalytic species regardless of the FeP.…”

“…[1][2][3][4][5] Over the last years, researchers have made great efforts to develop routes that can generate robust synthetic metalloporphyrins (MPs), [6][7][8][9][10] aiming to mimic biological enzymes such as cytochrome P450 (biomimetic approach). Indeed, MPs can efficiently and selectively catalyze hydrocarbon oxidation.…”

“…13 The first MP-based catalytic system relied on the Fe(III) complex [Fe(TPP)Cl] as catalyst and iodosylbenzene (PhIO) as oxidant; 14 it mimicked cytochrome P450 in many reactions. Since then, the use of MPs, specially FePs and MnPs, in oxidative systems [6][7][8][9][10][11][14][15][16][17][18][19][20][21] has attracted considerable attention, because these complexes can effectively and selectively catalyze a series of oxidation reactions in homogeneous medium, among which epoxidation and hydroxylation stand out. [15][16][17][18][19][20][21] Despite their efficiency in homogeneous systems, the use of this family of complexes in solution has raised concerns.…”

“…10 Another difficulty posed by homogeneous catalysts is their recovery, reuse, and recycling, which could prevent the design of a technological process. 8,15,18 To minimize such problems, researchers have turned to the synthesis of new robust and resistant porphyrin structures 10,22 as well as to immobilization of these catalysts in different inorganic supports. [22][23][24][25][26][27][28][29][30][31][32][33] Catalyst immobilization can facilitate catalyst recovery from the reaction medium, to enable their reuse and recycling.…”

“…Some kind of interaction involving the modifier on the support and/or on the MP might occur, which shall not only increase the rate of MP immobilization, 40 but also provide a new solid catalyst with unprecedented efficiency and selectivity. 8,18,50 There has been a recent surge in scientist's interest in nanostructured LDHs. This type of solid can be achieved by controlling the textural properties of the material in terms of morphology, particle size, specific area, and porosity.…”