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Transformações de cetonas α,β- e α,β,γ,δ-insaturadas. Novas rotas de síntese de 2,3-diarilxantonas

Santos, Clementina M.M.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
Português
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17.34%
Esta dissertação é constituída por duas partes: na primeira parte reportam-se estudos de epoxidação em cetonas α,β- e α,β,γ,δ-insaturadas, catalisados por um complexo de salen Mn(III), conhecido como catalisador de Jacobsen; na segunda parte desenvolvem-se novas rotas de síntese de 2,3-diarilxantonas em que se recorre à reacção de Heck de cromonas bromadas com estirenos. Os estudos de epoxidação apresentados na primeira parte desta dissertação foram efectuados em três sistemas carbonílicos α,β- e α,β,γ,δ-insaturados: (E)-calconas, (E,E)-cinamilidenoacetofenonas e (E)-2-estirilcromonas e utilizando o peróxido de hidrogénio e o iodosilbenzeno como oxidantes. As reacções de epoxidação de (E)-calconas originaram os respectivos trans-epóxidos em bons rendimentos enquanto que nas (E)-2’-hidroxicalconas isolaram-se os produtos de ciclização dos respectivos trans-epóxidos, as trans-3-hidroxiflavanonas em rendimentos moderados. As reacções de epoxidação de (E,E)-cinamilidenoacetofenonas proporcionaram a formação dos respectivos γ,δ-trans-monoepóxidos e α,β:γ,δ- trans,trans-diepóxidos. De referir que no caso da (E)-4-nitrocinamilidenoacetofenona foi também possível isolar o α,β-trans-monoepóxido. Para as (E...

Epoxidation of (E,E)-cinnamylideneacetophenones with hydrogen peroxide and iodosylbenzene with salen-mnIII as the catalyst

Santos, Clementina M.M.; Silva, Artur; Cavaleiro, José; Lévai, Albert; Patonay, Támas
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.88%
http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=Refine&qid=9&SID=X22NMCKHdF5lcLIJG6o&page=1&doc=2&colname=WOS; (E,E)-Cinnamylideneacetophenones 3a–j were epoxidized under mild conditions with Jacobsen’s catalyst 4 and hydrogen peroxide or iodosylbenzene as oxidants. γ,δ-Monoepoxides and a diastereomeric mixture of α,β:γ,δ-diepoxides were obtained in each case, and only the α,β-monoepoxide of 4- nitrocinnamylideneacetophenone (3d) was isolated. The presence of a methyl group in the vinylic moiety of substrates 3i,j allowed the formation of two γ,δ-monoepoxide diastereomers. The epoxidation of (E,E)-2 -hydroxycinnamylid- Introduction Salen MnIII complexes are efficient catalysts for the epoxidation of various olefinic compounds.[1–3] Since the pioneering work of Kochi et al.,[4] many contributors have reviewed a wide range of applications of these powerful and selective catalysts.[5–7] Several oxidants have been used as effective oxygen donors in these epoxidations, with iodosylbenzene[ 8–11] and sodium hypochlorite[12–14] being the most frequently reported. Among other common olefin oxidants hydrogen peroxide,[15–17] oxone®,[18] dimethyldioxirane (DMD),[19–23] m-chloroperbenzoic acid (MCPBA)...

Epoxidation studies of 2-styrylchromones using Jacobsen’s catalyst and hydrogen peroxide and iodosylbenzene as oxidants

Santos, Clementina M.M.; Silva, Artur; Cavaleiro, José; Patonay, Támas; Lévai, Albert
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.67%
http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=4&SID=S2NjaL1GBbk143plPl1&page=1&doc=7&colname=WOS; The epoxidation of 2-styrylchromones 2a-h using Jacobsen’s Mn(III)[salen] complex 1 as catalyst is reported for the first time. Several studies were performed using both hydrogen peroxide and iodosylbenzene as oxidants, in order to obtain the α,β-epoxy-2-styrylchromones 3a-h regioselectively. Due to the low reactivity of the substrates and the highly unstable character of the formed epoxides, reactions should be interrupted at lower conversions to obtain acceptable yields, especially when hydrogen peroxide is used.

Epoxidation of (E,E)-Cinnamylideneacetophenones Using Salen Mn(III) as Catalyst

Santos, Clementina M.M.; Silva, Artur; Cavaleiro, José; Patonay, Támas; Lévai, Albert
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Conferência ou Objeto de Conferência
Português
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27.67%
Salen Mn(III) complexes are efficient and practical catalysts for the epoxidation of various α,β-unsaturated carbonyl compounds. Among common oxidants used are iodosylbenzene, sodium hipochlorite, oxone, peracids and dimethyldioxirane [1]. Although the epoxidation of cinnamylideneacetophenones have already been reported in literature (by Julia’s epoxidation using hydrogen peroxide as oxidant [2] and by oxidation with dimethyldioxirane [3]), no studies were performed using these kind of salen Mn(III) complexes as catalysts. On these basis, we developed a study on the epoxidation of cinnamylideneacetophenones 1, catalyzed by commercially available Jacobsen’s catalyst [salen Mn(III)] and using iodosylbenzene and hydrogen peroxide as oxidants. Several experimental conditions have been used and the γ,δ-monoepoxides 2 and, in same cases, the diasteriomeric mixture of α,β:γ,δ-diepoxides 3 have been obtained. In this communication, we report the synthetic details and structural characterisation of the mono 2 and diepoxides 3 obtained.

Synthesis of (-)-hinokinin by oxidation of (-)-cubebin catalyzed by biomimetic metalloporphyrin catalytic systems

ANDRADE, Leonardo N.; BIZAIA, Natalia; CAETANO, Bruno L.; SILVA, MArcio L. A.; CUNHA, Wilson R.; SILVA FILHO, Adernar A. da; CALEFI, Paulo S.; NASSAR, Eduardo J.; BASTOS, Jairo K.; CIUFFI, Katia J.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
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A catalytic system consisting of iron tetraphenylporphyrin supported on an alumina matrix for oxidation of (-)-cubebin with iodosylbenzene or hydrogen peroxide is reported. Conversion of (-)-cubebin is very efficient (100%) with 100% selectivity producing only (-)-hinokinin when iodosylbenzene is used as the oxidant and 70% conversion with 100% selectivity when hydrogen peroxide is the oxidant at room temperature under atmospheric pressure. (c) 2008 Elsevier B.V. All rights reserved.; CAPES; CNPq; FAPESP

Primidone oxidation catalyzed by metalloporphyrins and Jacobsen catalyst

LEOD, T. C. O. Mac; FARIA, A. L.; BARROS, V. P.; QUEIROZ, M. E. C.; ASSIS, M. D.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
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Primidone (PRM) oxidation by various oxidants such as iodosylbenzene (PhIO), tert-butyl hydroperoxide 70wt.% (t-BOOH), 3-chloroperoxybenzoic acid (m-CPBA) and hydrogen peroxide 30wt.%, mediated by either a salen complex or metalloporphyrins, was investigated. The catalytic systems led to phenylethyl-malondiamide (PEMA) and phenobarbital (FEND), the same metabolites obtained in vivo with P450 enzymes, although three other products were also detected. Product formation was highly dependent on the oxidant, co-catalyst (imidazole), pH and dioxygen. These biomimetic chemical models have potential application in the synthesis of drug metabolites. which should provide samples for pharmacological tests. They can also be employed in studies that pursue the elucidation of in vivo drug metabolism. (C) 2008 Elsevier B.V. All rights reserved.; FAPESP; CAPES; CNPq

Ironporphyrin immobilized onto montmorillonite as a bimimetical model for azo dye oxidation

BARROS, Valeria P.; FARIA, Andre L.; MACLEOD, Tatiana C. O.; MORAES, Luiz A. B.; ASSIS, Marilda D.
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
Português
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In this work, we studied the oxidation of the azo dye Disperse orange 3 (DO3) by hydrogen peroxide, catalyzed by 5,10,15, 20-tetrakis(4-N-methylpyridyl)porphyrin iron(III) chloride immobilized onto montmorillonite K10, FeP-K10. Results showed that the FeP-K10/H2O2 system is efficient for discoloration of the DO3 dye, especially at pH 3.0. The catalyst was shown to be relatively stable and could be recycled many times, leading to good yields. DO3 oxidation products were analyzed by gas chromatography and mass spectrometry, being 4-nitroaniline the main product. Tert-butylhydroperoxide and iodosylbenzene were also used as oxidants, giving rise to 4-nitroaniline as product too. The studied system is a good biomimetic model of oxidative enzymes, being a promising discoloring agent for azo dyes. (C) 2007 Elsevier Ltd. All rights reserved.

Carbamazepine oxidation catalyzed by iron and manganese porphyrins supported on aminofunctionalized matrices

FARIA, Andre L.; LEOD, Tatiana C. O. Mac; ASSIS, Marilda D.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
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This work describes the catalytic activity of manganese and iron porphyrins, Mn and Fe(TFPP)Cl, covalently immobilized on the aminofunctionalized supports montmorillonite K-10 (MontX) and silica (SilX), where X= 1 or 2 represents the length of the organic chain (""arms"") binding the metalloporphyrin to the support. These systems were characterized by UV-vis and Electronic Paramagnetic Resonance (EPR), and they were used as catalysts in the oxidation of carbamazepine (CBZ) by the oxidants iodosylbenzene (PhIO) and hydrogen peroxide. The manganese porphyrin (MnP) catalysts proved to be efficient and selective for the epoxide, the main CBZ metabolite in natural systems. MnMont1 was an excellent catalyst when PhIO was used as oxidant, even better than the same MnP in homogeneous system. Supports bearing short ""arms"" led to the best yields. Although H2O2 is an environmentally friendly oxidant, low product yields were obtained when it was employed in CBZ oxidation. Fe(TFPP)CI immobilized on aminofunctionalized supports was not an efficient catalyst, probably due to the presence of Fe(H) species in the matrix, which led to the less reactive intermediate PFe(IV)(O). (c) 2007 Elsevier B.V. All rights reserved.

Preparation, characterization and catalytic studies of V2O5-SiO2 xerogel composite

BARBOSA, Glauciane N.; LEOD, Tatiana C. O. Mac; GUEDES, Debora F. C.; ASSIS, Marilda D.; OLIVEIRA, Herenilton P.
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
Português
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In this work, we report the synthesis, characterization and catalytic properties of a vanadium oxide-silicon oxide composite xerogel prepared by a soft chemistry approach. In order to obtain such material, we submitted a vanadium pentoxide gel previously synthesized via protonation of metavanadate species to an ""in situ"" progressive polycondensation into silica gel. The material has been characterized by X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. Further, the catalytic activity of this material was evaluated for the epoxidation of styrene and cyclooctene using iodosylbenzene, hydrogen peroxide and m-chloroperbenzoic acid as the oxidizing agent.

Biomimetic Oxidation of Piperine and Piplartine Catalyzed by Iron(III) and Manganese(III) Porphyrins

SCHAAB, Estela Hanauer; CROTTI, Antonio Eduardo Miller; IAMAMOTO, Yassuko; KATO, Massuo Jorge; LOTUFO, Leticia Veras Costa; LOPES, Norberto Peporine
Fonte: PHARMACEUTICAL SOC JAPAN Publicador: PHARMACEUTICAL SOC JAPAN
Tipo: Artigo de Revista Científica
Português
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Synthetic metalloporphyrins, in the presence of monooxygen donors, are known to mimetize various reactions of cytochrome P450 enzymes systems in the oxidation of drugs and natural products. The oxidation of piperine and piplartine by iodosylbenzene using iron(III) and manganese(III) porphyrins yielded mono- and dihydroxylated products, respectively. Piplartine showed to be a more reactive substrate towards the catalysts tested. The structures of the oxidation products were proposed based on electrospray ionization tandem mass spectrometry.; CAPES; FAPESP[09/51812]; FAPESP[07/54241-8]; CNPq; INCT-if

Tetra-crowned porphyrin as P450 biomimetic model for carbamazepine oxidation

Silva Filho, Juvenal Carolino da; LEOD, Tatiana C. O. Mac; GOTARDO, Maria Carolina A. F.; ASSIS, Marilda das Dores
Fonte: ARKAT USA INC Publicador: ARKAT USA INC
Tipo: Artigo de Revista Científica
Português
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A substituted porphyrin bearing four crown ether units, H(2)(TCP), was synthesized from the reaction between (5,10,15,20-tetra(o-aminophenyl) porphyrin) and the acyl derivative of the ether (4-carboxy-18-crown-6). The free-base porphyrin was characterized by C, N, and H elemental analysis; UV-vis and IR spectroscopies; and (1)H NMR. The corresponding ironporphyrin, Fe(TCP)Cl, was obtained via iron insertion into H(2)(TCP). Fe(TCP)Cl was employed as catalyst for carbamazepine (CBZ) oxidation by iodosylbenzene (PhIO), 3-chloroperoxybenzoic acid (m-CPBA) or sodium hypochlorite (NaOCl), in methanol or in a biphasic water/dichloroethane system. The crowned ironporphyrin proved to be a highly efficient and selective catalyst for CBZ epoxidation even in the biphasic dichloroethane /H(2)O system, with no need for an additional phase transfer agent.; FAPESP; CNPq; CAPES

Novel manganese (III) porphyrin containing peripheral [RuCl(dppb)(X-bipy)](+) cations [dppb=1,4-bis(diphenylphosphino) butane and X = -CH3, -OMe, -Cl]. X-ray structure of the cis-[RuCl(dppb)(bipy)(4-Mepy)]PF6 complex

ROMUALDO, Lincoln Lucilio; BOGADO, Andre Luis; VALLE, Eliana M. A.; MOREIRA, Icaro S.; ELLENA, Javier; CASTELLANO, Eduardo Ernesto; ARAUJO, Marcio P. de; BATISTA, Alzir A.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
Português
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New tetraruthenated manganese (III) porphyrins were synthesized and characterized (P-31 NMR, cyclic voltammetry, UV-Vis). This new system presents four units of cationic ``[RuCl(dppb)(X-bipy)](+)``. The electrochemical and catalytic properties of the central manganese (III) show dependence on the characteristics of the peripheral ruthenium complexes as evidenced by the Mn-(III)/Mn-(II) reduction potential. The catalytic oxidation reactions of olefins, cyclohexene and cyclohexane, were carried out in the presence of tetrapyridyl manganese (III) porphyrins containing cationic ruthenium complex and using iodosylbenzene as oxygen donor. The performance of these new tetraruthenated porphyrins systems were evaluated and compared with the manganese porphyrin. (C) 2007 Elsevier Ltd. All rights reserved.

Catalytic oxidation of hydrocarbons by trinuclear mu-oxo-bridged ruthenium-acetate clusters: Radical versus non-radical mechanisms

NUNES, Genebaldo S.; ALEXIOU, Anamaria D. P.; TOMA, Henrique E.
Fonte: ACADEMIC PRESS INC ELSEVIER SCIENCE Publicador: ACADEMIC PRESS INC ELSEVIER SCIENCE
Tipo: Artigo de Revista Científica
Português
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27.34%
The [Ru(3)O(H(3)CCO(2))(6)(py)(2)(L)]PF(6) clusters, where L=methanol or dimethyl sulfoxide, can be activated by peroxide or oxygen donor species, such as tert-butyl hydroperoxide (TBHP) or iodosylbenzene (PhIO), respectively, generating reactive intermediates of the type [Ru(3)(IV,IV,III)=0](+). In this way, they catalyse the oxidation of cyclohexane or cyclohexene by TBHP and PhIO, via oxygen atom transfer, rather than by the alternative oxygen radical mechanism characteristic of this type of complexes. In addition to their ability to perform efficient olefin epoxydation catalysis, these clusters also promote the cleavage of the C-H bond in hydrocarbons, resembling the oxidation catalysis by metal porphyrins. (C) 2008 Elsevier Inc. All rights reserved.

Iron(III) Porphyrin Covalently Supported onto Magnetic Amino-Functionalized Nanospheres as Catalyst for Hydrocarbon and Herbicide Oxidations

Santos, Joicy Santamalvina dos; Faria, Andre L.; da Silva Amorin, Patricia M.; La Luna, Franco M.; Caiado, Kely L.; Silva, Debora O. C. e; Sartoratto, Patricia P. C.; Assis, Marilda das Dores de
Fonte: SOC BRASILEIRA QUIMICA; SAO PAULO Publicador: SOC BRASILEIRA QUIMICA; SAO PAULO
Tipo: Artigo de Revista Científica
Português
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16.7%
This work describes the covalent immobilization of an ironporphyrin, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin iron(III) chloride (FeTFPP), onto maghemite/silica magnetic nanospheres covered with aminofunctionalized silica. The resulting material (gamma-Fe2O3/SiO2-NHFeP) was characterized by diffuse reflectance infrared spectroscopy (DRIFTS) and UV-Vis absorption spectroscopy. The catalytic activity of this magnetic ironporphyrin was investigated in the oxidation of hydrocarbons (styrene, (Z)-cyclooctene and R-(+)-limonene) and an herbicide (simazine) by hydrogen peroxide or 3-chloroperoxybenzoic acid. Hydrocarbon and simazine oxidation reaction products were analyzed by gas chromatography (GC) and high performance liquid chromatography (HPLC), respectively. This catalytic system proved to be efficient and selective for hydrocarbon oxidation, leading to high product yields from styrene (89%), cyclooctene (71%) and R-(+) -limonene (86%). Simazine oxidation was attained with 100% selectivity for a dechlorinated product (OEAT), while several oxidation products were obtained for the same catalyst in homogeneous media. The catalyst can be easily recovered through application of an external magnetic field and washed after reaction. Catalyst reuse experiments for R-(+)-limonene oxidation have shown that the catalytic activity is kept at 90% after 10 consecutive reactions.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)

Biomimetic in vitro oxidation of lapachol: A model to predict and analyse the in vivo phase I metabolism of bioactive compounds

Niehues, Michael; Barros, Valeria Priscila de; Emery, Flavio da Silva; Dias-Baruffi, Marcelo; Assis, Marilda das Dores; Lopes, Norberto Peporine
Fonte: ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER; PARIS Publicador: ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER; PARIS
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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The bioactive naphtoquinone lapachol was studied in vitro by a biomimetic model with Jacobsen catalyst (manganese(III) salen) and iodosylbenzene as oxidizing agent. Eleven oxidation derivatives were thus identified and two competitive oxidation pathways postulated. Similar to Mn(III) porphyrins, Jacobsen catalyst mainly induced the formation of para-naphtoquinone derivatives of lapachol, but also of two ortho-derivatives. The oxidation products were used to develop a GC MS (SIM mode) method for the identification of potential phase I metabolites in vivo. Plasma analysis of Wistar rats orally administered with lapachol revealed two metabolites, alpha-lapachone and dehydro-alpha-lapachone. Hence, the biomimetic model with a manganese salen complex has evidenced its use as a valuable tool to predict and elucidate the in vivo phase I metabolism of lapachol and possibly also of other bioactive natural compounds. (C) 2012 Elsevier Masson SAS. All rights reserved.; FAPESP; CNPq INCT_if [573663/2008-4]; CAPES (Brazil)

Modelos químicos do citocromo P-450: oxigenação de ligações C-H de alcanos catalisadas por metaloporfirinas sintéticas; Modelos Químicos do Citocromo P-450: Oxigenação de Ligações C-H de Alcanos Catalisadas por Metaloporfirinas Sintéticas

Vinhado, Fábio da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 18/03/2005 Português
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Oxifuncionalização de alcanos sob condições suaves de reação é uma difícil reação devido à elevada energia da ligação C-H nestas moléculas. Na natureza, algumas enzimas, com destaque para as monooxigenases do citocromo P-450, conseguem promover estas oxidações parciais com elevada eficiência e seletividade. Metaloporfirinas sintéticas têm sido estudadas como modelos químicos do citocromo P- 450, uma vez que estas enzimas possuem uma FeIIIporfirina como grupo prostético. Neste trabalho, estudou-se a oxifuncionalização dos alcanos cicloexano e npentano com iodosilbenzeno (PhIO) usando-se os catalisadores [Mn{T(4-N-MePy)P}]5+, [Mn(TPFP)]+, [Mn(TDCSPP)]3- e [Mn(TF4TMAPP)]5+ em meio homogêneo e suportados em matrizes de sílica quimicamente modificada via ligação iônica e/ou covalente, usando-se acetona, diclorometano e benzeno como solventes. Observou-se elevados rendimentos de produtos oxigenados (álcoois e cetonas), preferencialmente em reações catalisadas por [Mn(TF4TMAPP)]5+ tanto em meio homogêneo quanto suportada, tornando este catalisador como um dos mais promissores para oxidações de compostos orgânicos, principalmente quando imobilizado nos suportes SiSO3 - e SiSO3 -(IPG), uma vez que estes catalisadores suportados são facilmente obtidos e...

Catálise oxidativa de clusters de rutênio e porfirinas supramoleculares; Oxidative catalysis of ruthenium clusters and supramolecular porphyrins

Nunes, Genebaldo Sales
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 11/07/2005 Português
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A atividade catalítica de clusters trigonais de acetato de rutênio e porfirinas supramoleculares contendo quatro unidades de clusters periféricos ou complexos de bis(bipiridina)rutênio, na oxidação de substratos orgânicos por iodosil-benzeno ou terc-butil-hidroperóxido, é abordada nesta tese. Foram feitos estudos cinéticos para elucidar o mecanismo de catálise, com especial destaque para duas espécies supramoleculares isoméricas representadas por Mn(3-TRPyP) ou Mn(4-TRPyP), nos quais os complexos de bis(bipiridina)(cloro)rutênio se coordenam à tetrapiridilporfirina através das posições meta ou para da ponte piridínica, respectivamente. Além da maior seletividade proporcionada pelos catalisadores supramoleculares, a substituição do íon cloreto pela água nos complexos periféricos de rutênio, intensificou a atividade catalítica, gerando novos sítios ativos, do tipo Ru(IV)=O. Também foram estudados clusters trinucleares de rutênio, altamente reativos, no estado Ru(III)Ru(IV)Ru(IV)=O. Estes foram gerados eletroquimicamente em solução aquosa, apresentando pronunciada atividade catalítica na oxidação do alcool benzílico. Finalmente, uma espécie dimérica de cluster, ainda inédita, com ponte oxo, foi caracterizada e investigada do ponto de vista catalítico.; The catalytic activity of trinuclear ruthenium clusters and supramolecular tetrapyridylporphyrins containing four peripheral cluster units or bis(bipyridine)ruthenium complexes...

Metaloporfirinas como modelos biomiméticos do citocromo P450 na oxidação de pesticidas"; Metalloporhyrins as Biomimetical MOdels of Cytochrome P450 in the Oxidation of Pesticides

Gotardo, Maria Carolina Alves de Freitas
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/08/2006 Português
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Neste trabalho foi investigado o potencial de modelos metaloporfirínicos em mimetizar a ação do citocromo P450 na oxidação de um herbicida, a atrazina. Foram utilizadas as metaloporfirinas comerciais de segunda geração solúveis em solvente orgânico, cloreto de 5,10,15,20-tetrakis(2,6-diclorofenil)porfirina metal(III) [M(TDCPP)Cl] e cloreto de 5,10,15,20-tetrakis(pentafluorofenil) porfirina metal(III) [M(TFPP)Cl] (metal = ferro e manganês), tanto em solução homogênea como suportadas em montmorilonita K-10 aminofuncionalizadas; e metaloporfirinas solúveis em água, como a cloreto de 5,10,15,20-tetrakis-(N-metil-4-piridil) porfirina ferro(III), [Fe(TMPy)Cl], e cloreto de [5,10,15,20-tetra(4-carboxifenil)porfirina] ferro(III), [Fe(TCPP)Cl]. Os oxidantes testados foram iodosilbenzeno, ácido metacloroperbenzóico e peróxido de hidrogênio em água, metanol e acetonitrila. Os produtos de oxidação da atrazina foram identificados por cromatografia líquida de alta eficiência (CLAE). Os resultados mostraram que as metaloporfirinas foram capazes de oxidar a atrazina, um herbicida com características de persistência no meio ambiente, e mimetizar a ação da enzima in vivo e in vitro com formação de dois metabólitos: DEA e DIA...

Alkene epoxidation with iodosylbenzene catalysed by polyionic manganese porphyrins electrostatically bound to counter-charged supports

Sacco, H. C.; Iamamoto, Y.; Smith, JRL
Fonte: Royal Soc Chemistry Publicador: Royal Soc Chemistry
Tipo: Artigo de Revista Científica Formato: 181-190
Português
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Manganese(III) complexes of tetra-anionic and tetra-cationic porphyrins have been immobilised on counter-charged, surface-modified silica supports and on organic ion-exchange resins. The reactions of these supported manganese(III) porphyrin systems and analogous uncharged homogeneous systems have been examined using cyclooctene and (E)- and (Z)-4- methylpent-2-ene epoxidations, with iodosylbenzene (PhIO) as the oxygen donor.Comparisons using the manganese porphyrin systems as catalysts for the epoxidation of cyclooctene in acetonitrile reveal that, in low turnover reactions (maximum 136 turnovers), they all give an essentially quantitative yield of epoxide although the heterogeneous reactions are significantly slower than the homogeneous analogues. In large scale repeat-use experiments, however, the supported catalysts are clearly superior, giving markedly better yields.The epoxidations of (E)- and (Z)-4- methylpent-2-ene with all the catalysts show a very high stereoretention, with the (Z)-alkene reacting faster than the (E)-isomer. The sterically hindered manganese(III) 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphyrin (MnTDCSPP) shows the highest selectivity for the (Z)-isomer; by contrast the supported manganese(III) 5...

Catalytic activity of halogenated iron porphyrins in alkene and alkane oxidations by iodosylbenzene and hydrogen peroxide

Guedes,André Aparecido; Smith,John R. L.; Nascimento,Otaciro R.; Guedes,Débora F. Costa; Assis,Marilda das Dores
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2005 Português
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A poly-halogenated iron porphyrin, Fe(PCl8)Cl, has been synthesised and used as a catalyst in hydrocarbon oxidations by iodosylbenzene and hydrogen peroxide both in solution and covalently bound to aminopropylated silica. The poly-chlorinated iron porphyrin shows the same efficiency of the related Fe(P)Cl, in the epoxidation of alkenes but higher efficiency in the hydroxylation of alkanes by iodosylbenzene, with increased preference for the oxidation of secondary carbon in adamantane and primary carbon in the oxidation of pentane. These selectivities may reflect the steric constraints around the oxo-iron species or, alternatively, it may arise from the greater reactivity of the active oxidant from Fe(PCl8)Cl. The supported iron(III) porphyrin showed lower activity as compared with the homogeneous analogue and the related supported Fe(P)Cl. The poly-chlorinated iron porpyrin is a poor catalyst with hydrogen peroxide. Excessive substitutuion by electron withdrawing groups on the porphyrin periphery eventually prohibits the formation of the key intermediate in catalytic oxidations. The alternative oxidation mechanism could involve radical participation.