Epoxidation of styrene by a manganese(III) salen complex encapsulated in an aluminium pillared clay

• Tipo: Artigo em Revista Científica Internacional
• Data: 2004

Autores

Kuzniarska Biernacka, I (Autor) Outra; Silva, AR (Autor) Outra; Ferreira, R (Autor) Outra; Carvalho, AP (Autor) Outra; Pires, J (Autor) Outra; de Carvalho, MB (Autor) Outra; Freire, C (Autor) FCUP; de Castro, B (Autor) FCUP

Revista

Título: New Journal of Chemistry

Vol. 28

Páginas: 853-858

ISSN: 1144-0546

Editora: Royal Society of Chemistry

Indexação

ISI Web of Knowledge - 31 Citações

Scopus - 33 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Química

Outras Informações

ID Authenticus: P-000-D9Z

DOI: 10.1039/b401830c

Abstract (EN): The manganese(III) complex - carboxylate-[N, N'-bis(salicylaldehyde) cyclohexanediaminate] manganese( III), [Mn(salhd) CH3COO] - was encapsulated into an aluminium pillared clay ( denoted as Al-WYO) using a two-step liquid phase methodology: (i) adsorption of manganese(II) acetate in ethanolic solution within Al-WYO, followed by (ii) diffusion of N, N'-bis(salicylaldehyde) cyclohexanediamine in ethanolic solution. The new material was characterised by several techniques (ICP-AES, XPS, FTIR, UV - Vis and low temperature nitrogen adsorption) which showed that in situ synthesis of the manganese( III) complex took place within the aluminium pillared clay porous structure. The catalytic activity of the heterogenised [Mn( salhd) CH3COO] in the epoxidation of styrene was studied in acetonitrile, at room temperature, using iodosylbenzene or sodium hypochlorite as oxygen source. With PhIO the new heterogeneous catalyst showed high styrene epoxide chemoselectivity and could be reused at least 3 times without significant loss in styrene epoxide yield, suggesting that no complex leaching took place under the reaction conditions used. When sodium hypochlorite was used as oxidant, high selectivity in by-products was observed, as well as extensive leaching of the catalyst into solution. XPS spectra of the catalyst after the catalytic reaction confirm manganese complex leaching and also show a significant decrease in aluminium content, thus suggesting that partial damage of aluminium pillars took place in this reaction media, inducing complex leaching.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 6