resumo
Although several decades have passed since the introduction of homogeneous molybdenum catalysts for the bulk industrial production of epoxides from light olefins, the development of recyclable catalytic systems to produce more complex epoxides remains a challenge. In this work, we present a strategy for preparing a self-separating catalyst by exploiting reaction-induced precipitation, starting from the molybdenum(VI) tetrazolate complex [MoO(O2)(pto)2] (Hpto = 5-(2-pyridyl-1-oxide)tetrazole), which was synthesized via a one-pot approach and crystallographically characterized. High epoxide selectivities (96-100%) were achieved at high conversions (88-100%) under mild conditions (70 degrees C) in all the studied reactions, from that of the model substrate cis-cyclooctene to the epoxidation of biobased dl-limonene and fatty acid methyl esters. The catalytic reaction is homogeneous using tert-butyl hydroperoxide as the oxidant, whereas with hydrogen peroxide, a transformation to a self-separating catalyst takes place, which combines the high catalytic activity of a homogeneous catalyst with the easy recovery and reuse of a heterogeneous catalyst.
palavras-chave
STRUCTURAL ELUCIDATION; TETRACARBONYL COMPLEXES; OXYGEN ACTIVATION; MOLECULAR-OXYGEN; VEGETABLE-OILS; OXIDATION; PERFORMANCE; LIGANDS; HYBRIDS; ESTERS
categoria
Engineering
autores
Nunes, MS; Gomes, DM; Neves, P; Gomes, AC; Mendes, RF; Paz, FAA; Gonçalves, IS; Valente, AA; Pillinger, M
nossos autores
Ana Catarina Costa Gomes Alves
Investigador Auxiliar
Anabela Tavares Aguiar Valente
Investigador Principal
Filipe Alexandre Almeida Paz
Investigador Principal
Isabel Maria de Sousa Gonçalves
Professor associado
Martyn Pillinger
Investigador Principal
Patrícia dos Santos Neves
Investigador Auxiliar
Ricardo Faria Mendes
Investigador JúniorProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials (UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020), and LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020)), financed by national funds through the FCT (Fundacao para a Ciencia e a Tecnologia)/MCTES (Ministerio da Ciencia, Tecnologia e Ensino Superior) (PIDDAC). We acknowledge the support of the project with ref 2023.14213.PEX, financed by national funds through the FCT/MCTES (PIDDAC). M.S.N. (grant ref 2021.06403.BD, DOI 10.54499/2021.06403.BD) and D.M.G. (grant ref 2021.04756.BD, DOI 10.54499/2021.04756.BD) acknowledge the FCT for Ph.D. grants (State Budget, European Social Fund within the framework of PORTUGAL2020, namely, through the Centro 2020 Regional Operational Program). A.C.G. (ref CEECIND/02128/2017, DOI 10.54499/CEECIND/02128/2017/CP1459/CT0039) and R.F.M. (ref CEECIND/00553/2017, DOI 10.54499/CEECIND/00553/2017/CP1459/CT0034) thank the FCT/MCTES for research positions funded through the Individual Call to Scientific Employment Stimulus.