abstract
The horizons of epoxidation and sulfoxidation processes may be expanded by developing new, efficient, and versatile catalysts. In the present work, three pyrazine-bridged molybdenum(0/VI)-based coordination network solids have been investigated for the epoxidation of olefins and the oxidation of sulfides. The materials studied were the Mo0-based metal-organic framework (MOF) fac-Mo(CO)3(pyz)3/2.1/2pyz (1) with a structure consisting of stacked fac-Mo(CO)3(pyz)3/2 coordination layers, the cubic phase fac-Mo(CO)3(pyz)3/2 (2) with a dense framework consisting of two interpenetrating coordination networks, and the molybdenum oxide-pyrazine hybrid material [Mo2O6(pyz)] (3) with a structure consisting of perovskite-like MoO3 layers pillared by pyz molecules. In the model reaction of cis-cyclooctene with tert-butyl hydroperoxide (TBHP) at 70 degrees C, quantitative yields of the epoxide were obtained within 2 h for 1, 4 h for 2, and 24 h for 3. Catalysts 1-3 were further examined for the epoxidation of other olefins, including the bio-olefins dl-limonene, methyl oleate and methyl linoleate, and the reaction scope was expanded to include the oxidation of sulfides. In the reactions of the bio-olefins, 3 was highly selective, giving only diepoxide and/or monoepoxide products. While the tricarbonyl-pyrazine-molybdenum(0) compounds displayed higher activity, by-products were obtained in the reactions of dl-limonene and methyl linoleate, namely limonene-1,2-diol and hydroxytetrahydrofuran cyclization products, respectively. Catalysts 1-3 displayed high activity for the selective oxidation of sulfides (methyl phenyl sulfide and diphenyl sulfide) to sulfones under mild conditions (35 degrees C).
keywords
COORDINATION POLYMERS; OLEFIN EPOXIDATION; SELECTIVE EPOXIDATION; RATIONAL DESIGN; VEGETABLE-OILS; SPIN-CROSSOVER; METAL; COMPLEXES; PRECURSORS; HYBRIDS
subject category
Chemistry; Engineering
authors
Gomes, DM; Silva, AF; Gomes, AC; Neves, P; Valente, AA; Gonçalves, IS; Pillinger, M
our authors
Projects
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)
Sistemas ativados por estímulos para a terapia com monóxido de carbono (SASCOT)
Conversao catalitica de olefinas derivadas da biomassa (BiOle_AcidOxCat)
acknowledgements
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & 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 support and funding provided within the CENTRO 2020 Regional Operational Program (project references CENTRO-01-0145-FEDER-028031 and PTDC/QUIQOR/28031/2017) and the COMPETE 2020 Operational Thematic Program for Competitiveness and Internationalization (POCI-01-0145-FEDER-030075), co-financed by national funds through the FCT/MEC (Ministerio da Educacao e Ciencia) and the European Union through the European Regional Development Fund under the Portugal 2020 Partnership Agreement. D.M.G. (grant ref. 2021.04756.BD) acknowledges the FCT for a PhD grant (State Budget, European Social Fund (ESF) within the framework of PORTUGAL2020, namely through the Centro 2020 Regional Operational Program). A.C.G. thanks the FCT/MCTES for funding through the Individual Call to Scientific Employment Stimulus (CEECIND/02128/2017).