resumo
The one-dimensional organic-inorganic hybrid material [MoO3(2,2'-bipy)] (1) (2,2'-bipy = 2,2'-bipyridine) has been used as a starting material to prepare the bipy-deficient phases [Mo2O6(2,2'-bipy)] (2) and [Mo3O9(2,2'-bipy)(2)] (3) in excellent yields. The hybrid 2 was obtained by a solid-state thermal treatment of 1 (300 degrees C, 10 min) while 3 was obtained by a hydrothermal treatment of 1 (160 degrees C, 6 d). A study was performed to compare the catalytic properties of 1-3 in the epoxidation of cis-cyclooctene at 55 degrees C with tert-butylhydroperoxide (TBHP) or aqueous H2O2 as oxidant. In all cases Cy was converted to cyclooctene oxide (CyO) with 100% selectivity, and Cy conversions increased in the order 1 < 3 < 2, which parallels an increase in the Mo/2,2'-bipy molar ratio of the hybrid (1 < 1.5 < 2). With compound 2, CyO yields at 24 h were 96% for TBHP (cosolvent oc,a,a-trifluorotoluene) and 53% for H2O2 (cosolvent CH3CN). The catalytic reactions occurred in homogeneous phase with active species formed in situ from 1-3. All three hybrids react with aqueous H2O2 to give the catalytically active oxodiperoxo complex [MoO(O-2)(2)(2,2'-bipy)]. The 2:1 hybrid 2 was further examined for the epoxidation of other cyclic and linear non-functionalised olefins with TBHP, namely cyclododecene, 1-octene and trans-2-octene, and the biomass-derived olefins DL-limonene, oc-pinene and methyl oleate.
palavras-chave
OLEFIN EPOXIDATION; HYDROTHERMAL SYNTHESIS; MOLYBDENUM OXIDE; CRYSTAL-STRUCTURES; STRUCTURAL ELUCIDATION; OPEN-FRAMEWORKS; COMPLEXES; OXIDATION; PERFORMANCE; DERIVATIVES
categoria
Chemistry
autores
Bruno, SM; Nogueira, LS; Gomes, AC; Valente, AA; Goncalves, IS; Pillinger, M
nossos autores
Ana Catarina Costa Gomes Alves
Investigador Auxiliar
Anabela Tavares Aguiar Valente
Investigador Principal
Isabel Maria de Sousa Gonçalves
Professor associado
Lucie Solange Nogueira
Estudante de doutoramento
Martyn Pillinger
Investigador Principal
Sofia M. Bruno
Investigador AuxiliarProjectos
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)
Sistemas ativados por estímulos para a terapia com monóxido de carbono (SASCOT)
agradecimentos
This work was carried out with the support of CICECO - Aveiro Institute of Materials - POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013) and the CENTRO 2020 Regional Operational Programme (Project CENTRO-01-0145-FEDER-028031), co-financed by national funds through the FCT/MEC and the European Union through the European Regional Development Fund under the Portugal 2020 Partnership Agreement. The FCT and the European Union are acknowledged for a PhD grant to L. S. N. (PD/BD/109666/2015), and post-doctoral grants to S. M. B. (SFRH/BPD/108845/2015) and A. C. G. (SFRH/BPD/108541/2015), co-funded by MCTES and the European Social Fund through the program POPH of QREN.