Zirconium and hafnium polyhedral oligosilsesquioxane complexes ? green homogeneous catalysts in the formation of bio-derived ethers via a MPV/etherification reaction cascade [electronic resource]

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Ngôn ngữ: eng

Ký hiệu phân loại: 621.45 Wind engines

Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2021

Mô tả vật lý: Size: p. 211-218 : , digital, PDF file.

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ID: 262567

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The polyhedral oligosilsesquioxane complexes, {[(isobutyl)
7
Si
7
O
12
]ZrOPr
i
�(HOPr
i
)}2 (I), {[(cyclohexyl)
7
Si
7
O
12
]ZrOPr
i
�(HOPr
i
)}
2
(II), {[(isobutyl)
7
Si
7
O
12
]HfOPr
i
�(HOPr
i
)}
2
(III) and {[(cyclohexyl)
7
Si
7
O
12
]HfOPr
i
�(HOPr
i
)}
2
(IV), were synthesized in good yields from the reactions of M(OPr
i
)
4
(M = Zr, Hf) with R-POSS(OH)
3
(R = isobutyl, cyclohexyl), resp. I?IV were characterized by 
1
H, 
13
C and 
29
Si NMR spectroscopy and their dimeric solid-state structures were confirmed by X-ray analysis. I?IV catalyze the reductive etherification of 2-hydroxy- and 4-hydroxy and 2-methoxy and 4-methoxybenzaldehyde and vanillin to their respective isopropyl ethers in isopropanol as a ?green? solvent and reagent. I?IV are durable and robust homogeneous catalysts operating at temperatures of 100?160 �C for days without significant loss of catalytic activity. Likewise, I?IV selectively catalyze the conversion of 5-hydroxymethylfurfural (HMF) into 2,5-bis(isopropoxymethyl)furane (BPMF), a potentially high-performance fuel additive. Similar results were achieved by using a combination of M(OPr
i
)
4
and ligand R-POSS(OH)
3
as a catalyst system demonstrating the potential of this ?in situ? approach for applications in biomass transformations. A tentative reaction mechanism for the reductive etherification of aldehydes catalysed by I?IV is proposed.

1. 09 biomass fuels

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