TY - JOUR
T1 - Zirconium and hafnium polyhedral oligosilsesquioxane complexes - green homogeneous catalysts in the formation of bio-derived ethers via a MPV/etherification reaction cascade
T2 - Via a MPV/etherification reaction cascade
AU - Garg, Shipra
AU - Unruh, Daniel
AU - Krempner, Clemens
N1 - Funding Information:
This research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Catalysis Science Program, under Award DE-SC0019094. We are grateful to Anthony Cozzolino for calculating the van der Waals volume of complex III and Shiva Moaven for assisting in the DOSY-NMR experiments.
Publisher Copyright:
© The Royal Society of Chemistry.
PY - 2021/1/7
Y1 - 2021/1/7
N2 - The polyhedral oligosilsesquioxane complexes, {[(isobutyl)7Si7O12]ZrOPri·(HOPri)}2 (I), {[(cyclohexyl)7Si7O12]ZrOPri·(HOPri)}2 (II), {[(isobutyl)7Si7O12]HfOPri·(HOPri)}2 (III) and {[(cyclohexyl)7Si7O12]HfOPri·(HOPri)}2 (IV), were synthesized in good yields from the reactions of M(OPri)4 (M = Zr, Hf) with R-POSS(OH)3 (R = isobutyl, cyclohexyl), resp. I-IV were characterized by 1H, 13C and 29Si 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(OPri)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.
AB - The polyhedral oligosilsesquioxane complexes, {[(isobutyl)7Si7O12]ZrOPri·(HOPri)}2 (I), {[(cyclohexyl)7Si7O12]ZrOPri·(HOPri)}2 (II), {[(isobutyl)7Si7O12]HfOPri·(HOPri)}2 (III) and {[(cyclohexyl)7Si7O12]HfOPri·(HOPri)}2 (IV), were synthesized in good yields from the reactions of M(OPri)4 (M = Zr, Hf) with R-POSS(OH)3 (R = isobutyl, cyclohexyl), resp. I-IV were characterized by 1H, 13C and 29Si 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(OPri)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.
UR - http://www.scopus.com/inward/record.url?scp=85099726571&partnerID=8YFLogxK
U2 - 10.1039/d0cy01864c
DO - 10.1039/d0cy01864c
M3 - Article
SN - 2044-4753
VL - 11
SP - 211
EP - 218
JO - Default journal
JF - Default journal
IS - 1
ER -