- Phosphonium-based aminophosphines as bifunctional ligands for sequential catalysis of one-pot hydroformylation-acetalization of olefins
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A series of ionic phosphonium-based aminophosphines L1-L3 were prepared and fully characterized, in each of which the involved bifunctional moieties of the phosphine fragment and Lewis acidic phosphonium were linked together by stable chemical bonds and bridged by one N-atom. The molecular structure of the L2-ligated Rh-complex (Rh-L2) indicated that such bifunctionalities were well retained without incompatibility problems. Investigations on co-catalysis over L1-L3 showed that L3 exhibited the best sequential catalysis for both hydroformylation and acetalization. The phosphine fragment in L3 was responsible for hydroformylation together with the Rh-complex and the phosphonium acted as the Lewis acidic catalyst in charge of acetalization. The L3-Rh(acac)(CO)2 system also exhibited good generality to hydroformylation-acetalization of a wide range of olefins in different alcohols.
- Wang, Peng,Liu, Huan,Li, Yong-Qi,Zhao, Xiao-Li,Lu, Yong,Liu, Ye
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p. 3854 - 3861
(2016/06/14)
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- Co-catalysis of a bi-functional ligand containing phosphine and Lewis acidic phosphonium for hydroformylation-acetalization of olefins
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A novel ionic bi-functional ligand of L2 containing a phosphine and a Lewis acidic phosphonium with I- as the counter-anion was prepared and fully characterized. The molecular structure indicated that the bi-functionalities in L2 were well retained without the incompatibility problem for quenching of the acidity of the phosphonium cation by the Lewis basic phosphine fragment or the anionic I- when the incorporated phosphine fragment and the Lewis acidic phosphonium were strictly located in the confined cis-positions. The co-catalysis over L2-Rh(acac)(CO)2 in the ways of synergetic catalysis and sequential catalysis was successfully fulfilled for one-pot hydroformylation-acetalization, which proved not to be the result of the simple mixture of the mono-phosphine (L4) and the phosphonium salt (L4′). In L2, the phosphonium not only acted as a Lewis acid organocatalyst to drive the sequential acetalization of aldehydes, but also contributed to the synergetic catalysis for the preceding hydroformylation through stabilizing the Rh-acyl intermediate with the phosphine cooperatively. The L2-Rh(acac)(CO)2 system is also generally applied to hydroformylation-acetalization of a wide range of olefins in different alcohols. Advantageously, as an ionic phosphonium-based ligand, L2 could be recycled for 7 runs with Rh(acac)(CO)2 together in RTIL of [Bmim]BF4 without obvious activity loss or metal leaching.
- Li, Yong-Qi,Wang, Peng,Liu, Huan,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
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p. 1798 - 1806
(2016/04/01)
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- The mechanism of acetal formation in acid-free rh-catalyzed tandem hydroformylation-acetalization of olefins in MeOH
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The acetal formation mechanism under acid-free Rh-catalyzed hydroformylation-acetalization condition has been studied using different rhodium catalyst precursors in MeOH. In the absence of added acidic co-catalyst, the acetalization is catalyzed by the H+ formed in situ under hydroformylation condition, and Rh active site on Rhphosphine catalyst did not exhibit catalytic activity for acetalization. Whether H+ can be generated in situ is related with the structure of rhodium catalyst precursor. Under hydroformylation condition, added Bronsted acids as co-catalysts can improve acetalization efficiency, but the H+ concentration in the system should not be excessively high to avoid the acid-induced inhibition for hydroformylation.
- Jin, Xin,Zhao, Kun,Kong, Fangfang,Cui, Feifei,Liu, Qiangqiang,Zhang, Yaowu
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p. 192 - 196
(2014/03/21)
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- Zwitterionic phosphine ligand with a lysine tag and its application for hydroformylation of 1-octene in ionic liquid/MeOH system
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Here we report a highly active and selective hydroformylation of 1-octene in ionic liquid (IL)/MeOH system based on a zwitterionic phosphine ligand bearing a lysine moiety (L(NH2)COOH). The Rh-catalyst grafted lysine in the form of ammonium salt ([Rh-L(NH3 +)COOH]Tf 2N) was successfully immobilized in the IL [bmim]Tf2N and recycled for seventeen times without significant loss of activity, selectivity and Rh catalysts. This study has provided a novel strategy for efficient separation and recycling of Rh catalysts.
- Jin, Xin,Zhao, Kun,Kong, Fangfang,Cui, Feifei,Yang, Daoxing
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p. 839 - 843
(2013/08/23)
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- Formation of acetals under rhodium-catalyzed hydroformylation conditions in alcohols
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Hydroformylation of terminal alkenes in alcohol solvents leads to the selective formation of the corresponding acetals. The Xantphos ligand gave the best results as well as acetal selectivities higher than 99% and linear/branched ratios of up to 52 were obtained. The scope of the reaction was studied. Acetals were found to be unreactive under hydroaminomethylation conditions. Copyright
- Diebolt, Olivier,Cruzeuil, Clement,Mueller, Christian,Vogt, Dieter
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supporting information; experimental part
p. 670 - 677
(2012/04/23)
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- Photochemical Hydroformylation with Cobalt Catalysts in Methanol
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The photochemical hydroformylation of 1-octene with cobalt/phosphane complexes in methanol leads under mild conditions (80 deg C, 80 bar CO/H2) with >= 90percent selectivity to linear aldehydes.The reaction rate increases with temperature (Ea = 5 - 6 kcal/mol) and synthesis gas pressure, and is nearly independent of the cobalt source, e.g.Co(OAc)2, Co2(CO)8, or Co2(CO)6(PBu3)2.At low pressures hydroesterification is the preferred photoreaction of 1-octene.Isoprene reacts under similar conditions to give unsaturated oxoproducts and linear isoprene dimers.With unmodified octacarbonyldicobalt the hydroformylation of internal olefins is enhanced by UV light, but not the reaction of terminal olefins or dienes.UV irradiation of cobalt acetate under hydroformylation conditions leads to rapid reduction of the Co(II) species, thus decreasing the induction period from ca. 15 h (without irradiation) to ca. 30 min.
- Mirbach, Manfred J.,Topalsavoglou, Nikolaos,Phu, Tuyet Nhu,Mirbach, Marlis F.,Saus, Alfons
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p. 1422 - 1440
(2007/10/02)
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