- Recycling of two molecular catalysts in the hydroformylation/aldol condensation tandem reaction using one multiphase system
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Tandem reactions are of great importance to efficiently execute multiple conversions in one synthesis step. Herein we present a multiphase system for the hydroformylation/aldol condensation, which is able to recycle both optimized catalysts multiple times. The system consists of an organometallic rhodium/sulfoXantphos hydroformylation catalyst and basic NaOH as aldol condensation initiator, which are both immobilized in a polyethylene glycol phase. Under reaction conditions, NaOH is converted to sodium formate, which is still able to catalyse the aldol condensation. The reaction and recycling are demonstrated by the conversion of 1-pentene to the corresponding aldol product in a recycling experiment. During nine consecutive runs, no significant loss of activity is found with an overall TON of 8700 in regard to the rhodium catalyst and an average rhodium leaching of only of 0.07% per run is observed.
- Leitner, Walter,Strohmann, Marc,Vorholt, Andreas J.,Vossen, Jeroen T.
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p. 8444 - 8451
(2021/01/01)
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- Palladium supported on an acidic resin: A unique bifunctional catalyst for the continuous catalytic hydrogenation of organic compounds in supercritical carbon dioxide
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1% Palladium-doped acidic resin (Amberlyst 15; styrene-divinylbenzene matrix with sulfonic acid groups) is shown to be a highly active catalyst for the continuous catalytic hydrogenation of C=C bonds in supercritical carbon dioxide (scCO2) without affecting C=O bonds. This 1% Pd/Amberlyst-15 catalyst promotes the industrially important selective formation of 2-ethylhexanal from crotonaldehyde in a one-pot pathway involving hydrogenation and aldol condensation witha number of merits. The selectivity behavior of 1% Pd/Amberlyst-15 is strikingly different compared to that of 1% Pd/C and 1% Pd/Al2O3 due to its prominent bifunctional nature based on sulfonic acid groups adjacent to metallic Pd sites. Hybrid [Pdn-H]+ sites are suggested to act as bothmet al and acid sites promoting the bifunctional catalysis.
- Seki, Tsunetake,Grunwaldt, Jan-Dierk,Van Vegten, Niels,Baiker, Alfons
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p. 691 - 705
(2009/04/12)
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