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Immobilized Metal Complex Catalysts and Heterogeneous Precious Metal Catalysts on Polysiloxane Supports and Their Application in Organic Synthesis
Published in Mike G. Scaros, Michael L. Prunier, Catalysis of Organic Reactions, 2017
Hydroformylation of 1-octene. Commercial hydroformylation reactions are carried out using homogeneous Co or Rh catalysts7. While catalyst-recovery problems for large-scale hydroformylation products, such as butyraldehyde, have been satisfactorily solved 8, there is some interest in the use of heterogeneous catalysts for the conversion of speciality and long-chain olefins to the corresponding aldehydes or alcohols. Long catalyst life is required and only very little leaching of rhodium can be tolerated. An investigation of the hydroformylation of 1-octene (equation 4) yielded moderate n/iso- ratios of 1.4 to 1.6. Catalyst stability was good over a period of several weeks. Figure 1 illustrates the composition of the product stream.
Selective ethylene oligomerization bearing hyperbranched bispyridylamine chromium catalyst
Published in Journal of Coordination Chemistry, 2019
Jun Wang, Jinyi Liu, Tianyu Lan, Liduo Chen, Libo Wang
Linear alpha olefins (LAOs) are versatile chemical intermediates. The oligomerization of ethylene to synthesize higher linear α-olefins has been widely used. The C4-C8 olefins are used as comonomers, C6-C10 olefins are used as plasticizers, and C8-C18 olefins are synthesized as lubricants and detergents [1]. Hence, it is crucial to prevent the formation of unwanted polymeric materials for profitability of catalytic systems designed to produce higher linear α-olefins [2]. Because of the rapidly growing market demand, research for new efficient ethylene oligomerization catalysts has been stimulated [3–8]. Conventional process of ethylene oligomerization to produce linear α-olefins is generally based on the transition metal catalysts, which can produce a wide range of olefins. Among all the transition metal catalysts, chromium catalysts occupy a unique position, since they provide both selective (commercially viable trimerization and tetramerization catalytic systems) and nonselective ethylene oligomerization [9]. A few selective trimerization systems have been discovered [10]. The first selective trimerization system producing 1-hexene with more than 90% selectivity was reported by Chevron-Phillips Petroleum Company [11]. Subsequently, Mitsubishi significantly improved the performance of the same catalyst through precise control of the process and slight modification of the catalyst composition [12]. Following this, many new chromium-based ethylene trimerization and even tetramerization catalysts with various ligand systems have been reported [13, 14]. Tetramerization of ethylene to 1-octene has been achieved with up to 70% selectivity using a Cr-based catalyst system [15]. One was the Cr-PNNP system recently reported by Gambarotta and co-workers, which was found to produce 91% 1-octene with 9% 1-hexene as the only side product. As a result of ready interconversion between mono-, di-, and trivalent oxidation states of chromium, the same precursor might play different roles in selective or nonselective ethylene oligomerization. Typical examples are chromium catalysts bearing N°N°N [16], P°N°P [17] and S°N°S [18] ligands, which indicates that P and N donors are very likely to facilitate selective ethylene oligomerization [19–24].