A Highly Selective Ethylene Tetramerization Catalyst

Abstract

Kleine Änderung mit großer Wirkung: Die Einführung einer zusätzlichen CH2‐Gruppe in die Brücke von Liganden mit zwei P/N‐Einheiten führt zu unterschiedlichen Selektivitäten der entsprechenden chrombasierten Katalysatoren. Während 1 zu einem Ethylentrimerisierungssystem führt, ergibt 2 ein Ethylentetramerisierungssystem, das 1‐Octen mit hoher Reinheit sowie wenige bis keine Polymer‐Nebenprodukte produziert (siehe Schema; DMAO=Me3Al‐armes Methylaluminoxan).

[(SiO)TaVCl2Me2]: A Well‐Defined Silica‐Supported Tantalum(V) Surface Complex as Catalyst Precursor for the Selective Cocatalyst‐Free Trimerization of Ethylene

“…[1,2] Currently, numerous studies in this field have been reported and developed into industrial processes: titanium-based catalysts for the dimerization of ethylene (Alpha-butol, IFP); [3] chromium-based catalysts for the trimerization of ethylene (Phillips Petroleum), [4] and more recently chromium-bearing PNP ligand for ethylene tetramerization (SASOL). [1,2] Currently, numerous studies in this field have been reported and developed into industrial processes: titanium-based catalysts for the dimerization of ethylene (Alpha-butol, IFP); [3] chromium-based catalysts for the trimerization of ethylene (Phillips Petroleum), [4] and more recently chromium-bearing PNP ligand for ethylene tetramerization (SASOL).…”

PNPN‐H in Comparison to other PNP, PNPN and NPNPN Ligands for the Chromium Catalyzed Selective Ethylene Oligomerization

“…This was only a concept, but later Gambarotta and co‐workers supported this by some very important experiments . In one paper, they described the tetramerization of ethylene to 1‐octene with high purity and little or no polymer byproducts, in which solvents and co‐catalysts had a dramatic impact on the selectivity.…”

“…In one paper, they described the tetramerization of ethylene to 1‐octene with high purity and little or no polymer byproducts, in which solvents and co‐catalysts had a dramatic impact on the selectivity. From the mechanistic point of view, because very small changes in the bridging Ph 2 PN(R)(CH 2 ) n N(R)PPh 2 ligands (n=2, 3 in Scheme ) were responsible for the obtained selectivity from 70 % of the trimer 1‐hexene for n=2 to 91 % of the tetramer 1‐octene with n=3 with chromium salt and DMAO as activator (Scheme ) …”

“…This result fits nicely with the suggestion of a bimetallic catalytically active species which could be responsible for the formation of 1‐octene and “… that such a remarkable sensitivity could be explained in terms of monomer versus dimer formation.” (Scheme ) …”

Multidentate Pyridyl‐Aminophosphinite and Pyridyl‐Phosphoramidite Ruthenium(II) Complexes: Synthesis, Structure and Application as Levulinic Acid Hydrogenation Pre‐Catalysts

“…The design of multidentate ligands containing mixed‐donor atoms to functionalize transition metal centers is a subject of growing interest in coordination and organometallic chemistry Multidentate mixed‐donor ligands function cooperatively in stabilizing metal centers due to their different binding abilities and bridging effect between two or more metal centers . These synergistic effects are helpful in making complexes containing multidentate mixed‐donor ligands very attractive for several applications including catalysis .…”