Early‐Transition‐Metal Catalysts with Phenoxy–Imine‐Type Ligands for the Oligomerization of Ethylene

Abstract

Early-transition-metal complexes incorporating phenoxy-imine-type bidentate and tridentate ligands, after activation, can achieve selective as well as nonselective ethylene oligomerization to produce 1-hexene, linear α-olefins, and vinyl-terminated low-molecular-weight polyethylenes, all with high efficiency.

Catalytic Decarbonylation of Biosourced Substrates

“…The two main commercial processes to obtain LAO are the oligomerization of ethylene [1][2][3][4][5][6] and the Fischer-Tropsch process starting from syngas. Although longchain LAO (C 10 -C 14 )p lay an important role in the production of surfactants and lubricants, short-chain LAO (C 4 -C 8 )a re used in substantial amounts as co-monomers in the production of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE).…”

Oligomerization of Olefins

“…In contrast, Cr catalysts with some specific ligands have been found to promote selective trimerization and tetramerization of ethylene [2,6,8,10,11], while Ti and Ta catalysts are active for the trimerization are also known [2,12]. Those reactions proceed via a metallacycle mechanism.…”

“…The catalysts with smaller size ring (cyclopropyl and cyclobutyl) at the N atom cause lower a-selectivity for both C6 and C8 products with lower productivity (Table 5.3, runs 10, 11), whereas the increased a-selectivity and higher productivity are achieved as increasing the ring size of the substituents (Table 5.3, runs [12][13][14]. With N-cyclododecyl substituents, the a-selectivity for C6 and C8 products is increased to 84.6 and 99.4 %, respectively, and productivity reaches 757,720 g (g Cr) -1 h -1 (Table 5.3, run 14).…”

“…Quite recently, Kawamura and Fujita reported that Ti complex with phenoxyimine ligand with pendant aryl-OMe pendant 8a (Chart 5.8) is effective for trimerization of ethylene to give 1-hexene with very high productivity (6,590 kg (g Ti) (Table 5.2, run 25) [12,122]. Selectivity for C6 product is 92.3 wt%.…”

“…The a-olefins had been synthesized by Fischer-Tropsch synthesis or cracking of paraffin waxes. Oligomerization of olefins is more recent approach for a-olefins, which has become common and important in these several decades [1][2][3][4][5][6][7][8][9][10][11][12]. It is worth noting that the olefin oligomerization has advantage in atom economy, low energy cost, and production of the oligomer with even number of the carbon chain.…”