Preparation of ansa-metallocenes for production of poly(α-olefin) lubricants

Abstract

An ansa-zirconocene bearing methyl substituents at all positions adjacent to the bridgehead [(-C(Ph)HC(Ph)H-)(η(5)-2,5-Me2C5H2)2ZrCl2] (4) was prepared in high yields (78%) through the reductive dimerization of 1,4-dimethyl-6-phenylfulvene utilizing ZrCl2·DME generated in situ. The structure of 4 was subsequently confirmed using X-ray crystallography. 4 exhibited excellent catalytic performance with regard to 1-decene oligomerization, which was carried out with the intention of preparing lubricant base stocks. High activities (21 × 10(6) g mol(-1) Zr h(-1) activity; TON = 150 000; TOF = 42 s(-1)) were observed at temperatures as high as 120 °C and the oligomer distribution was appropriate for lubricant application. The simulated distillation (SIMDIS) data confirmed that a wide range of oligomers were formed, ranging from the dimer (2-mer) to 20-mer. A minimal amount of the dimer and oligomers larger than the 10-mer was formed (13 and 25 wt%, respectively). Alternatively, a typical unbridged complex such as (η(5)-nBuC5H4)2ZrCl2 primarily produced dimers (54 wt%), whereas the ansa-zirconocene (EBI)ZrCl2 primarily produced oligomers larger than 10-mer (62 wt%). The methyl substituents at the positions adjacent to the bridgehead in 4 played a significant role in the catalytic performance.

Experimental and Theoretical Study of Zirconocene-Catalyzed Oligomerization of 1-Octene

“…Therefore, the use of NB F instead of MAO seems feasible in terms of the yield of structurally uniform α-olefin oligomers. Note that it is this activation method that was used in prospective technologies of the production of PAOs [57][58][59][60][61][62][63][64].…”

Studies on Poly α‐Olefin Synthesis by AlCl3‐catalyzed Cationic Polymerization: Concentration Effect on Molecular Weight and Viscosity

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Conventional lubricants are formulated using base stocks, which mostly come from crude oils, namely mineral lubricants. [8][9][10] Lewis acid catalyzed cationic polymerization is simple and do not require rigorous conditions. Another class of lubricant base stocks, synthetic lubricants is obtained from chemical synthesis.

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“…2,3 Polymerization of long-chain α-olefins produces high-performance poly(α-olefin) base stocks which provide improved longevity, less maintenance, and better energy efficiency. [8][9][10] Lewis acid catalyzed cationic polymerization is simple and do not require rigorous conditions. 4 For the PAO synthesis, boron or aluminum Lewis acid mediated cationic polymerizations were mainly practiced with a long-chain α-olefin, representatively 1-decene (Scheme 1).…”

Copolymerization of 4-methyl-1-pentene with α,ω-alkenols

“…Studies on the polymerization of higher α-olefin have drawn considerable attention for long years. Polymerization of either linear or branched α-olefin has been fully explored by using various catalyst systems, including the traditional Ziegler-Natta catalyst [19,20], metallocene catalyst [21][22][23][24], non-metallocene single-site catalyst [25] and later transition metal catalyst [26,27]. Properties of poly(α-olefin) could be improved by incorporating the second monomer with a functional group, but the successful examples were limited so far [28,29].…”