Heterocene Catalysts and Reaction Temperature Gradient in Dec-1-ene Oligomerization for the Production of Low Viscosity PAO Base Stocks

Abstract

Hydrogenated oligomers of higher α-olefins (primarily, dec-1-ene) with uniform structure represent high-quality poly-α-olefin oil (PAO) base stocks. High yields of lightweight dec-1-ene oligomers (DP n = 3−4) can be achieved by using 5,10dihydroindeno[1,2-b]indole-based zirconium ansa-complexes, "heterocenes". Unusual catalytic behavior of heterocenes served as a starting point for the present study, during which new, more synthetically available and active heterocene precatalysts were synthesized, and a novel oligomerization method, based on a reaction temperature gradient, was developed. A gradual decrease of the oligomerization temperature as dec-1-ene was consumed resulted in decreased dimer formation (down to 10%) and increased oligomer yields (up to 84%). After hydrogenation, low-and medium-viscosity PAO base oils with uniform structure and high viscosity indexes were obtained.

MAO- and Borate-Free Activating Supports for Group 4 Metallocene and Post-Metallocene Catalysts of α-Olefin Polymerization and Oligomerization

“…The structures of the most active pre-catalysts are presented in Scheme 22 ; the results of the oligomerization experiments are given in Table 12 . As can be seen from this table, TOF of 10 5 h −1 and higher can be achieved when using SiO 2 /Al 2 O 3 (F), which is comparable to activities of the best oligomerization catalysts under homogeneous conditions with perfluoroborate activation [ 222 , 223 ].…”

Polyisobutylenes with Controlled Molecular Weight and Chain-End Structure: Synthesis and Actual Applications

“…Finally, one cannot fail to note the structural similarity of HRPIBs and methylenealkanes, including vinylidene dimers and oligomers of α-olefins [ 180 , 181 ]. Apparently, the methods of HRPIB functionalization can be successfully applied in methylenealkane chemistry, and vice versa, especially in view of the progress achieved recently in catalytic transformations of methylenealkanes [ 182 , 183 , 184 , 185 , 186 , 187 ].…”

The Dimerization and Oligomerization of Alkenes Catalyzed with Transition Metal Complexes: Catalytic Systems and Reaction Mechanisms

“…Unsymmetrical complexes 50a – c , 51 , and 52 in the presence of AlBu i 3 , (PhHNMe 2 )[B(C 6 F 5 ) 4 ], and H 2 (1 bar) at a [Zr]:[Al]:[B]:[1-alkene] ratio of 1:100:1.5:100,000 at 100 °C catalyzed the formation of light 1-decene oligomers with an alkene conversion rate of 86–99% [ 65 ]. A gradual decrease in the reaction temperature as 1-decene was shown to reduce the content of dimers (down to 10%) and increase the proportion of oligomers (up to 84%) in the reaction products.…”

“…It is noted that electron-donating alkyl substituents in the ligand of the complex lead to a decrease in the electrophilicity of the Zr atom and, consequently, to a decrease in catalytic activity, for example, in the case of 49f vs. 50a and 50b . Nevertheless, the lower electrophilicity of Zr ( 49f ) or steric hindrances (for example, in the case of 51 or 52 ) of the ligand does not promote β-H transfer, which provides higher yields of C30+ or C50+ oligomers [ 65 ].…”

“…It is noted that electron-donating alkyl substituents in the ligand of the complex lead to a decrease in the electrophilicity of the Zr atom and, consequently, to a decrease in catalytic activity, for example, in the case of 49f vs. 50a and 50b. Nevertheless, the lower electrophilicity of Zr (49f) or steric hindrances (for example, in the case of 51 or 52) of the ligand does not promote β-H transfer, which provides higher yields of C30+ or C50+ oligomers [65]. Further, when considering the possible stages of alkene oligomerization (which are coordination, chain growth, and termination, involving the β-H transfer and β-H elimination stages), the authors noted [65] that in the case of heterocenes, the processes of β-H elimination apparently prevail at the final stage of the reaction, when most of the monomer is consumed, leading to the accumulation of C20 dimers in the products (Scheme 24).…”