Structure and Properties of Poly-α-olefins Containing Quaternary Carbon Centers

Abstract

In this paper, poly-α-olefins (PAO) containing quaternary carbon centers were prepared by two-step oligomerization using a metallocene catalyst followed by a Ziegler–Natta catalyst. First, the 1-decene dimer was oligomerized with [t-BuN­(Me)2C­(η5-C5H4)]­ZrCl2, and the effects of the oligomerization temperature, Al/Zr molar ratio, and catalyst loading on the oligomerization were investigated. In the second step, the obtained 1-decene dimers were copolymerized with 1-decene with TiCl4/Et2AlCl, and the effects of the catalysts, monomer/dimer ratio, and α-olefin species on the copolymerization were investigated. The composition and structure of the dimers and copolymerization products were characterized by gas chromatography (GC) and 1H NMR and 13C NMR spectroscopy. The results of GC and 13C NMR analyses indicated that the metallocene catalyzed the formation of the 1-decene oligomerization product, resulting in the branched olefin dimer being the major product, and the existence of quaternary carbons in the 1-decene/1-decene dimer copolymerization product could also be found. The polymerization mechanism for the formation of the quaternary carbon centers is proposed. The 1-decene/1-decene dimer copolymerization product containing quaternary carbon centers has a kinematic viscosity of 10.8 mm2/s at 100 °C, a viscosity index of 165, and a pour point of −52 °C; thus, the product with quaternary carbon centers has a better viscosity–temperature performance and low-temperature fluidity than those of the 1-decene oligomerization product and typical PAO products, but the kinematic viscosity is similar.

Ti Group Metallocene-Catalyzed Synthesis of 1-Hexene Dimers and Tetramers

“…Under the same conditions, the dimers produced in the first minutes of the reaction serve as substrates for the subsequent dimerization to afford dimers of dimer 7 in 75–79% yields in 180 min (entries 7, 8, Figures S26 and S27 ). According to 1 H and 13 C NMR data, the structures of these products correspond to those proposed earlier [ 16 , 22 , 24 , 25 , 26 ]. Dimerization of 5 occurs probably via participation of cationic species formed upon the reaction of CHCl 3 with ClAlR 2 or MMAO-12.…”

“…Thus, vinylidene dimer 5 is formed in a high yield and with high selectivity under the action of [Cp 2 ZrH 2 ] 2 -ClAlBu i 2 -MMAO-12 or [Cp 2 ZrH 2 ] 2 -MMAO-12 in CH 2 Cl 2 . Chloroform facilitates the formation of a non-classical tetramer of 1-hexene ( 7 ), which could be used as a component of lubricants [ 16 , 24 , 25 , 26 ].…”

Catalytic Properties of Zirconocene-Based Systems in 1-Hexene Oligomerization and Structure of Metal Hydride Reaction Centers

“…They provide the most efficient stabilization of the electronic and steric environment of transition metal atoms owing to the high energy of metal–ligand bonds and allow variation of the electrophilicity and geometry of catalytically active sites due to broad possibilities of π-ligand modification. It has been shown that the electronic and steric features of the ligand, the nature of the activator, and the reaction conditions [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ] determine the productivity and selectivity of catalytic systems.…”

Catalytic Properties of Zirconocene-Based Systems in 1-Hexene Oligomerization and Structure of Metal Hydride Reaction Centers

“…They most efficiently ensure the stability of electronic and steric environment of transition metal atom due to the high energy of metal-ligand bond and vary the electrophilicity and geometry of catalytically active centers due to the large structural modification possibilities of π-ligand. Thus, it has been shown that the electronic and steric factor of the ligand, the nature of the activator, and the reaction conditions [8][9][10][11][12][13][14][15] determine the productivity and selectivity of catalytic systems.…”