Cationic Oligomerization Research Articles

Production of polyalfaolefin-based lubricants using new (poly)ionic liquid /AlCl3 catalysts as environmentally friendly alternatives to commercial AlCl3 route

Aiming to decrease corrosive AlCl3 dosage in polyalphaolefin production, two new (poly)ionic liquid /AlCl3 catalysts were synthesized from the reaction of 1-vinylimidazole with benzyl chloride (to yield IL) and subsequent polymerization of its vinyl bond by radical route, to achieve polyionic liquid (PIL). Cationic oligomerization of three α-olefin monomers, from 1-hexene to 1-decene, was accomplished using IL(or PIL)/AlCl3 catalysts with 50:50 wt.% composition to halve the usage of hazardous AlCl3. Microstructure and flow characteristic of the obtained PAO oligomers were characterized by 1HNMR, 13CNMR, GPC, viscometry, GC-Mass, and SimDis analyses and compared with those of PAOs from neat AlCl3. Results from GPC, viscometry and GC revealed that molecular weight decreases using lighter α-olefin monomers. Notably, while the PAOs from IL/AlCl3 have almost heavier fractions, the ones from PIL/AlCl3 and neat AlCl3 demonstrated similar molecular weight and KV100 amounts. The PAOs from PIL/AlCl3 and IL/AlCl3 represented a more uniform structures, with low short chain branching, beneficial to higher viscosity index (VI). This achievement featured PIL/AlCl3 as a suitable alternative to corrosive AlCl3, which besides its more environmentally friendly character, thanks to PIL presence, is capable of producing PAOs with the same KV100, however, with much higher VI values.

Selective Trimerization of α-Olefins with Immobilized Chromium Catalyst for Lubricant Base Oils

The demand for poly(α-olefin)s (PAOs), which are high-performance group IV lubricant base oils, is increasingly high. PAOs are generally produced via the cationic oligomerization of 1-decene, wherein skeleton rearrangement inevitably occurs in the products. Hence, a transition-metal-based catalytic process that avoids rearrangement would be a valuable alternative for cationic oligomerization. In particular, transition-metal-catalyzed selective trimerization of α-olefins has the potential for success. In this study, (N,N′,N″-tridodecyltriazacyclohexane)CrCl3 complex was reacted with MAO-silica (MAO, methylaluminoxane) for the preparation of a supported catalyst, which exhibited superior performance in selective α-olefin trimerization compared to that of the corresponding homogeneous catalyst, enabling the preparation of α-olefin trimers at ~200 g scale. Following hydrogenation, the prepared 1-decene trimer (C30H62) exhibited better lubricant properties than those of commercial-grade PAO-4 (kinematic viscosity at 40 °C, 15.1 vs. 17.4 cSt; kinematic viscosity at 100 °C, 3.9 vs. 3.9 cSt; viscosity index, 161 vs. 123). Moreover, it was shown that 1-octene/1-dodecene mixed co-trimers (i.e., a mixture of C24H50, C28H58, C32H66, and C36H74), generated by the selective supported Cr catalyst, exhibited outstanding lubricant properties analogous to those observed for the 1-decene trimer (C30H62).

Carbenium ion-mediated oligomerization of methylglyoxal for secondary organic aerosol formation

Secondary organic aerosol (SOA) represents a major constituent of tropospheric fine particulate matter, with profound implications for human health and climate. However, the chemical mechanisms leading to SOA formation remain uncertain, and atmospheric models consistently underpredict the global SOA budget. Small α-dicarbonyls, such as methylglyoxal, are ubiquitous in the atmosphere because of their significant production from photooxidation of aromatic hydrocarbons from traffic and industrial sources as well as from biogenic isoprene. Current experimental and theoretical results on the roles of methylglyoxal in SOA formation are conflicting. Using quantum chemical calculations, we show cationic oligomerization of methylglyoxal in aqueous media. Initial protonation and hydration of methylglyoxal lead to formation of diols/tetrol, and subsequent protonation and dehydration of diols/tetrol yield carbenium ions, which represent the key intermediates for formation and propagation of oligomerization. On the other hand, our results reveal that the previously proposed oligomerization via hydration for methylglyoxal is kinetically and thermodynamically implausible. The carbenium ion-mediated mechanism occurs barrierlessly on weakly acidic aerosols and cloud/fog droplets and likely provides a key pathway for SOA formation from biogenic and anthropogenic emissions.

Cationic Oligomerization of Octene Fraction under Flow Conditions

Laboratory studies have been conducted to explore the possibility of obtaining poly-α-olefin oil PAO-20 under flow conditions on the basis of the domestic industrial octene fraction of α-olefins. The features of cationic oligomerization have been revealed by varying the catalyst concentration and the reaction temperature; process parameters to ensure the maximum yield of desired target product have been determined.

Synthesis of New Aliphatic Hydrocarbon Resins on the Basis of Isoprene

Cationic oligomerization of isoprene using a wide range of catalyst systems based on various Lewis acids has been studied. It has been shown that fully soluble isoprene oligomers can be synthesized with the TiCl4–tert-butyl chloride catalyst system throughout the entire range of monomer conversion. The conditions for preparing isoprene oligomers with a softening point of 100–120°C characteristic of aliphatic hydrocarbon resins have been determined. The developed method for preparing aliphatic resins on the basis of isoprene is characterized by a simple technology and a possibility of controlling the softening point of the resins during the process.

Cationic Oligomerization of the Pyrolysis C5 Fraction

The cationic oligomerization of the pyrolysis C5 fraction in the presence of catalyst systems based on AlCl3, VOCl3, BF3 · O(C2H5)2, and a Gustavson complex has been investigated. It has been shown that the use of the diisopropyl ether-modified Gustavson complex in the reaction makes it possible to synthesize fully soluble oligomers in high yields. The conversions of all the unsaturated components of the pyrolysis fraction to the oligomer at different durations of the oligomerization process have been determined. The synthesized oligomers are characterized by high unsaturation and exhibit the properties of film-forming compounds.

Modeling of the Kinetic Experiment of Dicyclopentadiene Olygomerization

Regularities of the dicyclopentadiene cationic oligomerization under influence of the catalytic system AlEt2Cl: TiCl4 in toluene solution were studied. The most probable mechanism of polymerization in this system is the propagation chain on the contact or solvate-separated ion pairs. The effective rate constant of solvation of the catalyst and chain propagation were calculated. The thermal oligomerization effect and heat of the catalyst system components solvation are determined by heat of oligomerization raw material containing dicyclopentadiene. When taking into account the data of both material and thermal balance the experimental data were described adequately.

Dry Deposition of Biogenic Terpenes via Cationic Oligomerization on Environmental Aqueous Surfaces.

Unraveling the complex interactions between the atmosphere and the biosphere is critical for predicting climate changes. Although it is well-recognized that the large amounts of biogenic volatile organic compounds (BVOCs) emitted by plants must play important roles in this regard, current atmospheric models fail to account for their fate due to missing chemical sinks. Here, we applied online electrospray mass spectrometry to monitor aqueous microjets exposed to gaseous monoterpenes (α-pinene, β-pinene, and d-limonene) and found that these BVOCs are readily protonated (to C10H17(+)) and undergo oligomerization (to C20H33(+) and C30H49(+)) upon colliding with the surface of pH < 4 microjets. By considering that the yields of all products show inflection points at pH ≈ 3.5 and display solvent kinetic hydrogen isotope effects larger than 2, we conclude that the oligomerization process is initiated by weakly hydrated hydronium ions, H3O(+), present at the gas-water interface. Present results provide a universal mechanism for the dry deposition of unsaturated BVOCs and may account for recent observations on the uptake of terpenes in forest canopies and over grassland.

Chirality Transfer in the Formation of Poly(oxymethylene) Helices by Anionic Polymerization

AbstractIn this article, we present the synthesis of a series of oligo(oxymethylenes) capped with 1‐phenylethanol and MeOH. The anionic condition affords enantiomerically pure oligo(oxymethylene) oligomers, while the cationic oligomerization leads to a racemic mixture of the oligo(oxymethylene) chain.

Protonation and Oligomerization of Gaseous Isoprene on Mildly Acidic Surfaces: Implications for Atmospheric Chemistry

In a global process linking the Earth's climate with its ecosystems, massive photosynthetic isoprene (ISOP) emissions are converted to light-scattering haze. This phenomenon is imperfectly captured by atmospheric chemistry models: predicted ISOP emissions atop forest canopies would deplete the oxidizing capacity of the overhead atmosphere, at variance with field observations. Here we address this key issue in novel laboratory experiments where we apply electrospray mass spectrometry to detect online the products of the reactive uptake of gaseous ISOP on the surface of aqueous jets as a function of acidity. We found that ISOP is already protonated to ISOPH(+) and undergoes cationic oligomerization to (ISOP)(2)H(+) and (ISOP)(3)H(+) on the surface of pH < 4 water jets. We estimate uptake coefficients, γ(ISOP) = (0.5 - 2.0) × 10(-6) on pH = 3 water, which translate into the significant reuptake of leaf-level ISOP emissions in typical (surface-to-volume ∼5 m(-1)) forests during realistic (a few minutes) in-canopy residence times. Our findings may also account for the rapid decay of ISOP in forests after sunset and help bring the global budget of volatile organic compounds closer to balance.

Water-tolerant catalyst systems for the bulk cationic polymerization of para-methylstyrene and indene

Water-tolerant catalyst systems have been investigated for the cationic oligomerization of technical-grade p-methylstyrene and indene, for the production of industrially relevant aromatic resins. Systems based on 1- p-tolylethanol and 1-indanol (ROH) as initiators, in association with Cu(OTf) 2, Bi(OTf) 3 (OTf = triflate) and B(C 6F 5) 3 as co-initiators/catalysts, show interesting productivities at 60 °C under air, with as low as 0.2–1.0 mol% catalyst loading. Most of the reactions are not controlled in terms of molecular weights of the products, except for indene oligomerization by the borane catalyst where experimental M n values match well the theoretical values, as determined by the amount of added initiator over a 5-fold range (with 2–10 mol% vs. monomer). The ROH/tris(pentafluorophenyl)borane system offers the best compromise in terms of productivity and control over the molecular weights of the oligomers, which can be manipulated by the amount of initiator and reaction temperature.

Oligomerization of 1-decene under the action of catalytic systems based on Al-aluminum activator-RCl and Al-RCl

Novel catalytic systems for the cationic oligomerization of 1-decene into synthetic poly(α-olefin) oils have been worked out; these systems include a highly disperse (0.1–40 μm) aluminum, an aluminum activator [I2, Mg, (C2H5)nAlCl3 − n, (CH3)3CCl and some other RX, HCl, benzene, and toluene], and a cocatalyst based on organic halide compounds RX (R is primary, secondary, or tertiary alkyl, allyl, or benzyl; X is Cl, Br, or I). We study the effect of various factors (characteristics of Al, nature of aluminum activator, RCl: Al molar ratio in the catalyst, concentration of Al, temperature, benzene additives, reaction duration) on the conversion of 1-decene into poly(α-olefins), the fractional composition of oligomerization products, the content of chlorine in poly(α-olefins), and the structure and physicochemical characteristics of fractions.

Cationic oligomerization of alfa-hydroxy-gamma-butyrolactone

Cationic polymerization of 5-membered cyclic ester a-hydroxy-γ-butyrolactone (BL-OH) proceeds according to activated monomer (AM) mechanism and leads to low molecular weight polymers. Elimination of water from growing macromolecules occurs during the polymerization process. The extent of dehydration depends on the catalyst and is the lowest in the case of scandium triflate [(CF 3 SO 3 ) 3 Sc] catalyst. Spontaneous polymerization of BL-OH, occurring during vacuum distillation, leads to the oligomeric product without dehydration.

Oligomerization of substituted oxetanes and parameters of their molecular heterogeneity

Cationic oligomerization of disubstituted oxetanes promoted by trifluoroboron etherate in the presence of ethylene glycol was studied. The parameters of molecular-weight and functionality distribution of the resulting oligooxetane diols were determined by gel-permeation and liquid chromatography.

Cationic oligomerization and co-oligomerization of cholesteryl vinyl ether

Cationic oligomerization and co-oligomerization of cholesteryl vinyl ether

Copolymerization of 1-Vinyl-4,5,6,7-tetrahydroindole with Vinyl Chloride in the Presence of a Radical Initiator

Copolymerization of 1-vinyl-4,5,6,7-tetrahydroindole with vinyl chloride in the presence of azobis(isobutyronitrile) occurs as a two-step process. The copolymer is initially formed by the radical mechanism. Then, the eliminated hydrogen chloride initiates cationic oligomerization of 1-vinyl-4,5,6,7-tetrahydroindole, enriching the copolymer with units of this monomer.

Synthesis of Petroleum Polymeric Resin by Cationic Polymerization of the C 9 Fraction

Cationic oligomerization of the C9 fraction of liquid pyrolysis products of petroleum raw materials, catalyzed by aluminum trichloride diphenyl ether complex, was studied, and a procedure was developed for preparation of a petroleum polymeric resin and petroleum polymerizate to be used as film-forming agents in paint-and-varnish materials.

Photoinitiated cationic oligomerization of terminal and internal epoxides

Photoinitiated cationic oligomerization of terminal and internal epoxides

Photoinitiated cationic oligomerization of terminal and internal epoxides

The iodonium salt-catalyzed, photoinduced cationic oligomerization of terminal and internal monoepoxides from oleochemical as well as the petrochemical origin was studied. The ring-opening of terminal epoxides (1,2-octene oxide, phenyl glycidyl ether, 9,10-epoxy decanoic acid methyl ester and 10,11-epoxy undecanoic acid methyl ester) predominantly led to macrocyclic oligoethers (Mn = 650—1,100 g/mol) via backbiting in quantitative yields. Mixtures of cyclic and bishydroxy-terminated oligoethers (Mn = 1,050—1,500 g/mol) were achieved by the conversion of internal epoxides (7,8-tetradecene oxide and cis-9,10-epoxy octadecanoic acid methyl ester) in yields of 80—95%. Macrocyclization was completely suppressed by addition of 20 mol-% water or ethylene glycol receiving diol-oligoethers for potential application as soft segments for polyurethanes with molecular weights of approximately 1,300 g/mol.

The cationic oligomerization of p-aminostyrene 1. Trifluoroacetic acid-catalyzed polyaddition

It was found that p-aminostyrene (PAS) was easily oligomerized by CF3COOH (TFA) in CCl4 to give a low molecular weight oligomer 4 including phenylene, ethylidene and secondary amine groups in the backbone, i.e., the isomer of poly-p-aminostyrene 5. The NMR and IR spectra of the product are quite different from those of polymer 5 produced by 2,2'-azobisisobutyronitrile (AIBN) in toluene. The dimer D and trimer T were separated from the reaction solution through the preparative GPC. The reaction seems to proceed stepwisely to give D in the initial stage and finally the near pentameric oligomer 4 at the end of the reaction.