Quinolinyl Imidazolidin-2-imine Nickel Catalyzed Efficient Copolymerization of Norbornene with para-Chlorostyrene

Li, Yanqing; Zhou, Jian; Xiao, Ru; Cai, Zhengguo

doi:10.1007/s10118-020-2400-3

Cited by 11 publications

(3 citation statements)

References 51 publications

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“…Both series contain four compounds bearing substituents on the nitrogens of varying steric demand including methyl (Me), tert-butyl ( t Bu), mesityl (Mes), and 2,6-diisopropylphenyl (Dipp) groups. Unless the diamines C-R or the imidazolium salts IR-H + were commercially available, they were synthesized from the respective amines A-R and glyoxal, furnishing us with the diimines B-R. [51] Thereafter, the latter were reduced to respective diamines C-R and cyclized into saturated thioureas SIR-S with thiophosgene [52] or carbon disulfide. [53] Alternatively, the diimines B-R were converted into the imidazolium salts IR-H + , [54] which were eventually transformed into the unsaturated thioureas IR-S via reaction of the liberated respective carbene with elemental sulfur.…”

Section: Chemistry-a European Journalmentioning

confidence: 99%

Synthesis of Sterically Encumbered Thiourea S‐Oxides through Direct Thiourea Oxidation

Medvedko

Ströbele

Wagner

2022

Chemistry A European J

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Thiourea S‐oxides can be viewed as formal analogs of the currently unknown diamino‐substituted Criegee intermediates (urea O‐oxides). However, the preparation of such S‐oxides is rather challenging, and the direct oxidation of thioureas typically only leads to formation of desulfurized products. Employing the accurate revDSD‐PBEP86‐D4 double hybrid density functional, it was found that the peracid mediated oxidation of thiourea S‐oxides exhibits a lower reaction barrier than the oxidation of the corresponding thiourea itself in contrast to most other ordinary thioketones. The undesired overoxidation reactivity, which is associated with strong π‐donation from the thiourea's nitrogen atoms, can be partially suppressed by introduction of bulky substituents and the utilization of protic solvents. In this regard, we managed to prepare two sterically encumbered thiourea S‐oxides in isolated yields of 35–40 %. The S‐oxides are stable in the solid state and in alcoholic solutions at room temperature for extended periods of time, but swiftly decompose in aprotic solvents by disproportionation. A dimesityl‐substituted thiourea S‐oxide complexed with residual mCBA could be characterized by means of X‐ray crystallography, confirming the importance of hydrogen bonding in the stabilization of the amino‐substituted C=S+−O− moiety.

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Section: Chemistry-a European Journalmentioning

confidence: 99%

Synthesis of Sterically Encumbered Thiourea S‐Oxides through Direct Thiourea Oxidation

Medvedko

Ströbele

Wagner

2022

Chemistry A European J

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“…Norbornene (NB) can be polymerized through three different catalytic approaches: ring-opening metathesis polymerization, cationic/radical polymerization, and vinyl-type addition polymerization. − Among them, the vinyl-type polynorbornene (PNB) obtained by the transition-metal-catalyzed coordination polymerization of NB exhibits unique properties, such as high thermal stability, good chemical resistance, and excellent transparency, owing to its rigid structure. The development of NB-based copolymers through the copolymerization of NB with substituted NB derivatives, ethylene, − propylene, , higher α-olefins, − styrenes, − and dienes , achieved further improvements to the polymer properties, such as toughness, solubility, and surface properties. Moreover, the structure and properties of these copolymers can be further tailored by the appropriate choice of catalyst together with a variation of the comonomer contents, structures, and sequence distributions.…”

Section: Introductionmentioning

confidence: 99%

Norbornene Copolymerization with Polar Monomers Catalyzed by Palladium Catalysts Containing Imidazolidin-2-imine/Guanidine Ligands

Li,

Cai,

Eisen

2023

Inorg. Chem.

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The development of a palladium catalyst that has enhanced catalytic performance, such as low aluminum cocatalyst loading, good copolymerization ability, high molecular weight, and excellent solubility of the (co)polymers, is still a challenge in norbornene copolymerizations. Here, a series of PdCl 2 and PdMeCl complexes containing differently substituted anilines and imidazolidin-2-imine/guanidine ligands was successfully synthesized and characterized. X-ray diffraction analysis results revealed that these Pd complexes adopted an almost square-planar geometry, and the six-membered chelate ring showed structural distinctions as compared to traditional N^N-based α-diimine and β-diimine Pd complexes. These Pd complexes were activated by EtAlCl 2 and then exhibited moderate activity (10 4 −10 5 g mol −1 h −1 ) and good thermal stability (up to 90 °C) for norbornene polymerization to produce high-molecular-weight PNBs (M n up to 96.4 kg mol −1 ) with narrow polydispersities (PDI as low as 1.39). These Pd complexes also exhibited good polar group tolerance in the copolymerization of norbornene with methyl 5-norbornene-2carboxylate and methyl 10-undecenoate, in which the activity was achieved up to 7.04 × 10 4 g mol −1 h −1 . It furnished polar functionalized norbornene-based copolymers with high molecular weight (M n up to 63.1 kg mol −1 ), narrow PDI, reasonable polar monomer incorporation, and good solubility. These Pd catalysts exhibited an enhanced copolymerization ability to produce PNB or NB-based copolymers, representing significant progress in this field.

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“…The developments of direct olefin copolymerization with polar monomers using less electrophilic palladium catalysts allow us to synthesize polar functionalized polyolefins with precisely controlled microstructure of polymers. In contrast, earth-abundant and low-cost nickel catalysts usually exhibit poor properties toward ethylene copolymerization with polar monomers because of their high electrophilicity. − Therefore, recent research interests have been focused on the rational design of nickel catalysts by adjusting steric effects and electronic properties of the ligand to control the electrophilicity of the nickel center. − …”

Section: Introductionmentioning

confidence: 99%

Phosphinobenzenamine Nickel Catalyzed Efficient Copolymerization of Methyl Acrylate with Ethylene and Norbornene

Cao

Cai

2022

Macromolecules

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A series of phosphinobenzenamine-based nickel complexes bearing substituted phenylphosphine ligands were synthesized and characterized. These nickel complexes combined with methylaluminoxane (MAO) exhibited very high activity (∼10 6 g mol −1 h −1 ) and good thermal stability for norbornene polymerization. The nickel catalysts were able to conduct copolymerization of norbornene and methyl acrylate (MA) with high activity (3.76 × 10 5 g mol −1 h −1 ) to give high-molecularweight functionalized cyclic olefin copolymer (COC) with reasonable MA incorporation (2.39−6.47 mol %). Moreover, the nickel catalysts also promote the copolymerization of ethylene and MA with moderate activity (∼10 4 g mol −1 h −1 ) to produce semicrystalline high-molecular-weight polar functionalized polyethylene (PE). The MA incorporation in the copolymer was controlled in a wide range (up to 15.5 mol %). These complexes without any sterically bulky substituent on the ligand are distinctive examples of earth-abundant nickel complexes toward the direct copolymerization of ethylene or norbornene with the challenging vinyl polar monomer MA.

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Quinolinyl Imidazolidin-2-imine Nickel Catalyzed Efficient Copolymerization of Norbornene with para-Chlorostyrene

Cited by 11 publications

References 51 publications

Synthesis of Sterically Encumbered Thiourea S‐Oxides through Direct Thiourea Oxidation

Synthesis of Sterically Encumbered Thiourea S‐Oxides through Direct Thiourea Oxidation

Norbornene Copolymerization with Polar Monomers Catalyzed by Palladium Catalysts Containing Imidazolidin-2-imine/Guanidine Ligands

Phosphinobenzenamine Nickel Catalyzed Efficient Copolymerization of Methyl Acrylate with Ethylene and Norbornene

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