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李弘, Zheng Wang, Hong Li *, Binglin He
Journal of Molecular Catalysis A: Chemical 159(2000)121-125,-0001,():
-1年11月30日
The macroligand effect of the catalytic system WCl6-Et2AlCl for ring opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) was investigated. The experimental results show that macroligand effect varies with the structure of the ligands. The macroligands bearing benzene group and steric hindered phenolic unit not only can obviously increase the yield of synthesized polydicyclopentadiene (PDCPD) but also improve the synthesized polymer's mechanical properties. The mechanism of macroligand effect is discussed. The synthesized PDCPD was characterized by methods of scanning electron microscopy (SEM) and X-ray diffraction.
Ring opening metathesis polymerization, Polydicyclopentadiene, Macroligand effect
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【期刊论文】Tailoring of polymer-supported metal catalysts for selective hydrogenation1
李弘, Hong Li *, Binglin He
Reactive & Functional Polymers 26(1995)61-66,-0001,():
-1年11月30日
Several functional polystyrene-supported metal (Ru, Rh, Pd) catalysts were synthesized. The hydrogenation selec-tivity of these catalysts for polyunsaturated cycloolefines (1,5,9-cyclododecatriene, cyclopentadiene) and unsaturated carbonyl compounds (mesityl oxide, crotonaldehyde acrylic aldehyde) was investigated. Some important factors (pore size, crosslinkage of polymer supports, donor atoms and substituents thereon) for the tailoring of supports and ligands which have great influence over the hydrogcnation selectivity of the supported metal catalysts are discussed.
Polymeric catalysts, Selective hydrogenation, Ruthenium, Rhodium, Palladium
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李弘, Hong Li, Franqois Gauvin and John F. Harrod*
Organometallics 1993, 12, 575-577,-0001,():
-1年11月30日
Neither dimethylhafnocene nor [1, 2-bis (tetrahydroindenyl) ethane] dimethylzirconium, 1, reacts at anappreciable rate with phenylsilane. In the case of the hafnium compound, this results in complete masking of catalytic activity toward dehydrocoupling of phenylsilane, while in the case of 1 activity is greatly suppressed. This behavior is governed by the low reactivity of the M-C bonds toward σ-bond metathesis with silanes. Catalysts generated by reaction of MeLi and PhSiH3 with hafnocene dichloride or [1,2-bis (tetrahydroindeny1)-ethune] dichlorozirconium, 2, show high activities toward PhSiH3coupling. The molecular weights of the resulting polymers are significantly higher than those of polymers derived from CpzTiMez and CpzZrMez catalysts, and the hafnocene catalyst gives unusually low proportions of low molecular weight cyclic products. It is proposed that the catalyst species, probably a hydrido silyl complex, in these new systems are generated by reaction of a reactive lithium hydride, resulting from rapid reaction of MeLi with PhSiH3, with the chloro complexes.
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李弘, Hong Li *, Zheng Wang, Yuqin Wang, Binglin He
Reactive & Functional Polymers 33(1997)193-200,-0001,():
-1年11月30日
Ring-opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) was carried out by using (ArO)6-xWClx-Et2A1C1 (ArO: 2,6-ditertiarybutyl-p-cresoxy, x=3, 4, 6) and the corresponding polymer-supported catalytic systems. Influences of different homogeneous catalysts, polymerization conditions and immobilization of the homogeneous catalytic systems on polymerization (gelation time, monomer conversion) and synthesized polydicyclopen-tadiene's (PDCPD's) mechanical properties were investigated. The experimental results show that using the polymer-supported catalytic systems can not only increase the monomer conversion of polymerization but also improve the synthesized polymer's mechanical properties to a certain extent.
Ring-opening metathesis polymerization, Polydicyclopentadiene, Dicyclopentadiene, Polymer-supported catalysts
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