- Preparation and Catalytic Application of a Novel Very Rigid Group 4 Ansa-Metallocene System
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Treatment of 2,5-hexandione with cyclopentadiene in the presence of pyrrolidine yields the corresponding bisfulvene (5) that has been converted to the ligand system, isolated as the dilithio compound 8.Subsequent reaction with the group 4 metal halides MCl4 (M=Ti, Zr, Hf) gives the rigid ansametallocene dichlorides 9a-c.Their reaction with methyllithium yields the corresponding dimethyl-ansa-metallocenes 10a-c.Complexes 9a-c and 10a-c were characterized by X-ray diffraction.The zirconium and hafnium systems all exhibit very low D1-M-D2 angles (D1 and D2 denote the centroids of the Cp-ring systems) at around 116 deg.Consequently the homogeneous metallocene/methylalumoxane Ziegler-type catalyst systems derived from the zirconium complex 9b produce low molecular weight propene oligomers (in contrast to high molecular weight polypropylene formed at the titanium containing 9a/MAO catalyst system), which is probably due to an electronic control of the kpropagation/ktermination-ratio of the propene polymerization process.It is forseable that such ansa-metallocene derived catalyst systems favouring the formation of low molecular weight products instead of high molecular weight polyolefins will find increasing application in organic synthesis.
- Erker, Gerhard,Psiorz, Christian,Froehlich, Roland,Grehl, Matthias,Krueger, Carl,et al.
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- POLYMERIZATION CATALYSTS
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Embodiments of the present disclosure directed towards polymerization catalysts having improved ethylene enchainment and/or improved catalyst productivity. As an example, the present disclosure provides a polymerization catalyst of Formula (I), wherein each of R1 to R12 is independently a C1 to C20 alkyl, aryl or aralkyl group, or a hydrogen, wherein at least one of R4 to R7 is not a hydrogen, wherein M is a Group 4 metal, and wherein, each X is independently a halide, C1 to C20 alkyl, aralkyl or hydrogen
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- Dimerization method for high activity and selectivity propylene
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The invention provides a dimerization method for high activity and selectivity propylene. The method includes the following steps that methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) is used as a catalyst promoter, and the propylene is subjected to a dimerization reaction under the catalytic action of an ethylidene bridged substituted diindene titanium group metal complex catalyst; and the ethylidene bridged substituted diindene titanium group metal complex catalyst is an internal compensation (meso-) ethylidene bridged substituted diindene titanium group metal complex catalyst or a racemization (rac-) ethylidene bridged substituted diindene titanium group metal complex catalyst. Compared with the prior art, the dimerization method provided by the invention is high in catalytic activity and high in dimerization selectivity, the rate can reach 99%, numerous follow-up operation steps in separation of products with the high degree of polymerization are omitted, the industrialization cost is reduced, and the industrial production needs can be met.
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Paragraph 0076; 0077; 0078
(2017/06/02)
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- Synthesis of 7-substituted derivatives of 5, 8-dimethylisoquinoline
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7-Bromo-5,8-dimethylisoquinoline was selectively synthesized by the bromination of 5,8-dimethylisoquinoline obtained in five steps from p-xylene as a starting material. Further,7-bromo-5,8-dimethylisoquinolinegave 7-amino-5,8-dimethylisoquinoline by the reaction with ammonia and various 7-anilino-5,8-dimethylisoquinolines via a palladium-catalyzed coupling reaction with anilines.
- Nagao, Yukinori,Hirota, Katsuaki,Tokumaru, Mizuho,Kozawa, Kozo
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experimental part
p. 593 - 602
(2009/09/28)
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- Bridged metallocene complex for the (co) polymerization of olefins
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A “bridged” bis-cyclopentadienyl complex which can be advantageously used for the formation of a catalytic system active in the (co)polymerization of ethylene and other a-olefins is represented by means of the following formula (II): wherein: M represents a metal selected from titanium, zirconium or hafnium; A′ and A″ each independently represent an anion containing an η5-cyclopentadienyl ring coordinated to M; or R″ each independently represents a group of an anionic nature a-bound to the metal M; B represents an unsaturated bivalent organic residue having from 1 to 30 carbon atoms bound, respectively, to the ring of group and to the -CH2- methylene group by means unsaturated carbon atoms. This complex, combined with a suitable cocata forms a catalyst with a high activity in the poization of olefins, producing polymers with molecular weight, especially in the case of the merization of ethylene with a second α-olefir.
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- Bridged metallocene complex for the (co)polymerization of olefins
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A "bridged" bis-cyclopentadienyl complex which can be advantageously used for the formation of a catalytic system active in the (co)polymerization of ethylene and other α-olefins is represented by means of the following formula (II): wherein: M represents a metal selected from titanium, zirconium or hafnium; A' and A'' each independently represent an anion containing an η5-cyclopentadienyl ring coordinated to M; R' or R'' each independently represents a group of an anionic nature ?-bound to the metal M; B represents an unsaturated bivalent organic residue having from 1 to 30 carbon atoms, bound, respectively, to the ring of group A' and to the -CH2- methylene group by means of unsaturated carbon atoms. This complex, combined with a suitable cocatalyst, forms a catalyst with a high activity in the polymerization of olefins, producing polymers with a high molecular weight, especially in the case of the copolymerization of ethylene with a second α-olefin.
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- Process for the preparation of amorphous polymers of propylene
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It is possible to prepare substantially amorphous polymers of propylene endowed with high molecular weights, operating at temperatures of industrial interest, by carrying out the polymerization reaction of propylene in the presence of metallocene catalysts comprising particular bis-indenyl or bis-4,5,6,7-tetrahydroindenyl compounds substituted in the 2-position on the indenyl or tetrahydroindenyl groups.
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- Process for preparing cyclopentadienyl group-containing silicon compound or cyclopentadienyl group-containing germanium compound
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Disclosed is a process for preparing a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, comprising reacting (i) a lithium, sodium or potassium salt of a cyclopentadiene derivative with (ii) a silicon halide compound or a germanium halide compound in the presence of a cyanide or a thiocyanate. The cyanide or the thiocyanate is preferably a copper salt. According to the process of the invention, a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, which is very useful for the preparation of a metallocene complex catalyst component, can be prepared in a high yield for a short period of time.
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- Indenes via Fulvene Intermediates
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Substituted indenes are prepared from 1,4-dicarbonyl compounds by treatment with base and cyclopentadiene.
- Coe, Jotham W.,Vetelino, Michael G.,Kemp, Daniel S.
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p. 6627 - 6630
(2007/10/02)
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- Process for the preparation of substituted indenes
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The compounds of the formula I or Ia STR1 in which R1 is alkyl, aryl, alkoxy, alkenyl, arylalkyl, alkylaryl, aryloxy, fluoroalkyl, halogenoaryl, alkynyl, trialkylsilyl or a heteroaromatic radical, R2, R3 and R4, in addition to hydrogen, have the meanings given under R1 and R5 is hydrogen, alkyl, fluoroalkyl or alkenyl, can be obtained in a one-stage process by reaction of a compound II STR2 with (substituted) cyclopentadiene in the presence of a base. The compounds I and Ia are suitable as ligands for metallocene complexes which are used as catalysts in olefin polymerization.
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- Cyclophane, XXVII. - Indenophane Mono- and Dianions: Preparation and Nuclear Magnetic Resonance Spectra
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The preparation and chemical and physical properties of negatively charged polycyclic cyclophanes are reported.The through-space electronic interactions and the through-space anisotropy effects were deduced from proton and carbon nuclear magnetic resonance data.The systems studied belong to two main groups: a) 4n ?-polycyclic dianions which are paratropic, e.g. benzochrysenophane dianion (122-), and b) (4n + 2)?-polycyclic mono- and dianions, which are diatropic.In the dianions both layers are charged, e.g. syn-indenocyclophane (132-) and its anti iomer (142-).The monoanions studied are benzoindenocyclophane (151-), 4,5,17,18-tetramethylbenzoindenocyclophane(161-), and 12-methylbenzoindenocyclophane (171-).The spectroscopic properties of the layered anions were compared with those of 1,4-dimethylindenyl anion (111-) and with the literature data of the neutral cyclophanes, viz. 1-11.A differentiation between the anisotropy and charge-transfer effects has been made and it enables the estimation of the net through-space interaction. - Keywords: Cyclophane anions/ Indene derivatives
- Frim, Ron,Rabinovitz, Mordecai,Bodwell, Graham,Raulfs, Friedrich-Wilhelm,Hopf, Henning
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p. 737 - 744
(2007/10/02)
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