Showing papers on "Ring-opening metathesis polymerisation published in 1987"

Linear polymerization of endo‐dicyclopentadiene initiated by metathesis catalysts

Abstract: The polymerization of endo-dicyclopentadiene1 (endo-DCP) by the metathesis catalyst ReCl5/(CH3)4 Sn gave a substantial yield of a linear polymer with high molecular weight and high content of cis double bonds. The kinetics of the early stage of the reaction was studied by calorimetry. The polymerization proceeds via an oligomerization reaction followed by the formation of polymers. A mechanistic scheme is proposed to explain the generation of the primary active species and the two-step polymerization process.

Rhenium-containing catalyst for the production of olefins by metathesis

Abstract: Process for manufacturing a rhenium-containing catalyst comprising three steps of: dry impregnation of an alumina-containing porous carrier, at a temperature lower than 80° C, for at least 10 hours, first thermal treatment at 85°-250° C, and second thermal treatment at 400°-1000° C The obtained catalyst can be used for producing olefins by metathesis of other olefins

Thermally activated two component metathesis catalyst system

Abstract: Disclosed is a method of reducing the activation rate of an alkyl aluminum activator in the metathesis polymerization of strained ring cycloolefins. Activation rate is reduced by use of certain nucleophilic Lewis bases as the reaction rate moderator.

Metathesis polymerization of cycloolefins

Abstract: A process for producing a molded article by introducing a reactive liquid mixture which comprises a cycloalkene containing dicyclopentadiene, a norbornene-type monomer containing at least one N-substituted 5-membered cyclic imide group and a metathesis polymerization catalyst system and which has moderated metathesis polymerizability into a mold in which the liquid mixture is metathesis polymerized, and a multi-part polymerizable composition for producing the molded article.

Anionic to metathesis transformation polymerisation

Abstract: An anionic to metathesis transformation reaction has been devised to study the mechanism of initiation of the metathesis ring-opening polymerisation of cyclic alkenes and, by inference, the metathesis of alkenes also. The products of the reaction have been analysed by g.p.c. using a dual detector system to establish that block copolymers are formed when polystyryl lithium and tungsten hexachloride are used as initiator for the polymerisation of cyclopentene. A mechanism is proposed for the incorporation of polystyrene segments during the initiation step involving the formation of a bimetallic bridged complex that rearranges to form the active centre. There is also evidence that polystyrene segments are introduced during the termination reaction of the kinetic chain.

Untersuchungen von Polymerisations-und Metathesereaktionen, X. Mitt. [1] Polymerisation, Trimerisation und Metathese von Allenen und Heteroallenen mit reduziertem Phillips-Katalysator / Studies of Polymerisation and Metathesis Reactions, Part X [1] Polymerisation, Trimerisation and Metathesis of Allenes and Heteroallenes with Reduced Phillips Catalyst

Abstract: The reduced Phillips Catalyst - a surface chromium(II) on silica - catalyses the polymerisation of the allene 1,2-butadiene to yield predominantly 1,2-polybutadiene, yields trimerisation products with isocyanates, and gives metathesis of 2 differently substituted carbodiimides.

A process and composition for metathesis polymerization of cycloolefins

Abstract: A process for producing a molded article by introducing a reactive liquid mixture which comprises a cycloalkene containing dicylopentadiene, a norbornene-type monomer containing at least one N-substituted 5-membered cyclic amide group and a metathesis polymerization catalyst system and which has moderated metathesis polymerizability into a mold in which the liquid mixture is metathesis polymerized, and a multi-part polymerizable composition for producing the molded article.

Catalytic Metathesis of Alkenes

Abstract: The metathesis of alkenes is undoubtedly one of the most appealing reactions of hydrocarbons discovered in the last decades. The word metathesis stems form greece (μeταϑeσις), and means transposition or interchange.

Process for preparing molded objects using a rate moderated two component metathesis catalyst system

Abstract: Disclosed is a method of reducing the activation rate of an alkyl aluminum activator in the metathesis polymerization of polycyclic cycloolefins. Activation rate is reduced by use of a bidentate Lewis base as the reaction rate moderator.

Molded products of plasticized polymer, its production and combination with reactive solution

Abstract: PURPOSE: To obtain the title molded product which is suitable for parts of various carriers by copolymerization of metathesis monomers having long side- chains to internally plasticize and improve shock resistance. CONSTITUTION: In the bulk polymerization, in the presence of a metathesis polymerization catalyst system, of a starting monomer mixture containing 3W50mol.%, based on the total metathesis monomers, of a monomer bearing at least one of metathetically polymerizable groups and at least one of monovalent aliphatic organic group having 5 or more carbon atoms which are not inhibited from rotating, a reactive solution of the metathesis polymerization monomers containing catalyst components for the metathesis polymerization catalyst system such as a tungsten compound and another reactive solution of metathetically polymerizable monomers containing an activating component for metathesis polymerization catalyst such as tetraalkyl tin are separately prepared beforehand. Then, they are rapidly mixed and immediately cast in the mold to effect hardening. COPYRIGHT: (C)1988,JPO&Japio

The Photocatalytic Metathesis Reaction of Olefins

Abstract: Structure of metal complex catalysts for olefin metathesis reaction and its mechanism are intensively studied since many years. Most of catalytic systems involve tungsten complexes combined with alkyl aluminium compound, WCl6/C2H5A1C12. The currently accepted mechanism is based on carbene complex formation which next coordinates olefins in such a way that the metallocycle may be formed with high selectivity. However, the formation of the first carbene is still controversial. Highly active metathesis catalysts have been prepared only with Mo, W or Re soluble complexes. So, there is also some limitation to the metal. If metal carbonyls are used as catalyst precursors they are often activated photochemically or by addition of Lewis acid type cocatalysts.