Abstract: A process for preparing a catalyst for the polymerization of butadiene to obtain a polymer containing a very high content of cis isomer in which a specified neodymium carboxylate, an aluminium hydrocarbyl or aluminium hydrocarbyl hydride and a source of halogen are contacted using a particular procedure.

Abstract: The invention relates to a catalyst system comprising (a) a compound of a rare earth element and, as cocatalyst, a second component (b) comprising an organomagnesium compound. In the polymerization of a conjugated diene this catalyst gives a polymer having a very high content of trans 1,4 isomer. A third component (c) which is a Lewis acid alters the reaction to give a polymer having a very high content of cis 1,4 isomer. If desired reaction can be initiated using components (a) and (b) alone and component (c) then added at the desired conversion to produce a block polymer having a block of high trans content followed by a block of high cis content.

Abstract: The invention relates to a catalyst system comprising (a) a compound of a rare earth element and, as cocatalyst, a second component (b) comprising an organomagnesium compound. In the polymerization of a conjugated diene this catalyst gives a polymer having a very high content of trans 1,4 isomer. A third component (c) which is a Lewis acid alters the reaction to give a polymer having a very high content of cis 1,4 isomer. If desired reaction can be initiated using components (a) and (b) alone and component (c) then added at the desired conversion to produce a block polymer having a block of high trans content followed by a block of high cis content.

Abstract: The invention relates to a method of polymerizing one or more conjugated diene monomers to a polymer having an exceptionally high cis content employing a three component catalyst comprising (a) a rare earth compound, (b) an organo magnesium compound and (c) a Lewis acid in which a particular order of component addition is used. Under optimum conditions it is possible to obtain nearly 100% conversion to polymers of 98% or more cis content at very low concentrations of rare earth compound with respect to monomer.

Abstract: Titanium trichloride for use as a component of a Ziegler polymerization catalyst is modified in order to enhance the activity and/or stereospecificity of the catalyst in the polymerization of olefins, especially propylene, by heating the titanium trichloride with phosphorus oxytrichloride in an aromatic hydrocarbon diluent for several hours in the absence of the organo aluminium component of the catalyst. Ball milling, or shearing, during the modification reaction is not required. The use of aromatic hydrocarbon gives unexpected improvement compared with any other hydrocarbon diluent and the modification reaction gives improved results compared with addition of the titanium trichloride, phosphorus oxytrichloride and the organo aluminium component to the reactor at the beginning of a batch polymerization.