Isoprene homogeneous catalysis

Table IV lists some diene polymers prepared by homogeneous catalysis. The cobalt catalyst for butadiene and the lithium catalyst for butadiene and isoprene are believed to be used commercially in the United States to prepare the so-called stereoelastomers (32, 36).

Monakov YB, Marina NG, Sabirov ZM (1994) Polym Sci USSR (Engl. Trans.) 36 1404 Taube R, Sylvester G, (1996) Stereospedfic polymerization of butadiene or isoprene. In Comils B, Herrmann WA (eds) Applied homogeneous catalysis with organometallic compounds, vol. 1 VCH, Weinheim, p 280... 

Abstract This review deals with the synthesis and the catalytic application of noncyclopentadienyl complexes of the rare-earth elements. The main topics of the review are amido metal complexes with chelating bidentate ligands, which show the most similarities to cyclopentadienyl ligands. Benzamidinates and guanidinates will be reviewed in a separate contribution within this book. Beside the synthesis of the complexes, the broad potential of these compounds in homogeneous catalysis is demonstrated. Most of the reviewed catalytic transformations are either C-C multiple bond transformation such as the hydroamination and hydrosilylation or polymerization reaction of polar and nonpolar monomers. In this area, butadiene and isoprene, ethylene, as well as lactides and lactones were mostly used as monomers. 

For example, see Taube, R. Sylvester, G. Stereospecific polymerization of butadiene or isoprene. In Applied Homogeneous Catalysis with Organometallic Compounds ComUs, B. Herrmann, W. A., Eds. Wiley-VCH Weinheim, 1996 Vol. 1, pp 280-318. 

The first successhil use of lithium metal for the preparation of a i7j -l,4-polyisoprene was aimounced in 1955 (50) however, lithium metal catalysis was quickly phased out in favor of hydrocarbon soluble organ olithium compounds. These initiators provide a homogeneous system with predictable results. Organ olithium initiators are used commercially in the production of i7j -l,4-polyisoprene, isoprene block polymers, and several other polymers. 

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