Organometallic monomers synthesis

NEW VINYL ORGANOMETALLIC MONOMERS SYNTHESIS AND POLYMERIZATION BEHAVIOR... 

Two major approaches to the formation of materials of this type have involved the derivatization of preformed organic polymers with organometallic functions and the synthesis and polymerization of organometallic monomers that contain vinyl substituents For the transition metals, condensation polymerizations have also been investigated. However, the reactions have generally been conducted at elevated temperatures, and the resulting products have often not... 

We now report an extension of this chemistry to a new and apparently general route for the synthesis of a wide variety of Ti -vinyl-cyclopentadienyl organometallic monomers.This method provides a convenient means of introducing vinyl substituents onto n cyclo-pentadienyl rings in systems which are incapable of undergoing electrophilic aromatic substitution. 

Liquid-crystalline polysiloxanes containing 1,3- or l,l -disubstituted ferrocene moieties in their sidechains were also synthesized through a reaction of vinyl organometallic monomers with preformed polysiloxanes. " The synthesis of one such liquid-crystalline metal-containing polysiloxane 55 is shown in scheme 17. 

The synthesis of tailor-made star-shaped polymers can be performed in several ways by means of a plurifunctional organometallic initiator, or by reacting a living precursor polymer with a plurifunctional reagent, to build the centra] body, or by block copolymerization involving a diunsaturated monomer (Scheme 3). 

A large number of studies on the polymerization and copolymerization of tin-containing monomers and the synthesis of new organotin polymers have been reported. In this review article the results are discussed and further ways for research in this interesting and important field of organometallic and polymer chemistry outlined. 

In this study the relationship between the structure of organometallic compounds and their ability to polymerize vinyl monomers and olefins will be examined. The objective is to identify methods of synthesis for polymerization catalysts that are more selective and more active than the systems currently available. 

Silicon carbides are generally synthesized by the pyrolysis of precursors, prepared by liquid phase methods. One possible way for precursor synthesis is the addition of carbon black or sucrose, to a gelling silica.8 In this method, the carbon is introduced from an external source. A more intimate contact between the carbon and silicon in the precursor is assured with the use of organometallic polymer precursors. The use of silane polymers for silicon carbide production was initiated by Yajima.9,10 Polymers having a -[Si-C]- backbone are crosslinked and pyrolysed to yield SiC." In the initial work, dimethyldichlorosilane was used as a starting monomer, which was subjected to a sodium catalyzed polymerization (reaction (C)). 

Scheme 7 Synthesis of hyperbranched organometallic polymer from AB2-type monomer...

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