Catalyst system, bridged-acetate

The bridged-acetate catalyst system is reasonably well characterized in that the [Ru(CO)2(OCOCH3)(amine)]2 complexes are present and can be recovered at any stage throughout the reaction. Further, it is clear from the blank reaction that the dimers are precursors to the true catalyst which must be formed via interaction with further carbon monoxide. The... 

The mechanism of particle formation at submicellar surfactant concentrations was established several years ago. New insight was gained into how the structure of surfactants influences the outcome of the reaction. The gap between suspension and emulsion polymerization was bridged. The mode of popularly used redox catalysts was clarified, and completely novel catalyst systems were developed. For non-styrene-like monomers, such as vinyl chloride and vinyl acetate, the kinetic picture was elucidated. Advances were made in determining the mechanism of copolymerization, in particular the effects of water-soluble monomers and of difunctional monomers. The reaction mechanism in flow-through reactors became as well understood as in batch reactors. Computer techniques clarified complex mechanisms. The study of emulsion polymerization in nonaqueous media opened new vistas. 

Acidic hydrolysis of CCT catalysts is described as a possible problem. Few actual measurements of the catalyst hydrolysis have been made. Addition of only 1% of acetic acid in MMA leads to a rate of cobaloxime deactivation of about 1.2% min 1 at 60 °C.296 The stability of the BF2-bridged cobaloxime is believed to be higher.119,338,342 The complex (dmgBF2)2-Co11 decays at room temperature at a rate of about 0.6% min 1 at pH = 1 but is practically stable at neutral pH.309,310 It should be noted, however, that these measurements were made in a benign solvent rather than in an active polymerization system involving free radicals. 

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