Bateup mechanism

This is again consistent with the Bateup mechanism (8) where the order with respect to monomer is higher for the initiation of polymerization chains than for the formation of non-polymeric side-products. 

Preliminary results on the kinetics of the polymerization and the efficiency of initiation of the isotactic polymerizations initiated by t-BuMgBr in toluene solution are consistent with the Bateup mechanism proposed for the stereoblock and syndio-tactic-like polymerizations initiated by n-BuMgBr in THF-rich solution — a mechanism which involves initiation and propagation through monomer — active centre complexes (5,8). 

A number of mechanisms proposed to explain the stereospecificity in polymerizations involve complexing of the monomer to a metal prior to addition to the chain (2). Kinetic evidence has shown that such a mechanism does occur with n-BuMgBr, n-BujMg and s-BuMgBr in THF-toluene solution. These polymerizations follow an internal zero-order rate equation. Bateup (1,8) proposed that the mechanism is... 

At 273 and s 9.02 the polymerization followed first order kinetics. At 225 (Figure 4) the conversion curve was indistinguishable from a zero-order plot up to 40 percent conversion but if the whole curve was examined the internal order was seen to lie between zero and one. At 250 the internal order also lay between zero and one but the fit was nearer to the first-order plot in monomer. The kinetics are consistent with a Bateup-Yerusalimskii mechanism. At low temperatures the limiting condition of Equation 3 is approached. As the temperature rises the stationary state concentration of the complex decreases and the mechanism shifts to its other limit... 

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See also in sourсe #XX -- [ , ]

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