Oligomerization kinetics

Since iminoboranes are thermodynamically unstable with respect to their oligomerization (Section IV,A), they can be isolated under laboratory conditions by making the oligomerization kinetically unfavorable. Low temperature, high dilution, bulky groups R and X, or a combination of these is necessary. 

Samiee, K. T., Foquet, M., Guo, L., Cox, E. C., and Craighead, H. G. (2005). Lambda repressor oligomerization kinetics at high concentrations using fluorescence correlation spectroscopy in zero-mode waveguides. Biophys. J. 88 2145-2153. 

Tsuchida, E., and S. Mimashi, Analysis of oligomerization kinetics of styrene on the electronic digital computer, J. Polym. Sci. A, 3, 1401-1434 (1965). 

Quann, R. J. Krambeck, F. J., Olefine Oligomerization Kinetics over ZSM-5, In Chemical Reactions in Complex Mixtures, Sapie, A. V. Krambeck, F. J. (Eds.), Van Nostrane Reinhold, 1991. 

Schmidt and coworkers [551] have reported the effect of organoaluminum compounds on the catalytic properties of complex catalysts used in the oligomerization of propylene. The selectivity for the process depends strongly on temperature, pressure, and contact time. In a continuous process of oligomerization of propylene at 200 atm with AlEts activation it is observed that the yield of oligomers increases with temperature [552]. Studies on the oligomerization kinetics [553,5541 have shown that the reaction order with respect to propylene is close to unity. Activation energies of 11.7 and 14 kcal mol have been reported [553,554]. 

Mel nikov, V N., Matkovskyi, P. E., Russiyan, L. N., and Bucheva, Z. G., Mechanism of interaction between zirconium isobutyrate and sesquiethylaluminum chloride in catalysts for ethylene oligomerization, Kinet. Kat., 29, 124, 1988. 

Kucherov, A. W., Catalysis of higher olefin oligomerization, Kinet. Katal., 30, 193, 1989 (Russian). 

The principle cost determinant in typical hydrolytic or phenolic resolutions is the cobalt catalyst, despite the relatively low catalyst loadings used in most cases and the demonstrated recyclability with key substrates. From this standpoint, recently developed oligomeric (salen)Co complexes, discussed earlier in this chapter in the context of the hydrolytic desymmetrization of meso-epoxides (Scheme 7.16), offer significant advantages for kinetic resolutions of racemic terminal epoxides (Table 7.3) [29-31]. For the hydrolytic and phenolic kinetic resolutions, the oligo-... 

The concentration of monomers in the aqueous phase is usually very low. This means that there is a greater chance that the initiator-derived radicals (I ) will undergo side reactions. Processes such as radical-radical reaction involving the initiator-derived and oligomeric species, primary radical termination, and transfer to initiator can be much more significant than in bulk, solution, or suspension polymerization and initiator efficiencies in emulsion polymerization are often very low. Initiation kinetics in emulsion polymerization are defined in terms of the entry coefficient (p) - a pseudo-first order rate coefficient for particle entry. 

The kinetics of these oligomerizations initiated by a-lithio-methylisobutyrate (monomeric living polymethyl methacrylate) was reported by Muller et al. 50). A modified flow-tube technique, that permits to follow the polymerization for times as short as 0.02 s, was employed in this study. The reaction was performed in THF at... 

The resin system selected to initiate these studies is a step-growth anhydride cured epoxy. The approach to the kinetic analysis is that which is prevalent in the chemical engineering literature on reactor design and analysis. Numerical simulations of oligomeric population density distributions approximate experimental data during the early stages of the cure. Future research will... 

---