Initiators, anionic cumylcesium

The extensive use of alkyllithium initiators is due to their solubility in hydrocarbon solvents. Alkyls or aryls of the heavier alkali metals are poorly soluble in hydrocarbons, a consequence of their more ionic nature. The heavier alkali metal compounds, as well as alkyllithiums, are soluble in more polar solvents such as ethers. The use of most of the alkali metal compounds, especially, the more ionic ones, in ether solvents is somewhat limited by their reactivity toward ethers. The problem is overcome by working below ambient temperatures and/or using less reactive (i.e., resonance-stabilized) anions as in benzylpotassium, cumylcesium and diphenylmethyllithium. 

Figure 11. Integral distribution functions obtained by BW fractionation of anionic poly(methyl methacrylate)s prepared at different reaction temperatures under otherwise identical reaction conditions initiator, cumylcesium in the presence of about 10 3 mole/1 cesium triphenylcyanoborate (19)...

Shulz and collaborators in their kinetic polymerizations done anionically in with cumylcesium initiators. Their main concern was to determine the statistics which best described the tactic addition of monomer. By NMR analysis of sequence lengths they concluded that the system obeyed Markovian rather than Bernoulli an statistics. ... 

---