Effect of the structure of alkyllithium on the polymerization kinetics of isoprene

Abstract

The kinetics of polymerization of isoprene in benzene initiated with ethyl-, propyl-, butyl-, hexyl-, octyl-, 2-butyl-, 3-hexyl-, 2-octyl-, and 6-methylheptyllithium was investigated. With the exception of ethyllithium , a distinct initial induction period decreasing steeply with increasing concentration of the initiator was observed for all n-alkyllithium initiators. No induction period was observed with the other initiators. The reaction orders decreased at the highest concentrations for most of the initiators, sometimes even to negative values. In the case of ethyl-, 2-butyl- and octyl-lithium this phenomenon has not been observed in the range investigated.