Kinetics of polymerization of butadiene, isoprene, and styrene with alkyllithiums. Part II. Rate of initiation

By gas chromatographic analysis of the hydrolyzed polymerization solutions, the per cent of BuLi unreacted was measured at various conversions. The effects of BuLi concentration, the structure of the butyl group, and the solvent type were studied. The rates of initiation (Ri) for butadiene, isoprene, and styrene were determined. For dienes, the order was sec‐BuLI > i‐PrLi > tert‐BuLi > i‐BuLi > n‐BuLi. For styrene, it was sec‐BuLi > i‐PrLi > i‐BuLi > n‐BuLI > tert‐BuLi. With n‐BuLi, the order was styrene > butadiene > isoprene. For any particular monomer–initiator combination, the order was toluene ≫ n‐hexane > cyclohexane. The results obtained here proved that Ri = ki [RLi] [M] for all three monomers.