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

Abstract

The kinetics were determined for the polymerization of butadiene, isoprene, and styrene with n‐, sec‐, and tert‐BuLi in hydrocarbon solvents. Polymerization has the mechanism of a homogeneous, “intermittent” stepwise addition reaction with no true termination reaction. In cyclohexane, n‐hexane or toluene at 5–50°C. there is no chain transfer. When n‐BuLi was used, the rate of polymerization was a combined rate of initiation and propagation. It was proportional to [M]² and dependent on [n‐BuLi] at low initiator concentration and almost independent at high concentration. The limits are established and discussed. The rate constants calculated for the monomers were in the order styrene > isoprene ≫ butadiene. For the solvents the order was toluene ≫ cyclohexane > n‐hexane.