Anionic telomerization of butadiene with toluene and diphenylmethane: microstructure and molecular weight

The frequency of chain transfer of polybutadienyllithium to toluene and diphenylmethane is increased in the presence of N, N, N′, N′-tetramethylethylenediamine. When the reactor is fed with monomer at a constant rate, the molecular weight of telomer falls steeply as the ratio [base]:[lithium] increases from zero to unity but much more slowly thereafter. Whenever an anionic chain end has a penultimate 1,2-placement, cyclization to form a vinylcyclopentane competes with propagation the more favourably the lower the monomer concentration. In consequence, telomers prepared in toluene have a far greater cyclic content than those prepared in diphenylmethane.