Butyllithium Polymerization of Butadiene. II. Effects of Solvent and Temperature on Association of Polybutatadienyl Lithium

Publisher Website
Google Scholar
Abstract
In the butyllithium polymerization of butadiene in aliphatic solvents at 25°C, the first few monomer units are incorporated largely in a 1, 2 manner. With increasing degree of polymerization the extent of 1, 2 addition decreases to a limiting value of about 10% at a degree of polymerization of about 50. However, within this region of high 1, 2-addition increasing solvent basicity, i.e., changing from aliphatic to aromatic solvents, markedly reduces extent of 1, 2 addition and also narrows the molecular weight distribution. Further, in aliphatic solvents, increasing polymerization temperature from 25 to 60°C also results in a marked reduction in 1, 2 addition. These results are consistent with the concept that an ion pair of the associated organolithium complex, [R (n-1 Lin] ⊕R⊖, is the active polymerization species and that changes in mode of monomer incorporation are due to changes in the degree of association of the entire organolithium system.

This publication has 9 references indexed in Scilit: