Unlocking regioselectivity: steric effects and conformational constraints of Lewis bases in alkyllithium-initiated butadiene polymerization.

ABSTRACT: In nonpolar solvents, alkyllithium-initiated 1,3-butadiene polymerization exhibits high 1,4-selectivity, which shifts towards 1,2-selectivity upon the addition of Lewis bases. For the past 50 years, the prevailing hypothesis has suggested that Lewis bases primarily influence regioselectivity through electronic effects. However, our study reveals that steric hindrance also plays a crucial role. Using X-ray single-crystal diffraction, we analyzed the structure of the active species and proposed a new model for the chain-growth transition state. Techniques such as in situ NMR spectroscopy, isotope labeling studies, and density functional theory (DFT) calculations were employed to compare the impact of electronic and steric effects of various Lewis bases on regioselectivity. Our finding

SUBMITTER: Tang J 

PROVIDER: S-EPMC11583766 | biostudies-literature | 2024 Dec

REPOSITORIES: biostudies-literature