Synthesis of Well-Defined Bifunctional Oligobutadienes as Initiated by Dilithium Alkanes Soluble in Hydrocarbons

Disecondary dilithium alkanes of general formula CH₃CHLi(CH₂)_nCHLiCH₃ (DSDLAs) are efficient initiators (soluble in hydrocarbons) for ‘living’ polymerization of conjugated dienes. These compounds are prepared by reaction between lithium and appropriate dichloroalkanes in hydrocarbons under mild conditions. Polymerization of butadiene in the presence of initiators leads (under some conditions) to formation of oligomers with narrow molecular weight distribution (polydispersity indices below 1.2) over a wide range of molecular weights (3000–12 000). Upon treatment with functionalizing agents, the functionality of synthesized oligomers may attain a value about 1.9. The amount of 1,4-units (both cis and trans) in the oligomers was found to be above 80%.