Lithium diisopropylamide polymerization

The lithium enolate generated using lithium diisopropylamide [4111-54-0], lithium 2,2,6,6-tetramethylpiperidide [58227-87-1], or lithium hexamethyldisilazide [4039-32-17 is a chemical reagent that reacts with other reactants to give a variety of products (37). In the quest for improved stereospecificity, enolates with different cations such as silicon, aluminum, boron, and zinc have also been used (38). In group transfer polymerization, ketene silyl acetals, eg, (CH3)2C=C [OSi(CH3)3] (OCH3) are employed as initiators (39). 

Aminoboranediyl-bridged ansa- Cp-Flu) zirconocene dichloride 1195 has been prepared according to the salt metathesis approach shown in Scheme 281, which involves sequential reactions of 9-fluorenyllithium and CpNa with (Pr1)2NBCl2, followed by treatment with lithium diisopropylamide and ZrCl4.922 The molecule has ( -symmetry both solution spectroscopic and solid-state X-ray data reveal a partial double bond character between N and B atoms as a result of the B-N 7r-bonding. Upon activation with MAO, this complex polymerizes propylene to syndiotactic PP ([rr] =81%). 

It has been found recently that lithium diisopropylamide is able to initiate isoprene polymerization at 80° C to an oligomer having the alkylamino group at the end of the polymer chain. The reaction conditions are more severe than those in previous study. 

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