Initiators, anionic fluorenyllithium

The anionic polymerization of the MM block was initiated with fluorenyllithium (14) in THF at -78°C. After several hours, t-butyl methacrylate was introduced, and the polymerization was allowed to slowly rise to room temperature. The reaction was quenched with a few drops of methanol and precipitated from ligroin. The dried polymer was analyzed by NMR, IR, and GPC. The 1H NMR spectrum displays signals at 0.85, 1.02, and 1.13 (shoulder) ppm for the... 

Powells et al. pdymerized stereospecifica% deuterated acrylic and methr acrylic esters to h y isotactic polymers tmder several conditions with a number of anionic initiators. They analyzed the polymers by NMR spectroscopy to get the information on the mode of monomer approach to the growing anion. The results of the polymerization initiated with fluorenyllithium suggest that there are two transition states leading to an isotactic placement which differ in the degree of solvation. One is derived from a naked contact ion pair and forms the polymer of threo-meso configuration. The other is apparently formed by the specifically solvated contact ion pair and forms erythro-meso. A very similar study was reported on the anionic polymerization of deuterated ntethyl acrylate. " ... 

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