Abstract
AbstractAnionic polymerizations of 2‐, 3‐, and 4‐fluorostyrenes (2‐, 3‐, and 4‐FSt) were carried out at −78°C in THF with sec‐butyl‐lithium, oligo(α‐methylstyryl)lithium, ‐dipotassium, and (1,1‐diphenyl‐3‐methyl‐pentyl)lithium as initiators to give the respective polymers in quantitative yields. The propagating carbanion derived from 2‐FSt is found to survive at least for 5 min at—78°C, affording the anionic living poly(2‐FSt) with predictable molecular weight and very narrow molecular weight distribution. The addition of styrene to the anionic living poly(2‐FSt) in THF affords poly(2‐FSt)‐block‐polystyrene in quantitative efficiency, indicating the high nucleophilicity of the propagating carbanion of 2‐FSt. During the polymerization of 3‐FSt, the benzyne intermediate is formed probably due to meta‐fluoro substitution to cause polymer coupling reaction. Poly(4‐FSt) produced has narrow molecular weight distribution and slightly higher molecular weight than the calculated one. The results of the polymerizations of 2‐FSt and 4‐FSt suggest that persistency of the propagating carbanionic species of 4‐FSt is slightly lower than that of 2‐FSt at −78°C.
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