QUANTITATIVE ANIONIC SYNTHESIS OF PYRENE-END-LABELED POLYSTYRENE AND POLYBUTADIENE

Omega-pyrenylpolystyrenes and omega-pyrenylpolybutadienes were synthesized in quantitative yield by reacting polystyryllithium and polybutadienyllithium, respectively, with 1-phenyl-1-(1'-pyrenyl)ethylene in benzene. The addition of tetrahydrofuran (2 vol %) was required for polybutadienyllithium because of the slow rate of addition in benzene. The addition reaction can be monitored by UV-visible spectroscopy at 476 nm, lambda-max of the 1-phenyl-1-pyrenylalkyllithium anion. The functionalization reaction is not a termination reaction; the addition product is a living carbanion that can initiate polymerization of monomers to produce in-chain, pyrene-labeled polymers. The pyrene-labeled polymers were characterized by size-exclusion chromatography, vapor phase osmometry, ultraviolet-visible spectroscopy, and both H-1 and C-13 NMR. No evidence for unlabeled polymer was observed. The ultraviolet-visible spectra for the pyrene-labeled polymers show absorption bands at 330 and 346 nm, which are bathochromically shifted relative to the corresponding bands of pyrene. 1-Phenyl-1-(1'-pyrenyl)ethylene was synthesized in 34% yield starting from 1-pyrenecarboxaldehyde.