Naphthalene ended polyvinyl aromatic

Metalation of Naphthalene Ended Polyvinyl Aromatic Chains by Potassium in THF At RT... 

Naphthalene-terminated polyvinyl aromatics and polyisoprene were obtained successfully. These functional polymers were metalated by potassium in THF at 25°C. The formation of a stable dinegative ion is observed unless the naphthalene is directly attached to the end of the polyvinyl aromatics, in which case a few isoprene units can be advantageously inserted between the naphthalene end group and the polyvinyl aromatics. The polymeric and stable dinegative ion polymerizes oxirane by both anionic sites and forms three-branched starshaped block copolymers. 

Four carbonions can be formed per naphthalene end group (Figure ) whereas the naphthalene end group is completely released at the end of the metalation. This phenomenon has been thoroughly studied and will be published elsewhere (22). Briefly when naphthalene is conjugated to an aromatic nucleus the potassium dianion is unstable and the naphthalene end group is released whereas the polyvinyl anion is freed and finally isomer-ized eqs 13 to 17 summarize these observations. 

Similar instability of conjugated anionic systems has already been observed Lagendijk and Szwarc have reported that di(a-naphthyl)ethane dianion ( - ) in ether solvent undergoes scission of the central C-C bond vith formation of two monoanion (NN 2 —> 2N ) (26) To suppress the deleterious effect of conjugation and to obtain a stable dianion terminated PS or PTBS, at least one isoprene unit is to be inserted between the polyvinyl aromatic chain and the naphthalene end group this opportunity has been successfully applied. 

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