Surapich Loykulnant

Recent advance in living anionic polymerization of functionalized styrene derivatives

Abstract This review covers recent advance of living anionic polymerization of styrene derivatives with functional groups. Although there have so far been reported several successful systems of living anionic polymerization of functionalized styrene derivatives, most useful functional groups are not amenable to the conditions of living anionic polymerization of styrene. Therefore, we herein present two generalized strategies to be able to achieve the living anionic polymerization of styrenes with such functional groups that are normally incompatible with carbanionic species. The first strategy involves protection of the functional group and living anionic polymerization of the resulting protected monomer, followed by deprotection to regenerate the original functional group after the polymerization. In the second strategy, an electron-withdrawing functional group is introduced into the benzene ring of styrene to purposefully lower the reactivity of the generated chain-end carbanion, thereby allowing the functional group and the carbanion to coexist. The living anionic polymerization of a number of styrene derivatives with functional groups became indeed possible by employing two proposed strategies. Their scopes, limitations, and possibilities are also discussed.

Anionic living polymerization of functional monomers. Precise synthesis of various functionalized polystyrenes with monosaccharide residues by anionic living polymerization and living functionalization reaction

*Entered Department of Polymer Chemistry, Faculty of Engineering, Tokyo Institute of Technology (Japan), April 1993, and graduated March 1997, B. Eng. *Entered Department of Polymer Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology (Japan), April 1997, and graduated March 1999, M. Eng. Thesis Theme: Anionic Polymerization of Styrene Derivatives Containing Monosaccharide Residues. *Entered Polymeric and Organic Materials Department, Graduate School of Science and Engineering, Tokyo Institute of Technology (Japan), April 1999, and graduated March 2002, D. Eng. Thesis Theme: Precise Synthesis of Monosaccharide-Functionalized Polymers by Means of Living Anionic Polymerization.

Living Anionic Polymerization of Monomers with Functional Groups, 15. Anionic Polymerization and Reaction of Styrene and 1,1-Diphenylethylene Derivatives Substituted with Alkoxymethyl Groups

Anionic polymerizations of ortho-, meta-, and para-substituted styrene derivatives with alkoxy-methyl groups have been studied. It was found that their polymerization behaviors were significantly affected by the substituted position of the alkoxymethyl group. The meta- and ortho-substituted styrenes successfully underwent living anionic polymerization in THF at -78°C with the initiators having K + as a counter cation such as cumyl-potassium and oligo (α-methylstyryl ) potassium, and potassium napthalenide. On the other hand, no appreciable polymerization of the para-substituted styrenes occured under the identical conditions. The similar positional effect was also observed in the reactions of polystyryl-lithium with o,o-, m,m-, and p,p-disubstituted 1,1-diphen-ylethylene (DPE) derivatives with methoxymethyl groups. Instead of the expected 1 : 1 addition products, undesirable high molecular weight polymers were formed especially using p,p-disubstituted DPE. In order to account for such anomalous polymerization and reaction behaviors of the para-substituted styrene and DPE derivatives, we postulated the reaction pathway based on the anion-mediated rearrangement followed by a 1,6-elimination reaction to produce very reactive p-xylylene and/or biradical inter-mediates that were coupled to each other. This postulated reaction pathway was discussed throughout the results of the stoichiometric reaction of sec-BuLi with p-methoxy-methylstyrene and 1-(4-methoxymethylphenyl)-1-pheny-lethylene.