Halogen‐Bonding‐Mediated and Controlled Cationic Polymerization of Isobutyl Vinyl Ether: Expanding the Catalytic Scope of 2‐Iodoimidazolium Salts

Abstract

Metal-free initiating systems for living cationic polymerizations are desirable from the viewpoint of environmentally benign polymer synthesis. We describe here the development of a halogen-bonding-mediated and controlled cationic polymerization of isobutyl vinyl ether (IBVE) using 2-iodoimidazolium salts as an organocatalyst. Due to the ionic nature of the catalysts, the polymerization should be performed in CH Cl . The HCl-adduct of IBVE was the most suitable initiator, and the polymerization was carried out at -10 °C under the catalyst concentration of 10 mm to suppress alcohol elimination from the polymer chain. The addition of a small amount of nBu NCl (0.02 equivalent) was effective to accomplish the controlled cationic polymerization and obtain polyIBVE, having the molecular weight distribution below 1.3.

Halogen Bonding in Solution: Anion Recognition, Templated Self‐Assembly, and Organocatalysis

“…The iodoimidazolium system used for the living cationic polymerization of isobutyl vinyl ether (IBVE);I nit = initiator. [64] Angewandte Chemie Minireviews neutral systems,for example,achiral bis(imidazolidine)iodobenzene for aMichael/Henry reaction, [65] molecular iodine as the simplest catalytically active XB-based catalyst, [66,67] CBr 4 as the XB donor for the activation of benzaldehydes, [68] and recently the XB contribution in as ide-chain iodination of electron-deficient benzylic hydrocarbons with iodohydantoins [69] were also investigated.…”

“…The XB‐mediated halide abstraction reaction was used for the first time in mid‐2017 for a controlled cationic living polymerization of isobutyl vinyl ether (IBVE) . The bidentate iodoimidazolium XB donor 27 enabled the formation of a dormant and an active species by a reversible halide transfer between the propagating chain end and the catalyst (Figure ).…”

“… The iodoimidazolium system used for the living cationic polymerization of isobutyl vinyl ether (IBVE); Init=initiator …”

Halogenbrücken in Lösung: Anionenerkennung, Templat‐gestützte Selbstorganisation und Organokatalyse

“… Iodimidazoliumsystem als Katalysator in einer lebenden kationischen Polymerisation von IBVE; Init.=Initiator …”

Cationic polymerization of n‐hexyloxyallene by using halogen‐bonding organocatalysts

“…We have recently developed the metal‐free cationic polymerization of isobutyl vinyl ether (IBVE) by using 2‐iodoimidazolium derivatives as a halogen‐bonding organocatalyst . Although many metal‐free living cationic polymerizations have been reported, this is the first example applying the halogen‐bonding interaction in the polymerization chemistry.…”