Vinyl polymerization by lithium organocuprates

Abstract

Vinyl polymerizations initiated by lithium organocuprates under several conditions were investigated. It was observed that this catalyst was effective in the polymerization of specific monomers such as α,β‐unsaturated nitrile and carbonyl analogues. The rate of polymerization was rapid but retarded by the addition of pyridine, nitrobenzene, or hydroquinone. Polymerization of methyl methacrylate (MMA) with lithium di‐n‐butylcuprate as initiator produces predominantly isotactic poly(methyl methacrylate) (PMMA) in toluene. The overall activation energy was estimated as 3.5 kcal/mol deg. Lithium di‐n‐butylcuprate exerts a higher stereoregulating effect on the addition of monomers than other organolithium initiators. It is proposed that polymerization proceeds via a coordinated anionic mechanism.

Lanthanide borohydrido complexes for MMA polymerization: syndio‐ vs iso‐ stereocontrol

“…28 Anionic polymerisation of MMA initiated by cuprate reagent resulted in highly syndiotactic materials when the experiments were conducted in polar solvent, 29 and predominantly isotactic in toluene. 30 In the course of our studies concerning the valorisation of lanthanide borohydrides for polymerisation, 10 times higher), denoting that only a small percentage of the catalyst had initiated the reaction. However, these preliminary results were considered motivating since a significant control of the tacticity (rr 76 %) was observed, in sharp contrast with the conventional, aspecific, radical polymerisation of MMA.…”

Anionic polymerization of MMA initiated by organolithium/cuprum diphenylphosphide (Ph2PCu) and synthesis of its block copolymer

“…Given the possibility of living polymerization of alkyl (meth)acrylate under mild conditions, lithium organocuprates ([R 2 Cu] − Li + ), also known as Gilman reagents, have been used as anionic initiators35–39 because they favor 1,4‐addition reactions and behave with high regio‐ and stereoselectivity when reacted with various α,β‐unsaturated esters and ketones. Gregonis was the first to prepared stereoregular poly(hydroxyethyl methacrylate) with Bu 2 CuLi in toluene 35.…”

“…Gregonis was the first to prepared stereoregular poly(hydroxyethyl methacrylate) with Bu 2 CuLi in toluene 35. Han synthesized stereoregular poly(methyl methacrylate)(PMMA) using the same initiator 36. Kawaguchi prepared poly(tert‐butyl methacrylate) (PTBMA) and PTBMA‐b‐PMMA with Me 2 CuLi39 and polymerization was proven to be partially living 37, 39.…”

“…35 Han synthesized stereoregular poly(methyl methacrylate)(PMMA) using the same initiator. 36 Kawaguchi prepared poly(tert-butyl methacrylate) (PTBMA) and PTBMA-b-PMMA with Me 2 CuLi 39 and polymerization was proven to be partially living. 37,39 However, these lithium homocuprates were easily thermally decomposed and had low initiation efficiencies (<10%), and the resulting polymer showed broad molecular weight distributions (MWDs) (1.2-2.0).…”

Organocuprates Initiated Anionic Living Polymerization of tert-Butyl Methacrylate

“…7 It was shown by Grigonis et al 8 that benzoxyethyl methacrylate polymerization initiated with lithium din-butylcuprate ((n-Bu)zCuLi) in toluene affords highly isotactic polymers (5% syndiotactic, 15% heterotactic, and 80% isotactic triad contents). Han et al 9 reported (n-Bu) 2 CuLi to be an effective initiator for O!,/J-unsaturated monomers, MMA, acrylonitrile, acrolein, and Nacryloylpyrrolidone to afford highly isotactic polymers in toluene. They, however, did not report any evidence related to the molecular weight distribution (MWD) of the polymers and the possibility that the reaction may proceed in a living manner.…”