Synthesis of Linear α-Olefins via Polyhomologation

Abstract

Linear R-olefins (LAOs) of controlled molecular weight and low PDI were synthesized in high yield by the polyhomologation reaction of dimethylsulfoxonium methylide (1) with triallylborane (2). Following polymerization, propionic acid or trimethylamine N-oxide dihydrate (TAO) was used to afford R-vinyl-ω-methyl or R-vinyl-ω-hydroxy end-functionalized polymethylene, respectively. Controllable molecular weights up to 13 kDa were obtained by varying the initial monomer/catalyst ratio, and the resultant polymers had very narrow polydispersities (PDI < 1.08). Although polymer yields were generally high, quantities of oxidized side products were observed in R-vinyl-ω-methyl samples; however, these oxidized side products could be removed for samples of low molecular weights (C n e 36).

C1 polymerization: a unique tool towards polyethylene-based complex macromolecular architectures

“…The molecular weight of these α,ω-difunctionalized PEs ranges from 650 to 20000 g mol -1 and the polydispersity Đ < 1.1. 16,17 Obviously, more functional boranes will lead to more diverse functionalized PEs. Scheme 3 Synthesis of block copolymers by using different macroborane initiators for the polyhomologation of the methylylide Different block copolymers have been successfully synthesized by Shea's group through polymeric borane initiators.…”

Polymethylene‐Based Copolymers by Polyhomologation or by Its Combination with Controlled/Living and Living Polymerizations

“…[ 8,9 ] A very few catalytic polymerizations of ethylene, which satisfy the criteria of living ethylene polymerization, can afford linear PE and a few other structures (e.g., star). [ 1,10,11 ] Recently, Shea and co-workers [12][13][14][15][16][17] developed a novel polymerization methodology leading to linear PMs. The general reaction scheme involves the formation of an organoboron zwitterionic complex by reaction of a methylide (monomer) with a trialkylborane Lewis acid (initiator) followed by an intramolecular 1,2-migration.…”

“…C1-polymerization. [13][14][15][16]18,19 ] In theory, this method allows the growth of perfect linear PM backbone; however, the existence of dimethylsulfoxonium ethylide impurity in the dimethylsulfoxonium methylide monomer is bound to generate 1%-1.5% side methyl groups on the backbone as revealed by NMR. By purifying the monomer, the amount of methyl groups can be decreased to 0.2%.…”

“…Recently, Shea and co‐workers developed a novel polymerization methodology leading to linear PMs. The general reaction scheme involves the formation of an organoboron zwitterionic complex by reaction of a methylide (monomer) with a trialkylborane Lewis acid (initiator) followed by an intramolecular 1,2‐migration.…”

“…The resulting star is subsequently oxidized/hydrolyzed to give perfectly OH‐end‐capped linear PMs. For this type of polymerization, Shea coined the term polyhomologation or C1‐polymerization . In theory, this method allows the growth of perfect linear PM backbone; however, the existence of dimethylsulfoxonium ethylide impurity in the dimethylsulfoxonium methylide monomer is bound to generate 1%–1.5% side methyl groups on the backbone as revealed by NMR.…”