Nonaqueous and Aqueous Emulsion ROMP Reactions Induced by Environment-Friendly Latent Ruthenium Indenylidene Catalyst Bearing Morpholine Substituted Bidentate (N, O) Schiff Bases

Abstract

In this study, a novel latent ruthenium indenylidene catalyst, bearing morpholine substituted bidentate (N, O) Schiff base is used in nonaqueous emulsion ring‐opening metathesis polymerization (ROMP) reactions for the first time. This novel catalyst has unique features such as latency and high silica gel affinity. The performance of the catalyst is tested on ring‐closing metathesis (RCM), ROMP reactions, and aqueous emulsion ROMP reactions. In addition, nonaqueous (using immiscible binary organic solvents: n‐hexane and dimethylformamide) emulsion ROMP reactions are carried out for the first time using latent ruthenium catalysts. The latency of the catalyst allows us to control the molecular weight of emulsion ROMP polymers by varying HCl/Ru ratio, keeping the nanoparticle sizes stable between 26 and 75 nm in aqueous emulsion and 51 and 208 nm in nonaqueous emulsion ROMP reactions. In addition, high silica gel affinity of the catalyst allows us to synthesize pure RCM products with ruthenium contamination less than 1 ppm.

Encapsulation of the Hoveyda–Grubbs 2nd generation catalyst in magnetically separable alginate/mesoporous carbon beads for olefin metathesis reactions in water

“…3 To tackle these limitations, ionic and non-ionic hydrophilic group-tagged Grubbs catalysts were developed to improve the solubility of the catalysts in aqueous media. 3–5 Grubbs catalysts were also immobilized on hydrophilic, hydrophobic and amphiphilic polymers, and biomolecules to conduct olefin metathesis reaction in water. 6 The encapsulation of Grubbs-type ruthenium catalysts in confined spaces emerges as a novel strategy for developing efficient metathesis catalyst systems with the improved performance, selectivity, and sustainability.…”