Alkylphosphine makes difference: Highly robust Palladium(II) phosphine sulfonate catalysts for nonalternating copolymerization of ethylene with carbon monoxide.

[Display omitted] • Pd catalysts are used for nonalternating copolymerization of ethylene with CO. • Alkyl substituents on phosphorus moiety exhibits 29.2 mol% extra C2 incorporation. • T m value of nonalternating polyketone was reduced to 162 °C. • Such Pd catalyst exhibits high thermally robust nature in this copolymerization. Production of polyketone realizes the direct conversion of cost effective and abundant olefin and carbon monoxide (CO) monomers. However, copolymerization of ethylene with CO shows a high tendency for the formation of strictly alternating structures, and they feature a high melting temperature (T m) of 260 °C that impedes the processing by using the conventional injection molding and extrusion. Nonalternating preference in such copolymerization is a very promising method to circumvent the processability issues. In this study, we present a series of phosphine-sulfonate Pd catalysts for nonalternating copolymerization of ethylene and CO, since rare study has investigated the electronic and steric nature systematically in such ligand platform in this field. The usage of dicyclohexyl substituents on phosphorus moiety exhibits unexpected nonalternating preference with up to 29.2 mol% extra ethylene incorporation, thus lowing the T m values to 162 °C. Notably, such alkyl substituted phosphine sulfonate Pd catalyst exhibits high thermally robust nature in this nonalternating copolymerization. [ABSTRACT FROM AUTHOR]