1,2-Syndiotactic polymerization of butadiene catalyzed by iron (III) acetylacetonate in combination with exogenous phosphate

Abstract

In this work, a group of acetylacetonate iron compounds variation of steric and electronic properties are synthesized. In the presence of exogenous triphenyl phosphate derivatives, these compounds can be uniformly transformed to active species for efficient catalyzing butadiene polymerization following 1,2 insertion up to 96.9 % with syndiotactic configuration of 98.0 % (penta ada: rrrr). Introduction of electronic withdrawing groups on the ligand and additive both promotes the activity, whereas bulky group has detrimental effect. Positive effect is exceptionally reached for methoxy-positioned additive probably ascribed from the weak interaction with active species. Significant stability against temperature, alkylaluminum, even the iron compounds in terms of activity, stereoselectivity, thus the stable thermal properties of resultant polymers are achieved. This catalyst components are readily accessible without tedious synthesis, and the polymerization is mild and operationally simple, allowing access to crystalline 1,2 polybutadienes in useful yields.