Room-Temperature Synthesis of Amine-Phloroglucinol Covalent Organic Polymers in an Aqueous Medium: Catalysts for Epoxide-CO2 Cycloaddition Reactions

Three phloroglucinol-amine covalent organic polymers (COPs), PG-TETA, PG-DETA, and PG-EDA, were facilely synthesized in an aqueous medium via a room-temperature, one-pot polymerization reaction of triethylenetetramine (TETA), diethylenetriamine (DETA), and ethylenediamine (EDA) with phloroglucinol, respectively. These as-synthesized COPs were utilized as catalysts for the conversion of a number of epoxides into their corresponding cyclic carbonates via the cycloaddition of epoxides with CO₂ in the presence of the KI cocatalyst. Both PG-TETA/KI and PG-DETA/KI demonstrated to be efficient catalyst systems by showing 100 and 89% conversion of epichlorohydrin (ECH), respectively, to its corresponding cyclic carbonates under the reaction conditions [COP (30 mg), KI (2 mol %), 80 °C, CO₂ (balloon), 24 h]. However, the PG-EDA/KI catalyst showed significantly lower conversion of ECH (50%) to cyclic carbonate under the reaction conditions. Moreover, PG-TETA COP by itself demonstrates effectiveness in the CO₂/epoxide coupling reaction, showing 47% conversion under the reaction conditions [80 °C, CO₂ (balloon), 24 h], revealing its ability to serve as a single-component catalyst.