Biocompatible and recyclable amino acid binary catalyst for efficient chemical fixation of CO2

In this work, the cycloaddition reactions of CO₂ with various epoxides to form five-membered cyclic carbonates catalyzed by an efficient amino acid based biocompatible catalyst were investigated. It was found that the activity of amino acid could be obviously enhanced in the presence of alkali metal salts, and the l-tryptophan catalytic system was the most efficient among the catalysts employed. Based on the result, a possible mechanism for the synergetic effect of catalyst was proposed. The process reported here represents a simple, ecologically safer, cost-effective route to cyclic carbonates with high product quality, as well as easy catalyst recycling.