One-Step Synthesis of Lactide

Abstract:

Polylactic acid （PLA） is widely considered to be one of the most promising biodegradable polymers. The promulgation of the national “banning plastic bags” has led to an unprecedented expansion of PLA production and application areas. The chemical purity， optical purity， and production cost of lactide （LD）， a key intermediate of bioplastic PLA， directly determine the quality and economic value of PLA. The two-step synthesis technology is standard in the industry nowadays， and the pre-polymerization-depolymerization approach ensures the conversion rate of lactic acid. Still， its main problems are LD racemization， low selectivity， and high energy cost. The one-step method as an alternative strategy is well suited to overcome some disadvantages of the two-step LD synthesis. Therefore， this review focuses on the one-step synthesis of LD and describes and compares the different methods technically.