Selective Catalytic Dehydrogenative Oxidation of Bio‐Polyols to Lactic Acid

• Published in: Angewandte Chemie International Edition Vol. 59; no. 33; pp. 13871 - 13878
• Main Authors: Wu, Jiajie, Shen, Lingyun, Duan, Sai, Chen, Zhe‐Ning, Zheng, Qingshu, Liu, Yaoqi, Sun, Zheming, Clark, James H., Xu, Xin, Tu, Tao
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 10-08-2020
• Edition: International ed. in English
• Subjects: bio-polyols; Bioplastics; Catalysis; Catalysts; Chemical synthesis; Coordination Complexes - chemistry; Coordination polymers; Dehydrogenation; Hydrogenation; Industrial production; Iridium; Iridium compounds; Lactic acid; Lactic Acid - chemistry; N-heterocyclic carbene iridium complex; Oxidation; Oxidation-Reduction; oxidative dehydrogenation; Polymers; Polymers - chemistry; Polyols; Selectivity; self-supporting; Sorbitol; lactic acid; self-supporting; N-heterocyclic carbene iridium complex; bio-polyols; oxidative dehydrogenation
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202004174

The global demand for lactic acid (LA) is increasing due to its successful application as monomer for the manufacture of bioplastics. Although N‐heterocyclic carbene (NHC) iridium complexes are promising molecular catalysts for LA synthesis, their instabilities have hindered their utilization especially in commercial applications. Here, we report that a porous self‐supported NHC‐iridium coordination polymer can efficiently prevent the clusterization of corresponding NHC‐Ir molecules and can function as a solid molecular recyclable catalyst for dehydrogenation of bio‐polyols to form LA with excellent activity (97 %) and selectivity (>99 %). A turnover number of up to 5700 could be achieved in a single batch, due to the synergistic participation of the Ba2+ and hydroxide ions, as well as the blockage of unwanted pathways by adding methanol. Our findings demonstrate a potential route for the industrial production of LA from cheap and abundant bio‐polyols, including sorbitol.
Bio‐polyols conversion: A series of 3D porous self‐supported NHC‐iridium coordination polymers were prepared and could function as recyclable solid molecular catalysts for dehydrogenation of bio‐polyols to lactic acid with excellent activity and selectivity due to the synergistic participation of the Ba2+ and hydroxide ions, as well as the blockage of unwanted pathways by adding methanol.