Catalytic Aerobic Oxidation of Lignocellulose-Derived Levulinic Acid in Aqueous Solution: A Novel Route to Synthesize Dicarboxylic Acids for Bio-Based Polymers

Abstract

The world is facing grand and ever-increasing pressures on energy and environmental issues. Using carbon-neutral biomass to prepare monomers such as dicarboxylic acids for degradable polymers is of great significance and an urgent but challenging task. Herein, we report a catalytic route for the synthesis of 2-hydroxy-2-methylsuccinic acid, an excellent monomer: e.g., it is able to remarkably enhance the comprehensive properties of polybutylene succinate as shown herein. By catalytic aerobic oxidation of levulinic acid, a bulk platform chemical derived from lignocellulose, the target product was obtained with a very high selectivity of up to ca. 95%. The mild reaction conditions below 100 °C in water and the low-cost reusable heterogeneous catalyst further make the process highly attractive for applications. This process was also found to be effective for the conversion of homologues of levulinic acid to dicarboxylic acids. We studied the C−C bond rearrangement and the roles of catalysts in the reaction that are highly likely involved in a superoxide anion radical mechanism. This study may provide inspiration for the synthesis of bio-based dicarboxylic acids via alternative routes.

Monomers and Macromolecular Materials from Renewable Resources: State of the Art and Perspectives

“…In recent years, the indirect exploitation of levulinic acid to the design of original polymers has gained attention. The catalytic conversion of levulinic acid into 2-hydroxy-2-methylsuccinic acid (citramalic acid) was also reported [ 165 ], which is a high-value chemical that can replace succinic acid in polybutylene succinate, enhancing its properties. The synthesis of a cyclic diester via the ketalization of levulinic acid with pentaerythritol was described ( Figure 9 a), and the obtained monomer was polymerized by transesterification with 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and 1,4-cyclohexanedimethanol, yielding fully amorphous polyesters with glass transition temperatures ranging from 12 to 49 °C and thermal stability up to 300 °C [ 166 ].…”

Recent Advances in Lignocellulose-Based Monomers and Their Polymerization

“…Xu et al obtained a from-5-HMF-to-maleic anhydride yield of 52% using VO(acac) 2 as a catalyst after a reaction at 90 °C for 4 h in acetonitrile through the simultaneous oxidation of hydroxymethyl group and C–C bond cleavage of 5-HMF [ 27 ]. Levulinic acid is an important biomass-derived platform chemical as an intermediate for the preparation of polymer monomers such as succinic acid [ 28 , 29 , 30 ]. The acid-catalyzed decomposition of 5-HMF for the preparation of levulinic acid has been widely reported, but most of them were limited by low yields and deficient economic efficiency.…”

Making Persistent Plastics Degradable

“…[87] Although the most widely applied synthetic procedure is still fossil based, there are intensive efforts to develop PBS synthetic methodology using environmental benign, renewable feedstocks including fermentation and catalytic methods. [88][89][90][91] PBS is a highly biodegradable polymer. It is used not only for "green" packaging but also for in many biomedical application.…”