Insight into the green route to dimethyl succinate by direct esterification of bio-based disodium succinate using CO2 and CH3OH

Abstract

The fermentation for succinic acid production outperforms other methods by low energy consumption and environmental benignity, with the resulting products mainly as disodium succinate (DSA). By directly esterifying DSA using CO2 and CH3OH, it is expected to avoid the use of inorganic acids. By high-resolution mass spectrometry analysis and theoretical calculation, this study establishes that the reaction consists of three steps, i.e., first forming 3-carboxypropanoate, then monomethyl succinate (MMS), and finally dimethyl succinate (DMS). A detailed kinetic analysis is further performed, the results demonstrate that the transformation of DSA to MMS is regarded to be a second-order reaction for reactant DSA, while the transformation of MMS to DMS is a first-order reaction for reactant MMS. The activation energy for the generation of MMS from DSA is 37.15 kJ·mol−1, and that for the generation of DMS from MMS is 85.80 kJ·mol−1, indicating the latter one is the rate-determining step.