As a key intermediate in the synthesis of various chemical products, organic diacids still exhibit non-negligible drawbacks in the industrial preparation process, such as strong heat release during the reaction process, poor mass transfer effects, and prolonged reaction times. Against this backdrop, traditional batch reactors are gradually being replaced by microreactors. This study centers on the continuous-flow microreactor system and produces diacid esters from methyl oleate as the raw material by serially connecting two microreactors. Under the green solvent system, catalyst-free conditions, and with water (H2O) present, the yields of monomethyl azelate and nonanoic acid exceeded 96% and 86%, respectively, by reducing solvent dosage. Notably, this study investigated the reaction mechanism involving H2O, confirming that water (H2O) was consumed as a reactant, and proposed the reaction pathway between H2O and Criegee radicals. This work not only establishes an efficient and green oxidative cracking pathway for the preparation of diacids from methyl oleate but also verifies the reaction pathway between Criegee radicals and H2O, explains the origins of byproduct formation, enhances the controllability of Criegee radical reactions, and provides a novel reaction route for olefin ozonolysis reactions.
Ning et al. (Thu,) studied this question.