A mild and efficient oxidation of 2,3,6-Trimethylphenol to Trimethyl-1,4-benzoquinone with high-velocity air as an oxidant in a continuous-flow microreactor

Abstract

2.3.5-trimethyl-1.4-benzoquinone (TMQ) is an important intermediate in the synthesis of vitamin E, and the oxygen oxidation of 2.3.6-trimethylphenol (TMP) is commonly used to prepare TMQ in the industry. However, the slow mass transfer of oxygen from the gas phase to the liquid phase in the gas-liquid two-phase reaction greatly limits the oxidation reaction rate. Therefore, this study presents a mild and efficient synthesis of TMQ by catalytic oxidation of TMP using high-velocity air as an oxidant in a self-built continuous flow microreactor. The continuous flow microreactor shows excellent mass transfer performance, and high- velocity air was used to drive the feedstock liquid to do circular motion. The effects of different operating conditions and microreactor parameters on TMP conversion and TMQ yield were investigated. The results show that the TMP conversion and TMQ yield reach 100% and 89.9% under the optimal conditions of the continuous flow microreactor, respectively. Compared with the tank reactors, this continuous-flow microreactor has broad application prospects in the production of TMP catalytic oxidation. In a state of continuous high-speed circular motion, efficient mass transfer in a narrow pipe enables full contact between the liquid and gas phases. As a result, reaction time is reduced from approximately 5 hours to merely 78.5 seconds.