Synthesis of 2,3,5-trimethylbenzoquinone from 2,3,6-trimethylphenol and tert-butyl hydroperoxide in microreactors

The synthesis of 2,3,5-trimethylbenzoquinone (TMBQ) from 2,3,6-trimethylphenol (TMP) and tert-butyl hydroperoxide (TBHP) was carried out in microreactors. The yield of TMBQ increased first and then decreased with raising the reaction temperature. The reaction temperature and the residence time were optimized to be 40 °C and 12 min, respectively. The effects of the inner diameter of microreactor and the total volumetric flow rate on the reaction performance were found to be negligible under involved operational conditions. In order to reduce the overoxidation in the initial stage, the influence of the molar ratio of TBHP to TMP and the injection strategy of TBHP were investigated. The results showed that the optimal yield of TMBQ could reach 73% at 12 min residence time and 40 °C with the molar ratio of TBHP to TMP being 3 and the two-injection strategy for TBHP. The space-time yield in the microreactor was significantly improved compared to the batch reactor, indicating the effectiveness of this continuous-flow protocol for the process intensification in the TMBQ synthesis.Graphical Abstract