Two types of expeditious and highly efficient continuous-flow processes for the dinitration of o-toluic acid were described. The o-toluic acid was dinitrated with mixed acid (sulfuric acid and nitric acid) to give 3,5-dinitro-2-methylbenzoic acid with 96% isolated yield and achieved a productivity of 1586 g/h. Based on batch trials, an isothermal continuous-flow process was designed and intensified, and the intrinsic kinetics of the dinitration was studied to obtain the precise residence time. As a result, the amount of reagent and the reaction time were reduced significantly, purity and yield of target product were both greatly increased compared to batch process. Then, as a further trial, the dinitration was conducted in an adiabatic continuous-flow system. An online temperature detection was used to monitor reaction progress and obtain corresponding optimal residence time. These two continuous-flow processes have the similar characteristics of short residence time and high reaction yield, although the operation conditions are totally different.

Continuous-flow dinitration of o-toluic acid in isothermal conditions or adiabatic system

描述了用于邻甲苯甲酸二硝化的两种快速和高效的连续流方法。该Ø-甲苯甲酸用混合酸（硫酸和硝酸）氮化，得到3，5-二硝基-2-甲基苯甲酸，分离产率为96％，生产率为1586g / h。在批量试验的基础上，设计并强化了等温连续流工艺，并研究了硝化的内在动力学，以获得精确的停留时间。结果，与分批处理相比，试剂的量和反应时间显着减少，目标产物的纯度和产率均大大提高。然后，作为进一步的试验，在绝热连续流系统中进行脱硝。在线温度检测用于监测反应进程并获得相应的最佳停留时间。

等温或绝热系统中邻甲苯甲酸的连续流硝化