Process intensification and waste minimization for ibuprofen synthesis process

In China, the most commonly used method for the synthesis of ibuprofen is aryl-1,2–translocation rearrangement, which comprises several main processes: the Friedel-hydrolysis reaction, ketal reaction and so on. There are some problems in the process of industrial production. The temperature control of the Friedel-hydrolysis reaction is a problem because excessive temperatures will lead to the occurrence of side reactions, and low temperatures will lead to the crystallization of raw reaction materials. The reaction time of the ketal reaction is up to 24 h, which limits the productive capacity of ibuprofen. Otherwise, the emissions of the ibuprofen synthesis processes are more than 5000 m3/h of waste gas with VOC contents of over 1000 mg/m3 and highly concentrated organic wastewater, with a COD up to 20,000 mg/L. Therefore, process intensification and waste minimization of the ibuprofen synthesis process is described in this paper. A new reactor is designed for the Friedel-hydrolysis reaction. The reaction temperature can be precisely controlled at 13–15 °C, which effectively inhibits the occurrence of side reactions. The industrial applications showed that the ketal reaction time is reduced from 24 h to less than 8 h. The VOC content is reduced to less than 100 mg/m3, and the COD value is reduced to 150 mg/L in the improved processes, which meet national emissions standards.