Online monitoring quickly provides conversion rate results, shortening the research and development cycle by 10 times compared to offline laboratory monitoring.
4-Nitro-o-xylene and 3-nitro-o-xylene are important organic synthesis intermediates and one of the important raw materials for the production of new environmentally friendly pesticides with high efficiency, low toxicity and low residue. In industry, most of them are synthesized by nitrating o-xylene with nitrate-sulfur mixed acid. The key monitoring indicators in the o-xylene nitration process include the content of o-xylene raw materials and the isomer ratio of the nitration products, etc.
At present, the laboratory analysis method for these important indicators is usually liquid chromatography, which requires a relatively tedious process of sampling, sample pre-treatment and professional analysis technicians, and the whole process takes more than 30 minutes. During the development of the continuous flow process for this reaction, the reaction itself can be completed in about 3 minutes, and the time cost of offline analysis is high. If a large number of process parameter conditions need to be screened in a short period of time, researchers need a real-time and accurate online detection method to quickly provide content information and guide the direction of process optimization.
Online spectroscopy technology can quickly provide spectral information of o-xylene, 3-nitro-o-xylene, and 4-nitro-o-xylene in the reaction solution. The peak areas of the characteristic peaks marked by the arrows in the figure above reflect the relative contents of the three substances respectively. In the figure below, the software intelligently analyzes the raw material and product content ratios under 12 different processes. It is obvious that the raw material conversion rate under condition 2 is the highest, and the raw material under condition 8 has almost no reaction. Researchers can quickly judge the quality of process parameters based on the contents of the three substances in the reaction solution, quickly screen the optimal parameters, and increase research and development efficiency by more than 10 times.
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Post time: Jan-09-2024