LAUSR

Abstract The microreactor based hydroxylation process of 1,2,4-trichlorobezene for producing 2,5-dichlorphenol, the key intermediate of dicamba, is energy efficient and cost effective. But the 2,5-dicholorphneol is present in a mixed state after production. The reaction mixture contained the main by-product 2,4-dichlorophneol, low-content by-product 3,4-dichlorophneol, and other impurities. The difficulty in separation and analysis limits the application of this process widely. The current work aimed at establishing effective analysis methods by gas chromatography (GC) and high performance liquid chromatography (HPLC). The GC method was not able to separate 2,5-dichlorophenol and 2,4-dichlorophenol completely, but the developed HPLC method worked efficiently. The linear correlation coefficients of 2,5-dichlorophenol and 2,4-dichlorophenol were both higher than 0.999, and the average recovery was 100.33% for 2,5-dichlorophenol and 100.13% for 2,4-dichlorophenol, respectively. The relative standard deviations from precision tests were both less than 1%. The contents of 2,5-dichlorophenol and 2,4-dichlorophenol were determined with external standard method. The HPLC method has the advantages of simple operation, good separation efficiency, high accuracy and precision, and was successfully applied for both qualitative and quantitative analysis of 2,5-dichlorophenol and 2,4-dichlorophenol of the sample solution.