Method for synthesizing 5-nitroisophthalic acid

The invention discloses a method for synthesizing 5-nitroisophthalic acid, which comprises the following steps: step 1, dissolving isophthalic acid in concentrated sulfuric acid to obtain a first mixed solution, the molar ratio of isophthalic acid to concentrated sulfuric acid being 1: 1 to 1: 15; step 2, mixing concentrated sulfuric acid and fuming nitric acid in a micro-channel reactor through two pumps to prepare a second mixed solution, the molar ratio of fuming nitric acid to concentrated sulfuric acid being 1: 0.5 to 1: 3; step 3, controlling parameters of the micro-channel reactor, andrespectively pumping the first mixed solution and the second mixed solution into the nitration reaction micro-channel reactor for mixing and reaction; and step 4, quenching and collecting the reactionproduct with 2-10 times of ice water, washing the reaction product with water to be neutral, and filtering and drying the reaction product to obtain 5-nitroisophthalic acid. The method provided by the invention has the advant