Production process of high-purity medicinal gimeracil

The invention discloses a production process of high-purity medicinal gimeracil. According to the method, malononitrile and trimethyl orthoacetate are taken as starting raw materials, and are subjected to condensation reaction, cyclization reaction, chlorination reaction and hydrolysis reaction to obtain gimeracil, and the method is characterized in that sulfonyl chloride and acetic acid are not distilled in the chlorination step, methanol is added after cooling and crystallization, and pulping and refining are performed; and in the hydrolysis step, sulfuric acid is used for removing methyl and cyano, the pH is directly adjusted for precipitation without concentration, and then absolute ethyl alcohol is adopted for refining. After the technology is adopted, corrosion to equipment and pipelines is reduced, the content of 4-Me-CDHP, N-Me-CDHP, CN-CDEP and other unknown single impurities is controlled to be smaller than or equal to 0.03%, and the method is more suitable for the requirement of industrial producti