The invention relates to the technical field of
organic synthesis, and particularly discloses a synthesis process of 2-chloronicotinic acid. The synthesis process of the 2-chloronicotinic acid comprises the following steps: S1, mixing water, concentrated
sulfuric acid, 3-cyanopyridine and a composite catalyst, performing pre-reaction, adding
hydrogen peroxide, performing oxidation reaction, adjusting pH, performing
solid-liquid separation, and washing to obtain an
oxide intermediate; s2, in an
inert atmosphere, adding
phosphorus oxychloride into a reactor, adding the
oxide intermediate and
triethylamine for a chlorination reaction, recovering
phosphorus oxychloride after the reaction is finished, hydrolyzing remaining materials, and performing
solid-liquid separation and washing to obtain
chloride; and S3, carrying out alkali
dissolution,
neutralization, decoloration and acidification on the
chloride, carrying out
solid-liquid separation, washing, carrying out secondary alkali
dissolution,
neutralization and secondary decoloration, adding a complexing agent, carrying out secondary acidification, carrying out solid-liquid separation, washing,
drying and crushing to obtain the 2-chloronicotinic acid. The 2-chloronicotinic acid prepared by the method disclosed by the invention has relatively high purity and yield.