The invention discloses a preparation process of 5-bromonicotinic acid, which comprises the following steps: sequentially adding
ethyl nicotinate and
pinacol borane into a reaction kettle, heating to react, adding N-
bromosuccinimide into the reaction kettle, maintaining the
reaction temperature, and filtering to remove a byproduct
succinimide after the reaction is finished. And carrying out reduced pressure
distillation to recover the
solvent to obtain the ethyl 5-bromonicotinate. Adding ethyl 5-bromonicotinate into another reaction kettle, adding an alkali solution, heating, stirring for reaction, cooling reaction liquid after the reaction is finished, dropwise adding
hydrochloric acid to adjust the pH value, cooling, crystallizing, filtering, washing a
filter cake, and
drying to obtain a 5-bromonicotinic acid finished product. The total yield gt of the preparation process of the 5-bromonicotinic acid; the HPLC purity is gt; 99%. The process is simple and convenient to operate and easy to implement, raw materials are cheap and easy to obtain,
reaction conditions are mild, high-temperature and high-pressure reaction is not needed, and requirements on equipment are reduced. The whole process is
safer to the environment, and green and
pollution-free production can be realized.