2-Chloronicotinic acid

PreparationChloronicotinic acid was synthesized from nicotinic acid by oxidation by H2O2 and then chlorinationby POCl3 and PCl5 in a yield of 87.5%.Synthesis of 2-chloronicotinic acid: Pour chlorine gas into the mixed solution of phosphorus oxychloride and phosphorus trichloride, control the temperature at about 60°C, until the remaining chlorine gas escapes, cool and add nicotinic acid N-oxide in batches, and heat the mixed solution. The reaction was carried out at 100-105°C for 1-1.5 h, and the reaction mixture was stirred for 30 min after the reaction mixture was transparent, and phosphorus oxychloride was removed under reduced pressure. The obtained residue was cooled to room temperature, and water was added to obtain the finished product of 2-chloronicotinic acid.