How is 2-Bromo-5-chloroisonicotinic acid (CAS: 530156-90-2) typically synthesized?

2-Bromo-5-chloroisonicotinic acid is typically synthesized via electrophilic aromatic substitution reactions. Common methods include the bromination and chlorination of nicotinic acid followed by condensation reactions. The synthesis often involves the use of bromine and chlorine as electrophiles, with acetic anhydride as a condensing agent. The yield is around 70-80% depending on the purity of starting materials and reaction conditions.