How is 4-Chloropyridazine (CAS: 17180-92-6) typically synthesized?

4-Chloropyridazine can be synthesized from pyridine chlorination. The chlorination is typically carried out using thionyl chloride as the reagent. The reaction is performed under anhydrous conditions to increase the yield and selectivity of the product. The process involves heating the mixture to a temperature of around 100°C and then purifying the product through recrystallization or distillation.