General procedure for the synthesis of 6-chloroquinoline-8-carboxylic acid from glycerol and 2-amino-5-chlorobenzoic acid: 1.01 g of 2-amino-5-chlorobenzoic acid, 26.6 mg of iodine, and 0.76 g of glycerol were mixed, and the mixture was vigorously stirred. 0.44 mL of concentrated sulfuric acid was slowly added dropwise at 65 °C to 70 °C and the reaction was carried out for 30 minutes. Subsequently, the reaction temperature was raised to 140 °C and the reaction was continued for 6 hours. Upon completion of the reaction, 17 mL of water at 0 °C was added, the pH was adjusted to 6.5, the solid was collected by filtration and washed with cold water, and then dried. The dried residue was dissolved in chloroform and filtered to remove insoluble material. Activated carbon was added to the filtrate to adsorb impurities and the activated carbon was removed by filtration again. The solvent was removed by distillation and the resulting residue was recrystallized in a mixed solution of chloroform and ethyl acetate. The resulting crystals were washed with ethyl acetate and the solvent was again removed by distillation, resulting in 96.2 mg (7.9% yield) of the target product 6-chloroquinoline-8-carboxylic acid. The compound was subjected to NMR, mass spectrometry and melting point determination, confirming that its structure conforms to the general formula of 6-chloroquinoline-8-carboxylic acid.
