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A mixture comprising 57.2 g of tetrachlorophthalic anhydride, 25.0 g of malonic acid and 60 ml of pyridine was stirred at 70° to 75° C. for 1.5 hours. After adding 200 ml of water and 200 ml of conc. hydrochloric acid, the mixture was boiled for 10 minutes. After allowing to cool, the precipitate was collected by filtration and dried. The solid product thus obtained was extracted with 600 ml of hot ether. The extract was concentrated and the residue was recrystallized from dilute ethanol. Thus, 25.2 g of 2-acetyl-3,4,5,6-tetrachlorobenzoic acid was obtained. NMR (270 MHz, CDCl3): δ 2.03 (s,3H). IR (KBr) ν (C=O) 1770 cm-1, ν (OH) 3380 cm-1.

1. waitthe mixture was boiled for 10 minutes
2. temperatureto cool
3. filtrationthe precipitate was collected by filtration
4. customdried
5. customThe solid product thus obtained
6. extractionwas extracted with 600 ml of hot ether
7. concentrationThe extract was concentrated
8. customthe residue was recrystallized from dilute ethanol