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To 70 g of diethyl 2-chloro-4,5-difluorobenzoylmalonate, 90 cc of water was added for emulsification. Then, 0.2 g of p-toluenesulfonic acid was added thereto, and the mixture was refluxed for three hours under vigorous stirring. After cooling, the reaction mixture was extracted three times with 150 cc of methylene chloride, and the extract was washed with a saturated sodium chloride aqueous solution, dried over anhydrous sodium sulfate, concentrated and then recrystallized from methylene chloride/n-hexane to obtain 32 g of the desired compound. The physical properties of obtained ethyl 2-chloro-4,5-difluorobenzoylacetate were as follows. From the results of the NMR analysis in chloroform-d1, this compound was found to be a mixture of a keto form and an enol-form. ##STR26##

1. temperaturethe mixture was refluxed for three hours under vigorous stirring
2. temperatureAfter cooling
3. extractionthe reaction mixture was extracted three times with 150 cc of methylene chloride
4. washthe extract was washed with a saturated sodium chloride aqueous solution
5. dry with materialdried over anhydrous sodium sulfate
6. concentrationconcentrated
7. customrecrystallized from methylene chloride/n-hexane