A stirred mixture of 2-(p-chlorophenyl)-2-methyl-4,5-dichloro-6-hydroxyindan-1,3-dione (3.06 g., 0.00863 mole), potassium carbonate (2.26 g., 0.0163 mole) and ethylbromoacetate (2.72 g., 0.0163 mole) in dimethylformamide (50 ml.) is warmed at 55°-60°C. for two hours, then treated with water (50 ml.)-10N sodium hydroxide solution (2.5 ml., 0.025 mole) and heated at 80°C. for 1 hour. The reaction mixture is added slowly to water (500 ml.)-12N hydrochloric acid (10 ml.) to precipitate [1,3-dioxo-2-(p-chlorophenyl)-2-methyl-4,5-dichloro-6-indanyloxy]acetic acid.
