Hydrochloric Acid → 2-(2,4-Dichlorobenzoyl)cyclohexane-1,3-dione

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Reaction Steps

1,3-Cyclohexanedione [11.2 grams (g), 0.1 mole], 20.0 g (0.1 mole) 2,4-dichlorobenzoyl cyanide and 13.6 g (0.11 mole) anhydrous, powdered zinc chloride were combined in 100 milliliters (ml) methylene chloride. Triethylamine (10.1 g, 0.12 mole) was slowly added with cooling. The reaction mixture was stirred at room temperature for 5 hours and then poured into 2N hydrochloric acid. The aqueous phase was discarded and the organic phase was washed with 150 ml 5% Na2CO3 four times. The aqueous washings were combined and acidified with HCl, extracted with methylene chloride, dried and concentrated to yield 25.3 g of crude product. The crude product was dissolved in ether and stirred with 250 ml of 5% copper (II) acetate. The resulting copper salt was filtered, washed with ether and stirred with 6N hydrochloric acid to destroy the salt. The extract was washed with ether to yield 22.15 grams of the desired product m.p. 138°-140° C. (77.7% yield). The structure was confirmed by instrumental analysis.

Provenance & Evidence