Hydrochloric Acid → 1-(4-Chlorophenyl)-5-(2-methoxyethoxy)-4-oxo-1,4-dihydrocinnoline-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A solution of 255 g of potassiam hydroxide (3.9 moles, pellets, 85+%) in 3.2 l of methoxyethanol was stirred at 45° C. as 450 g of solid methyl phenylcinnoline-carboxylate (1.29 moles) from step 3 was added in portions. The reaction vessel was fitted with a distillation head and placed under reduced pressure (approx. 40 mmHg). The reaction was heated at 50° C. for 1 hr., then at 65° C. for 1 hr. to distill off methanol and some methoxyethanol (total volume removed 280 ml). The distillation head was replaced with a reflux condenser and the reaction was heated between 90° C. and 110° C. for 1 hr. The reaction was allowed to cool to 50° C. before the addition of 1 liter of water and was cooled to 25° C. before the resulting slurry was poured into 4 l of a cold 0.8N hydrochloric acid solution (3.1 moles HCl). The resulting precipitate was isolated by filtration, washed with water (2×2 l), and dried under reduced pressure at 50° C. to give 472 g (98%) of an off-white solid.

Provenance & Evidence