Arsenic Acid → alpha-Methyl-2-phenyl-6-quinolineacetic acid

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Reaction Conditions

Reaction Steps

45 ml of cinnamaldehyde are added dropwise to a mixture of 38 g of p-aminophenylacetic acid, 71 g of arsenic acid and 300 ml of phosphoric acid. The reaction mixture is stirred for 2 hours at 120°C, 50 ml of polyphosphoric acid are then added and the whole is again stirred for 16 hours at 110°-120°C. The reaction mixture is cooled to 0°C and adjusted to a pH of 5-6 first with 2 N sodium hydroxide solution and then with solid sodium carbonate. This suspension is extracted with ethyl acetate and the organic phases are then extracted 6 times with 50 ml of 1 N hydrochloric acid at a time. The hydrochloric extracts are combined and a few pinches of sodium nitrite are added. The solution is left to stand for 15 minutes at room temperature and is then adjusted to pH 5.6, using a pH-meter, by adding sodium carbonate. This solution is extracted with ethyl acetate and the organic layers are washed with water, dried over sodium sulphate and evaporated. The residue obtained is crude 2-phenyl-6-quinolineacetic acid. Melting point 176°-179°C (from methanol-pentane). α-Methyl-2-phenyl-6-quinolineacetic acid of melting point 161°-162°C (from ethanol-water) is obtained analogously.

Provenance & Evidence