Hydrochloric Acid → 2-Methyl-4-((2-methylbenzoyl)amino)benzoic acid

Participants

Reaction Conditions

Reaction Steps

The isomer mixture of 1-{2-[2-methyl-4-(2-methylbenzoylamino)phenyl]-2-oxoethyl}pyridinium chloride and 1-{2-[4-methyl-2-(2-methylbenzoylamino)phenyl]-2-oxoethyl}pyridinium chloride obtained in the above Reference Example 6 (207.3 g, 0.544 mole) is suspended in methanol (0.4 L) and thereto is added a solution of sodium hydroxide (52.5 g, 1.31 mole) in water (0.6 L), and the mixture is stirred at 60-76° C. for about 4 hours to complete the reaction. To the reaction mixture is added concentrated hydrochloric acid (0.108 L) at the same temperature to adjust pH=1. The mixture is stirred under ice cooling for one hour, and the precipitated crystals are separated by filtration. The resulting crystals are washed with water and dried at around 60° C. to give the crude product (125.5 g, yield 85.6%). A part of this crude product (20 g) is recrystallized from methanol (340 mL) and dried at 60° C. to give the desired product (12.1 g, yield 60.5%, purity by HPLC 99.7%).

Provenance & Evidence