Bromoacetic Acid → (4-Fluoro-2-nitro-phenylamino)-acetic acid

Bromoacetic acid (5.34 g, 32.0 mmol, 0.5 eq) is added dropwise to 4-fluoro-2-nitro-phenylamine (10.0 g, 64.1 mmol, 1.0 eq) at 120° C. After the addition, the reaction mixture is stirred for 2 hours at 120° C. then xylene (10 mL) is added. The resulting reaction mixture is heated at 130° C. for 1 hour, then it is made alkaline with 25% ammonia aqueous solution. Xylene is removed under reduced pressure and the residue is diluted with water (100 mL). The mixture is filtered at 60° C. and the insoluble residue is extracted twice with 10% ammonia aqueous solution at 60° C. The aqueous layer is acidified with hydrochloric acid to pH 5, the precipitated product is filtered, washed with water and ethanol, dried under vacuum to afford (4-fluoro-2-nitro-phenylamino)-acetic acid as a red solid (2.98 g, 34% yield).