Sulfuric Acid → 5-Fluoro-2-nitrophenol

Participants

Reaction Conditions

Reaction Steps

159.1 g (1 mol) of 2,4-difluoronitrobenzene and 550 g of water are initially introduced and are heated to 55° C. With vigorous stirring, 241.2 g (2.15 mol) of 50% strength potassium hydroxide solution are added dropwise over 4 hours and the temperature is maintained at 55° C. (exothermic reaction). Stirring is then continued for another 2 hours at this temperature. The pH is then adjusted to 4.3 (25° C.) using 88 g of sulfuric acid, and 74.1 g of calcium hydroxide are added. The pH is readjusted to 5.0 and the introduction of steam is started. During distillation the pH is decreased from 5 to 1.5 by dropwise addition of sulfuric acid. The product is isolated by cooling and filtering the distillate. After drying, 117.9 g (0.750 mol, 75% of theory) of bright yellow 2-nitro-5-fluorophenol is obtained, which is more than 99.9% pure according to GC and HPLC (solidification point 32.1° C.).

Provenance & Evidence