2-(4-CHLORO-2-NITROPHENYL)ACETIC ACID

Preparation

The filtrate of Step A, above, is adjusted to pH 8-9 with 2 N sodium hydroxide and is heated at 35-40 °C. while adding a 3-6% aqueous hydrogen peroxide solu tion until samples no longer turn dark on treatment with 2N sodium hydroxide. The tan precipitate is suspended in 1500 ml. of water, adjusted to pH 8-9 and similarly treated with aqueous hydrogen peroxide. The combined reaction mixtures are then acidified with concentrated hydrochloride acid to obtain a precipitate which are re covered by filtration, washed 3 times with water and dried in vacuo. The crude product (mp 145-150°C) is recrystallized from ether to obtain 4-chloro-2-nitro phenylacetic acid, m.p. 156-159°C.