O-Amino-p-Chlorophenol

Using p-chlorophenol as a raw material, 2-nitro-p-chlorophenol can be made through nitration, and then reduced to make p-chloro-o-aminophenol.

(1) Production of 2-nitro-p-chlorophenol: Using p-chlorophenol as raw material, nitrification with nitric acid. Add the distilled p-chlorophenol slowly into the stirred tank with 30% nitric acid, keep the temperature at 25-30℃, stir for about 2 hours, add ice to cool to below 20℃, precipitate, filter, and wash the filter cake to Congo Red, the product 2-nitrop-chlorophenol is obtained.

(2) There are two methods for the reduction of 2-nitro-p-chlorophenol. One is to reduce with sodium disulfide. Firstly, 30% sodium hydroxide solution and sulfur powder are used to make sodium disulfide solution, and 2-nitro-p-phenol is added in proportion to react at 95-100°C, and the reaction is over. After hot filtration, the filtrate is neutralized with baking soda water, cooled to 20°C, filtered, and the filter cake is washed to neutrality to obtain the finished product 2-nitro-p-chlorophenol.

The second is the hydrogenation reduction method. In the presence of a nickel catalyst, the aqueous suspension of 2-nitro-p-chlorophenol is adjusted to pH=7 with sodium dihydrogen phosphate hydrate and sodium hydroxide aqueous solution at a hydrogen pressure of 4.05Mpa and Hydrogenation reduction at 60°C. After the reaction is complete, release the pressure, replace with nitrogen, heat to 95°C, adjust pH=10.7 with sodium hydroxide, add activated carbon and diatomaceous earth, stir vigorously, and filter. The filtrate was adjusted to pH=5.2 (20°C) with concentrated hydrochloric acid, cooled to 0°C, filtered, dried, and treated with sodium bisulfite. Repeat the operation four times, then distill at 2.67kpa, collect the fractions around 80°C, and dry them to obtain the product with a yield of 97.7%.