METHOD AND UNIT FOR OBTAINING PARA-AMINOPHENOL FROM PHENOL BY SEQUENTIAL NITROSATING AND REDUCTION WITH AMMONIUM SULFIDE Russian patent published in 2023 - IPC C07C213/02 C07C201/00 

FIELD: chemical technology.

SUBSTANCE: invention is related to a method for producing para-aminophenol from phenol by successive nitrosating and reduction. The method contains stages a)-j). Stage a) nitrosating phenol to obtain para-nitrosophenol is the simultaneous supply and mixing in the reactor of an aqueous solution of phenol, an aqueous solution of sodium nitrite, an aqueous solution of sulfuric acid. At stage b), the reaction mass obtained in step a) is stirred in a reactor to obtain a suspension of a mixture of para-nitrosophenol and crystalline sodium sulphate. At stage c) a solid precipitate of the mixture of para-nitrosophenol and crystalline sodium sulphate is separated by removing the reaction mass from the reactor into a suction filter. At stage d), a solution of para-nitrosophenol in aqueous ammonia is prepared, with simultaneous separation of the insoluble sodium sulphate precipitate using a suction filter. At stage e), the obtained para-nitrosophenol is reduced to form para-aminophenol by simultaneously supplying a solution of para-nitrosophenol from stage d) and an aqueous solution of ammonium sulphide. At stage f) after complete addition of the reaction solutions at stage e), the reaction mixture is evacuated until the ammonia is completely removed. At stage g), the vacuum is released, and the reaction mixture is cooled. At stage h), the reaction mixture is withdrawn from the reactor into a suction filter. At stage i) the solid para-aminophenol is separated using the filter and washed with water. At stage j), para-aminophenol is discharged from the suction filter and dried to obtain the final product. The invention is also related to a unit for production of para-aminophenol by said method.

EFFECT: obtaining para-aminophenol with high yield and purity without additional purification steps.

21 cl, 4 dwg, 1 ex