Preparation method of p-phenylenediamine

Abstract

The invention discloses a preparation method of p-phenylenediamine. The preparation method comprises the following steps: adding paradichlorobenzene, ammonia water, the concentration of which is 35-45%, a catalyst and a Mannich alkaline ligand into a high pressure kettle; heating the mixture to 130-150 DEG C; stirring the mixture at a rotating speed of 600 rpm, wherein the reaction pressure is 2.0-4.5 MPa, carrying out an insulating reaction for 6-24 hours; after the reaction, reducing the temperature and relieving the pressure to recover ammonia; and carrying out desolventization and negativepressure distillation on kettle materials to obtain p-phenylenediamine, wherein the molar ratio of paradichlorobenzene and ammonia water is 1: 10 to 1: 20; the molar ratio of the catalyst and paradichlorobenzene is 0.005: 1 to 0.1: 1; the molar ratio of the Mannich alkaline ligand and the catalyst is 1: 1 to 3: 1; the catalyst is one of cuprous iodide, cuprous chloride, cuprous bromide, cuprous oxide, copper sulfate, copper chloride, cupric acetate and copper trifluoroacetate; the Mannich ligand structure is as shown in a formula, in which R is t-Bu or Cl or CH3. The preparation method is mild in reaction condition, efficient, good in selectivity, high in yield and suitable for industrial production of p-phenylenediamine on a large scale.

Description

technical field [0001] The invention belongs to the field of organic synthesis, and in particular relates to a preparation method of p-phenylenediamine. Background technique [0002] p-Phenylenediamine, also known as Wuersi D, is one of the simplest aromatic diamines, with a white to lavender crystal appearance, a melting point of 140°C, a boiling point of 264°C, and a relative density of 1.21. Slightly soluble in cold water, soluble in hot water, easily soluble in alcohol, ether and chloroform. As a traditional chemical intermediate, it is widely used in dyestuff, rubber, national defense and other industries. Azo dyes can be produced in the dye industry, rubber antioxidants can be produced in the rubber industry, and para-aramid fibers can be produced in the national defense industry. In addition, p-phenylenediamine is also the main raw material of gasoline polymerization inhibitor and photographic developer. At present, in the field of rubber additives, the new rubber ...

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Problems solved by technology

[0008] Among the above synthetic routes, route one is the main method of industrialization at present, with mature technology, high yield and good selectivity, but the raw material p-nitroaniline needs to be obtained by nitration of chlorobenzene and ammonolysis, the synthesis of raw materials is cumbersome, the utilization rate of atoms is low, and the nitration The process pollution is serious; the raw material of route 2 is easy to get, can be directly obtained by benzene chlorination, the utilization rate of atoms is high, and the pollution is small, but high temperature, high pressure and long reaction time must be used in the ammonolysis process, and the by-product ammonium chloride is more corrosive to equipment Serious, increase equipment investment, there are potential safety hazards

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