Method for preparing arylamines compounds by arene nitro compound catalysis hydrogenation in H2O-CO2 system

Abstract

The invention relates to a method for preparing arylamine compounds by the catalytic hydrogenation of arene nitro compounds in a H2O-CO2 system, wherein H2O-CO2 is taken as reaction medium, and the arylamine compounds are prepared by the selective hydrogenation of the arene nitro compounds(ANCs) at a low temperature(between 25 and 100 DEG C), and the catalytic process is controllable, highly efficient and green. Under the action of supported metal catalysts, the existence of CO2 obviously increases the hydrogenation speed of -NO2 base groups of ANCs in the H2O phase and inhibits the generation of byproducts; the selectivity of target products is more than 99 percent; the hydrogenation speed increases along with the pressure increase of CO2. The effect of CO2 is quite obvious when the pressure of CO2 is less than the range of the critical pressure, and by adjusting the pressure of CO2, the adjustment and control of the speed of the strongly exothermic reaction of the hydrogenation of ANCs are realized; moreover, the reaction in the H2O phase is easy to realize the even distribution of the reaction heat, the added H2O and CO2 both have inflaming retarding characteristics, thereby lowering the risk of explosion, etc.

Description

technical field [0001] The present invention relates to the method for preparing aromatic amine compounds by catalytic hydrogenation of aromatic hydrocarbon nitro compounds (ANCs), specifically relates to H 2 O-CO 2 A method for preparing aromatic amine compounds by catalytic hydrogenation of aromatic hydrocarbon nitro compounds in the system. Background technique [0002] Aromatic amine compounds are intermediates in the production of important chemical products such as pesticides, medicines, explosives, dyes, pigments, plastics, rubber and petroleum solvents. Aromatic amine compounds can be prepared from ANCs by iron powder reduction method or catalytic hydrogenation method. [0003] The traditional iron powder or zinc powder reduction method is to prepare aromatic amines by reducing ANCs with iron powder or zinc powder in acidic aqueous solution such as hydrochloric acid. This process has the disadvantages of large consumption of iron powder, large amount of iron sludg...

AI Technical Summary

Problems solved by technology

[0005] At present, the main problems encountered in the catalytic hydrogenation method are: (1) ANCs hydrogenation is a strong exothermic reaction, for example, the reaction heat released by the hydrogenation of nitrobenzene to aniline is 493kJ / mol

(3) The liquid-phase catalytic hydrogenation process uses a large amount of volatile organic solvents, causing environmental pollution and increasing the burden on the product separation process

In addition, the hydrogenation reaction system (H 2 , ANCs and organic solvents) are flammable and explosive, which increases the risk of the production process

(4)H 2 O and CO 2 Non-toxic, flame retardant, rich in sources, it is a green reaction medium, using H 2 O or scCO 2 Some progress has been made in the research of alternative organic solvents, but there are still many challenges

with H 2 O or scCO 2 As the reaction medium, the following problems are usually encountered: the reactant ANCs is insoluble in water; different substances in scCO 2 Solubility varies greatly in , and the solubility often decreases with increasing temperature, therefore, for scCO 2 For substances with low solubility in medium, or systems with high reaction temperature, when it is necessary to form a uniform reaction phase, it is usually necessary to add a co-solvent or increase the scCO 2 pressure

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