Method for preparing arylamine compounds through selective hydrogenation of aromatic nitrocompounds

Abstract

The invention relates to a method for preparing arylamine compounds through selective hydrogenation of aromatic nitrocompounds containing substituent groups easy to reduce. According to the method, in the green solvent H2O, supercritical carbon dioxide, ethanol, n-heptane or H2O-n-heptane, Pt-Sb / TiO2 is used as a catalyst, selective hydrogenation of the aromatic nitrocompounds nitrostyrolene, nitrobenzaldehyde, nitrobenzonitrile and halogenated nitrobenzene is catalyzed, and then the corresponding arylamine compounds are prepared. Pt-Sb / TiO2 has high selectivity to nitryl hydrogenation of the compounds and is inert to hydrogenation of substituent groups easy to reduce such as vinyl. Under an optimized condition, the yield of aminostyrene and aminobenzaldehyde can be larger than 97%, the yield of aminobenzonitrile and halogenated aniline can be larger than 99%, and accumulation of harmful midbody such as phenylhydroxylamine is avoided during reaction.

Description

technical field [0001] The invention relates to a method for preparing aromatic amine compounds through catalytic hydrogenation of aromatic nitro compounds. Specifically related to Pt-Sb / TiO 2 As a catalyst, in the green solvent H 2 O, supercritical carbon dioxide (scCO 2 ), ethanol, n-heptane, H 2 In the O-n-heptane system, the method for preparing aromatic amine compounds by catalyzing the selective hydrogenation of aromatic nitro compounds containing easily reducible substituents. Background technique [0002] Aromatic amine compounds containing substituents are an important class of organic chemical intermediates, widely used in the fields of medicine, pesticides, dyes and high molecular polymers. The selective hydrogenation of aromatic nitro compounds is a relatively economical process for the preparation of aromatic amine compounds with little environmental pollution. [0003] Simple hydrogenation of aromatic nitro compounds has mature technology in industry, but ...

AI Technical Summary

Problems solved by technology

The disadvantage of this catalyst is that during the hydrogenation reaction, sulfur-containing by-products are produced, which reduces product quality and limits the reuse of solvents

[0004] At present, the catalytic hydrogenation of aromatic nitro compounds containing easily reducible groups to prepare aromatic amines has the following main problems: (1) The reaction is mostly carried out in toxic, harmful and volatile organic solvents such as toluene and tetrahydrofuran

(2) The CoS mentioned above 3 、Co 3 o 4 , Fe 2 o 3 As well as catalysts such as Au and Ag, the activity is low, and the reaction requires a higher temperature (110-160°C) and a longer time

(3) The method disclosed in WO2009071727, which uses the strong interaction between the metal and the support produced by high-temperature reduction to modify the metal center, has the following disadvantages: after high-temperature reduction, the activity of the catalyst decreases significantly; in addition, the metal loading is low, if Increasing the metal loading will lead to a significant decrease in catalyst selectivity

(4) The above-mentioned catalysts such as Au and Ag are active for the hydrogenation of aminostyrene C=C bonds. Therefore, after the reactant is completely converted, the reaction time is continued to be extended, and the generated aminostyrene will be further hydrogenated, resulting in its The yield is reduced, which increases the difficulty of controlling the reaction in production ((Shimizu, Miyamoto et al., J. Catal., 2010), (Shimizu, Miyamoto et al., J. Phys. Chem. C, 2009))