Method for preparing aromatic azoic compound by catalyzing aromatic amine with metal nanocrystals

Abstract

Disclosed is a method for preparing an aromatic azoic compound by catalyzing aromatic amine with metal nanocrystals. In the method, the aromatic amine serves as a substrate, the metal nanocrystals serve as catalysts, the substrate, the catalysts and alkali are dissolved in organic solvents in normal-pressure air atmosphere, and the aromatic azoic compound is prepared by means of reaction. The method has the advantages of simplicity and convenience in process, environmental friendliness, catalyst recyclability, high universality of metal catalysts and the like, and avoids the shortcomings that environment-unfriendly metal salt catalysts or oxidants are used in an existing synthetic route, high temperature and high pressure are needed, the catalysts are poor in universality, asymmetric aromatic azoic compound is synthesized by a two-step method and the like. A series of aromatic azoic compounds can be prepared, and the method has a wide industrial application prospect.

Description

technical field [0001] The invention relates to a method for preparing aromatic azo compounds, in particular to a method for preparing aromatic azo compounds by using metal nanocrystals to catalyze aromatic amines. Background technique [0002] Aromatic azo compounds have been widely used as dyes, indicators, pigments, food additives, free radical reaction initiators and therapeutic agents. Aromatic azo compounds can be prepared through the condensation reaction of aromatic nitro compounds and aromatic amines, the reduction reaction of aromatic nitro compounds, or the oxidation reaction of aromatic amines. At present, the existing preparation methods of aromatic azo compounds have the following disadvantages: (1) the yield of aromatic azo compounds prepared by metal catalysis is usually low; (2) most of the oxidants used are stoichiometric manganese salts , lead salts and mercury salts, which are harmful to the environment; (3) the preparation of asymmetric aromatic azo com...

AI Technical Summary

Problems solved by technology

At present, the existing preparation methods of aromatic azo compounds have the following disadvantages: (1) the yield of aromatic azo compounds prepared by metal catalysis is usually low; (2) most of the oxidants used are stoichiometric manganese salts , lead salts and mercury salts, which are harmful to the environment; (3) the preparation of asymmetric aromatic azo compounds usually requires a two-step process: first, the aromatic amine is oxidized to an azo salt or Nitrosobenzene intermediate, and then add another aromatic amine to couple with this intermediate to obtain an aromatic azo compound, but the reaction system also produces the same amount of inorganic by-products

However, this method has the disadvantages of using a large amount of catalyst (the molar ratio of catalyst to substrate is 6% to 10%) and cannot be recovered, and needs to add pyridine as a ligand.

At the same time, the universality of the catalyst is poor, and salts containing various metals such as Au, Ag, Fe, Pt, Pd, Co and Mn are not suitable for this system

Images